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SLUDGE COMPOST MARKETING AND DISTRIBUTION
REGULATORY REQUIREMENTS IN THE UNITED STATES
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SLUDGE COMPOST MARKETING AND DISTRIBUTION
REGULATORY REQUIREMENTS IN THE UNITED STATES
prepared by: Metcalf & Eddy, Inc.
Dr. Robert J. Reimold, Project Manager
Dr. Burton B. Bryan, Project Biologist
Ms. Katherine D. Walker, Senior Toxicologist
Ms. Betsy Shreve, Environmental Planner
Ms. Laura Labadini, Chemist
prepared under: U.S. EPA Contract No. 68—04-1015
prepared for: Mr. Ronald G. Manfredonia, Project Officer
Mr. Walter M. Newman, Project Monitor
U.S. Environmental Protection Agency
Water Quality Branch
Environmental Evaluation Section
JFK Federal Building
Boston, Massachusetts 02203
in cooperation Ms. Fifi Nessen
with: Mr. Steve Lipman
Mr. Ron Lyberger
Commownealth of Massachusetts
Department of Environmental Quality Engineering
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SLUDGE COMPOST REGULATORY REPORT
This report has been sponsored and reviewed by the U.S.
Environmental Protection Agency (EPA) in cooperation with the
Massachusetts Department of Environmental Quality Engineering
(DEQE). Review of the contents of this report does not signify
that the material necessarily reflects the views and policies of
EPA or DEQE. It is important to note that EPA is currently
developing comprehensive technical criteria for the use and
disposal of sewage sludge pursuant to Section 405 of the Clean
Water Act. EPA has also proposed state sludge program regula-
tions that will require states to use these federal technical
criteria as a minimum for managing sewage sludge use and
disposal. However, states will be free to enact more stringent
requirements based upon special factors or considerations.
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TABLE OF CONTENTS
Page
VOLUME I
I. INTRODUCTION
A. Background and Purpose. . . . . . . . . . . . . . . . . 1
B. Contents of the report........... ............ 2
II. SUMMARY OF STATE REGULATIONS AND GUIDELINES FOR
SLUDGE LAND APPLICATION AND SALE/GIVE AWAY
A • Ba c kg round and S ununa r y • . . . . . . . . . 4
B. Regulatory treatment of key parameters............. 27
1. Degree of stabilization — Criteria for use.... 27
2. Sludge quality (limits for constituents)...... 29
3. Land application rate limits 33
4. Siting restrictions...... . . . . . . . . . . . . . 49
5. Reporting requirements. . . . . . • . .. . . .. 52
6. Permit procedure . 52
7. Dedicated sites . . . . . . •. 54
III. RISKS ASSOCIATED WITH SLUDGE COMPOST USE:
SURVEY AND RECOMMENDATIONS
A. Introduction 60
B. Federal regulations and guidelines .... 62
C. New England conditions affecting land
applicationofsludges 68
1. Soil chemistry . . . . . 68
2. Physical site characteristics 70
D. Metalsinmunicipalsiudges... 74
1. Cadmium 77
2. Lead . . . . 90
1
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TABLE OF CONTENTS (Continued)
Page
E. Organic chemicals in niunicipa]. sludges............. 97
F. Pathogens in municipal sludges. . 106
1 Pathogens in sludge: overview....... ......... 107
2. Pathogen kill effectiveness of PSRP/PFRP 113
3. Fate of pathogens in compost once applied
to ].and.............. ............ ... ... ...... 124
4. Routes of animal and human exposure to
pathogens in sludge—amended soils............ 128
G. Conclusions and Recommendations....... . ... .. ....... 142
1. Cadmium, lead, and organic chemicals.......... 144
2. Pathogens . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 156
IV. REFERENCES. . . . . . . . . . . . . . . . . . . . . . . . . . . 164
VOLUME II: Appendices
Appendix I: Regulations and Guidelines for Land
Application and Use of Sludge in the
United States
Appendix II: Processes to Significantly Reduce
Pathogens and Processes to Further
Reduce Pathogens
Appendix III: Summary of State Contacts and Basis
for State Regulations in the Northeast
ii
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LIST OF TABLES
Table Page
1. Regulations in force: Land application . 6
2. Regulations in force: Give away, public
distribution, compost management.. . 14
3. Regulations in force: Land reclamation and
dedicated sites. . . . . . . . . . . . . . . . . . . . . . . . . 20
4. Summary of maximum sludge constituent
concentrations for land application of sludge,
Northeast(NewEngland,N.Y.,N.J.)..................... 31
5. Summary of maximum sludge constituent
concentrations for give away, public distribution,
and compost management programs in the United States.... 34
6. Summary of loading limits in the Northeast
forlandapplicationofsludge......... ...... 37
7. Summary of loading limits in the Northeast
for give away, public distribution, and
compost management...... . ........... .. . . . . . . . . . . . . . . . . . . 50
8. Summary of maximum sludge constituent
concentrations for land reclamation and
dedicatedsiteprograms,Northeast...................... 57
9. Summary of loading limits in the Northeast for
landreclamationanddedicatedsites... 58
10. sludge pollutants evaluated by U.S. EPA 65
ll.SoilpHintheEast—Northeast....... ............ 71
12. Soil conservation service classification of
soils in the northeast 73
13. Inorganic contaminants in sludge evaluated
by U.S. EPA (1985).. . . 75
14. Maximum recommended limits for metals in sludges
acceptable for composting 83
15. Organic contaminants of municipal sludge
evaluated by U.S. EPA 99
iii
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LIST OF TABLES (Continued)
16. Mean and 95th percentile sludge pollutant
concentrations...... ........ . . . . ........ . •....... . . . •... 100
17. Bacterial pathogens in sludge and their associated
diseases . .. .... ... ... . . . ........ ...... ......... •...... 108
l8.Densityofbacteriainrawsludges...................... 108
19. Viruses insewagesludge............. 109
20.Parasitesinsewagesludge.............................. 111
21. Percentage of final sludge samples in the northern
states with viable eggs of Ascaris, Trichuris,
Trichiura, T. Vulpis , and Toxocara , and mean
numbers of eggs found.. . . . . . . . . . . . . . . 112
22. Time required for a 10-fold population reduction
of various microorganisms 55°, D—value. 116
23. Pathogen reduction factors for PSRP and PFRP
using D—values at 55°C.................................. 118
24. Estimated reduction in pathogens population after
composting by PSRP and PFRP, using D-value at 55°C...... 119
25. Survival of pathogens on plants and in soil............. 125
26. Amount of compost needed to be ingested to
cause an infection... . . . . . . . . •........ . . . . . . . . •... 133
27. Recommendations for cadmium and lead: General
Public Use 145
28. Recommendations for cadmium, lead and PCBs:
controlled land application . . . 152
29. Recommendations for pathogens in composted sludge:
general public use.. . . . . •. . . . . . . . . . . . . . . . . . 158
30. Recommendations for pathogens in composted sludge:
controlled land application 160
iv
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LIST OF FIGURES
Figure Page
1 The Effect of Sludge Cadmium 1 Soil pH, and
Sludge—Applied Cadmium on Cadmium in
Romaine Lettuce. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81
V
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SLUDGE COMPOST MARKETING AND DISTRIBUTION REGULATORY
REQUIREMENTS IN THE UNITED STATES
I. INTRODUCTION
A. Background and purpose
The Clean Water Act has set a national policy to
encourage the recycling and beneficial reuse of municipal
wastewater sludge. Composting, which is a biological process
for stabilizing the sludge prior to use is considered a reuse
process. Composting increases the acceptability of sludge
for agricultural and related uses by converting organic waste
into a humus—like material useful as a soil conditioner. The
Massachusetts Executive Office of Environmental Affairs has
selected sludge composting as the preferred method of sludge
management for the wastewater treatment facilities serving
the Boston metropolitan area. However, use of this compost
may be limited because of its heavy metal content, which may
exceed limits established by the Massachusetts Department of
Environmental Quality Engineering (DEQE) in November 1983.
The implementation of a large—scale composting program for
the Boston metropolitan area may therefore be impeded by
limitations on the marketing, distribution and ultimate use
of the compost. Implementation of a successful composting
program will either require a more effective pretreatment
program by industries discharging to the metropolitan system,
thereby reducing the metals discharged to the systems, or a
review and possible revision of the regulatory limits
governing the distribution and use of the sludge.
1
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A primary purpose of this report is to provide an infor-
mation base for the Massachusetts DEQE which will constitute
the initial basis for the review and possible revision of the
limits currently regulating the marketing, distribution and
use of wastewater sludge compost. However, other New England
states, as well as other states in the Northeast and other
parts of the U.S., should find the information valuable. It
is important to note that EPA is currently developing
national comprehensive technical criteria for the use and
disposal of sewage sludge pursuant to Section 405 of the
Clean Water Act. These criteria will result in proposed
regulations in early 1987. This report is intended to
provide an updated interim information base which will be
supplemented by the proposed EPA regulations.
Contents of this Report
This report is divided into three sections. Section I
summarizes the background and purpose of the report.
Section II is an extensive compilation of current state and
federal sludge use regulations, and Section III describes the
risks associated with sludge compost use and, where appro-
priate, recommends regulatory approaches and further study.
Section II describes the main informational sources used to
prepare state guidelines and regulations, and summarizes the
overall trends and most common features in those regulations.
The analysis of loading limits and maximum constituent limits
concentrates on the northeast, where local conditions are
2
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most relevant to the problems faced in [ JSEPA Region I. A
more detailed summary of the information on which Section II
is based is contained in Appendix A.
In Section III, separate discussions are presented on
the three main agents of health risks in sludge: metals,
organic compounds, and pathogens. Because an extensive study
of these risks is currently being conducted by USEPA national
headquarters, the present study concentrates on health risks
and solutions of greatest importance to USEPA Region I.
3
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II. SUMMARY OF STATE REGULATIONS AND GUIDELINES FOR SLUDGE LAND
APPLICATION AND SALE/GIVEAWAY
A. Background and Summary
Approximately 40 states either have composting facilities in
operation or under consideration (Goldstein, 1985). These
states, as well as the District of Columbia and the Federal
government, were contacted and a compilation made of relevant
regulations or guidelines pertaining to the distribution/sale and
reuse of sludge. Most states’ regulations do not distinguish
between the various forms of sludge such as dry compost, liquid
sludge, cake, etc. Therefore, information was gathered on land
application and reuse of sludge, with emphasis on dry compost as
a category of sludge.
Discussions with representatives of the state and/or federal
agencies administering the regulations, as well as a careful
review of the regulations/guidelines, focused on several key
parameters:
• degree of stabilization
sludge quality (constituent levels)
• land application rate limits
• siting restrictions
• reporting requirements
• permit procedures
• use on dedicated sites
4
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A summary was prepared of each state’s regulations
indicating the extent to hich the state’s regulations or
guidelines addressed the above parameters. The individual state
summaries are compiled in Appendix I. The information gathered
is presented in the same format for each state, allowing direct
comparison between states’ regulations and guidelines, and
facilitating evaluation of major similarities and differences.
Although some states’ regulations are lengthier than others, the
information for each criterion can usually be found on the same
page for each state. For example, information regarding the
acceptability of sludge can usually be found on page 2 of each
individual state summary.
Thirty—eight states have existing or proposed regulations/
guidelines which specifically address the land application of
sludge to agricultural land, or to dedicated or reclaimed
sites. Fifteen states also have specific regulations/guidelines
addressing give—away or distribution programs.
Summary Tables 1, 2, and 3 were developed from the
individual state summary tables in Appendix A. These summary
tables indicate which states address the above listed key
parameters in their land application or distribution programs.
A more detailed discussion of the different state programs
and their regulations/guidelines as they relate to the key
parameters follows. Although the degree of regulation,
discretionary powers of the administrative agency, criteria for
use, and required submittals for use approval vary from state to
5
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TABLE 1.
REGULATIONS IN FORCE: LAND APPLICATION
FED. AK AL AR AZ CA CO CT t OC DE FL FL GA HI IA IA (ID) IL
I II EK. NEK.
STATE CONTROL:
REGULATIONS K K K K K K K K K K K K
GUIDELINES K K K K
ACCEPTABILITY OF SLUDGE:
PERMITORAPPROVALREQUIRED K K K K K K K K K K K K K K K
SLUDGESAMPLINGREQUIRED K K K K K K K K K K
MAXIMUM SLUDGE CONSTITUENT
CONCENTRATIONS:
NUTRIENTS K
METALS K K K K K K K
PCBS K K K K K
OTHER CONTAMINANTS K
LAND APPLICATIO 1 1:
PERMIT OR APPROVAL REQUIRED K K K K K K K K K K
CRITERIA FOR USE:
DEGREE OF STABILIZATION:
STABILIZATION REQUIREMENT K K K K K K
PSRP K K K K K K K
PFRP K K K K K K K K K
SOILSAMPLING K K K K K K K K K
WATER QUALITY MONITORING K K K K K K K K K
MAKIMUM SLUDGE LOADING LIMIT:
N(ANNUAL) K K K K X K K K K
METALS K K K K K K K K K
PCBS K
OTHER
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TABLE 1.
REGULATIONS IN FORCE: LAND APPLICATION
FED. AK AL AR AZ CA CO CT DC DE FL FL GA NI IA IA (ID) IL
I II EN. NEN.
LAND USE RESTRICTIONS:
CROPS N N N N N N N N N
GRAZINGORGREENCNOP N N N N N N N N N N N N
PUBLICACCESS N N N N N N N N N
pMOFSO IL N N N N N N N N N N N
SITING RESTRICTIONS:
SOILCONDITIONS N N N N N N
BUFFER REQUIREMENTS N N N N N N N N N
GROUNDWATER PROTECTION N N N N N N N N N N N
SURFACE WATERPROTECTION N N N N N N N N N N N
RUNOFFANDEROSIONCONTROL N N N N N N N N N N N N
MANIMUNSLOPELIMIT N N N N N N N N
STORAGE N N N N N
TRANSPORTAION N N
• . NORTN EASTERN STATES
() . STATES NOT CONTACTED
F . SANE AS FEDERAL REQJLATION
1 ,1 1,111 . REFER TO SLUDGE
EN. •NEN. - EXEMPT, NONEXEMPT
COY. -GOVERNMENT FACILITIES
PRIV. -PRIVATE SITES
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TABLE 1.
REGULATIONS IN FORCE: LAND APPLICATION
IN KS (KY) (LA) MA MA MD ME MI MN MN (MO) MS MT NC (ND) NE NH
I 11,111 GOV. PRIV.
STATE CONTROL:
REGULATIONS K K K K K K K K K K K
GUIDELINES K K
ACCEPTABILITY OF SLUDGE:
PERMITORAPPROVALREOUIRED K K K K K K K K K K K K
SLUDGE SAMPLING REWIRED K K K K K K K K K
e q.
MAXIMIJI SLUDGE CONSTITUENT
CONCENTRATIONS: F F
NUTRIENTS
METALS K K K K K
PCBS K K K K K K K
OTNER CONTAMINANTS K
LAND APPLICATION:
PERMIT OR APPROVAL REWIRED K K K K K K K F K
CRITERIA FOR USE:
DEGREE OF STABILIZATION:
STABILIZATION REWIREMENT K F
PSRP K K K K K K K K K
PFRP K K K K K K K K
SOILSAMPLING K K K K K K K K
WATER QUALITY MONITORING K K K K K K K K K
MAKIMIJI SLUDGE LOADING LIMIT: F
N(ANNUAL) K K K K K K K K K K
METALS K K K K K K K K
PCBS K K N K
OTNER
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TANLE I.
REGULATIONS IN FORCE: LAND APPLICATION
IN KS (KY) (LA) NA NA MD IE NI MN MN (MO) MS MT NC (ND) NE NH
I II 1 III COy. PRIV.
LAND USE RESTRICTIONS:
CROPS N N K N N N X N N
GRAZINGOR OREENCHOP N N w N X N X N
PUBLICACCESS N N N N N N F
ØIOFSOIL N N N N N N N N
SITING RESTRICTIONS:
SOIL CONDITIONS N N N X N X N N
BUFFERREGUIREMENTS N N N N N N N N N N
CROJNDWATER PROTECTION N N N N N N N X N N
S uRFACE WATER PROTECTION N N N N X N N N N N
RUNOFF AND EROSION CONTROL N N N N N N N N
SLOPE LiMIT N N N N N N N N
STORAGE N N N N N N N N N
TRANSPORTAIGN N N N N N N
• NORTN EASTERN STATES
C) • STATES NOT CONTACTED
F SAME AS FEDERAL REGULATION
1 .11,111 - REFER TO SLWCE
EN. ,NEN. EXEMPT 1 NONEXEMPT
COV.-GOVERNMENT FACILITIES
PRIV.-PRIVATE SITES
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TABLE 1.
REGULATIONS IN FORCE: LARD APPLICATION
NJ (NM) NV NY ’ NY ’ OH (OX) OR PA RI’ SC (SD) IN TX UT VA VT WA
I II III
STATE CONTROL:
REGULATIONS K X X X X K K K K K K K K
GUIDELINES K K K K K K K K K
ACCEPTABILITY OF SLt GE:
PERMITORAPPROVALREOUIRED K K K K K K K K K K K K K K
SL U DGESAMPLINGREQIJIRED K K K K K K K K K K K K
MAK1MUM SUXGE CONSTITUENT
CONCENTRATIONS:
NUTRIENTS K
METALS K K K K K K K K K
PCBS K K K K
OTHER CONTAMINANTS K K K
LAND APPLICATION:
PERMITORAPPROVALREQUIRED K K K K K K K K K K K K K
CRITERIA FOR USE:
DEGREE OF STABILIZATION:
STABILIZAT1ON REQUIREMENT K K K K K K K K
PSRP K K K K K K K K
PFRP K K K
SOIL SAMPLING K K K K K K K K K K K K
WATER QUALITY MONITORING K K K K K K K K K
MAXIMUM SLUDGE LOADING LIMIT:
N(ANNUAL) K K K K K K K K K K K K
METALS K K K K K K K K K K K K K
PCBS K
OTHER
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TABLE 1.
REGULATIONS IN FORCE: LAND APPLICATION
NJ (NH) NV NT NY ON (Os) OR PA RI Sc CSD) TN TX UT VA VT WA
1,11 III
LAND USE RESTRICTIONS:
CROPS X N N N N X X N N N N N N N
GRAZINGORGREENCNOP N N N N N N N N N N N N N
PUBLICACCESS N N N N N N N N N
pNOFSOIL N X N N N X N N X N N N N
SITING RESTRICTIONS:
SOILCONDITIOWS N N N N N N N N N
BUFFERREOUIRENENTS N N N X N N N N N N N N
GR3JNDWATER PROTECTION N N X N N N N N N N N N
SURFACEWATERPROTECTION N N N N N N N N N N N N
RUNOFFANDEROSIONCONTROL N N N N N X N N N N N N N
HANIHUNSLOPELIMIT N N N N N N N N N N N N
STORAGE N N N N N N N N N N
TRANSPORTAION N X X N N
- NORTH EASTERN STATES
C) - STATES NOT CONTACTED
F SANE AS FEDERAL REGULATION
1 , 1 1, 1 1 1 - REFER TO SLUBGE
EX.,NEN. - EXEMPT, NONENEHPT
COy. -GOVERNMENT FACILITIES
PRIV. -PRIVATE SITES
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TABLE 1.
REGULATIONS IN FORCE: LAND APPLICATION
VI (WV) WV
STATE CONTRa:
REGULATIONS X X
GUIDELINES X
ACCEPTABILITY OF SLUDGE:
PERMIT OR APPROVAL REQUIRED X X
SLUDGE SAMPLING REQUIRED X X
MAXIMUM SLIXGE CONSTITUENT
CONCENTRATIONS:
NUTRIENTS
METALS N N
PCBS N
OTHER CONTAMINANTS
LAND APPLICATION:
PERMIT OR APPROVAL REQUIRED N X
CRITERIA FOR USE:
DEGREE OF STABILIZATTOII:
STABILIZATION REQUIREMENT X
PSRP X
PFRP N
SOIL SAMPLING N N
WATER QUALITY KO$IITORING
MAXIMUM SLUDGE LOADING LIMIT:
N(ANNUAL) N N
METALS X N
PCBS N
OTHER
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TABLE 1.
REGULATIONS IN FORCE: LAND APPLICATION
W I (WV) WY
LAND USE RESTRICTIONS:
CROPS X X
GRAZING OR GREENCNOP X
PUBLIC ACCESS X X
pH OF SO1L X
SITING RESTRICTIONS:
SOIL CONDITIONS
BUFFER REQUIREMENTS X X
GROUNDWATER PROTECT ION N
SURFACE WATER PROTECTION X X
RUNOFF ANO EROSION CONTROL X
MAXIMUM SLOPE LIMIT X X
STORAGE X
TRANSPORTAION
* NORTH EASTERN STATES
0 STATES Not CONTACTED
F - SANE AS FEDERAL REGULATION
I II,III - REFER TO SLUDGE
EX. ,NEX. - EXENPT, NONEXEHPT
GOV -GOVERNMENt FACILITIES
PRIV -PRIVATE SITES
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TABLE 2.
REGULATIONS IN FORCE: GIVE AWAY, PUBLIC OISTRIBUTION, COMPOST MANAGEMENT
AK AL AR AZ CA CO CT DC DE FL GA NI IA (ID) IL IN KS (KY)
STATE CONTROL:
REGULATIONS N N N
GUIDELINES N
ACCEPTABILITY OF SLUDGE:
PERMIT OR APPROVAL REQUIRED X N N N
SLUDGE SAMPLING PARAMETERS N N
MAXIMUM SLUDGE CONSTITUENT
CONCENTRATIONS:
NUTRIENTS F
METALS N N
PCBS N
OTHER CONTAMINANTS
LAND APPLICATION:
PERMIT OR APPROVAL REOUIRED x x
CRITERIA FOR USE:
OEGREE OF STABILIZATION:
STABILIZATION REQUIRED N x
PSRP x
PFRP A x
SOIL SAMPLING K
WATER QUALITY MONITORING N
MAXIMUM SLUDGE LOADING LIMIT:
N(ANNUAL) N
METALS N N
PcBS N
OTNER
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TABLE 2.
REGULATIONS IN FORCE: GIVE AWAY 1 PUBLIC DISTRIBUTION, CONPOST MANAGEMENT
AK AL AR AZ CA CO CT DC DE FL GA NI IA CID) IL iN KS (KY)
LAND USE RESTRICTIONS:
CROPS X N K
GRAZING OR GREENCNOP K
PUBLIC ACCESS
pIIOFSOIL K
SITING RESTRICTIONS:
SOIL CONDITIONS N
BUFFER REGUIRENENTS K N
GROUNDWATER PROTECT ION N
SURFACE WATER PROTECTION N
RUNOFF AND EROSION CONTROL N N
MMIMUM SLOPE LIMIT N
STORAGE N N
TRANSPORTAION N
* - NORTH EASTERN STATES
• SLLEGE P 5 1ST BE APPROVED BEFORE II
CAN BE DISTRIBUTED FOR USE
C) - STATES NOT CONTACTED
F - SANE AS FEDERAL
C.M. CCI4POST MANAGEMENT
UC, CON. - UNCONTROLLED, CONTROLLED
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TABLE Z.
(LA) MA MD ME M l MN CC) MS MT NC (ND) NE NH NJ (NM) NY OH ON
I C i i.
STATE CONTROL:
REGULATIONS N N N N N N
GUIDELINES N N N N N
ACCEPTABILITY OF SLUDGE:
PERMIT OR APPROVAL REQUIRED ** N N N N N N N N
SLUDGE SAMPLING PARAMETERS N N N X N N N
MAXIMUM SLUDGE CONSTITUENT
CONCENTRATIONS:
NUTRtENTS N
METALS N N N N N N N
PCBS X X N K K N
OTHER CONTAMINANTS N
LAND APPLICATION:
PERMIT OR APPROVAL REQUIRED N N X K
CRITERIA FOR USE:
DEGREE OF STABILIZATION:
STABILIZATION REQUIRED N x X
PSRP N
PFRP N N N N N N
SOIL SAMPLING
WATER QUALITY MONITORING
MAXIHIRI SLUDGE LOADING LIMIT:
N(ANNUAL) N x x
METALS K N
PCBS
OTHER
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TABLE 2.
(LA) MA IC NE NI MN (MO) MS MT NC (ND) NE NN’ NJ (NM) NY ON ON
I C.M.
LAND USE RESTRICTIONS:
CROPS X N N N N N
GRAZING OR GREENCNOP
PUBLIC ACCESS N
p IIOFSOIL N
SITING RESTRICTIONS:
SOIL CONDITIONS N N
BUFFER RE JIREMENTS N N
GROUNDWATER PROTECTION
SURFACE WATER PROTECTION N N
RUNOFF AND EROSION CONTROL N N N
MAXIMUM SLOPE LIMIT
STORAGE N N N
TRANSPORTA ION N
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TABLE 2.
(OX) OR PA R1 Sc (SD) TN TX TX UT VA VT WA WI (WV) WY
(IC CON.
STATE CONTROL:
REGULATIONS X X N X N
GUIDELINES N
ACCEPTABILITY OF SLUDGE:
PERMIT OR APPROVAL REQUIRED ° N N N N N
SLUDGE SAMPLING PARAMETERS N N N
MAXIMUM SLUDGE CONSTITUENT
CONCENTRATIONS:
NUTRIENTS
METALS N N N
PCBS N N
OTHER CONTAMINANTS
LAND APPLICATION:
PERMIT OR APPROVAL REQUIRED N N
CRITERIA FOR USE:
DEGREE OF STABILIZATION:
STABILIZATION REQUIRED N N
PSRP N
PFRP N N N
SOIL SAMPLING
WATER QUALITY MONITORING
MAXIMUM SLUDGE LORDING LIMIT:
N(ANNUAL) N
METALS N N N
PCBS
OTHER
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TABLE 2.
(OX) OR PA R 1 Sc (SD) TN TX TX UT VA VT WA WI (WV) WY
UC CON.
LAND USE RESTRICTIONS:
CROPS N N N N N
GRAZING OR GREENCNOP N N
PUBLIC ACCESS N N
piIOFSOIL N N
SITING RESTRICTIONS:
SOIL COI ITIOSIS N
BUFFER REQUIREMENTS N N
GRUJNDWATER PROTECTION N N
SURFACE WATER PROTECTION N N
RUNOFF MID EROSION CONTROL N
MAXIMUM SLOPE LIMIT N
STORAGE N
TRANSPORTAION
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TABLE 3.
REGULATIONS IN FORCE: LAND RECLAMATION AND DEDICATED SITES
AK AL AR AZ CA CO CT DC DE FL GA HI IA (ID) IL IN KS (KY)
STATE CONTROL:
REGULATIONS N
GUIDEL INES
ACCEPTABILITY OF SLUDGE:
PERMIT OR APPROVAL REQUIRED N
SLUDGE SAMPLING PARAMETERS
MANIKiN SLUDGE CONSTITUENT
CONCENTRATIONS:
NUTRIENTS
METALS
PCBS
OTHER CONTAMINANTS
LAND APPLICATION:
PERMIT OR APPROVAL REQUIRED N
CRITERIA FOR USE:
DEGREE OF STABILIZATION:
STABILIZATION REQUIRED N
PSRP
PFRP
SOIL SAMPLING
WATER QUALITY MONITORING
MAXIMUM SLUDGE LOADING LIMIT:
N C ANNUAL
METALS
PCBS
OTNER
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TABLE 3.
REGULATIONS IN FORCE: LAND RECLAI4ATION AND DEDICATED SITES
AK AL AR AZ CA CO CT DC DE FL GA HI IA (ID) IL IN KS (KY)
LAND USE RESTRICTIONS:
CROPS
GRAZING OR GREENCHOP
PUBLIC ACCESS
pH OF SOIL
SITING RESTRICTIONS:
SOIL CONDITIONS
BUFFER REQUIREMENTS
GROUNDWATER PROTECTION
SURFACE WATER PROTECTION
RUNOFF AND EROSION CONTROL
MAXIMUM SLOPE LIMIT
STORAGE N
TRANSPORTAION N
* NORTH EASTERN STATES
o - STATES NOT CONTACTED
F - SAME AS FEDERAL
L.R. - LAND RECLAMATION
D.S. - DEDICATED SITES
(1) SEPARATELY REGULATED PROGRAMS ONLY
-------
TABLE 3.
(LA) 1 4A ND NE ’ NI MN (140) MS MT NC (ND) NE NK’ PiN’ NJ CNN) NY’ ON
L.R. D.S.
STATE CONTROL:
REGULATIONS IC N IC IC IC
GUIDELINES IC N IC IC
ACCEPTABILITY OF SLUDGE:
PERMIT OR APPROVAL REWIRED IC IC IC IC N
SLUDGE SAMPLING PARAMETERS IC IC IC IC I C
MAXIMUM SLUDGE CONSTITUENT
CONCENTRATIONS:
NUTRIENTS
METALS IC
PCBS IC
OTNER CONTAMINANTS
LAND APPLICATION:
PERMIT OR APPROVAL REQUIRED IC IC IC IC I C
CRITERIA FOR USE:
DEGREE OF STABILIZATION:
STABILIZATION REQUIRED IC IC
PSRP I C I C IC
PFRP IC IC IC
SOILSAMPLING IC IC IC IC IC
WATER QUALITY MONITORING IC IC
MAXIMUM SLUDGE LOADING LIMIT:
N(ANNUAL) IC
METALS IC IC IC IC IC
PUS
OTHER
-------
TABLE 3.
CLA) MA m NE NI MN (NO) MS NT NC (ND) NE UN Nfl NJ(KN) NT ON
L.R. 0.5.
LAND USE RESTRICTiONS:
CROPS K K K
GRAZING OR GREENCNOP K
PUBLIC ACCESS K K
pNOFSOIL K K K
SITING RESTRICTIONS:
SOIL CONDITiONS K K K K
SUFFER REQUIREMENTS K K K
GROUNDWATER PROTECTION K K K K K
SURFACE WATER PROTECTION K K K K
RUNOFF AC EROSION CONTROL K K K K K
MAXIIQJI SLOPE LIMIT K K K
STORAGE
TRAJISPCRTAION
• NORTH EASTERN STATES
C) STATES NOT CONTACTED
F SAME AS FEDERAL
L.R. LAND RECLAMATION
D.S. - DEDICATED SITES
C l) SEPARATELY REGULATED
-------
TABLE 3.
(OX) OR PA R1 SC (SD) TN IX UT VA V1 WA WI (WV) WY
STATE CONTROL:
REGULATIONS N X
GUIDELINES X X
ACCEPTABILITY OF SLUDGE:
PERM iT OR APPROVAL REQUiRED N X
SLUDGE SAMPLING PARAMETERS N
MAXIMUM SLUDGE CONSTITUENT
CONCENTRATIONS:
NUTRIENTS
METALS
PCBS
OTHER CONTAMINANTS
LAND APPLICATION:
PERMIT OR APPROVAL REQUIRED N N X
CRITERIA FOR USE:
DEGREE OF STABILIZATION:
STABILIZATION REQUIRED
PSRP
PFRP
SOIL SAMPLING N
WATER QUALITY MONITORING N X
MAXIMUM SLUDGE LOADING LIMIT:
N(ANNUAL) X
METALS N N
PCBS
OTNER
-------
TABLE 3.
(OK) OR PA RI SC (SD) TN TX UT VA VT WA WI (W) WY
LAND USE RESTRICTIONS:
CROPS N N
GRAZING OR GREENCNOP
PUBLIC ACCESS
pIIOFSOIL N N
SITING RESTRICTIONS:
SOIL CONDITIONS
BUFFER REQUIREMENTS N
GROUNDWATER PROTECTION N
SURFACE WATER PROTECTION N
RUNOFF AND EROSION CONTROL N
MAXIMUM SLOPE LIMIT N
STORAGE N
TRANSPORTAION
* . NORTN EASTERN STATES
C) - STATES NOT CONTACTED
F SAME AS FEDERAL
L.R. LAND RECLAMATION
D.S. DEDICATED SITES
(1) SEPARATELY REGULATEC
-------
state, the following general observations can be drawn from a
review of the regulations.
The degree of stabilization and permitted levels of
sludge constituents depend upon the ultimate use (and
sometimes user) of the product and whether the use can
be controlled.
Where the use cannot be easily controlled, as in public
distribution, sludge quality is more carefully analyzed
and monitored, the degree of required pathogen reduction
is greater and permissible levels of heavy metals are
lower. In most instances, the user does not have to
obtain a permit or approval, although the producer is
often required to maintain records of distribution and
provide guidance and warnings to the final user.
Where the use of the sludge product can be more con-
trolled and public access can be restricted, as in the
application of sludge to agricultural lands, the
required degree of stabilization and pathogen reduction
is lower, and the permissible levels of heavy metals are
higher. However, restrictions on siting and methods of
application are generally specified, and loading rates
are controlled in order to limit metals accumulation,
26
-------
runoff and erosion, ground and surface water degrada-
tion, and food product contamination. Regulations and
guidelines addressing application of sludge to reclaimed
or dedicated sites may have the same restrictions on
runoff, erosion, water quality, and siting, but may
allow higher heavy metal loading rates.
In preparing the regulations or guidelines, most states
relied heavily on USEPA guidance. Among the USEPA pub-
lications most often referred to are USEPA (1979), USEPA
(1983), and USEPA, USFDA, and USDA (1981). Several
states, including Connecticut and Ohio, also rely on
more recent research efforts to define sludge con-
stituent levels and loading rates. The recent studies
cited are Penn. State U. (1985) and Brown (1985).
B. Regulatory Treatment of Key Parameters
Regulations vary from state to state in regard to sludge
disposal programs. The following paragraphs summarize how
different states address the key parameters used to implement
their sludge disposal programs.
Degree of Stabilization — Criteria for Use
Stabilization of sludge can be achieved through a variety of
different means such as anaerobic digestion, aerobic digestion,
27
-------
lime stabilization, and composting. It reduces the potential for
odors, reduces pathogen levels, and usually reduces volatile
solids content. Almost all state regulations require that sludge
be stabilized before application to land or distribution to the
public. In addition, most states specify the level to which
pathogens must be reduced. Pathogens are disease causing
bacteria, viruses, protozoa, and ova (eggs) of parasitic worms
which become concentrated in sludges during wastewater treatment.
The USEPA has defined processes by which pathogens can be
reduced. These processes are categorized into two levels o
treatment: Processes to Significantly Reduce Pathogens (PSRP)
and Processes to Further Reduce Pathogens (PFRP). These
processes are described in 40 CFR 257, Appendix II, Sections A
and B. Bbecause of their importance in addressing the issues in
this report, this reference is reprinted in Appendix II.
In almost all cases, states require PFRP when sludge is
applied to agricultural land on which crops for direct human
consumption are to be grown within a certain period of time,
unless certain conditions are met. For example, Massachusetts,
which classifies sludge into three categories based on heavy
metals content, requires that Type II sludge undergo PFRP if it
is to be applied to agricultural land on which crops for direct
human consumption will be grown within 24 months, unless the
sludge is incorporated into the soil. Maryland also requires
PFRP for sludge for land application if crops for direct human
consumption are to be grown within three years.
28
-------
Most states also require PFRP when the use of the sludge
cannot be carefully controlled, such as in public giveaway
programs. Maryland has a giveaway program for cornposted sludge,
and requires this product to meet PFRP criteria.
Some states require both PFRP and a warning that the sludge
is not suitable for home vegetable gardens. For example, New
Hampshire, New York, and New Jersey regulate composted sludge
giveaway programs, but do not promote the use of compost on home
vegetable gardens.
Sludge Quality (Limits for Constituents )
States can control the total amount of nutrients, heavy
metals, or organic compounds applied to agricultural or other
lands either by regulating the levels of nutrients and heavy
metals in the sludge or by limiting the rate at which the sludge
is applied. Some states address both with carefully regulated
programs.
Approximately 60% of those states regulating land applica-
tion programs establish constituent levels for nutrients and/or
heavy metals. The only organic chemicals normally regulated are
polychiorinated biphenyls (PCBs). Massachusetts, however,
requires that there be no significant concentrations of organic
chemicals for which drinking water standards exist if sludge is
to be applied over an existing or potential groundwater public
water supply. Other organic chemicals which may require
29
-------
regulation are currently being researched (see Section III of
this report). Among those states regulating land application and
distribution programs, heavy metals are more often regulated than
nutrient and PCB levels. There is a variability among states
regarding the maximum levels of heavy metals allowed in sludge,
and often the levels are based upon type of crop grown or method
of application. A summary of maximum sludge constituent
concentrations for land application of sludge in the northeastern
states (Table 4) indicates that permitted cadmium levels range
from a low of 2 mg/kg in Massachusetts Type I sludge ai d New
Hampshire sludge to a high of 25 mg/kg in several of the other
states. The U.S. Environmental Protection Agency, the U.S. Food
and Drug Administration, and the U.S. Department of Agriculture
have developed an interagency policy statement on utilization of
sewage sludge on cropland, defining a “high quality” sludge as
containing less than 25 mg/kg cadmium (USEPA, USFDA, USDA, 1981).
This policy may change as EPA proposes and subsequently promul-
gates comprehensive federal regulations for the use/disposal of
sludge under Section 405(d) of the Clean Water Act. Constituent
levels established by states outside the northeast can be
compared by referring to the “maximum sludge constituent” section
of each state summary in Appendix A.
30
-------
a UNLESS ADJUSTED SOIL p11 ‘6.5
b UNLESS INCORPORATED OR NOT INCORPORATED
IF: PCR IN FEED <.2 PPM PCB 1)1 MiLK <1.5
FAT BASIS
c OTHER ELEMENTS OR COMPOUNDS CONSIDERED CASE BY CASE
d DINERWISE SPECIAL REQUIREMENTS
e MAY SEEK 90 DAY VARIANCE IF ONLY ONE METAL LEVEL EXCEEDS
LIMITS BY <25%
f 2 PPM FOR FERTILIZER. I PPM FOR SOIL CONDITIONER
2 PPM FOR USE ON PASTURE LAND
g TYPE III IF ANY LEVELS EXCEED
h FOR DAIRY AND SORE FOOD CROPS
I IDDO FOR DAIRY OR SOME FOOD CROPS
PESTICIDES OR PERSISTANI ORGANICS NOT TO
EXCEED RESIDUE LIMITS IN CROPS SET BY FED. REGS.
I c NO SLUDGE TO BE APPLIED THAT EXCEEDS RI TOX.
LIMiTS FOR METALS
OR 1% OF ZN LEVEL
TABLE 4.
SUMMARY OF MAXIMUM SLUDGE CONSTITUENT CONCENTRATIONS FOR
LAND APPLICATION OF SLUDGE, iIORTNEAST (NEW ENGLAND , NY, NJ)
FED CT ME NA MA
TYPE I TYPE 11,111
N i l NJ NY
1 ,11
MAXIMUM SLUDGE CONSTITUENT
CONCENTRATIONS
CONDUCTIVITY CMMHOS/CI4)
NUTRIENTS fl aY DRY WEIGHT)
N
P
K
METALS (MG/KG SLUDGE DRY WEIGHT)
AS
CD
PB
NI
ZN
CU
CR
HG
MO
B
FE
ORGAN I CS
PCB
WATER
OTHER CONTAMINANTS
I I
I I
1<2 PPM a 125
11000
1200
I 12500
I 11000
11000
I 110
I I
I I
I 1
1<10 PPM b 110 MG/KG
I I
I I
I I
I I
I I
I
I
I
I
I
I
I
12d
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
e
I
a
I
I
I
I
I
I
I
I
I
110
12
125
12 (RI
a
I
I
I
jIO CC)
1700
1300
11000
1100
1200
1200
1200
1200
12000
12500
12500
12000
11000
11000
11000
11000
11000
11000
11000
11000
110
110
110
110
I
110
110
I
I
1300
1300
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
liD
12 f
110
lID
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I I
18
(IN EXTRACTI
I I
I I
I I
I I
I I
I I
125 h 125
I I
11000 1 11000
I 1200
I 12500
I 11000
11000
I l I D
I I
I I
I I
I I
I I
I 110
I I
I I
I I
I I
I I
I i I
I I
C
-------
TABLE 4.
NY RI VT
III
MAXIMUM SLUDGE CONSTITUENT
CONCENTRATIONS I I I I
I I I
CONDUCTIVITY (NKHOS/CM) I I I
I I I I
NUTRIENTS (XSY DRY WEIGHT) I I I I
N I I I I
P I I I
K I I I
I I I
METALS (HG/KG SLUDGE DRY WEIGHT) I I k I I
I I I I
AS I I I I
CD 125 115 REC 1 125 I
I I I I
PB 11000 1500 REC F lOOD I
NI 1200 1200 REC 1200 I
ZN 12500 12000 REC 12500 I
c i 11000 11000 RECI I 0 00 I
CR 11000 I 11000 I
HG 110 I HAN 110 I
HO I I I I
B I I I I
FE I I I I
I I I I
ORGANICS I I I
I I I I
PCB 110 110 HG/KG I I
1 IMM I I
I I I I
I I I
I I I I
WATER I I I I
I I I I
OTHER CONTAMINANTS C I
I I I I
R-REGULATION
C-GUIDELINE
MAN-MANDATORY
REC- RECONMENDED
I,11 1 111-REFER TO SLUDGE CLASSIFICATION
-------
The level of lead permitted in sludge also varies. In
Massachusetts, Type I sludge can have a maximum of 300 mg/kg
lead, while Type II and III sludges can contain a maximum of
1,000 mg/kg. The Federal Government has suggested a maximum of
1,000 mg/kg lead concentration for “high quality” sludge (tJSEPA,
USFDA, USDA, 1981).
Only ten states specify the levels of nutrients, heavy
metals, or organics in the sludge to be distributed to the
public. Table 5 summarizes the maximum sludge constituent
concentrations for giveaway, public distribution, and compost
management programs in the United States. The limits established
for cadmium and lead are lower for distribution programs than for
land application programs. These lower limits are due to the
difficulty of controlling the loading rates of sludge in public
distribution programs, compared to agricultural or dedicated site
land application programs.
Land Application Rate Limits
As indicated above, one method of controlling the amount of
nutrients, metals, and/or PCBs applied to agricultural or other
lands is to limit the application rate. Over 75% of the states
regulating land application have established maximum annual or
cumulative loading rates. Montana and North Carolina, however,
prefer to address each situation on a case-by-case basis.
33
-------
TABLE 5.
SUMMARY OF MAXIMUM SLUDGE CONSTI1UENT CONCENTRATIONS FOR GIVE AWAY, PUBLIC DISTRIBUTION, AND CONPOST MANAGEMENT P*OGRAI4S
IN THE UNITED STATES.
ME MA MD NI l NY CA IL OH TX WI
MAXIMUM SLUDGE CONSTITUENT
CONCENTRATIONS I I I I I I I I I
I I I I I 1 I I I I
CONDUCTIVITY CMMNOS/CM) I I I I I I I I I I
I I I I I I I I I I
NUTRIENTS (SOY DRY WEIGHT)I I I I I I I I I I
N I I I I I I I 1 I I
P I I I I I I I I I I
K I I I I I I I I I I
I I I I I I I I I
METALS (MG/KGSLUDGEDRY I I I I b I I I I I I
WEIGHT) I I I I I I I I I I
AS I I I I I I I I I I
C O lID 12 112.5 1 l I D ISO 125 112.5 125 110 PPM
I I I I I I I I I I
PB 17 0 0 1300 1500 I 1250 I 1500 1500 1250 PPM
NI 1200 J200 1100 I 1200 I I 1100 1200 I
ZN 12000 12500 11250 I J2500 I I 1100(3 12000 1
CU 11000 11000 J500 I 11000 I I 1500 11000 I
CR 11000 11000 1 I 11000 I I I I I
NG 110 l I D IS I 110 I I I I I
MO I h O I I I I I I I I
S I 1 300 140000 I I I I I I I
FE I I I I I I I I I I
I I I I I I I I I
ORGANICS I I I I I I 1 1 I I
I I I I I I I I I I
PCB 110 12 a IS I I i 12 I I S I2PPM IZPPM
I I I I I I I I I I
I I I I I I I I I I
I I I I I I I I I I
I I I I I I I I I I
WATER 1 I I I I I I0NLTDRIEDI I I
I I I I I I ISLUDGECANI I I
OTHER CONTAMINANTS I I I I I I IBE GIVEN I I I
I I I I I IAWAY I I I
I I I I 1 I I(15 %SOL.)l I I
a 2 PPM FOR FERTILIZER, 1 PPM FOR SOIL CONDITIONER
2 PPM FOR USE ON PASTURE LAND
b METALS LIMITS AS APPROVED
IREFER TO SLUDGE CLASSIFICATION
-------
Among those states establishing loading limits, the rates
are based on the soil cation exchange capacity (CEC), which is
the sum of the exchangeable cations a soil can adsorb. CEC is a
measure of the soil’s ability to immobilize metal cations and is
related to the soil’s clay type and content. In some states,
such as Indiana and Wyoming, the loading rates are also dependent
upon the soil pH. A soil with pH of 6.5 or higher immobilizes
the metals. In a few other states, the loading rates are based
in part upon organic matter content of the soil. In Rhode
Island, the maximum cumulative appiicatian of cadmium is
3.37 kg/ha if the percent of soil organic carbon (SOC) content is
less than 4.8, and 5.62 kg/ha if the percent of soil organic
carbon content is greater than 4.8.
Limits for nutrients are less commonly established than
those for heavy metals. In most cases, the nutrient levels are
established by the nitrogen uptake requirements for a particular
crop. Most states provide formulas for use in establishing the
uptake requirements on individual crops grown on different soil
types. Indiana provides formulas to calculate the amount of
available nitrogen in the sludge, waste product, and/or
wastewater.
States have generally established both annual and maximum
cumulative loading rates for cadmium, but have specified only
maximum cumulative rates for other metals. State agency repre-
sentatives indicate that EPA guidelines (40 CFR 257) and other
EPA publications (U.S. EPA 1983; and U.S. EPA, U.S. DA, U.S. FDA
35
-------
1981) are the primary sources used to establish loading limits
for metals. The loading limits listed in the referenced
guidelines are given in kilograms per hectare (kg/ha). Some
states, however, specify loading limits in pounds per acre
(lb/ac), as in earlier EPA guidance documents. This difference
in units accounts for small variation in some loading rates
presented in the matrices in Appendix A and in the summary
tables. For example, the State of Illinois established maximum
metal loading limits based upon soil CEC for its public distri-
bution program. The limits established for cadmium are expressed
in pounds/acre, yet the figures are the same as the EPA limits in
40 CFR 257 expressed in kilograms/hectare. Therefore, when
pounds/acre are converted to kilograms/hectare for comparison
purposes as shown below, the Illinois limits for cadmium are
slightly higher than the EPA guidelines.
Illinois EPA
if CEC <5: 5 lb/ac (5.5 kg/ha) 5 kg/ha
if 5l5: 20 lb/ac (22 kg/ha) 20 kg/ha
(CEC measured in milliequivalents per 100 grams.)
Land application loading limits for the northeastern states
(Table 6) reveal that there is some variation in heavy metal
loading rates among states. The maximum cumulative loading rate
for lead in Connecticut, which based its regulations on the 1985
Penn State study cannot exceed defined background levels by 337
36
-------
(<.5 KG/HA-TOBACCO, LEAFY VEGS, OR
(ROOTS FOR HUMAN CONSUMPTION
Ni .25 KG/HA-BEFORE 1/1/87
<.5 KG/HA-AFTER 1/1/87
<5 KG/HA-SOIL pH <6.5
(<5 KG/HA-SOIL pH >6.5 AND CEC <5
1 <10 KG/HA-SOIL pH >6.5 AND 56.5 AND CEC >10
(UNLIMITED IF:
FOOD CHAIN CROPS ARE ANIMAL FEED
I pH >6.5 FOR FOOD CHAIN CROPS
PLAN TO PREVENT HUMAN CONSUMPTION
FUTURE OWNERS NOTIFIED BY DEED
I I
I I
(RECOMMENDED FERTILIZER N FOR
(CURRENT CROP, BASED ON:
IAVAILABLE NcAMMONIA N + ORGANIC N I
IPERCENTAGE DETERMINED BY SLUDGE TYPE
I I
I I
I I
I I
(.5 KG/NA I
I I
I I
I I
I I
I(MAL CUM EXCLUDING SOIL BACKGL) I
(337 KG/HA (3 LB/AC) I
I I
I I
I I
I I
I I
I I
I I
I(ANNUAL)
167.4 KG/HA (60 LB/AC)
((MALGUM. EXCL SOIL BACKGRJ
(337 KG/HA (300 LB/AC)
I(ANNUAL)
13 3- 7 KG/HA (30 LB/AC)
I(HAX. CUM EXCL. SOIL BACKGRJ
(168 KG/HA (150 LB/AC)
((ANNUAL)
116.8 KG/HA (15 LB/AC)
((MAX. CUM. EXCL SOIL BACKGR.)
(85.2 KG/HA (75 LB/AC)
ONNECTIGUT
LIMITED BY ANY OF THE FOLLOWING CANNUAL CR CUMULATIVE)
TABLE 6.
SUMMARY OF LOADING LIMITS IN THE NORTHEAST FOR LAND APPLICATION OF SLUDGE
FEDERAL
MAX1MLIM SLUDGE LOADING LIMITS (KG/HA UNLESS OTHERWISE SPECIFIED)
(CEC IN MED/1000 SOIL)
SLUDGE APPLICATION WILL BE
SLUDGE
N (ANNUAL)
METALS
CD
ANNUAL
MAL CUMULATIVE
PB
ZN
CU
-------
TABLE 6.
SUMMARY OF LOADING LIMITS IN THE NORTHEAST FOR LAND APPLICATION OF SLL GE
FEDERAL CONNECTICUT
I ICAN 1 1AL) I
I 167.4 KG/HA (60 LB/AC) I
I I(MAX. CUM. EXCL. SOIL BACKGR.) I
I 1337 KG/HA (300 LB/AC)
I I I
NI I ICANNUAL) I
16.7 KG/HA (6 LB/AC) I
I (MAX. CUM. EXCL. SOIL BACKGR.) I
I 133.7 KG/HA (30 LB/AC) I
I I I
HG I I
I I I
I I I
I I I
I I I
ORGAIIICS I I I
PCBS I I I
I I I
I I I
I,II 1 IIIREFER TO SLUDGE CLASSIFICATION
-------
TABLE 6.
SUMMARY OF LOADING LIMITS
MAINE MASSACHUSETTS
TYPE I
SLUDGE j I
I I I
I I I
I I I
I I I
I I I
N CANNUAL) IAGRONQ IIIC PATES BASED ON INORGANIC ISHOLJLD NOT EXCEED NITROGEN UPTAKE
+ PERCENTAGES OF ORGANIC I I
ISURFACE APPLiED: UP TO 1.5 CROP I
NEEDS I I
I I
I I I
METALS I I I
CD I I I
ANNUAL IS KG/HA IF USED FOR FOW CHAIN I
I CROPS I I
I I I
I I I
I I I
MAX. CUMULATIVE 12.5 KG/HA IF CEC c5 I
ISKG ,HAIFCEC)5 I I
I I I
I I
I I
I I I
I I I
I I
I I I
I I I
P B ICMAX. CUMULATIVE) I
1500 KG/HA IF CEC c5 I
11000 KG/HA IF 5’CEC<15 I I
12000 KG/HA IF CEC 15 I I
I I
I I I
ZN ICMAX- CUMULATIVE) I
1250 KG/HA IF CEC c5 I I
f500 KG/HA IF 5CCECC15 I I
11000 KG/HA IF CEC ’lS I I
I I I
CU ICKAX. CUMULATIVE) I I
1125 KG/HA IF CEC <5 I I
1250 KG/HA IF ScCEC<15 I
1500 KG/HA IF CEC >15 I
I I I
-------
TABLE 6.
SUMMARY OF LOADING LIMITS
MAINE MASSACHUSETTS
TYPE I
CR (MAX. CUMULATIVE) I
25O KG/HA IF CEC (5 I I
1500 KG/HA IF 5CEC15 I I
11000 KG/HA IF CEC >15 I I
I I I
MI ICHAX. CUMULATIVE) I I
150 KG/HA IF CEC 5 I I
1100 KG/HA IF 5CEC15 I
2OO KG/HA IF CEC >15 I I
I I I
HG I I I
I I I
I I I
I I I
I I I
ORGANICS I I I
PCBS I I I
I I I
I I I
-------
TABLE 6.
SUMMARY OF LOADING LiMITS
MASSACHUSETTS
TYPE 11,111
NEW HAMPSHIRE
ICROP NEEDS
METALS I
CD I
ANNUAL .5 C/NA (.45 LB/AC)
MAX. CUMULATIVE ( KG/HA C4.5LB/AC)CEKCLUDING
SOIL BACKGROUND LEVELS)
110 T/AC (DRY) AGRICULTURE
I T/AC CLEAR CUT FOREST
uS T/AC LAND RECLAMATION
I I
ICROP FERTILIZER RATES I
SO 1E ALLOWANCE FOR NH4
VOLATILIZATION WHEN SURFACE
APPLIED, N RELEASED DURING SLUDGE
IDEC O NPOSITION, AND N PRESENT IN 5011.1
I I
I I
1.5 KG/NA (.45 LB/AC) I
I I
I I
12.5 KG/NA (2.2 LB/AC) IF CEC <5
15 KG/HA (4.5 LB/AC) IF 515 I
RAND REC:
5 LB/AC I
I I
I I
I I
I I
I I
SLUDGE I
N (ANNUAL)
PB
ZN
CU
(MAX. ANNUAL, lNCLUDIHG SOIL I(MAX. CUMULATIVE)
BACKGROUND LEVELS) 1562 KG/NA (500 LB/AC) IF CEC c5
KG/HA (445 LB/AC) IF CEC <5 11123 KG/NA (1000 LB/AC) IF ScCECc15
f673 KG/NA (600 LB/AC) IF CEC 4 12246 KG/HA (2000 LB/AC) IF CEC >15
1W’ 10802 KG/HA (715 LB/AC) lF APPR.ILAHD REC.: 1000 LB/AC
I I
(MAX. CUMULATIVE, EXCLUDING SOIL I(MAX. CUNULATIVE)
BACKGROUND LEVELS) 1281 KG/NA (250 LS/AC) IF CEC <5
j280 KG/HA (250 LB/AC) IF CEC <5 1562 KG/NA (500 LB/AC) IF 5CCEC CI5
1561 KG/NA (500 LB/AC) IF CEC >5 11123 KG/NA (1000 LA/AC) IF CEC >15
I ILAND REC.: 500 LB/AC
I(MAX. CUMULATIVE, EXCLUDING SOIL I(MAX. CUMULATIVE)
BACKGROUND LEVELS) 1140 KG/HA (125 LB/AC) IF CEC <5
1140 KG/HA (125 LB/AC) IF CEC <5 1281 KG/NA (250 LB/AC) IF SCECC15
1280 KG/NA (250 LB/AC) IF CEC >5 1562 KG/NA (500 LB/AC) IF CEC ‘IS
I ILAI 1D REC.: 250 LB/AC
-------
TABLE 6.
SUMPIARY OF LOADING LIMITS
ORGANICS
PCBS
MASSACHUSETTS
TYPE 11,111
UMAX. CIJIULATIVE , EXCLLDING SOIL
BACKGROUND LEVELS)
156 KG/HA (50 LB/AC) IF CEC c5
1112 KG/HA (100 LB/AC) IF CEC ‘5
(MAX. CUIIJLATIVE, INCLUDING SOIL
BACKGROUND LEVELS)
12.5 KG/HA C2 LB/AC) . MAX. 2 PPM ON
PASTURE LAND
NEW HNIPSHIRE
(MAX. CIWULATIVE)
1140 KG/HA (125 LB/AC)
1281 KG/NA (250 LB/AC)
1562 KG/NA (500 LB/AC)
ILAJID REC.: 250 LB/AC
I(MAX. CIMULATIVE)
156.2 KG/HA (50 LB/AC)
1112 KG/MA (100 LB/AC)
1225 KG/HA (200 LB/AC)
ILAND REC.: 100 LB/AC
l(MM. OILATIVE)
1.6 KG/HA (.5 LB/AC) IF
11.1 KG/HA (1 LB/AC) IF
12.2 KG/HA (2 LB/AC) IF
ILAND REC.: 1.0 LB/AC
CR
NI
HG
1F CEC (5
IF SCEC15
IF CEC ‘15
IF CEC (5
IF 5 CCEC C15
IF CEC >15
CEC (5
5CECIS
CEC >15
-------
TABLE 6.
SUMMARY OF LOADING LIMITS
METALS
cD
ANNUAL
NEW JERSEY
ILIQUID:
125000 GAL/ACRE/APP., COARSE SOIL
115000 GAL/ACRE/APP., MEDIUM SOIL
11000 GAL/ACRE/APP.. FINE SOIL
10k 30 T/ACRE/YR DRY COMPOST
ICROP REQUIREMENT, DEPENDING
IN CONTENT OF ORGANIC AND INORG.
N (MUST USE FERTILIZER TO SUPPLY
P & K IF NECESSARY)
BASED ON CROP AND SOIL
PRODUCTIVITY CLASS
11.25 KG/HA
1 (s KG/HA-CEC 5
1<10 KG/HA- 5CECC1O
1<20 KG/HA-CEC >10
ICANNUAL) 112 LB/AC
I(MAX. CUMULATIVE)
1560 KG/HA IF CEC €5
11120 KG/HA IF 5€CEC15
12240 IF CEC >15
(MAX. CUMULATIVE)
1280 IF CEC (5
1560 OF 5cCECI5
11120 IF CEC 15
I(MAX. CUMULATIVE)
1140 IF CEC 15
NEW YORK
CATEGORY 1,11
CATEGORY I: 1-3 T/YR
IBASED ON P NEEDS
CATEGORY II: 5-12 T/YR
IBASED ON N NEEDS
ICROP REQUIREMENTS
11.25 KG/HA BEFORE 1/1/87
1.5 KG/HA-AFTER 1/1/87
Ill KG/HA (DEDICATED SITES)
13-4 KG/HA: SOIL GROUPS 1,2,3
15 KG/HA
11123 KG/HA (DEDICATED SITES)
1337 KG/HA: SOIL GROUPS 1,2,3
1561 KG/HA (DEDICATED SITES)
1168 KG/HA: SOIL GROUPS 1,2,3
1281 KG/HA (DEDICATED SITES)
84 KG/HA: SOIL GROUPS 1,2,3
SLL GE
N (ANNUAL)
MAX. CUMULATIVE
PB
ZN
CU
-------
TABLE 6.
SUMMARY OF LOADING LIMITS
NEW JERSEY NEW YORK
CATEGORY I , !!
CR I ITO SE EVALUATED
I I33 KG/NA: SOIL GROUPS 1,2,3
I I I
I I I
I I I
NI (MAX. CtJ4ULATIVE) 1168 KG/NA (DEDICATED SITES) I
1140 IF CEC 4 1 ’ KG/HA: SOIL GROUPS 1,2,3 I
1280 IF SCECc1S I I
560 OF CEC ‘15 I I
I I I
HG JTO BE EVALUATED I
I I I
I I I
I I I
I I
ORGANICS I I I
PCBS I I I
I I I
I I I
-------
TABLE 6.
SUMMARY OF LOADING LIMITS
NEW YORK
CATEGORY III
RHODE ISLAND
METALS
GD
110 T/AC DRY
IF0UR TIMES CROP NEEDS
SLLDGE
IU P TO 50 T/AC
IBASED CIt MAXIMUM LOADING
LIMITS FOR METALS
N
(ANNUAL)
I
ANNUAL
I
MAX. CUMULATIVE
15 KG/NA
PB
1500 KG/HA
ZN
1250 KG/HA
w
1125 KG/HA
ICI IAX. CUMULATIVE)
11.1 KG/NA (1 LB/AC)
IF CEC <5 OR SOC <1.6
J3.3T KG/NA (3 LB/AC)
IF 5iCECIS OR 1.6cSOC C4.8
15.62 KG/NA (5 LB/AC)
I IFCEC>ISORSOC>4.8
ICMAX. CUMULATIVE)
1561 KG/NA IF CEC c S OR SOC cl.6
11123 KG/NA IF 5CECdS OR 1.6cSOC<4.
12242 KG/NA IF CEC ‘15 OR SOC >4.8
I (500,10OO 200O LB/AC. REP.)
I I
ICMAX. CUMULATIVE) I
J281 KG/NA IF CEC 4.8 I
(250.500,1000 LB/AC, RESP.) I
I IMAX. CUMULATIVE) I
1140 KG/HA IF CEC 4 OR SOC <1.6 I
1281 KG/HA IF 5CCECclS OR 1.6cSOCc4.8 1
1562 KG/HA IF CEC >15 OR SOC >4.8 I
025,250,500 LB/AC. RESP.) I
-------
TABLE 6.
StJO RY CF LOADING LItUTS
NEW YORK RN E ISLAND
CATEGORY II I
C R ITOBEEVALIJAT E D I I
I I
I I I
I I I
1 I I
N t 50 KG/NA jCKM. OJGJLATIVE) I
I j56.1 KG/HA IF CEC 4 0* SOC (1.6 I
1112 KG/HA IF SCEC 1S OR 1.6CSOCC4.8I
I IZaKG/HAIFCRC 15ORS0t>4.8
(5O IOO ,2OO LB/AC . PESP.) I
HG ITO BE EVALUATED 1 I
I I
I I I
I I I
I I I
ORGAI UCS I I
PCBS I I
I I I
-------
TABLE 6.
SUMMARY OF LOADING LIMITS
VERMONT
SLUDGE I I
I I
I I
I I
I I
I I
N (ANNUAL) ICROP REQUIREMENT BASE ON AVAIL. I
INORGANIC AND ORG. N I
I I
I I
I I
I I
METALS I I
CD I I
ANNUAL .5 KG/HA (0.45 LB/AC) ON LAND USED
IF0R LEAFY VEG., TOBACCO OR ROOT CROPSI
IFOR HUMAN CONS. FOR ALL OTHER FOOD I
IDRAIN CROPS: TIL 12/86-1.25 KG/HA
1(1.1 LB/AC) AFTER 1/87 0.5 KG/HA I
MAX. CUMULATIVE 5.62 KG/HA (5 LB/AC) FOR LOAMY SAND
AND SANDY LOAM I
111.2 KG/HA (10 LB/AC) FOR
FINE SANDY LOAM, LOAM, SILT LOAM I
122.5 KG/HA (20 LB/AC) FOR CLAY LOAM
SILTY CLAY AND CLAY I
I I
I I
I I
I I
I I
PB I(MAX. DiM.) I
1200 KG/HA (178 LB/AC) FOR LS.SL I
1400 KG/HA (356 LB/AC) FOR FSL, L, SIL$
I I
ZN I(MAX. DiM.)
1281 KG/HA (250 LB/AC) FOR LS,SL
1562 KG/HA (500 LB/AC) FOR FSL, L, SiI
11123 KG/HA (1000 LB/AC) FOR CL, SIC,CI
CU l(MAX. CUM.)
1140 KG/HA (125 LB/AC) FOR LS, SL
1281 KG/HA (250 LB/AC) FOR FSL,L,SiL
1562 KG/HA (500 LB/AC) FOR CL ,S1C,C
-------
TABLE 6.
SUMMARY OF LOADING LIMITS
VERMONT
CR ICHAX. GUM) I
1140 KG/HA (125 LB/AC) FOR LS, SL I
1281 KG/HA (250 LB/AC) FOR FSL ,L ,SIL I
1562 KG/HA (500 LB/AC) FOR CL,SIC ,C I
I I
NI (MAX. aiM.) I
56.2 KG/HA (50 LB/AC) FOR LS,SL I
1112 KG/HA (100 LB/AC) FOR FSL, L, SiLl
1224 KGFHA (200 LB/AC) FOR CL, SICIC I
I I
HG (NAX. am.) I
5.6 KG/HA (5 LB/AC) FOR LS,SL I
11.2 KG/HA (10 LB/AC) FOR FSL, L,S IL
122.5 KG/HA (20 LB/AC) FOR CL,SIS,C I
IFSL-FIME SANY LOAM, LLOAM , SIL ,S!LT
ORGANICS ILO 1’ . CL-CLAY LOAM, SC-SILTY CLAY
PCBS I I
I I
I I
-------
kg/ha, while Maine has established a maximum lead cumulative
loading rate of 50 to 2000 Kg/ha, depending upon CEC.
Cadmium levels for almost all states follow tJSEPA guidelines
in 40 CFR 257 (1979), although some states, such as Maine, have
established a more conservative rate. Maine allows only
2.5 kg/ha if CEC is less than five milliequivalents per 100 grams
(meg/bOg) or 5 kg/ha if CEC is greater than five meq/lOOg.
Connecticut, in its land application program, allows only
3.37 kg/ha maximum cumulative loading excluding soil background.
Eigh states with public distribution or giveaway programs
have regulatory criteria for maximum sludge loading limits as
part of these programs. These are controlled public distribution
programs, and notification is given to the users regarding safe
metals application rates. The users may be required to maintain
records indicating their compliance with application rates. (See
Reporting Requirements).
A summary of loading limits in give—away, public distribu-
tion, and compost management projects in the Northeast is presen-
ted in Table 7. New Jersey is the only state which addresses
annual or cumulative loading rates. These rates are similar to
those established for the land application of sludge.
Siting Restrictions
Almost all of the states have established siting restric-
tions in their land application programs. These restrictions
include buffer requirements (distance to water supplies, distance
to residences), ground and surface water protection measures, and
49
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TYPE I
TABLE 7.
SUMMARY OF LOADING LIMITS IN THE NORTHEAST FOR GIVE AWAY 1 PUBLIC DISTRIBUTION AND COMPOST MANAGEMENT
MASSACHUSETTS NEW JERSEY RHOOE ISLAND
MAXIMUM SLUDGE LOADING LIMITS (KG/HA UNLESS OTHERWISE SPECIFIED)
(CEC IN MEG/l000 SOIL)
SLUDGE APPLICATION WILL BE
SLUDGE
LIMITED BY ANY
OF THE
FOLLOWING (ANNUAL OR CUMULATIVE)
I
130 T/AC/YR DRY MAY BE
110 T/AC DRY
I
I
GREATER WITH APPROVAL
I
I
I
I
I
I
I
I
I
N (ANNUAL)
ISHOULD NOT
I NITROGEN
I
I
EXCEED
UPTAKE
ICROP REQUIREMENTS
I
I
I
I
I
I
I
I
I
I
METALS
I
I
I
CD
I
I
I
I
ANNUAL
I
I
I
I
I
I
I
I
I
I
I
I
MAX. CUMJLATIVE
I
I
1
I
I
I
I
<5 KG/HA•CEC 4
1<10 K6/HA ICCEC <1O
c20 KG/HA-CEC >10
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
PB
I
I
I
I
I
I
I(MKUAL) 100 LB/AC
ICMAX. CUMULATIVE)
1560 KG/HA IF CEC <5
11120 KG/HA IF 5’cCECc15
12240 IF CEC 1S
I
I
I
I
I
I
I
I
I
I
I
ZN
I
I
I
I
ICHAX. CUMULATIVE)
I28OIFCEC4
1560 CF 5CCECI5
11120 IF CEC >15
I
I
I
I
I
I
I
I
I
I
CU
I
I
I
I
(MAX. CUMULATIVE)
I I4OIFCEC4
1280 IF 5cCECc15
1560 IF CEC 15
I
I
I
I
I
I
I
i
I
I
CR
I
I
I
I
I
I
I
I
I
I
I
I
NI
I
I
I
I
I
l(MAX. CUMULATIVE)
j56 IFCEC<5
1112 IF 5
-------
erosion control measures. In some states, counties may have
local bylaws which establish additional buffer requirements.
Some counties in Maryland have established zoning bylaws, which
specifically address compost operations.
The buffer requirements vary substantially between states.
For example, the required distance to a private well is 1000 feet
in Rhode Island, but only 150 feet in Illinois. Often, the buf-
fer requirements are based upon the method of application.
Incorporation of sludge into the soil enables application to be
made closer to residences, while surface or spray application
requires a greater buffer. The State of Georgia requires a
buffer of 300 feet to residences if the sludge is injected or
incorporated into the soil, and a buffer of 2000 feet if the
sludge is applied through high pressure spraying.
Most states require measures be taken to preserve ground and
surface water supplies. These measures include siting restric-
tions such as depth to mean annual high groundwater, depth to
bedrock, and distance to streams and seasonal stream beds. The
method and time of application often affect the specific siting
requirements.
Approximately eight states with public distribution or
giveaway programs have some siting restrictions. Again, these
are controlled distribution programs in which the sludge producer
is responsible for notifying the user of certain siting
requirements. In New Hampshire’s distribution/composted sludge
giveaway program, the producer must provide the user with
51
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information regarding use restrictions, and the user must sign a
form acknowledging an awareness of these restrictions. The
state’s control of the user is essentially limited to maintaining
records of these forms.
Reporting Requirements
There is no consistent policy among states regarding
reporting requirements. Some states are very specific about
recordkeeping and reporting requirements (including type of
£nformation to be obtained and frequency of submittal), while
other states do not address reporting at all, or only indicate
that reporting requirements will be established through permit-
ting procedures.
Vermont requires only that records of sludge quantity and
location of application sites be kept. Massachusetts requires an
annual report and records detailing the location of application,
date applied, method of application, crop or animal information,
transportation modes, amount of sludge authorized to apply, the
amount spread, and the annual and cumulative loading rates. New
Hampshire requires only that records and reports be prepared as
determined on an individual basis.
Permit Procedure
Approvals or permits are required by most states for sludge
land application and public distribution programs. Approvals can
either be part of the wastewater treatment facility’s NPDES per-
52
-------
mit if done under state authority, or can be part of a separate
permit application. In some states, separate approvals are
required for the acceptability and for the use of the sludge. For
example, Massachusetts requires that sludge producers submit
detailed applications to the Department of Environmental Quality
Engineering to obtain approval and classification of sludge if
the sludge is applied to agricultural land. In addition, a
separate land application certificate, renewable annually, must
be obtained through submittal of a detailed application form.
Other states, such as Maine, require only one approval regarding
sludge acceptability and the suitability of the land application
site and operation.
Approvals are also required for sludge distribution and
giveaway programs. In some states, the producer acquires
approval for sludge quality and distribution operations, and the
user is required to sign off on a notification form or informa-
tion sheet. In New Jersey, under the controlled compost distribu-
tion program, the producer must obtain approval of the sludge and
must guarantee that the compost will be used in accordance with
the New Jersey Department of Environmental Protection s
provisions. In addition, a compost application site form must be
submitted indicating the amount of compost required, the
location, owner, type of land uses in the vicinity, and general
site conditions.
In New Jersey’s uncontrolled compost distribution program,
which is limited to public agencies or general contractors, the
53
-------
receiver of compost must sign a form acknowledging conditions for
use of the compost.
Dedicated Sites
Dedicated sites are publicly owned and controlled sites
which are set aside for a specific use, such as parks, forests,
and highway mediums and buffer strips. Reclaimed sites are those
in which disturbed areas such as landfills, strip mines, and
gravel pits are restored to where they can support vegetation.
Only eight states (Illinois, Maryland, New Hampshire, New
Jersey, New York, Pennsylvania, Tennessee, and Virginia) regulate
specific land application programs on dedicated or reclaimed
sites. Information on states having distinct programs is
summarized in Appendix A. Other states may briefly mention
dedicated site or land reclamation programs in their agricultural
land application regulations, but do not specify separate program
regulations. For example, Florida regulates application to
dedicated sites, such as highway shoulders and medians, with the
same regulations they apply to agricultural land.
Other states’ agricultural land application regulations
permit sludge application to dedicated sites and establish
loading rates that can be increased with approval. New Jersey’s
regulations for land application to privately—owned agricultural
land indicate that sludge application rates for dedicated sites
may be increased, upon approval, as long as monitoring and public
access requirements are maintained.
54
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Table 3 indicates which states regulate distinct land
reclamation or dedicated site programs, and the criteria that
their programs address.
Of the states that specifically address sludge application
to reclaimed or dedicated sites, only a few specify sludge
constituent levels or loading rates. Tables 8 and 9 summarize
the maximum sludge constituent concentrations and loading rates
for northeastern state programs, respectively. As seen, New York
is the only northeastern state which addresses sludge consituent
levels for application to dedicated or reclaimed sites. These
levels, which are for the application of composted sludge, are
the same as for application of sludge to agricultural land.
Several states address loading limits for application to
reclaimed and dedicated sites. New Hampshire allows greater
amounts of sludge to be applied to reclaimed land than to
dedicated sites, but the permitted maximum cumulative loading
rates are less. Both New Hampshire’s land reclamation and
dedicated site programs allow higher loading rates than does New
York’s controlled compost distribution program to dedicated
sites. However, the New York guidelines for application of
Category I and II sludge to agricultural land allow for higher
loading levels to dedicated sites.
Before a determination can be made regarding the adequacy of
state regulations and guidelines for the use and distribution of
sludge, an understanding of safe threshold levels and human expo-
sure limits must be obtained. The following chapters address
55
-------
quality standards and environmental risks associated with the use
and distribution of sludge.
56
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TABLE 8.
SUMMARY OF MAXIMUM SLUDGE CONSTITUENT CONCENTRATIONS FOR LAND RECLAMATION AND DEDICATED SITE PROGRAMS, NORTHEAST 1
NH NH NJ NY
LR DS DS DS*
MAXIMUM SLUDGE CONSTITUENT
CONCENTRATIONS I NO I NO I NO I I
LIMITS LIMITS LIMITS I
CONDUCTIVITY (MMHOS/CM) I I I I I
I I I I I
NUTRIENTS (%8Y DRY WEIGHT) I I I I I
N I I I I
P I I I I I
K I I I I I
I I I I I
METALS (MG/KG SLUDGE DRY WEIGHT) I I I I I
I I I I I
AS I I I I I
CD I I I 125 I
I I I I I
PB I I I 11000 I
NI I I I 1200 I
ZN I I I 12500 I
CU I I I 11000 I
CR I I I 11000 I
HG I I I 110 I
MO I I I I I
B I I I I I
FE I I I I
I I I I I
ORGANICS I I I I I
I I I I I
PCB I I I 110 I
I I I I I
I I I I I
I I I I I
I I I I I
WATER I I I I I
I I I I
OTHER CONTAMINANTS I I I I
I I I I I
I I I I I
I I I I I
I I I I I
I I I I I
I I I I I
LR- LAND RECLAMATION COMPOSTED SLUDGE ONLY
DS- DEDICATED SITES 1 SEPARATELY REGULATED PROGRAMS
-------
TABLE 9.
SUMMARY OF LOADING LIMITS IN THE NORTHEAST FOR LAND RECLAMATION AND DEDICATED SITES
NEW HAMPSHIRE NEW HAMPSHIRE
LAND RECLAMATION HIGHWAYS/DEDICATED
MAXIMUM SLUDGE LOADING LIMITS (KG/HA UNLESS OTHERWISE SPECIFIED)
(CEC IN MEQ/1000 SOIL)
SLUDGE APPLICATION WILL BE LIMITED BY AHY OF THE FOLLOWING (ANNUAL OR CUMULATIVE)
SLUDGE 115 T/AC(DRY) 15 T/AC
I I I
I I I
I I I
I I I
I I I
N (ANNUAL) I I I
I I I
I I I
I I
METALS I I
CD 1.5 KG/HA (.45 LBFAC) KG/HA (.45 LB/AC) I
ANNUAL I I I
I I I
I I I
MAX. CUMULATIVE I I
5 KG/HA (4.5 LB/AC) 110 KG/HA (9 LB/AC) I
I I I
I I I
I I I
I I I
PB (MAX. CUMULATIVE) (MAX. CUMULATIVE) I
1123 KG/HA (1000 LB/AC) 12246 KG/HA (2000 LB/AC) I
I I I
I I I
I I I
ZN I(MAX. CUMULATIVE) l(MAX. CUMULATIVE) I
1562 KG/HA (500 LB/AC) 11123 KG/HA (1000 LB/AC) I
I I I
I I I
Cu IU4AX. CUMULATIVE) I(MAX. CUMULATIVE) I
1281 KG/HA (250 LB/AC) 1562 KG/HA (500 LB/AC) I
I I I
I I I
CR ICKAX. CUMULATIVE) ICI4AX. CUMULATIVE) I
1281 KG/HA (250 18/AC) 1562 KG/HA (500 LB/AC) I
I I I
I I I
NI I(MAX. CUMULATIVE) I(MAX. CUMULATIVE)
1112 KG/HA (100 LB/AC) 1225 KG/HA (200 LB/AC)
I I I
I I I
HG I(MAX. CUMULATIVE) I(MAX. CUMULATIVE) I
11.1 KG/HA (1 LB/AC) 12.2 KG/HA (2 LB/AC) I
I I I
ORGANICS I I I
PCBS I I I
(1) SEPARATELY REGULATED PROGRAMS ONLY CONPOSTED SLUDGE ONLY. NEW YORK ALLOWS HIGHER LOADING LTS.
FOR APPLIC. OF SLUDGE TO DED. SITES.
-------
TABLE 9.
NEW JERSEY NEW YORK
CASE II *
MAXIMUM SLUDGE LOADING LIMITS
(CEC IN MEQ/100G SOiL)
SLUDGE APPLICATION lULL BE UN
SLUDGE IL 1 QUID: I I
125000 GAL/ACRE/APP., COARSE SOIL 1 I
115000 GAL/ACREJAPP., MEDIUM SOIL I
11000 GAL/ACRE/APP., FINE SOIL I I
(DRY COMPOST APP.25 TO 100 T/AC/YR I
I I I
N (ANNUAL) ( ONSISTANT WITH PLANT UPTAKE (CROP REQUIREMENTS I
MAYBE UNITEDBYP I I
I I I
I I
METALS (METAL LOADING LIMITED TO PREVENT I
CD IMPAIRMENT OF FUTURE SITE I
ANNUAL USEFULNESS (1.25 KG/NA BEFORE 1/1/81
1.5 KG/NA AFTER 1/1/81 I
I I
MAX. CUMULATIVE I IS KG/HA I
I I I
I I
I I
I I
I I
PB I 1500 KG/HA
I I
I I
I I
ZN I 1250 KG/HA I
I I I
I I
I I 1
CU I 1125 KG/NA
I I
i I
I I
CR I ITO BE EVALUATED I
I I I
I 1
I I I
NI I ISO KG/HA
I I I
I I I
I I I
HG I ITO BE EVALUATED I
I I
I I I
ORGANICS I I
PCBS I (
-------
III. RISKS ASSOCIATED WITH SLUDGE COMPOST USE: SURVEY AND
RECOMMENDATIONS
A. Introduction
The debate over acceptable levels of toxic chemicals and
pathogenic organisms in sludges intended for land application has
been active for over a decade, and is far from over. This
section of the report examines the factors governing land
application of sludges containing heavy metals, organic
chemicals, and pathogens in the northeast region of the United
States. The objective of the section is to assess the basis and
need for regulations governing the use of composted sludge. In
particular, this section examines he public health and
environmental basis for:
Maximum quality limits
Application rates (annual and max. cummulative)
Siting restrictions
Stabilization requirements (for pathogens)
The differences in these requirements that might be permitted for
sale/give away programs versus more controlled uses are also
discussed.
The scope of this project has necessitated focus on only two
of the several metals identified in sludge. Cadmium and lead
60
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were selected for evaluation because of cadmium’s strong tendency
to bioaccumulate and lead’s association with adverse human health
effects at low level environmental exposures. Zinc, copper and
nickel also warrant careful consideration (USEPA, USFDA, USDA,
1981). EPA currently is evaluating cadmium, lead, chromium,
selenium, iron, mercury, arsenic, and molybdenum for potential
deelopment of criteria for land application.
This section has six parts. The first part assesses
existing ongoing federal guidelines and standards development.
The second part assesses the soil chemistry and site conditions
typical of the northeast which can play a limiting role in the
land application of sludges. The next three parts focus in turn
on the scientific basis for regulation of metals, organic
chemicals, and pathogens in composted sludges applied to land.
The final part discusses the implications of the report’s
findings for state and federal agency policy on land application
of composted sludges.
It is important to note that the USEPA in Washington is
nearing completion of a massive four—year program designed to
look at the same questions raised in this report. Draft risk
assessment methodologies for the evaluation of public health
risks from land application of municipal sludges have been
completed by the Environmental Criteria and Assessment Office
(ECAO) in Cincinnati. These methodologies have been used to
support development of comprehensive technical regulations for
use and disposal of sewage sludge under Section 405(d) of the
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Clean Water Act, and will be available for public comment and
review at the time the regulations are proposed for public
comment in early 1987. They are ultimately intended for use by
federal and state environmental agencies in standard setting.
Final drafts of these methodologies are not expected to appear
until late 1987.
This report does not intend to duplicate the efforts of the
federal program. It attempts to provide a basis for the critical
review of the federal program results so that they can be applied
judiciously to the development of land application regulations
appropriate for the New England states. The report relies as
much as possible on recent field and epidemiologic studies to
characterize the complex and often poorly understood
relationships governing availability, uptake, and exposure to
inorganic, organic, and pathogenic constituents of municipal
sludges.
B. Federal Regulations and Guidelines
The federal regulations governing land application of
municipal sludges are relatively limited. The 1979 EPA regula-
tions focused only on annual and maximum cumulative application
rates for cadmium, maximum PCB content of sludges, and
stabilization requirements for pathogen control. The problems
potentially resulting from unregulated sale or give away programs
for composted sludge were not specifically addressed.
Because of the limited scope of the 1979 regulations, many
questions remained about the safety of and recommended limits for
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land application of sludges which contain several other poten-
tially toxic inorganic and organic chemical constituents. Recog-
nizing these concerns, the USEPA, USFDA, and USDA published “Land
Application of Municipal Sewage Sludge for the Production of
Fruits and Vegetables; a Statement of Federal Policy and
Guidance” in 1981. This guidance further explained the 1979
regulations but in addition provided a definition of ‘high
quality’ sludge that has formed the basis for the quality limits
imposed on sludges by several states. They recommended that, for
fruit and vegetable production only, sludges intended for land
application contain no more than 25 mg/kg cadmium, 1000 mg/kg
lead, and 10 mg/kg PCBs on a dry weight basis (USEPA, USFDA,
USDA, 1981). Several northeastern states were contacted as part
of the present study and most cited this 1981 guidance as the
basis for their regulations or guidelines on quality limits for
sludges (see Appendix C for state representatives contacted and
regulatory bases cited). A 1977 paper by R. Chaney and P.
Giordano has been cited by other investigators as the source of
recommended quality limits for zinc (2500 mg/kg), copper (1000
mg/kg), chromium (1000 mg/kg), nickel (200 mg/kg), and mercury
(10 mg/kg) (Penn. State, 1985).
Since the publication of the 1981 guidelines, the USEPA
Office of Water Regulations and Standards has begun a far more
comprehensive review of the toxic constituents of municipal
sludges and the need for further regulations. Section 405 of the
Clean Water Act requires that the USEPA develop and issue regu-
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lations which: “(1) identify uses for sludges including disposal;
(2) specify factors to be taken into account in determining the
measures and practices applicable for each use or disposal
(including costs); and (3) identify concentrations of pollutants
which interfere with each use or disposal.” (tJSEPA, 1985). The
previously published 1979 regulations did not meet these
statutory requirements.
The tJSEPA’s approach to meeting their obligations under the
Clean Water Act has been (1) to identify the potential pollutants
of concern for landfilling, ocean dumping, incineration, and land
application of municipal sludges, (2) to determine the environ-
mental pathways of concern for each pollutant and method of dis-
posal, and (3) to assess the degree of hazard potentially associ-
ated with each pollutant and pathway of concern (USEPA, 1985).
In practice, this approach has evolved in the last four years
into three distinct phases of regulation development: identifica-
tion and screening of initial pollutants of concern; detailed
review of the pollutants of concern and development of method-
ologies for assessing the risks to public health and the environ-
ment; and use of the methodologies to promulgate criteria or
regulations on sludge quality, application rates and land
management practices.
The first two phases of this program are nearly complete as
of this writing (Lomnitz, 1986 personal communication). Expert
committees convened by USEPA identified 50 potential pollutants
of concern to undergo preliminary hazard evaluation (see Table
10). These pollutants were then screened to
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TABLE 10. SLUDGE POLLUTANTS EVALUATED BY U. S. EPA
*A ldrjn/Dje ldrjfl *Se lenjum
Arsenic TCDL)
Benzene TCDF
Benzidine Tetrachioroethylene
Benzo(a)anthracene *Toxaphefle
*Benzo(a)pyrene Trichioroethylene
Beryllium 2,4,6—Trichlorophenol
Bis( 2—ethylhexyl)phthalate Tricresyl phosphate
*Cadmium Vinyl chloride
Carbon tetrachioride Zinc
*Chlor ide
Chloroform
*Chromjum
*Cobalt
*Coppe r
Cyanide
*DDT/DDE/DDD
3, 3—Dichlorobenzidine
Dichloromethane
2, 4—Dichiorophenoxyacetic acid
Dimethyl nitrosamine
Endrin
*Fluor ide
*Heptachlor
*Hexachlorobenzefle
*Hexachlorobutadjene
* Iron
*Lead
*Ljndane
MOCA
Malathion
*Mercury
Methyl ethyl ketone
*Molybdenum
* Nickel
*pCB • s
Pentachiorophenol
Phenanthrene
Phenol
SOURCE: U.S. EPA, 1985
* Identified for detail risk evaluation.
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identify those compounds which warranted more detailed assessment
and, potentially, regulatory action. The screening process
involved developing environmental profiles or data bases to
characterize the chemical/physical properties and major
environmental pathways for each contaminant. Simple worst case
exposure models were then developed to estimate potential
exposures to both human and environmental receptors under
conditions of sludge use. Hazard indices were then developed by
calculating the ratio of the predicted exposure to an
‘acceptable’ level. For example, projected human daily intake of
non—carcinogenic chemicals for given exposure scenarios were
compared to the respective acceptable daily intakes (ADI) for
those chemicals. Contaminants with a ratio or hazard index less
than one were considered to pose sufficiently low hazard to be
eliminated from further detailed investigation.
For land application/distribution and marketing, 32 contam-
inants were evaluated for 13 separate environmental pathways in-
cluding:
• toxicity to soil biota
• toxicity to predators of soil biota
• phytotoxicity
• plant uptake
• toxicity to animals resulting from plant consumption
• toxicity to animals from soil/sludge consumption
• human toxicity from plant ingestion
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• human toxicity from ingestion of contaminated animal
products
• direct soil ingestion by humans.
Contamination of groundwater or surface water supplies was not
evaluated for the land application disposal option at this stage
of rulemaking (pollutant identification), but these pathways will
be evaluated for certain pollutants in subsequent steps of
rulemaking (criteria generation) (USEPA, 1985).
This screening process identified 22 contaminants which
warranted detailed evaluation for at least one of the exposure
pathways considered (USEPA, 1985). Table 10 identifies the
contaminants that were considered and eliminated from detailed
evaluation. A full discussion of these results is included in
the USEPA summary report (1985).
The USEPA has currently completed the first drafts of the
risk assessment methodologies that will be used in the detailed
assessments and ultimately in the promulgation of regulations.
These draft methodologies are not available at this time however
(Lomnitz, 1986, personal communication). The Office of Water
Regulations and Standards expects to propose draft regulations
using these methodologies in the spring of 1987. Careful review
of the applicability of methodologies and regulations to the
needs of the northeast is advisable at that time.
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C. New England Conditions Affecting Land Applications Of Sludges
One of the primary objectives of this project is to evaluate
the impacts of land application of municipal sludges in light of
soil or other conditions characteristic of the northeast. This
section of the report describes briefly the principal factors
affecting or limiting land application of sludges in the
northeast, and provides a basis for evaluating the adequacy of
existing or proposed state and federal regulations.
There are two broad factors which can play a critical role
in the nature and magnitude oE impact that land—applied sludges
have on public health and the environment: soil chemistry and the
physical characteristics of the site. The pH, cation exchange
capacity (CEC), and background concentrations of soil
constituents can each influence the mobility, bioavailability,
and uptake of toxic constituents of sewage sludges, particularly
of heavy metals. The slope, drainage, and proximity to ground
and surface water sources can also prevent contamination of water
supplies by metals, organic chemicals and pathogens.
Soil Chemistry
The pH of soils has long been recognized as an important
factor in the soluble metal concentration and bioavailability of
most metals. In general, lower pH or greater acidity increases
metal bicavailability through hydrolysis of hydroxide species, by
a reduction in the adsorption of metals to pH—dependent
adsorption sites on mineral surfaces, and by lowering the CEC of
soil organic matter (Logan and Chaney, 1983). Plant uptake of
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heavy metals is significantly reduced at soil pH values greater
than 6.5. Molybdenum and selenium are exceptions to this rule as
they tend to increase in availability with increasing pH. Uptake
of lead does not typically increase with decreasing pH since lead
is not significantly translocated into plant tissues.
Background soil pH can influence metal availability over
long periods of time. Studies of sludge application to un].imed
soils at rates of 2—10 metric tons/hectare, dry weight (Mt/ha DW)
by investigators at Ohio State University indicate that
application of sludge results in an initial increase in soil pH
which then drops over time. For soils with pH less than 6.0,
investigators saw a significant increase in extractable cadmium
on unlimed soil 85 days after sludge application (Brown, 1985).
Controlling pH over time can effectively prevent the in-
creasing availability and uptake of metals by plants. Logan and
Chaney (1983) reported on a 1980 review of the available data on
the residual availability of cadmium and zinc to crops after
termination of sludge application. The review indicated that
soluble metal concentrations increased as pH decreased, but that
if pH were maintained at a constant level, soluble metal
concentrations remained constant or decreased. No increase over
time of the soluble metal concentrations in soils maintained at
constant pH was observed. These results indicate the importance
of careful land management practices well after applications of
sludges to the land have ended (Logan and Chaney, 1983).
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Cation exchange capacity (CEC) is also commonly cited in the
scientific literature as an important factor in the soluble metal
concentration, bloavailability, and uptake of metals cation. In
general, the higher the CEC of the soil, the lower the avail-
ability of cations. Logan and Chaney (1983) caution that CEC “is
best viewed as a general, but imperfect indicator of soil compos-
ition that limits the solubility of cadmium and zinc.” It is not
clear that CEC is a good indicator for other metal cations
although it is used in both federal and state regulations to
determine allowable application rates for several metals.
New England soils are typically low in both pH and CEC. A
recent review of the literature published by Pennsylvania State
University (1985) reports that the dominant soil types of the
northeast are the Spodosols and Inceptasols, both of which have
moderately to strongly acidic pH levels and low CEC levels.
Table 11, taken from the Penn. State study (1985), summarizes the
findings of soil pH studies throughout the northeast. The
results of these studies indicate roughly 80% of the northeast
soils sampled fell below the pH 6.5 recommended for lands
receiving sewage sludges and would therefore require long term
soil pH treatment.
Physical Site Characteristics
An other factor affecting the land application of sludge in
the northeast is the availability of cropland meeting the
necessary physical requirements to receive sludge safely.
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TABLE 11. SOIL pH IN THE EAST - NORTHEAST
Percent in
State Crop or use Duration Ave pH <5.5 5.6—6.0
each
pH
range
6.0—6.6
>6.6
Connecticut Corn 1980—81 6.2 12 25 38 25
Connecticut Other field crops 1980—81 6.0 24 30 30 16
Maine All 1945—55 5.4 62 28 8 2
Maine All 1945—55 5.5 62 21 13 4
Maine All 1965—75 5.4 62 23 12 1
Maine All 1975—80 5.8 39 30 19 12
Maryland Field 1967—71 6.1 16 25 35 24
Maryland Field 1972—76 6.2 15 24 34 27
Maryland Field 1977—81 6.3 15 24 34 27
Maryland Lawn & garden 1967—71 6.0 26 22 25 27
Maryland Lawn & garden 1972—76 6.0 25 22 25 29
Maryland Lawn & garden 1977—81 6.3 22 20 23 35
New York Alfalfa 1978—79 6.1 18 26 35 19
New York All 1978—79 6.0 25 29 32 15
New York Corn grain 1978—79 6.0 22 28 32 15
New York Corn silage 1978—79 6.0 20 30 31 14
New York Pasture 1978—79 5.8 38 27 25 10
Pennsylvania Agronomic 1966—79 6.4 —— — — —— ——
Pennsylvania Agronomic 1980 6.4 7 15 50 28
Vermont All farm 1980 5.8 — — —— — — ——
West Virginia All 1976—81 5.8 35 21 18 26
West Virginia Forage 1977—81 5.9 38 23 18 21
Source: Penn. State (1985)
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Careful selection of sites for land application is essential for
protection of ground water and surface water supplies from
contamination by inorganic and organic chemicals as well as by
pathogenic organisms. A recent review of soil classification of
the northeast indicates that a large percentage of cropland in
New England is characterized as unsuitable for land application
of sludges (Penn. State, 1985). These results underscore the
need for judicious land management (eg. siting) restrictions in
land application regulations.
Investigators cited in the Penn. State (1985) study defined
several criteria limiting cropland for the receiving sludges:
• Excessively well—drained soils
• Poorly drained soils
Soils with seasonably high water tables
Soils subject to flooding
Soils or slopes permitting rapid runoff
• Soils with low available water capacity
Soils or sites meeting these criteria are associated with a
higher probability of contaminating ground water and/or surface
water.
Table 12 provides a breakdown of soil classification of New
England crop land and the associated limitations for sludge
application based on the Soil Conservation Service Classification
system (Penn. State, 1985). As the table indicates, a large
proportion of cropland in New England falls into categories
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TABLE 12. SOIL CONSERVATION SERVICE
CLASSIFICATION OF SOILS IN THE NORTHEAST
Class
Percentage (%
of Total
Land in
Limitations for Cultivation New England
) Percentage (%)
of Crops
Land in
New EnglandC 1 )
I
Slight 1
5
II
Moderate limitations which 15
restrict choice of crops or
necessitate corrective procedures
42
III
Severe limitations restricting 19
crop choices or requiring
corrective practices
36
IV
Very severe limitations for 10
cultivation
12
V, VI,
VII, VIII
Generally unsuited for 55
cultivation
6
Source: Penn. State, 1985
1. Cropland defined as percentage (approx. 17%) of rural,
non—federal land.
which, on the basis of the criteria defined above, would be un-
suitable to receive sewage sludges. Taken together, a minimum of
30—40% ( approx. 37-50 million acres) of New England cropland
should be restricted from land application of sludges (Penn.
State, 1985).
Despite these restrictions, the acreage available for land
application of sludges is still considerable. As far as could be
determined, the Penn. State C 1985) study included only agricul-
tural land in its calculations leaving the availability of forest
lands open for further consideration. Nonetheless, the large
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percentage of cropland alone that should be restricted from
sludge application in order to prevent possible ground or surface
water contamination indicates the importance of siting and other
land management regulations in protecting human health and the
environment.
Subsequent sections of this report will evaluate how well
existing regulations address the particular conditions of
northeast soils. The discussion will focus on the issues
surrounding heavy metal limits and application rates for
naturally acidic, low CEC soils rather than on siting
restrictions.
D. Metals in Municipal Sludges
Several metals have been detected in municipal sludges
raising concerns about possible reduction in crop productivity
and hazards to human and animal health resulting from land
application of sludges. Table 13 provides a summary of the
metals detected in municipal sludge, their mean and 95th
percentile concentrations. The values reported in the table are
those identified by the JSEPA for detailed risk assessment in
their initial screening evaluation of toxic constituents of
municipal sludge (USEPA, 1985).
The variability in the quality of sludges is substantial and
depends on a variety of factors including the nature and level of
industrial discharge to the facility. The values reported in the
table are derived from national studies; no data has been
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TABLE 13. INORGANIC CONTAMINANTS IN SLUDGE EVALUATED
B! U.S. EPA (1985)
Concentration (mg/kg DW)
Identified for Detailed Evaluation Mean 95%
Arsenic 4.6 20.8
Cadmium 8.2 88.1
Chromium 230.1 1500
Cobalt 11.6 40
Copper 409 1430
Fluoride 86.4 739
Iron 28,000 78,700
Lead 248 1071
Mercury 1.5 5.8
Nickel 44.7 663
Selenium 1.11 4.85
Zinc 677 4580
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compiled to reflect the concentrations typical of New England
states. The variability, however, shows that difference must be
expected and that monitoring is essential to determine the
suitability of any given sludge for land application.
This study has focused on the public health and
environmental implications of cadmium and lead in sludges applied
to land. Because of cadmium’s tendency to bioaccumulate and its
association with both phytotoxicity and human toxicity, and
lead’s neurotoxicity at low levels of human exposure, the
acceptable limits set for these metals are typically low.
Cadmium and lead therefore tend to be controlling factors in the
acceptability of any sludge for land application, particularly
for distribution and marketing programs. This emphasis on
cadmium and lead does not indicate that other metals do not
warrant the same level of evaluation; however, the emphasis
reflects the disproportionate level of attention given cadmium
and lead in the scientific literature. With the studies being
completed by the USEPA, the hazards posed by other toxic metals
will likely come into clearer focus.
The following discussions of cadmium and lead attempt to
shed light on the scientific basis for their regulation under
existing land application regulations and guidelines, the
adequacy of that basis, and the applicability of these
regulations for the soil conditions in the northeast. For
example, what routes of exposure or exposure scenarios were
evaluated? What other routes of exposure should have been
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considered? What does recent research indicate about the level
of protection provided by existing regulations? How were
conditions like soil pH taken into account?
Cadmi urn
Cadmium is among the most well studied of metals in sludges
largely because of its demonstrated uptake in plants and the
widely reported incident of human poisoning (itai—itai disease)
from environmental cadmium contamination which occurred in Japan
in the late 1970’s. Although the factors influencing human
exposure to cadmium (uptake in plants, influence of soil pH,
effect of dietary deficiencies on human uptake, etc.) are better
understood than for most metals, many questions remain. Cadmium
in sludges is still an area for active research. This section
examines the basis for early cadmium regulations (USEPA, 1979)
and guidelines (USEPA, USFDA, USDA, 1981), their adequacy in
light of recent research, and their relevance to the northeast.
Logan and Chaney described the original basis for the 1979
USEPA cadmium regulations in a recent review (1983). Their review
indicates that the early regulations already accounted for the
influence of low soil pH on cadmium uptake and on potential human
exposure and toxicity. While the federal regulations on annual
and maximum cumulative application rates for cadmium were
intended for controlled use of sludges on agricultural and other
lands, they were derived from what was considered to be a worst
case exposure scenario —— the case of sludges applied to personal
‘acid gardens’ (Logan and Chariey, 1983).
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The assumptions incorporated into that scenario are
important in understanding the applicability of the early
regulations to northeast soil conditions and are listed here:
• The soil contains the maximum allowed cumulative cadmium
application 5 kg/ha.
• The soil is continuously acidic (pH 5.5)
• The gardener obtains 50% of his annual supply of garden
vegetables from the sludge amended, acidic soils
(potatoes, leafy, root and legume vegetable, and garden
fruits—tomatoes)
• The gardener eats from this garden for 50 years
• The individual is part of the sensitive-to—cadmium
population
• The individual has a dietary intake of 39 ug/day (based
on the teen—age male food intake).
Logan and Chaney (1983) assert that these assumptions are
each very conservative and therefore provide multiple factors of
safety. They contend that most gardeners growing 50% of their
vegetables are likely to be educated about the importance of pH
control in maintaining crop productivity and are therefore
unlikely to maintain their garden at a pH of 5.5. While their
criticism is debatable, Table 11 indicates that (with the
exception of Maine soils) the largest percentage of soils are at
pH 5.6 or above so the assumption is still conservative.
Vegetables also supply the micronutrients (zinc, iron, and
calcium) the deficiencies in which define the cadmium—sensitive
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individual; i.e. individuals with deficiencies in these elements
are more susceptible to the uptake and toxic effects of
cadmium. Third, increased cadmium in sludge grown vegetables
(chard and lettuce —— both ‘high uptake’ species USEPPA, USFDA,
USDA, 1981) does not necessarily lead to the theoretically
projected increase in kidney cadmium (Logan and Chaney, 1983).
Logan and Chaney (1983) cite a study by Ryan et al. (1982) that
concludes that in the U.S., sensitive individuals can safely take
in up to 150 ug cadmium/day which is higher than the acceptable
daily intake used in the scenario. Fourth, the teenage male’s
dietary intake of cadmium is typically much higher than that of
other age and sex groups and therefore is not representative of
the general population. More recent versions of this exposure
scenario recommend use of the average adult daily intake (Chaney
et al, 1986).
One of the most important pieces of research to emerge in
recent years is work done by Chaney et al. (1982) which
demonstrates in controlled field studies that the cadmium in “low
level” cadmium sludges (<25 ppm dry weight as defined by Chaney)
is less available for uptake than previously believed at the time
of the 1979 regulations. The research indicates that low and
high cadmium sludges applied to land will not result in the same
level of plant uptake of cadmium even if the total amount of
cadmium applied is the same. The uptake rate for cadmium in
sludges is not the linear function of cadmium concentration
predicted by studies where cadmium is applied as cadmium salts
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(Chaney, Sterret, Morella, and Lloyd, 1982). Lower amounts of
cadmium appear in plant tissues following sludge application than
would be predicted from studies with cadmium salts, particularly
for low cadmium sludges. This relationship holds at both low
(<6.5) and high (>6.5) pH soils. A new model introduced in 1980
to explain cadmium bioavailability suggests that sludges have
intrinsic sorption capacity for cadmium which, with high cadmium
sludges, begin to be saturated leaving more cadmium available for
uptake. It is this cadmium adsorption capacity, rather than
cadmium precipitation as an inorganic compound that regulates
cadmium bioavailability (Logan and Chaney, 1983).
Figure 1, taken from the Chaney et al. (1982) study
illustrates this relationship. There is a greater uptake of
cadmium in lettuce receiving the higher cadmium sludges, showing
the importance of initial sludge cadmium concentrations in
determining cadmium uptake. The figure also shows that the leaf
cadmium concentrations level out at increasing application rates
instead of increasing linearly as has been seen in experiments
with cadmium salts. This leveling off occurs at both low and
high pH levels. The figure also demonstrates the influence of
soil pH on cadmium uptake; much higher levels of leaf cadmium are
observed in lettuce grown on soil at pH 5.6 than at pH 6.6. Very
little difference in cadmium uptake is seen between low and high
pH for lettuce grown on soils amended with low cadmium sludge
(13.4 mg/kg) but a large difference is apparent for the high
cadmium sludge (210 mg/kg). These results, in part, provided
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FIGURE 1
Source : Chaney
1982
The Effect of Sludge Cd, Soil pH, and Sludge
Applied Cd on Cd in Romaine Lettuce
Sludge Cd Applied , kg/ha
R.L., S.B. Sterrett, M.C. Morella, and CA Lloyd,
Heat—Treated Sludge : Cadimium: 13.4 mg/kg dry weight
Cadmium/Zinc Ratio: 1.01
Lo pH - 5.4
Hi pH - 6.2
Nu-Earth : Cadmium: 210 mg/kg
Cadmium/Zinc Ratio: 5.07
Lo pH - 5.6
Hi pH - 6.6
dry weight
C)
>1
E
Q.
a
0
C.,
U
w
-J
0 1.5 3.0 10.5 21
81
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support for the 1981 policy guidelines published by the USEPA,
USFDA, and the USDA.
The findings illustrated in these experiments have also been
demonstrated for copper, zinc, and nickel indicating that the
plant uptake of these metals is also more strongly determined by
initial sludge metal concentration than by application rate
(Logan and Chaney, 1983).
On the basis of these and other findings, a recent USDA
bulletin published guidelines defining acceptable levels of
several metals in sludge (see Table 14). Sludges meeting these
requirements are considered low metal sludges (Hornick et al.,
1984). They are essentially the same levels recommended in
earlier quidelines (USEPA, USFDA, USDA, 1981) and in the recent
Penn State (1985) review.
In addition to research reported above, several
investigators noted both in their writings and personal
communications that there is another factor of safety in existing
guidelines and regulations of cadmium that is frequently
overlooked. The factor of safety lies in the recommendation that
sludges be applied on agricultural land at agronomic rates; that
is, at rates which primarily provide soil conditioning and,
secondarily, which help meet the nitrogen and phosphorus
requirements of the crop to be grown. (Hornick et al., 1984,
personal communication; Brown 1985; Logan, 1986, Personal
conunuriication). Agronomic rates are likely to be much lower than
the rates theoretically allowable by applying the maximum sludge
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TABLE 14. MAXIMUM RECOMMENDED LIMITS FOR METALS
IN SLUDGES ACCEPTABLE FOR COMPOSTING
Element
Arsenic (As)
Cadmium (Cd)
Chromium (Cr)
Cobalt (Co)
Copper (Cu)
Fluorine (F)
Iron (Fe)
Lead (Pb)
Manganese (Mn)
Mercury (Hg)
Molybdenum (Mo)
Nickel (Nj)
Selenium (Se)
Tin (Sn)
Cadmium:zinc (Cd:Zn)
“Maximum domestic
Sludge” (mg/kg_sludge dry weight)
25.0
1,000.0
200.0
1,000.0
1,000.0
4.0
1,000.0
10.0
25.0
200.0
2,500.0
1.5
Source: Hornick et al., 1984
cadmium. For example, investigators at Ohio State studying the
effect of land application of municipal sludges on human health,
animal health, and crop yield applied sludges in the range of 2
to 10 metric tons per hectare (Mt/ha). A recent USDA bulletin on
the utilization of low metal sewage sludge compost strongly
recomn end5; application rates of 10 to 20 Mt/ha — rates which
substantially improve the physical properties of the soil but
which do not necessarily meet the nitrogen requirements of the
crop (Hornick et al., 1984). Assuming a sludge cadmium content
of 25 mg/kg dry weight and the current maximum allowable annual
application rate for cadmium, 1.25 kg/ha (USEPA, 1979), 50 Mt/ha
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of sludge could be applied. This amount is several times the
agronomic rate recommended by the Ohio State study or by USDA.
Some investigators argue that it is a physically impractical and
expensive volume of sludge for farmers to handle; a combination
of sludge application and commercial fertilizers is likely to
meet the soil conditioning and mineral requirements of a crop
more economically (Hornick et al., 1984). However, assuming a
maximum acceptable sludge cadmium content of 25 mg/kg, the total
amount of sludge that can be applied will approach agronomic
rates when the 0.5 kg/ha maximum annual loading rate for cadmium
comes into effect in January of 1987 (USEPA, 1979). At that
time, the maximum sludge application rate will be 20 Mt/ha for
sludges containing 25 mg/kg cadmium.
Both the unexpectedly low rates of cadmium uptake from ‘low’
cadmium sludges and use of sludges at agronomic rates appear to
provide adequate protection of human health from excessive intake
of cadmium from commercial crops or personal vegetables grown on
sludge amended soils. However, the 1979 USEPA regulations and
later guidelines on sludge application (USEPA, USFDA, USDA, 1981;
Hornick et. al., 1984) do not explicitly address some of the
other routes of human exposure to cadmium and other toxic
constitutents of sludge that could also influence the selection
of quality limits or land management practices for land
application of sludge.
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The USEPA (1985) program currently under direction of the
Office of Water Regulations and Standards attempts to address
that oversight. As discussed earlier, the USEPA screened several
routes of transport and potential human and environmental
exposure to identify those routes which presented the most
concern. For cadmium, the routes of potential human exposure
that are being evaluated in greater detail include:
• ingestion of plants that have accumulated cadmium
• consumption of animal products from animals fed on
cadmium contaminated plants
• consumption of animal products from animals which have
inadvertently ingested sludge directly
• direct ingestion of sludge (eg. by children).
Draft risk assessment methodologies have been developed to
evaluate the impact of these possible exposures by the USEPA
Environmental Criteria and Effects Office in Cincinnati but they
are not yet available for general public or agency use (Lomnitz,
1986, personal communication).
The current USEPA approach considers possible contamination
of groundwater or surface water by heavy metals as a result of
land application of sludges. Groundwater contamination is also
being evaluated for landfilling of sludges.
Because the USEPA risk assessment methodologies were not
available for review, a search was conducted of the recent
scientific literature (1980—1986) for studies that could begin to
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address some of the questions raised about the importance of
other routes of exposure. Some evidence is available which
suggests that direct domestic animal consumption of sludge
adhered to forages or directly from soils while grazing can be an
important route of cadmium transport into the human food chain
(Logan and Chaney, 1983; Chaney et al., 1986; Reddy et al.,
1985). Professor Logan of the Agronomy department at Ohio State
University has reviewed some early results of the rJSEPA’s risk
assessments which indicate that direct animal ingestion of sludge
appears to be a significant route of human exposure (Logan, 1986,
personal communication). Direct ingestion effectively bypasses
the “soil—plant barrier” created by soil pH control,
phytotoxicity of the contaminant, or by the contaminant’s
inability to be translocated into plant tissues (Logan and
Chaney, 1983). Fortunately, the importance of this route of
exposure appears to be greater for “metal—rich” sludges than for
the recommended “low metal” (<25 ppm Cd) sludges. As in the case
of plant uptake, metals in “low metal” sludges are reported to be
less bioavailable than in “high metal” sludges (Chaney, Smith,
Baker et al., 1986).
Sludge adherence to forages is one of the primary ways in
which domestic animals can ingest sludges (Chaney, Smith, Baker
et al., 1986). Several factors affect the amount of sludge that
adheres to forages: the higher the application rate (within
practical rates), the greater the amount of sludge adherence; the
higher the percent solids, the greater amount of adherence; and
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if sludges are allowed to dry on forages (as opposed to being
injected or otherwise incorporated), they will adhere strongly
even during subsequent rainfall. Forages can reach up to 15—30%
sludge (dry weight basis) following application, but other
investigators report that “in practical grazing management”
(undefined), 2 to 3% is more likely (Chaney, Smith, Baker, et
al., 1986). Applying sludge to a recently mowed field and
waiting for the crop to grow can keep the sludge content of
forage to 3 to 5% by dry weight (Logan & Chaney, 1983).
Direct ingestion of sludges in soils is also a route of
exposure, although its significance is difficult to separate from
that of sludge contaminated forages. Chaney, Smith, Baker, et
al., (1986) cited studies showing that animals ingested 1 to 3%
sludge in their diet even when no detectable sludge adhered to
forages. Other studies showed ingestion of up to 8% sludge in
the diet of animals grazing from pastures (Chaney, Smith, Baker,
et al., 1986).
Chaney, Smith, and Baker (1986) report that sludge—borne
microelements do not appear to be very bioavailable; they do not
necessarily cause the health effects seen in toxicologic studies
based on use of metal salt in the diet. They cite studies in
which cattle, sheep and swine were fed “low metal” sludges and no
increased tissue concentrations of cadmium, zinc, or lead were
observed. When the animals were fed “high” cadmium sludges,
increased concentrations of cadmium were observed in the liver
and kidney, the primary target organs for cadmium.
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Metal uptake by cattle was recently evaluated in a major
field study conducted by Ohio State University. Reddy et al.,
(1985) compared the metal uptake in calves and cows grazed on
sludge—amended pastures to levels in animals grazed on unamended
control pastures. The sludge—amended pastures received sludges
at a rate of 2 to 10 Mt/ha. The sludges contained on average, 78
mg/kg DW cadmium, 557 mg/kg DW lead, 5223 mg/kg DW zinc and
therefore would be considered “high” metal sludges in light of
federal guidelines. Metal uptake was measured by fecal and
tissue metal levels.
The study contained several important findings. First,
fecal cadmium levels fell to pre—sludge application levels 3—8
months after grazing began on the pastures, indicating the
importance of a delay between application and grazing. Second,
the study found a significant increase of cadmium and lead in the
kidney cortex in sludge exposed calves compared to control calves
but found no differences among the cows. No significant
differences in zinc or copper uptake were observed in either
calves or cows. The study also detected a tendency (not
significant) for lead to accumulate in the bones of calves and a
statistically significant (p<.05) increase in blood lead of
exposed cows versus that of controls. Despite the appearance of
lead in blood, there was no evidence of metals accumulation in
muscle tissues. The authors concluded that the biological
significance of the metal uptake was therefore minimized since
metals did not appear to accumulate in the primary edible tissue
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of the animals (Reddy, et al., 1985). No discussion of metal
content of dairy products was discussed.
Reddy (1985) also evaluated exposures of farm families to
sludge—borne cadmium compared to control farms but found no
significant differences. The study monitored fecal cadmium in an
attempt to evaluate cadmium exposures from a variety of potential
sources: inhalation of cadmium laden dust while working in the
fields, ingestion of cadmium from ground water draining the
fields, or ingestion of meat products from animals grazing on
sludge amended soils. Families were not permitted to grow
vegetables on sludge—amended gardens. The primary limitations of
this study were the relatively small sample size and the absence
of any data to indicate what real exposures might have been (eg.
via air or ground water). The latter problem in particular makes
it difficult to determine whether farm families are at no greater
risk of exposure to metals in sludges applied at 2 to 10 Mt/ha or
that the exposures encountered have any biological significance.
Contamination of ground and surface water supplies have
often been cited as an area of concern but they have not been
studied much to date. The preliminary indications from available
data are that leaching of metals appears to be less of a concern
than runoff (Logan and Chaney, 1983). Each route of transport
will be discussed briefly.
Metal cations do not leach readily from soil. However when
sludge is heavily applied to a soil with low pH, metals can move
up to several meters. Some of the examples cited by Logan and
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Chaney include a case where chromium, copper, and zinc were
detected 2 meters below a sludge drying bed and nickel and
cadmium were detected at 3.5 meters below the bed. Cadmium was
detected 45 centimeters beneath agricultural land receiving
135—148 Mt/ha. In both cases, the volumes of sludges were much
higher than agronomists recommend for agricultural uses of
sludge. (The initial metal content of the sludges was not
specified). Logan and Chaney (1983) suggested that application
rates below 15 Mt/ha should pose no threat to groundwater
supplies.
Even less information is available in the literature
reviewed on the potential impact of land application of metal
containing sludges on surface water. Logan and Chaney (1983)
noted that runoff is a potentially greater problem but felt that
“proper site selection and sludge application management should
be adequate to protect water resources from metal contamination
from surface water runoff and erosion.”
Lead
Although lead is not as well studied as cadmium in the
context of land application of municipal sludges, it has received
considerable attention as an environmental contaminant because of
its adverse effects on the nervous system associated with even
low levels of exposure. The absence of federal regulations
governing sludge quality limits or land application rates for
lead has been rectified in part by subsequent federal guidelines
(USEPA, USFDA, USDA, 1981) and several state regulations.
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Unlike the case of cadmium, the basis for these guidelines
and regulations (i.e. the scenarios or assumptions used) are not
clear. Lead is not phytotoxic and its limited uptake by plants
is not strongly affected by pH and other characteristics of soil
that are important for cadmium uptake. As for cadmium, though,
the USEPA is in the process of developing risk assessment
methodologies with which to evaluate the public health impact of
lead in sludges applied to land. Since those methodologies are
not yet available, this section of the report evaluates some of
the recent scientific evidence on the importance of various
routes of exposure to lead in municipal sludges. This evaluation
can then serve as a basis for the critical assessment of the
methodologies and their use in regulation development.
In its screening of the potential public health and
environmental impacts from land application of municipal sludges,
the USEPA evaluated the same routes of human exposure to lead as
were considered for cadmium and the other contaminants; uptake
from plants, consumption of animal products from animals fed on
plants which had taken up lead, consumption of animal products
from animals which directly ingested sludge or sludge—amended
soils, and direct human ingestion of sludge or sludge—amended
soils (USEPA, 1985).
The results of the screening were that the only routes of
exposure identified for detailed evaluation in the second phase
of the USEPA program were consumption of contaminated plants and
direct ingestion of sludges or sludge amended soils. These
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results are partly at odds with conclusions reached in the review
of scientific literature during this study. It is not clear that
the USEPA will rely solely on the results of the screening
process to dictate the routes of exposure to be considered in
detail. A discussion with Professor Logan of Ohio State
University indicated that direct consumption of sludges by
animals and subsequent human ingestion of animal products
appeared to be an important route of exposure to sludge
contaminants on the basis of detailed risk assessments completed
by USEPA (Logan, 1986, personal communication).
The USEPA screening evaluation indicated that consumption of
plants grown on sludge amended soils warranted further evaluation
as a route of exposure to lead. This result is surprising in
light of scientific research findings. The USEPA screening model
considered only the uptake of a contaminant into plant tissues.
Lead is a non—essential element for plants as well as animals.
Chaney (1983) (cited in Logan and Chaney, 1983) reported that
plants do not have a tendency to incorporate lead unless the lead
content is “very high”, such as the levels associated with land
treatment of hazardous wastes or under conditions where the
phosphate levels in soil are very low. Low phosphate levels in
soil appear to promote lead translocation into plant tissues
(Penn. State, 1985). In fact, as for cadmium, application of
lead in low metal sludges appears to decrease plant—available
lead even though the concentration of lead in the soil is
increasing. This phenomenon was observed in all crops studied
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including grains, fruits, tubers, edible roots, and leafy
vegetables (Logan and Chaney, 1983). The mechanism for limiting
the availability of lead may be similar to the sludge sorption
capacity reported for cadmium.
Concern about exposure to lead from plants grown on sludge
amended soils might better be focused on surface contamination of
root crops (Penn. State, 1985). Plant lead is usually much
higher in roots than in the tops. Report correlated with the
lead levels in soils indicating that adherence of particulate
lead to plant surfaces may be an important mechanism for lead
contamination of plants (Penn. State, 1985). This finding
argues strongly for limitations on the maximum cumulative levels
of lead that can be added to soils by land application of
sludges, particularly because the addition of lead is essentially
“permanent and irreversible” (Penn. State, 1985). Monitoring for
background levels of lead in soils receiving sludges would also
be advisable given the demonstrated and ongoing contribution of
lead in gasoline to soil lead levels.
The USEPA, USFDA, USDA (1981) guidelines recommend a maximum
cumulative lead application of 800 kg/hectare. They further
recommend that “crops grown on sludge - or compost - amended
soils particularly root crops and low growing fresh fruits and
vegetables, be processed in accordance with established industry
practices”.
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Direct ingestion of sludges or sludge amended soils is a
potentially important route of exposure to lead for young
children or infants who intentionally ingest small quantities of
soil (a condition known as pica) or inadvertently ingest soil
from soiled hands or toys. Exposures to low levels of lead
create concern because of studies which suggest that neurological
impairment (defined by lower IQ, school achievement, and other
problems in classroom behavior) is associated with increased
levels of lead in deciduous (baby) teeth (Weedleman, 1979, 1980;
Winneke et al., 1981). Lead levels in deciduous teeth indicate
lead exposures at a young age.
Despite these concerns, the consensus in the literature
reviewed for this report is that further research is needed on
the effect of low lead sludges on infants and children. Logan
and Chaney (1983) cite several studies indicating that
individuals may absorb “excessive” amounts of lead by ingesting
soils “rich in lead”, 500—1000 mg/kg. The relevance of these
findings to lead exposures in children versus that in adults is
not clear. The detailed evaluations of this route of exposure
currently underway by the tJSEPA should provide valuable
assistance in answering this question. The ultimate importance
of this route should provide a basis for setting more stringent
lead limits in sludges intended for use in private gardens or
other locations where young children may play.
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The USEPA’s apparent elimination of direct animal ingestion
of sludges as a route of human exposure to lead may be an
important oversight. As in the case of cadmium, although plant
uptake of lead is minimal under normal conditions, this “soil
plant” barrier can be bypassed effectively by animals ingesting
sludge directly. The section on cadmium discussed in detail how
animals can take in sludges adhered to forages or directly from
soils while grazing. The scientific debate revolves around the
biological and toxicological significance of this route of
exposure.
Logan and Chaney (1983) concluded that “domestic” or “low”
metal sludges as defined in the USEPA, USFDA, and USDA policy
guidelines (1981) and in recent USDA (Hornick et a., 1984)
guidance (Table 14) pose no risk to livestock or human adults
through plant uptake or soil ingestion by animals. While plant
uptake of lead may not be significant, investigators at Ohio
State University have recently completed field studies of the
uptake of metal contaminants in sludge by grazing animals that
indicate that animal uptake of metals does occur via direct
ingestion. The study, discussed in more detail in the cadmium
section, looked at differences in fecal and tissue lead levels
between calves and cows grazing on sludge—amended pastures and
animals grazing on control pastures. Pastures received sludges
at application rates of 2-10 Mt/ha and with average lead
concentrations of approximately 557 mg/kg dry weight (Reddy et
al., 1985). The average lead concentrations therefore appeared
to be within the commonly recommended levels (1000 mg/kg).
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The study did find some association between grazing on
sludge—amended pastures and tissue lead levels, although the
significance of those levels for human health was not discussed.
Lead concentrations were higher in the kidney cortex of exposed
calves compared to control calves but not in cows. The study
found a significant (p<.05) increase in lead in cow blood and a
tendency (not significant) for lead to accumulate in calf
bones. There was no evidence of lead or other metal accumulation
in muscle tissue, the predominant source of meat for human
intake. Although it is not clear how the tissue analysis was
conducted, it appears possible that human exposure to lead in
muscle tissue could still occur as a result of the blood lead
observed in the study. Risk evaluation of the lead levels
observed would be necessary and advisable to determine if the
calves’ lead exposure was excessive.
Despite these equivocal finding, Professor Logan at Ohio
State University noted recently that from his review of the
USEPA’s draft risk assessments, direct animal consumption of
sludges appeared to be a significant route of human exposure and
one which might well provide a driving force behind new federal
regulations, particularly those governing land management
practices (Logan, 1986, personal communication). Lead was not
mentioned specifically in this conversation so the tJSEPA’s risk
assessment methodologies should be carefully evaluated in light
of the findings of the field studies discussed above. Studies
like that completed by investigators at Ohio State University are
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uncommon and provide an important touchstone for the more
theoretical risk assessment models.
E. Organic Chemicals in Municipal Sludges
Until recently, organic chemical contaminants of municipal
sludge have not received the research or regulatory attention
accorded their inorganic counterparts. Polychiorinated biphenyls
(PCBs) are the only class of organic chemicals currently covered
in federal and state land application regulations. Organic
priority pollutants have also been detected in studies evaluating
the quality of sludges from wastewater treatment facilities. The
ultimate fate of these compounds, in subsequent composting or
other stabilization processes and once they have been applied to
the land, has not been well characterized. The USEPA is
currently evaluating the public health and environmental risks
posed by various organic contaminants of municipal sludge. Other
investigators, both at EPA and at universities, are evaluating
aspects of the fate arid impact of specific organic chemicals in
municipal sludges. In the words of one investigator, however,
the detailed research and field investigations necessary to
document the land treatment behavior of specific organics has
only just begun “ (Overcash, 1983).
This section reviews the initial basis for the PCB
regulations, the work to date on organic chemicals in municipal
sludge, and the relevance of the recent work to concerns of the
northeast. Despite the limited amount of research available on
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the fate, public health , and evironmental impact of organic
chemicals in composted sludges applied to land, some conclusions
can be made. The more persistant, less biodegradable chemicals
pose the greatest potential hazards to public health and the
environment largely because they survive the treatment and any
subsequent stabilization processes in greater concentrations than
volatile or more readily degradable compounds.
A summary of the organic priority pollutants that have been
identified in municipal sludges appears in Table 15 (USEPA,
1985). These are the constituents that the USEPA selected to
screen initially for potential public health and environmental
impacts. The screening process ultimately identified 10
compounds, principally pesticides, for further detailed risk
assessment. Those compounds, their mean and 95th percentile
concentrations (mg/kg dry weight) are reported in Table 16. The
detailed risk assessments to be completed this year by the USEPA
will ultimately help determine whether these compounds warrant
regulatory action.
It is not clear that either the initial chemicals screened
or those identified for detailed assessment are representative of
significant contaminants of sludges in the northeast. Several of
the 10 compounds are pesticides which have been banned or
severely restricted for use in the United States
(aldrin/dieldrin, chlordane, heptachior, and DDT, in particular)
in recent years. Data on a wide range of organic chemicals are
generally not available on a regional basis and do not easily
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TABLE 15. ORGANIC CONTAMINANTS OF 1NICIPAL SLUDGE
EVALUATED BY USEPA (
Identified for Detailed Eliminated from Detailed
Evaluation Evaluation
Aldrirt/dieldrin Benzene
Benzo(a)pyrene Benzidine
Chloroane bis(2—ethyl hexyl) phthalate
DDT/DDE/DDD Benzo ( a ) anthracene
Heptachlor Carbon tetrachioride
Hexachlorobenzene Chloroform
Hexachiorobutadiene 3, 3—Dichlorobenzidine
Lindane Dichioromethane
PCBs 2, 4-Dichlorophenoxy
Toxaphene acetic acid
Dimethyl nitrosamine
Endrin
Malathion
Methyl ethyl ketone (2)
Pentachiorophenol
Phenanthrene
Phenol
TCDD (2)
TCDF (2)
Tetrachloroethylene
Trichloroethylene
2,4, 6—Trichiorophenol
Tricresyl phosphate
Vinyl chloride
(1) Source: U.S. EPA, 1985
(2) Insufficient data to evaluate
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TABLE 16. MEAN AND 95TH PERCENTILE SLUDGE
POLLUTANT CONCENTRATIONS (1)
Mean 95%(2)
mg/kg DW
Aldrin/die ldrin 0.07 0.81
Benzo(a)pyrene 0.14 1.94
Chiordane 3.2 12
DDT/DDE/DDD 0.28 0.93
Heptachior 0.07 0.09
Hexachlorobenzene 0.38 2.18
Hexachiorobutadiene 0.3 8
Lindane 0.11 0.22
PCBs 0.99 2.9
Toxaphene 7.88 10.79
(1) Source: U.S. EPA, 1985.
(2) 95% of observations are at or below this level.
permit comparisons between domestic and more industrial sludges
(Overcash, 1983).
Analytical data for effluents and/or sludges from 12
Massachusetts cities and towns, primarily located in the eastern
half of the state, were reviewed during this study. The purpose
of the review was to make a preliminary determination about the
presence of the 10 compounds listed in Table 16 in New England
sludges. Unfortunately, no determination could be made on the
basis of the data supplied. Of the 12 plants, only one analyzed
its sludge for organic priority pollutants. Three plants
analyzed for and reported detectable concentrations of lindane
and toxaphene but the analysis conducted was for EP Toxicity, a
measure of the leachability, rather than for total concentration
of each compound in sludge. Therefore, the results are not
comparable to the values reported for USEPA. No analyses were
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conducted for any of the other organic compounds identified by
the USEPA for detailed consideration.
The limitations of the data illustrate the difficulties
involved in assessing the regional need for regulation of
specific organic contaminants based on the results of national
sludge quality surveys. Since monitoring for the organic
priority pollutants is not required for all sewage treatment
plants, the necessary data are not available. Monitoring for
non—priority pollutants that may be of concern locally is even
less common. A prudent initial approach would be to review
carefully the results of the USEPA’s detailed risk assessment,
identify those compounds that pose the greatest health risks,
evaluate the likelihood that these compounds would appear in
local or regional sludges, and where necessary, conduct a
carefully targeted sampling program.
The only organic chemicals currently included in regulations
governing land application of sewage sludges are the
polychiorinated biphenyls. The reason for the limited coverage
of the regulations was not clear from review of regulations and
scientific literature or from conversations with state and
federal regulators.
As with inorganic contaminants, there are several known and
theoretical routes of human exposure to organic contaminants in
sludges applied to land. The USEPA identified four routes of
exposure to evaluate for the 10 chemicals: human consumption of
plants, human consumption of animal products contaminated either
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by animal ingestion of plants or direct animal ingestion of
sludge, and direct human ingestion of sludge (eg. by infants or
children) (USEPA, 1985). Some recent research findings on the
significance of these routes follow.
Factors governing the uptake of organic chemicals by plants
are not very well understood. Overcash (1981,1983) has conducted
extensive reviews of the scientific literature on the fate of
organic chemials applied to land. In his 1983 paper he concluded
that, although a number of studies have been conducted on
individual chemicals, no good mechanisms for predicting the level
of chemical uptake in plants currently exist. The relationship
is highly soil—, chemical—, and plant—specific.
Investigators at the USEPA in Cinncinati are currently
evaluating plant uptake of organic chemicals in sludge applied to
land. They are evaluating the compounds that are most frequently
detected in the highest concentrations in sludges such as the
phthalate acid esters (di—n—butyl and bis—2—ethylhexyl
phthalates) and polycyclic aromatic hydrocarbons (eg. anthracene,
benzo(a)pyrene), p—dichlorobertzene, etc. (Ryan, 1986, personal
communication). Although some of these compounds were included
in the original list of chemicals to undergo screening, none of
them appeared in the list selected for detailed risk
assessment. Nonetheless, they are chemicals which are also
relatively persistant and difficult to biodegrade.
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Some of the preliminary conclusions reached by the
investigators at the USEPA are that most organic chemicals do not
partition into plant tissues with the exception of some
pesticides. Furthermore, the chemicals must typically be applied
in concentrations orders of magnitudes higher than concentrations
normally detected in sludges (Ryan, 1986, personal
communication). These findings appear to support the preliminary
screening results published by the USEPA (1985).
As for metals found in sludges, direct ingestion of sludge
by animals appears to be one of the most important ways in which
organic contaminants of sludges can be transmitted via the food
chain to humans. Sludges on forages can contribute 15—30% of the
total weight on a dry weight basis immediately following
application. This sludge content may be reduced to 2 to 5% where
waiting periods are imposed before harvest. Animals have been
reported to ingest from 1 to 8% sludge in their diet when grazing
from pastures (Chaney, Smith, Baker, et. al. (1986).
The current tJSEPA regulations for PCBs reflect concern about
the importance of direct ingestion of sludge on forages as a
route of human exposure. While it is unclear how the 10 mg/kg
limit was derived, the regulations require that “ solid waste
containing concentrations of PCBs equal to or greater that 10
mg/kg (dry weight) is incorporated into the soil when applied to
land used for producing animal feed, including pasture crops for
animals raised for milk” (USEPA, 1979). The 10 mg/kg limit
appears to be based on the final anticipated concentrations of
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PCBs in animal feed or in milk since the requirement can be
waived if the concentrations in feed and milk do not exceed 0.2
mg/kg (actual weight) and 1.5 mg/kg (fat basis) respectively.
However, Hornick et al. (1984) state that the 10 mg/kg of PCBs is
based on an assumption that “carrots receive appropriate
processing, including scrubbing and peeling”.
The USEPA is evaluating ground and surface water contamina-
tion as routes of human exposure to organic chemicals from
sludges. Little research has been done in this area. However,
two investigators have indicated that leaching does not appear to
be a major concern. Overcash (1983) wrote that leaching of
organics is “insignificant if;
1. the municipal effluent or sludge land treatment occurs
at normal [ undefined application rates,
2. a reasonable drainage and cyclic establishment of
sustained aerobic soil conditions occur, and
3. groundwater remains deeper than 1—2 feet from the soil
surface.”
Leaching has not been reported for such Itreasonable “ conditions.
The exceptions to these general observations might be sandy
or gravel conditions which allow rapid infiltration or conditions
which allow rapid runoff (Overcash, 1983). Ryan ( 1986, personal
communication) noted that the solubility and thus leachability of
organics is positively correlated with the ability to be
biodegraded. Since concentrations of organic chemicals typically
found in sludge are relatively low, biodegradation can
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successfully compete with leaching for the fate of some chemicals
applied to land in municipal sludges.
Several research objectives need to be met in order to
understand better the possible impact of the land application of
organic chemicals in sludges on human health (Overcash, 1983)
These objectives include:
• the relationship between the level of a contaminant in
vegetation and the annual human intake it represents
must be established to estimate human health impact
• the rates of decomposition of organic chemical occurring
in sludges must be understood better to verify or
correct data collected on pure compounds
• non—priority pollutants detected in sewage sludges need
to be evaluated in terms of their potential human or
enviromental impact and added to the priority pollutant
list if appropriate.
The first of these objectives may begin to be met by the detailed
risk assessment methodologies currently under development, but
the latter two are areas for ongoing research.
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F. Pathogens in Municipal Sludge
The purpose of this section is to assess the public
health and environmental risks associated with land
application of compost that has undergone processes to
significantly reduce pathogens (PSRP) and processes to
further reduce pathogens (PFRP). The review provides a basis
for assessing the likelihood of surface or ground water
contamination from runoff or leachate of compost—amended
soils, and the likelihood of animal or human infection from
applications of sludge between hay crops that has undergone
only PSRP. The scope of this project limited the assessment
to composting as the only form of PSRP or PFRP evaluated.
The approach taken to assess the environmental and
health risks associated with compost—amended soils included:
• Identification of pathogens of most concern in primary
and secondary treated municipal wastewater sludge, their
densities, animal or human hosts
• Assessment of the effectiveness of composting by PSRP
and PFRP. What pathogens found during and after
composting are a problem?
• Evaluation of the environmental fate of surviving
pathogens in compost applied to land. How long will
they survive in soil, water, and on plants?
• Identification of the routes of animal and human
exposure to pathogens in compost amended soils——direct
ingestion, skin contact, and food and water
contamination. How likely is infection via these
routes? What do epidemologic studies addressing the
health risks of compost—amended soils indicate about the
risks associated with land application programs?
The following sections will address each issue.
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Pathogens in Sewage Sludge: Overview
This section will discuss the pathogens of most concern in
primary and secondary treated municipal wastewater sludge. It
reviews the occurrence, abundance, and significance of pathogens
in sewage sludge before evaluating the effectiveness of
composting and residual risk associated with land application of
composted sludge.
Pathogens found in sewage sludge can be divided into three
groups: bacteria, viruses, and parasites. A fourth group of
pathogens, fungi, proliferate during the composting process. The
significant pathogens from each group are discussed below.
Bacteria . There appears to be a general concensus among
contributors to the literature that the bacterial pathogens of
most concern to human health are those listed in Table 17
(Venosa, 1985). Many have important non—human reservoirs as
well. The most important bacteria are the enteric bacteria,
which originate in the human intestine and are discharged to
wastewater through urine and feces of infected individuals.
These pathogens have an affinity for the solid component of
wastewater that comprises sludge.
Table 18 summarizes the average densities of indicator
organisms and pathogens in primary and secondary treated
wastewater sludge. The densities reported for fecal indicator
bacteria range from io 6 to io8 per gram dry weight and for
pathogenic bacteria 101 to io per gram dry weight. Salmonella
and Shigella spp., are the most common bacterial pathogens in
municipal wastewater (Venosa, 1985).
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Organism
TABLE 17. BACTERIAL PATHOGENS IN SLUDGE AND
THEIR ASSOCIATED DISEASES
Disease
Source: Venosa, 1985.
TABLE 18.
DENSITY OF BACTERIA IN RAW SLUDGES
(AVERAGE
GEOMETRIC MEAN OF ORGANISMS PER GRAM
DRY WEIGHT)
Organism Primary
Secondary
Total coliforms 1 x io8
7 x
Fecal coliforms 2 x 1O 7
8 x 106
Fecal Streptococci 9 x i0 5
2 x 106
Salmonella spp. 4 x io 2
Pseudomonas aeruginosa 3 x 10
9 x io 2
1 x io
Source: Venosa, 1985.
Variability in literature values of pathogen densities in
sludge is high. The concentrations of these pathogens in
wastewater vary with the incidence of disease in the conununity
and, for some organisms, with fluctuations in climate. Fecal
coliforms and fecal streptococci tend to be more constant than
other pathogens in sludge because they are inherent organisms of
the general population.
Campylobacter jejuni
Escherichia coli
(enteropathogenic strains)
Leptospira sp.
Salmonella .
Shigella spp.
Vibrio cholerae
Yersinia spp.
Gastroenteritis
Gastroenteritis
Leptospirosis, infectious
jaundice
Gastroenteritis, enteric
fever
Acute dysentery
Cholera
Yersiniosis, gastroenteritis
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Another factor is the variability in methodologies used to
quantify the bacteria levels. Standardization of the quantitive
and qualitive techniques for analyses of bacteria will help
reduce the variability of data and ensure better interpretation
of the meaning of the results (Venosa 1985).
Viruses . More than 110 different virus types may be present
in raw sewage. Table 19 lists those that are generally of
greatest concern. These are viruses which infect either the
respiratory or gastorintestinal tracts of humans, which are
excreted in the feces of infected individuals, and/or which are
stable in the adverse environment found in wastewater treatment
and transport (Moore et. al., 1985).
Like bacteria, viruses are most concentrated in sludge
because of their affinity for solids. Literature values for the
concentration of viruses in primary sludge range from 2.1 to
TABLE 19. VIRUSES IN SEWAGE SLUDGE
Virus Associated Disease
Enteroviruses Gastroenteritis, heart
anomalies,
meningitis
Rotaviruses Gastroenteritis
Parvovirus—like agents Gastroenteritis
Adenoviruses Respiratory disease,
conjunctivitis
Hepatitis A virus Infectious hepatitis
Poliovirus Polio
Source: Taffel, 1978.
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1,429 plaque forming units per gram of total suspended solids.
Moore et al. (1985) reported anaerobically digested sludge which
contained a range of viruses from <0.1 to 148 plaque forming
units per gram of total suspended solids. Variability in
concentrations are dependent on population and climate as well as
on difficulties with available analytical methods.
Although enteroviruses appear to best define the relative
degree of viral contamination of sludges, problems with
analytical methods can mean that viruses of important public
health concern go unreported. Hepatitis A virus and rotavirus
require elaborate assay procedures, while others such as Norwalk
virus have not been grown outside the human host (Moore et. al.,
1985).
Parasites . Several parasitic organisms have been detected
in municipal sludges (Table 20). The parasites most commonly
found in domestic sludges are the ova (eggs) of Ascaris,
Trichuris and Toxocara species. Table 21 lists the percentage of
treatment plants in northern states which detected ova of these
parasites and the average number of ova found per kilogram of dry
weight of sludges destined for disposal.
Ascaris ova are considered to be the most resistant form of
any sewage pathogen (Little, 1985). Most wastewater treatment
processes are not effective in killing them (Little, 1985).
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TABLE 20 PARASITES IN SEWAGE SLUDGE
Pathogen Disease
Protozoa
Entamoeba histolytica Amoebic dysentery, amebiasis
Giardia lamblia Giardiasis
Balantidium coli Balantidiasis
Naegleria fowleri Meningoencephalitis
Acanthamoeba Meningoencephal it is
Helminths
NEMATODES
Ascaris lumbricoides Ascariasis
Ancylostoma duodenale Ancylostomiasis, hookworm
infection
Necator americanus Necatoriasis, hookworm
infection
Ancylostoma braziliense Cutaneous larva magrans
(cat hookworm)
Ancylostoma caninum Cutaneous larva migrans
(dog hookworm)
Enterobius vermicularis Enterobiasis
(pin worm)
Strongyloides stercoralis Strongyloidiasis
(threadworm)
Toxocara cati Visceral larva migrans
(cat roundworm)
Toxocara canis Viscera larva migrans
(dog roundworm)
Trichuris trichura Trichuriasis
(whipworm)
CESTODES
Taenia saginata Taeniasis
(beef tapeworm)
Taenia solium Taeniasis
(pork tapeworm)
Hymenolepis Nana Taeniasis
(dwarf tapeworm)
Echinococcus Granulosus Unilocular enchinococcosis
Echinococcus Multilocularis Alveolar hydatid disease
Source: Taffel, 1978.
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TABLE 21 PERCENTAGE OF FINAL SLUDGE SAMPLES NORTHERN STATES
VIABLE EGGS OF ASCARIS, TRICHURIS, TRICHIURA ,
T. VULPIS AND TOXACARA , AND MEAN NUMBERS OF EGGS FOUND
Parasite
Eggs
% of Samples
Containing Eggs
Northern States
N = 143
Mean No.
Kg Dry
Eggs!
Wt.
Ascaris
P. trichiura
48%
22%
38%
5%
782
107
170
143
T. vulpis
Toxocara
Source: Little, 1985
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Cysts of protozoa are occasionally recovered from untreated
sludges, however, they are rarely foui1d in treated sludges. Due
to their low specific gravity, they do not settle rapidly and
primarily end up in the effluent discharge (Little, 1985).
The detection of parasites in sludge presents several
problems which make it difficult to determine the level of
parasite contamination of sludge. The developmental stages of
parasites (principally ova) do not multiply in cultures and are
typically present in low densities. Each cyst or egg has to be
identified morphologically by a microscope, a time consuming
procedure requiring a highly trained technician.
Pathogen Kill Effectiveness of PSRP/PFRP Standards
The purpose of this section is to compare the pathogen kill
effectiveness of composting by processes to significantly reduce
pathogens and further reduce pathogens (PSRP/PFRP) in order to
evaluate the health or environmental risks from pathogens that
may be associated with land application of composted sludge.
Within the limits of this research, no study was found
specifically comparing PSRP and PRFP pathogen kill effective-
ness. In most of the studies reviewed (i.e., Venosa (1985),
Passman (1978), Reimers et al. (1985), Little (1985), Moore et
al. (1985)), where composting was mentioned, no distinction was
made between PSRP and PFRP conditions. The only study where it
was clear that PFRP conditions were met was in the two step
windrow system described by Hay et al. (1985).
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Destruction of viruses, protozan cysts and helminth ova
means irreversible elimination of these public health risks
unless more viruses, cysts, or eggs are introduced to the fin-
ished compost. In contrast, a small number of surviving bacteria
can proliferate in the rich organic matrix of finished compost if
post-composting conditions favor regrowth. Also, composting
itself promotes proliferation of many thermophilic fungi such as
Aspergillus fumigatus , actinomycetes, and mucorales.
The definitions of composting for PSRP and PFRP are given in
Appendix B in Volume II of this report. The key difference be-
tween the two levels of pathogen reduction are temperature and
time.
Processes to significantly reduce pathogens including the
in—vessel, static aerated pile, or windrow composting methods,
require the sludge to be maintained at minimum operating
conditions of 40°C for five days. For only four hours during
this period, the temperature must exceed 55°C.
Processes to further reduce pathogens require periods at
higher temperatures. Using the in—vessel or the static aerated
pile composting methods, the sludge must be maintained at
operating conditions of 55°C or greater for three days. When
windrow composting method is used, the sludge must attain a
temperature of 55°C or greater for at least 15 days during the
composting period.
For a sludge treatment process to qualify as a process to
significantly reduce pathogens, it must produce a reduction in
pathogens at least equivalent to that obtained by good anaerobic
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digestion (Venosa, 1985). This definition is based on the
observation that agricultural use of anaerobically digested
sludge as a fertilizer has been practiced for many years with no
evidence that the practice has caused illness, (Venosa, 1985).
The scientific information related to the survival and transport
of pathogens in sludge—amended soils was not incorporated.
None of the papers reviewed for this report defined the
basis for PFRP requirements, although it appears that they were
developed in recognition of the limited pathogen kill
effectiveness of PSRP.
Several factors affect pathogen survival during treatment
and their final concentration in composted sludge: temperature,
shielding by organic matter, and regrowth. Fungi present a
separate problem since they can proliferate during as well as
after the composting process.
In composting, heat is the primary factor contributing to
pathogen inactivation (Passman, 1978), but the heat resistance of
organisms is highly variable. The D—values listed in Table 22,
the time at given temperature required for a 10—fold reduction in
population, illustrates this variability. Some organisms, such
as bacteriophages, require several times longer periods at 55°C
to be inactivated than other organisms. The time for
bacteriophage, 4 hours and 27 minutes, is slightly longer than
the 4 hours at which sludge would be held at 55°C in PSRP. These
D—values are only a rough indicator of resistance since they were
obtained from pure cultures in liquid media under laboratory
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TABLE 22. TIME REQUIRED FOR A 10-FOLD POPULATION
REDUCTION OF VARIOUS MICROORGANISMS BY HEAT, D-VALUE.
D—Value at
ORGANI SM
55°C 60°C
Minutes
Adenovirus, 12 11.0 0.17
Ascaris ova _.(b) 1.3
Poliovirus, type 1 32.0 19.0
Hystolytica cysts 44.0 25.0
Salmonella 80.0 7.5
Coliforms 2.0
Staphiococci 3.3
Streptococci 15.0
Bacteriophage, f2 267.0 47.0
Sources: Hornick et al., 1984 and Burge et al., 1977
(a) D—Value: time necesary at a given temperature to cause a 10—
fold reduction in the number of organisms.
(b) ———— Dash indicates no value reported.
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conditions. Naturally occurring populations tend to be hardier
and more likely to persist under treatment conditions (Passman
1978).
Despite their limitations, the D-values reported here can be
used to illustrate the relative effectiveness of PSRP and PFRP.
Table 23 presents the reduction factors for various microorganism
calculated on the basis of their D—values and the time required
at 55°C for PSRP and PFRP. Table 24 presents the density of
organisms (per gram dry weight) in sludge estimated by multiply-
ing the reduction factors by reported initial concentrations of
various microorganisms in primary and secondary sludge. As Table
24 indicates, PFRP reduce organisms by a much greater factor than
PSRP. PSRP (55°C at 240 minutes or 4 hours) only reduces the
number of bacteriophage to 1 x io organisnt/gdw whereas PFRP
(55°C at 4320 minutes or 3 days) reduces the number of
bacteriophage to 1.3 x 10 per gdw.
In practice, a number of factors besides heat influence the
overall effectiveness of PSRP and PFRP at pathogen reduction.
Studies evaluating the effectiveness of composting and the
factors influencing survival for bacteria, viruses, parasites,
and fungi are discussed below.
Bacteria . Several authors have demonstrated that pathogenic
bacteria can be virtually eliminated during composting if aerobic
conditions and temperatures above 60°C can be maintained for
prolonged periods (Hay et al., 1985; Venosa, 1985). However,
even when populations are reduced to undetectable levels a
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TABLE 23. PATHOGEN REDUCTION FACTORS FOR
PSRP AND PFRP USING D-VALUES @ 550 C
Organism
D—Va lue
@ 55°C
PSRP
240 mm
(4 hours)
PFRP
4320 mm
(3 days)
Adenovirus
11.0
lx lO 22
1x10 340
Poliovirus
type 1
32.0
1x10 8
lx1O 30
Hystolytica
cysts
44.0
lx lO 6
1x10 98
Salmonella
80.0
1x 10 3
1x10 54
Bacteriophage f2
267.0
lxl0
lxi0 - 6
Sources: Hornick et al., 1984 and Burge et al., 1977.
(a) D—Value: Time necessary at given temperature to cause a 10—
fold reduction in the number of organisms.
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TABLE 24. ESTIMATED REDUCTION IN PATHOGENS POPULATION
AFTER COMPOSTING BY PSRP AND PFRP
USING D-VALUES @ 55°C
Initial Density
Organism
in Raw Sludge
(per gram
dry weight(a)
Projected Density
in Compost following:(b)
PSRP PFRP
Adenovirus
3.9x10 2 PFU(C)
3.9x10 2 ° PFU 3.9x10 391
PFU
Po].iovirus
type 1
3.9x10 2 PFU
3.9x10 6 PFU 3.9xl0 32 PFU
Hystolytica
cysts
2.lx].0 2 agm(d)
2.10x10 4 agm 2.10x10 96
agm
Salmonella
8.8x10— 2 agm
0.88 agm 8.8xl0 52 agm
Bacteriophage f2
l.3x10 5 agm
l.0x10 4 agm 1.3x10 11 agm
(a) Source: Hornick et al., 1984; Burge et al., 1977; Grasso et
al., 1985; and Ahisrom et al., 1985.
(b) Calculated using reduction factors presented in table 23.
(C) PFU — Plaque forming units.
(d) agm — Average geometric mean.
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sufficient residual population may persist to repopulate the
composted sludge once temperatures return to ambient levels if
the moisture content remains sufficiently high.
Hay et al., (1985) studied bacteria reduction in a two step
windrow composting system which met PFRP requirements. He
demonstrated a reduction of Salmonella sp. from 1.4 x most
probable number per gram dry weight (MPN gdw) at the start of
step 1 to <.2 MPN/gdw at the end of Step 2. The recommended
limit for Salmonella sp. in finished compost is < 1 MPN/gdw (Hay
et al, 1985).
Results from studies reported by Hay et al. (1985) suggest
that bacterial regrowth is minimal or non—existant in finished
compost that has been properly composted. One study monitored
regrowth of finished compost in 41 plastic bags stored at 35°C
and in 41 flower pots containing a mixture of compost and soil
that were stored out doors over 4 week periods. Most of the
compost samples that were well composted initially contained no
detectable Salmonella sp. and showed no regrowth.
Regrowth can occur if sufficient numbers of bacteria remain
after composting or are reintroduced. Venosa (1985) reported a
study where composted sludge was inoculated with Salmonella
enteritidis . After two days of incubation, the bacterial counts
were greater than 10 9 /g. Hay et al, (1985) cites evidence that
under certain conditions, Salmonella sp. regrowth can be very
rapid so that ingestion of a small amount of compost may result
in an infective dose.
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Factors which increase the likelihood of regrowth include
cross—contamination by airborne particulates from untreated
sludge entering the treatment plant, by contaminated equipment
(especially in small systems with limited equipment), or by
naturally occuring sources. The characteristics of the compost
can also play a factor in bacterial regrowth. Reimers et al.
(1985) reported that biological activity of Salmonella sp. is
fostered at a pH between 5.5 to 9, temperature between 10°C to
40°C, and a moisture content greater than 20%. Proper storage of
composted materials is extremely important to avoid
recontamination or regrowth. Monitoring for regrowth before
distribution to the public is also strongly advised.
Viruses . Limited data were available on the survival of
viruses in composting. Two studies reviewed indicated that well
managed compost systems can be effective at inactivating viruses.
According to Hay et al. (1985), typical density values of viruses
in a well managed windrow operation are less than .05 lU per gram
dry weight. The recommended concentration of viruses is .1 IU
[ ItJ not defined] per gram dry weight. (Hay et at., 1985).
Passman (1978) reported a study where polio virus type I was
added at a concentration of 580 TCID (tissue culture in dose) per
10 grams of sludge to an active compost pile (temperature 55°C to
60°C). Within one hour, virions could no longer be detected.
Passman (1978) reported a second study where sludge was seeded
with the bacteriophage f—2 at an initial concentration of 106
plaque forming units (PFtJ) per gram dry weight. The f—2
bacteriophages persisted for greater than 70 days in compost
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windrows, but were inactivated within 14 days in forced aeration
compost piles (Passman, 1978).
Adsorption of viruses onto particles may afford some
protection against virus inactivation. Other factors contributing
to the survival of a virus include: relative humidity, ionic
conditions, pH and particle aggregation. For example, at low
relative humidity, poliovirus I inactivation is greatly
accelerated.
Parasites . Most research and monitoring efforts have
depended on Ascaris lumbricoides persistance as the indicator of
protozoans and helminth survival during sewage treatment. The
general concensus is that A. lumbricoides is the most resistant
parasite in this group. Protozoan cysts probably do not survive
composting (Passman, 1978) although very little data are
available to support this conclusion. Field experiments must be
performed to demonstrate that this conclusion is, in fact, valid.
Temperature is the primary factor affecting survival of
helminths. Ascaris lumbricoides are much more resistant to low
temperature inactivation than high temperature. Passman (1978)
cited the threshold temperature for helminth ova destruction to
be 51°C. Below this threshold, ova may survive long periods of
time. PSRP for composting require temperatures of 550 for only
four hours.
The two step windrow process (PFRP) studied by Hay et al.
(1985) reduced the concentration of ova from 0.8 ova per gram dry
weight before Step 1 to <0.4 ova per gram dry weight at the end
of Step 2. Hay et al. (1985) reports the recommended limit of
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ova in compost to be 0.2—0.5 ova per gram dry weight. Thus, even
if PFRP conditions are achieved, there is a possibility that
helminth ova may be introduced into the soil in small numbers.
Fungi . Fungi pose a different type of problem than other
pathogens because they are common in nature and thrive under some
of the composting conditions intended to destroy their bacterial,
viral and, parasitic counterparts.
The fungi found in compost are ubiquitous in nature
(Passman, 1978). Passman (1978) reported the following thermo—
philic species to predominate in a municipal waste compost system
in Gainsville, Florida; Asperigillus fumigatus, Chaetomlum
Thermophile, Humicola lanuginosa, Mucor pusillus, Thermoascus
aurantious , and Torula thermophile . Some of these species have
also been isolated from self—heated industrial woodchip piles and
surtheated soils.
A. fumigatus is one of the most prevalent fungi in municipal
sludge compost during the period when compost temperatures range
from 50 to 60°C (Passman, 1978). The fungus thrives in a variety
of substrates, including stored hay or grain, decaying vegetation
and, soil (Clark et al. 1984). Passman (1978) reported a study
where compost produced from a forced aeration facility was moni-
tored for A. fumigatus . He noted that A. fumigatus in sludge,
wood chips and compost were comparable to concentrations in pot-
ting soils, manures and mulches. However, the concentration of
A. fumigatus in air surrounding the compost facility was several
orders of magnitude higher than that surrounding a control site.
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Hay et al. (1985) reported that the two step windrow compost
system designed to inhibit enteric pathogens should also
inactivate A. fumigatus . However, they reported that limited
research had been conducted on the survival of A. fumigatus
during composting. Taken together, these studies indicate that
A. fumigatus and possibly other thermophilic organisms may be a
problem both during and after composting. Further evaluation of
the public health impact of these organisms in composted sludge
applied to land is necessary.
Fate of Pathogens in Compost Once Applied to Land
The previous section showed that pathogens are likely to
remain in compost in some number after PSRP. Compost which has
undergone PFRP is more likely to be pathogens—free but PFRP is
not routinely required or used.
This section will attempt to assess the fate of bacteria,
viruses, parasites, and fungi in the environment if they survive
the composting process, or if regrowth or recontamination
occurs. The purpose of this analysis is to determine how well
pathogens survive once applied to soils in order to assess the
risks to domestic animal and public health.
Table 25 presents survival times of pathogens on plants and
soils. Many pathogens have been reported to survive for longer
than 1 month in soil and on plants. Salmonella have been
reported to survive up to 280 days on soil and 42 days on grass.
Ascaris ova has been reported to survive up to 7 years in soil
and 35 days on vegetables and fruits.
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TABLE 25. SURVIVAL OF PATHOGENS ON PLANTS AND IN SOIL
SURVIVAL TIME
ORGANISM PLANT SURFACE SOIL SURFACE
Coliforms grass and clover 6—34 days 38 days
vegetables 35 days
Streptococci 35—63 days
Feca]. streptococci 26—77 days
Sa lmonellae grass and clover 12—42 days 15—280 days
vegetables & fruits 3—49 days
Salmonella typhi vegetables 1—68 days 1—120 days
SLtigel] .ae on grass (raw sewage) 42 days
vegetables 2-10 days
Mycobacterium 10—49 days 90—450 days
Tubercie bacilli grass 180 days
Vibrio cholerae vegetables & fruits 1—29 days
Erysipelothrix 21 days
Leptospira 15—43 days
Entamoebia
histolytica cysts vegetables 1—3 days 6—8 days
Enteroviruses vegetables 4—6 days 8 days
Poliovirus
Ascaris ova vegetables & fruits 27—35 days up to 7 years
Hookworm larvae 42 days
Liver fluke cysts in dry hay few weeks
in improperly dried hay over a year
Source: Surge et a].., 1978; Hunt, 1985 and Taffel 1978.
-------
Bacteria. Many factors affect the survival of bacteria in
soil. They include: genetic and physiological characteristics
of the bacterium, the physiochemical characteristics of the soil,
atmospheric conditions (i.e., moisture, temperature, and exposure
to sunlight), the mode of application to the soil, biological
interactions among microbes in the compost and compost—soil
environments, and host—parasite relationships. Survival times of
bacteria increase with greater moisture, moisture capacity of the
soil and organic matter. Survival times decrease with greater
exposure to sunlight, lower pH, increased competition, antagonism
and predation. Venosa (1985) remarked that enteric bacteria
applied to sterilized soil survive longer than those applied to
unsterilized soil.
Passman (1978) reported moisture to be the primary factor
controlling Salmonella typhi survival in soils. He also reported
a study stating that pathogen survival was directly related to
the organic matter in soils. No study was found addressing the
question of pathogen persistance in compost—amended soil.
Except during heavy rain or snowmelt, bacteria tend to
adsorb to and be entrained in the upper few centimeters of the
soil. Once in the soil, pathogenic bacteria may persist for
periods ranging from hours to years depending on the various
environmental factors listed above.
Virus. Temperature and moisture content are probably the
most important factors limiting virus survival in soils. Button
et al. (1984) observed that viruses could survive up to 170 days
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in soil at 3° to 10°C and that survival was higher at 3° to 10°C
than at 18° to 23°C. Viruses survived no more than 15 to 25 days
in air—dried soil compared to 60 to 90 days in samples with
10 percent moisture (Bitton and Gerba et a].. 1984). Sunlight at
the soil surface is detrimental but its role is minor in
comparison to other environmental factors.
The characteristics of soil also influence the survival of
viruses. A study reported by Bitton and Gerba (1984) showed that
virus survival correlated with the extent of virus adsorption to
soil, soil saturation, pH, and exchangeable aluminum. Biological
factors may also play a role in virus inactivation in soil, but
no clear trend emerged from the literature.
Helminths. Since most of the processes used for PSRP will
not adequately reduce the number of viable helminth ova (Little,
1985) some ova inevitably make it into compost—amended soils.
The ova of Ascaris are considered to be the most resistant form
of any sewage pathogen. tinder some conditions these eggs may
survive in soil for several years. Little (1985) reported a
study where eggs of Ascaris that were still infective for animals
were recovered on experimental soil plots after 14 years.
Another study reported Ascaris eggs to be infective in garden
soil in Germany for 5 to 7 years.
Once applied to land, solar irradiation becomes a signifi-
cant factor operating against ovum persistance. Exposure to
sunlight and dessication account for reduced helminth ova
survival time on vegetable surfaces compared to those in feces
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or in soil. However, survival on crops such as lettuce, which
have short growing seasons, might be sufficient to allow
persistence through harvest (Passman, 1978).
The persistence of some parasite ova calls into question
some of EPA’S regulations governing grazing of animals on lands
which have received sludges treated by PSRP. The USEPA (1979)
requires only 1 month between application of sludges which have
undergone PSRP and grazing of food chain animals. Little (1985)
cited a study where grass land was treated with sludge containing
ova of P. saginata . Calves which were allowed to graze on
pastures 9 to 10 weeks after sludge was applied became infected
with P. saginata . However, when tested 17 to 18 weeks after
sludge application, the pasture was no longer infective to
calves.
Fungi . A. fumigatus and other fungi are natural soil
microbes. No specific studies indicating fate of fungi in
compost amended soil were found.
Routes of Animal and Human Exposure to Pathogens in Sludge—
Amended Soils
This section integrates the findings of earlier sections
into an assessment of the possible routes of human and animal
exposure to various pathogens and the likelihood of infection and
disease. The assessment attempts to account for the original
pathogen content of the compost and for the ability of the
pathogens to survive, proliferate, and be transported in the
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environment. Epidemologic studies of human exposure to composted
sludge either in compost facilities or on farms receiving
composted sludges are reviewed.
Comparisons of PSRP to PFRP are by necessity largely
theoretical. Processes to further reduce pathogens are not
widely used. Therefore, this study has relied on the theoretical
D—value discussed earlier to illustrate theoretical differences
in the pathogen—kill effectiveness of PSRP and PFRP. All the
caveats appied to the earlier discussion apply to this risk
evaluation as well.
As elsewhere, theory and practice do not always agree. In
theory, much higher concentrations of pathogens remain after PSRP
than PFRP. However, field studies and epidemologic studies have
not detected the level of infection and disease that might be
expected despite years of land application of sludges that have
undergone only PSRP. These factors have led some investigators
to comment that PFRP are unnecessary for general agricultural use
of sludge and that proper management practices —— loading rates,
grazing restrictions, slopes, buffer zones, etc. —— provide
adequate level of protection (Logan, 1986, personal
communication). PFRP is probably still advisable for sale/give
away programs to the general public where children may be at risk
of ingesting small quantities of compost (Chaney, 1986, personal
communication).
Several potential routes of exposure are discussed below:
inhalation, skin contact/penetration, direct ingestion (human and
animal), and ingestion of water contaminated by runoff or
leachate.
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Inhalation . Very little information was found on inhalation
exposures to pathogens except for aspergillus fumigatus exposures
to compost facility workers. General population exposures to
airborne pathogens resulting from land application of compost was
addressed only indirectly in one epidemologic study reviewed.
The transmission of pathogenic fungi via inhalation is
considered to represent a potentially serious health threat
particularly to compost workers. Asperigillus fumigatus is the
fungus of greatest concern, although thermophilic mucorales and
actinomycetes are also known to be present in compost (Taffel,
1978). A. fumigatus spores can produce severe asthmatic
reactions in atopic (sensitized or allergic) individuals (Taffel,
1978). Individuals with pre—existent lung desease are
susceptible to colonizing aspergilli, which form fungus balls in
the lung, a condition known as aspergillosis. The small
percentage of inununo—suppressed individuals in the general
population are at greater risk of aspergillosis.
Clark et al. (1984) has suggested that fungal spores at the
compost site could have caused such disorders as burning eyes,
skin irritation, abnormal ear and nose conditions, and upper
respiratory tract colonization in exposed compost workers.
Clark et al. conducted an epidemiological study of
wastewater sludge composting facilities from 1979—1981. All
facilities studied were thermophilic aerated pile processes and
produced from 15 to 125 dry tons per day. The study included 388
compost and control workers divided into three exposure groups:
Group I — workers directly involved in composting; Group II —
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workers occasionally involved in composting or whose job
locations are within 100 meters of a composting facility;
Group III — workers not involved in composting and whose job
locations are greater than 100 meters from a facility. Health
monitoring included: physical exams and chest x—rays; nasal and
throat cultures; antibody testing to fungi, Legionella ,
histoplasma and endotoxin; iminunochemical testing; and routine
blood analysis. Clinical specimens (nose and throat cultures and
sera) and health questionnaires were collected eight times during
the study.
Clark et al., 1984 reported that non—respiratory symptoms
were more prevalent among the compost (Group I) and control
workers than intermediate (Group II) workers in November 1980 at
one plant. Symptoms of burning eyes occurred more in Group II
and Group I workers than in control groups for several plants
combined in November 1980. Skin irritation was somewhat higher
among Group I and Group II for combined worker groups in
September 1978, September 1980 and February 1981 (Clark et al.,
1984)
Acute and chronic eyes and nose inflammation, possibly
compost related, was found in 19% of Group I workers, 20% of
Group II workers and 5% in control workers. Abnormal skin
conditions occurred in 12% of the Group I workers, 21% of the
Group II workers and 0% in the control individuals. The
percentage of workers with positive cultures for A. fumigatus
were directly related to exposure: Group I workers (70%),
Group II (intermediate exposure) (20%), and controls (5%).
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Skin Contact/Penetration . Skin contact and penetration are
not a major route of animal or human exposure. Only a few of the
pathogens potentially found in composted sludge are able to cause
an infection by penetrating the skin. These include the human,
dog and cat hookworm and the human threadworm. However, neither
the human or dog and cat hookworm are very common in the U.S. and
the human threadworm is seldom detected in sewage sludges.
Furthermore, Taffel (1978) states there is no evidence to suggest
that the ova of these parasites are hardy enough to survive the
composting process and subsequently mature to the infective
stage.
Ingestion . The most direct route of human or animal
exposure is through ingestion of the compost. For both humans
and animals, ingestion or compost of compost—amended soil could
occur directly or through contamination of food products and
forages.
Active infection depends on the concentration of pathogen in
the compost and the dose required to cause infection in the
exposed individual (infective dose). Table 26 lists infective
doses for a few pathogens and the amount of compost that would
have to be ingested to achieve an infective dose. This table
suggests that a large amount of compost and even greater amounts
of compost—amended soil would theoretically need to be ingested
to cause an illness. For example, Taffel (1978) reported the
infective dose of Salmonella for a 9 month old to be 44
organisms. Under PSRP conditions (assuming no regrowth) and
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TABLE 26. AMOUNT OF COMPOST CONTAINING
INFECTIVE DOSE VIA INGESTION
Organism
Infective Dose(a)
Amount of Ingested
to Cause an
Compost Required
Infection(b)
PSRP
PFRP
Salmonellae
44 organisms in 9 mo.
old.
105_106 Healthy males.
50 gdw (C)
1.1 x io6 gdw
5.0 x io52
1.1 x io56
gdw
gdw
Poliovirus
1 PFU (d) in infants
2.6 x i0 5 gdw
2.6 x io131
gdw
2 PFIJ in adults
5.2 x io gdw
5.2 x io131
gdw
Entomoeba
iol_ia4 organisms
4.8 x i0 3 gdw
4.8 x iO
gdw
histolytica
produced infection
without illness
(a)gource. Taffel, 1978
(b)gdw - gram dry weight
(C)Based on concentrations of organisms estimated in Table 24.
(d)pFu — plaque forming units
-------
using the D—value to calculate the final density of Salmonella in
compost, a baby would have to eat the equivalent of 50 gdw of
compost to become infected. A healthy male would have to eat 1.1
x io6 gdw or 1100 kg (over a ton) of compost to become infected,
an unrealistic amount.
In cases where composting is insufficient or regrowth
occurs, the potential for infection increases. Apparent regrowth
of coliform and Salmonella bacteria has been observed by a number
of investigators (Taffel, 1978). Bacteria can exist below
detectable levels in compost but at sufficient levels to regrow.
The fact that compost is a nutritive medium, free of competition,
makes it ideal for possible regrowth. Finished compost should be
monitored for regrowth before distribution.
Contamination of human food products grown in compost—
amended soils is a legitimate concern. As Table 25 indicates,
several types of pathogens can survive in plant surfaces and in
soils for long periods of time. Taffel (1978) reported a study
where radishes grown in soil fertilized with typhoid—infected
stools contained typhoid bacteria after 37 days. Also, he stated
that bacteria were not observed to penetrate vegetable skins, but
were able to enter decaying or injured parts of vegetables, and
stay viable to up to 42 days. Entamoeba histolytica cysts have
been observed to last only three days in dry weather on lettuce
and tomatoes. If composting has not been effective, regrowth has
occurred, or inadequate time has elapsed between application of
compost and growth of produce for human consumption, the risk of
infection increases. No studies were found that evaluated the
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presence and persistance of pathogens in soils or produce where
compost that had undergone PSRP or PFRP was applied.
As has been previously discussed for toxic inorganic and
organic constituents of sludge, available evidence suggests that
direct domestic animal consumption of sludge adhered to forages
or directly from soils while grazing can be an important route of
exposure to pathogens.
While animal ingestion of sludges adhered to forages and
mixed in soils is clearly possible, few studies have examined the
actual risk of infection. A study recently completed by investi-
gators at Ohio State University has evaluated the incidence of
domestic animal infection related to land application of sludges
which had undergone PSRP (digestion). The study, discussed in
greater detail at the end of this section, found no evidence of
increased animal infection.
Water supply contamination from leachate and runoff . Con-
tamination of ground and surface water supplies is a potential
problem associated with land application of composted sludges.
It is a problem that can be mitigated by requiring a high degree
of pathogen destruction (i.e., PSRP), by proper siting and
application restrictions, or both. It is not clear from the
brief review of the literature conducted for this report that
sludges must undergo PFRP to ensure the safety of ground and
surface water supplies. Stabilization by PSRP combined with
sound land management practices should provide comparable
protection. An exception to this general conclusion may be found
for distribution and marketing or sale/giveaway programs where
application restrictions are harder to control or enforce.
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As discussed in the section on the environmental fate of
pathogens, several pathogenic organisms can survive for several
months in soils depending on site—specific conditions. However,
in order for infection to occur, the following conditions must be
met:
• the organisms must be able to move freely either over or
through the soil to the receiving water body
• the organisms must survive both in soil and in water and
maintain virulence
• the organism must survive any treatment applied to the
water to make it fit for drinking
• the organisms must be present in large enough numbers to
infect an individual when the water is ingested.
Taffel (1978) concluded that the likelihood that pathogenic
organisms already at low levels in compost will pass through soil
and water to arrive in drinking water supplies in sufficient
quantities to initiate an infection is exceedingly small.
In the literature reviewed, incidences of ground water
contamination by various pathogens was most frequently reported
but usually in the context of application of sewage effluents,
not stabilized sludges. Gerba (1983) cited two studies which
concluded that land disposal of digested sludge has shown little
impact on bacterial contamination of groundwater unless the
ground water table is too high and/or the soil is not well
drained. Gerba cited other studies with sludge—amended soil
which indicated that viruses are not easily elutriated even after
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rainfall events and pose minimal threat to groundwater. Both
bacteria and viruses tend to be bound by sludge organic matter
which then limits their movement in soils. By contrast,
bacterial and viral movement in soils following land application
of sewage effluents can be substantial.
Protozoans and helminth ova pose no threat to groundwater
primarily because their relatively large size restricts their
movement through soil (Gerba, 1983).
Transport of pathogens by runoff to surface water supplies
is theoretically of greater concern. Bacteria, viruses, and
parasites applied in composted sludges are likely to remain in
the top layers of soil. If erosion occurs as a result of poor
site selection and/or heavy rainfall, pathogenic organisms can be
washed along with particles into surface water. They can pose a
threat to water supplies used for swimming as well as for
drinking.
The likelihood of human infection via contamination of
public drinking water is quite low if the water supplies are
treated prior to distribution. Human infection is more likely
when the water supply or the swimming area goes untreated.
Similarly, animal infection is possible if animals receive water
from contaminated surface water supplies such as farm ponds.
Despite the probability of pathogen transport in runoff, no
studies were reported in the literature reviewed for this report
that found evidence of surface water contamination and subsequent
human infection. This gap does not necessarily indicate that
such contamination has never occurred but may suggest that it is
less of a problem than theory predicts.
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Ohio Farm Study . A three year prospective epidemologic
study was conducted on 47 farms receiving sludge annually and 46
control farms in three locations in Ohio (Brown, 1985). The
objectives of this study were to evaluate the health risks to
rural residents and their livestock resulting from sludge applied
to cropland and to define and demonstrate management practices
for application of sludge to farmlands. This study provides a
basis for evaluating the aggregate risk from all routes of
exposure discussed above.
Annual surface applications of liquid or dewatered
anaerobically or aerobically digested sludge were applied at 2 to
10 dry metric tons per hectare. Although not specifically
stated, the digestion process is believed to have met PSRP
requirements (Logan, 1986, Personal comntunication). Corn,
soybeans, hay, and wheat were the principal crops grown.
One hundred and sixty-four individuals participated from
farms receiving sludge and 130 individuals from control farms.
Monthly questionnaires on illness symptoms for individuals and
their animals were distributed to all families. Baseline blood
samples were taken before the first application of sludge and
every four months thereafter. Stool samples were collected every
four months and analyzed for bacteria, viruses and parasites.
Tuberculin testing was performed annually. Fecal samples from
cattle were examined for bacteria and parasites. Slaughtered
calves were tested for tuberculin and forage samples were
collected over a one month period for parasite analysis.
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There were no major differences in digestive or respiratory
illnesses reported between families from control farms and farms
which received sludge. It was concluded that exposure to sludge
did not increase the antibody titer. There were no positive
tests for tuberculin and hepatitis A. There was no significant
difference in the frequency with which viruses or parasites were
found in stool specimens. Salmonella was isolated from three
individuals on sludge farms and one on control farm.
There were no differences in the health of domestic animals
on control and sludge farms. Four control and two sludge farm
animals were positive for salmonellae. Tuberculin tests were
found negative on the slaughtered calves.
Ova of toxocara were found in five of 52 sludge samples
examined for parasites (Jakubowski, 1985) and one ascarid ovum
was detected in a forage sample collected 14 days after the
application of sludge.
There was no evidence of human or animal health effects
resulting from the application of sludge to farmland at the rates
applied (2 to 10 Mt/ha). However, other authors have noted that
the exposure of most of the participants on the sludge farm was
probably very low and that caution should be used when applying
these results to higher sludge application rates (Jakubowski,
1985).
The negative results of the studies reported to date and the
lack of outbreaks associated with wastewater and sludge treatment
and disposal activities may indicate that there is little or no
problem with infectious disease from this exposure However, the
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low exposure and small populations in the reported studies may
account for the lack of effect found (Jakubowski 1985).
One problem associated with prospective epidemiological
studies such as the one discussed above is that symptoms are
usually grouped into broad categories——respiratory,
gastrointestinal, etc., that are not necessarily specific to
sewage sludge. For example, influenza is not a sewage—borne
organism but can cause similar symptoms (fever, headache, etc.)
as some of the sludge—borne pathogens. Also, transmission of the
sludge pathogens is not limited to sludge as the sole exposure
source, since pathogens can be transmitted from person to person
in food and in water. Furthermore, Jakubowski (1985) states that
reporting of such subjective symptoms may be subject to recall
bias. Individuals can tend to under-report symptoms if
sufficient time elapses between onset and reporting of symptoms
or may over or under report symptoms in an erroneous effort to
assist the study. This could account for the lack of differences
seen between sludge and control farms.
A second problem is the difficulty in quantifying the
exposure received by the individuals. In the Ohio Farm Study,
the highest sludge exposure was estimated to be only 1.5 hours
per week and could account for the lack of health effects
observed. However, the limited time spent in contact with or
exposed to sludge is in itself an important result.
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The recommendations of experts on epidemiological studies
has been changing over the past 12 years. In 1973, at a workshop
held in Champaign, Illinois, a panel of public health experts
agreed that more studies should be conducted relating to land
application of sludge. In 1979, a World Health Organization
report indicated that current epidemiological techniques are not
sensitive enough to detect low—level transmission of viruses
through water (Jakubowski, 1985). A conference sponsored by
Commission of European Communities in May 1985 concluded that
prospective epidemiology studies of sludge exposed populations
should not now be conducted because of design, interpretation and
expense considerations (Jakubowski, 1985). Instead, the members
concluded that monitoring programs should be developed and
implemented and that more information on the health effects of
composted sludge products is needed.
Jakubowski (1985) therefore concluded that prospective
studies will not be the approach to assessing and quantifying
health risks related to sludge disposal due to a number of
reasons including: identification of exposed individuals,
quantifying the exposure rates, and extrapolating one site to
another for use in guidelines. This last factor is a problem
because there are different conditions affecting pathogen
transport and survival for each site.
Another approach to risk assessment is by mathematical
modeling. This approach is theoretically attractive because it
can be site specific but is hampered by the complexity of data
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necessary to calculate risks with a reasonable degree of
certainty. No specific model—based risk assessments were found
within the scope of this research. Jakubowski (1985) reported
that two models for health risk assessment of sludge disposal
were under development but no details were given.
G. Conclusions and Recommendations
This review of the scientific basis for the limits on toxic
and pathogenic constituents of municipal sludge supports several
conclusions about acceptable limits for inorganic and organic
contaminants of sludge, reasonable annual and cumulative maximum
application rates, and acceptable levels of stabilization among
others. Some conclusions emerged regarding the differences in
regulatory requirements that may be appropriate for general
public use in sale/give—away programs versus those acceptable for
more highly regulated uses on agricultural or dedicated lands.
The conclusions are presented in the same three broad groups
defined in the body of the report: inorganic contaminants
(cadmium and lead), organic chemical contaminants, and pathogenic
organisms.
The conclusions do not address all the issues confronting
land application of municipal sludges. They focus on the primary
issues raised in the scope of work. For example, the conclusions
address acceptable limits and application rates for specific
constituents but do not address site selection and land
management practices except in general terms. The
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recommendations, like the body of the report, focus on factors
which most influence human exposure rather than animal exposures
to toxic or pathogenic constituents in sludges.
An overriding recommendation from this report is that any
new regulatory initiatives regarding land application of sludges
in the northeast should incorporate a careful review of the risk
assessment methodologies and recommendations approaching
completion by the U.S. EPA, Office of Water Regulations and
Standards. While this study found strong scientific support for
some existing standards and guidelines, primarily those for
cadmium, the scientific bases for regulation of other metals and
organic compounds are generally incomplete. Studies of sludge
contaminant uptake by plants, the effect of soil chemistry or
other physical site characteristics on exposures to animals and
humans, and of other routes of animal or human exposure that
should be taken into account in setting regulations have not been
conducted for all of the contaminants that may ultimately warrant
regulation. The federal study attempts to bridge some of these
scientific gaps using risk assessment techniques and may
ultimately play a key role in the development of new regulations
for several other chemical contaminants besides those currently
regulated by federal and state agencies. This report did not
attempt to duplicate the federal effort and therefore recommends
that the results of the federal study be evaluated carefully for
use in regulation development for northeast states.
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Recommendations for Cadmium, Lead, and Organic Chemicals
Use of composted sludge by the general public. Table 27
summarizes two basic recommendations for regulation of cadmium
and lead: one governs acceptable limits and the other addresses
general labeling requirements.
This report recommends that the maximum allowable
concentration for cadmium in sludges or sludge products to be
applied to land should be 13 mg/kg dry weight. Although several
investigators and review papers commonly endorse 25 mg/kg DW
cadmium as an appropriate maximum level in “domestic” sludges
(USEPA, USFDA, USDA, 1981; Hornick et al., 1984; Penn. State,
1985), the scientific basis underlying this number was never
clearly stated.
Some of the most convincing recent evidence supporting the
safety of low metal sludges comes from work by Chaney et al.
(1982) which studied cadmium uptake in lettuce leaves from plots
receiving sludge. Lettuce has a strong tendency to accumulate
cadmium as do several other plants such as spinach, chard, turnip
and beet greens, and carrots (USEPA, USFDA, USDA, 1981). Plots
receiving sludges with 13.4 mg/kg cadmium showed no demonstrable
increase in lettuce leaf cadmium concentrations at application
rates up to 3 kg cadmium/ha. The difference in lettuce leaf
cadmium levels between lettuce grown on soils at pH 5.6 and 6.4
was negligible indicating that the bioavailability of cadmium is
restricted even at the low pH levels more typical of northeast
soils. Chaney et al. (1982) and Logan and Chaney (1983) suggest
but do not state that the bioavailability of cadmium at
concentrations of 25 mg/kg would be similarly low.
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Chaney’s work is particularly important because it appears
that previous arguments f r lower maximum acceptable levels of
cadmium in sludge were based on studies using cadmium salts added
to soils. Such studies predicted a linear increase in plant
cadmium content with increasing cumulative application rate
regardless of initial sludge concentration. Chaney’s work with
cadmium applied in sludges indicates that this relationship does
not hold. Other investigators suggest that chemical factors in
the sludge, expressed generally as the “sludge—specific cadmium
adsorption capacity”, limit cadmium’s bioavailability (Logan and
Chaney, 1983). Only at high cadmium level -— levels beyond 25
mg/kg —— is the sorption capacity of the sludge apparently
exceeded. The initial concentration of cadmium is subsequently a
strong predictor of available cadmium for long periods beyond the
initial sludge application.
TABLE 27. RECOMMENDATIONS FOR CADMIUM AND LEAD IN SLUDGE:
USE BY GENERAL PUBLIC
Cadmium Lead
Maximum Acceptable Levels 13—25 mg/kg DW 500 mg/kg DW
Labeling Requirements
1. Maximum acceptable level of sludge contaminant.
2. Recommended sludge application rate based on soil
conditioning requirements 10—20 Mt/ha — 50—100 lbs/250
sq ft.
3. Recommend washing of all fruits and vegetables grown on
sludge—amended soils.
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Two factors argue for setting cadmium limits below 25 mg/kg
DW. One is that if pH levels are not maintained at pH 6.5,
cadmium bioavailability increases slowly over time. If soils are
not treated, pH levels tend to revert to background levels which
in the northeast are considerably below 6.5. very few studies,
if any, have been able to evaluate cadmium mobilization over long
periods of time (e.g. 10 to 20 years). The second factor is that
disposal of municipal sludges will continue to be a problem for
the forseeable future. However, if maximum cadmium levels in
soils are adhered to by the general public as well as by
commercial agricultural users land application of sludges is a
finite disposal option. The lower concentration extends the
useful and safe life of land application as a disposal option for
municipal sludges. Despite the widespread support for 25 mg/kg
DW cadmium, support for a lower limit is growing. Chaney
suggested recently that a workgroup on metals in sludge are
likely to recommend 12.5 mg/kg DW cadmium.
There is much evidence, however, to suggest that the 2 mg/kg
cadmium specified in Federal and Massachusetts regulations is
unnecessarily stringent even for sludge used in giveaway
programs. The iJSEPA, USFDA, and USDA (1981), for instance, give
evidence that, depending on soil CEC, it would take 50 to 200
years to reach cumulative Cd limits when sludge containing
25 mg/Kg Cd was applied at agronomic rates. Hornick et al .
(1984) define a good quality sludge as containing no more than
25 mg/Kg cadmium. With the addition of bulking agents, this
concentration may be diluted in the compost. Hornick et al .
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document that even without control over soil pH, it is difficult
to exceed the maximum recommended application rate with a good
quality sludge because the amounts of sludge materials needed
would be enormous and economically impractical. Logan and Chaney
(1983) indicate that the bioavailability of cadmium in crops
grown on sludge—amended soil is considerably less than in crops
grown on soil with cadmium from non—sludge sources, because other
materials present in sludge interact with the cadmium to reduce
the amounts absorbed and retained by animals and humans. This
property of sludges suggests that severe cadmium problems in
humans such as itai—itai disease may not be possible with crops
grown with sludge amended soils.
Logan and Chaney (1983), as has been discussed in the
section on cadmium risks, listed the extremely conservative
assumptions used to set the 1979 (JSEPA standard of 2 mg/kg.
Since these regulations were promulgated, newer research findings
cited by Logan and Chaney (1983) and by Page, et al . (1986) give
strong indications that a limit of 2 mg/kg is unnecessarily
restrictive. Page et al . have shown that sludges containing up
to 15 mg/kg Cd do not result in appreciable cadmium uptake even
by the most sensitive crops, regardless of the amount applied,
and even in acidic soils. In addition, the danger to health from
eating crops that may have been contaminated with cadmium was
probably overestimated in the past. This assessment is based on
improved dietary analysis, consideration of the portion of the
diet that a person would eat from sludge—amended soils, and new
research on populations that have consumed high-cadmium foods for
long periods of time.
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Page et al . (1986) concluded that even under the worst-case
assumption that one third of the human diet would be from crops
grown on sludge—amended soils over a 50—year period, there would
be no adverse impacts on human health even if the soil pH was as
low as 5.7, the sludge cadmium level was as high as 200 mg/kg,
and 100 metric tons of sludge was applied per hectare. With a
sludge Cd level of 25 to 50 mg/kg, there would be no adverse
dietary impact even if over 220 metric tons per hectare of sludge
were applied, and the soil pH were as low as 5.0.
Finally, an unfavorable soil pH may be adjusted upward
simultaneously with sludge compost addition by requiring the
incorporation of calcuim carbonate to the compost. The State of
Maryland has proposed regulations which permit unlimited
distribution to the public of compost containing up to 12.5 mg/kg
cadmium and 10% calcium carbonate equivalent.
The basis for a maximum acceptable level of lead in sludges
is more uncertain. Logan and Chaney (1983) cited several studies
which collectively indicated that “individuals may absorb
excessive lead” from soils containing over 500 to 1000 mg/kg
DW. The maximum level of lead recommended by most studies is
1000 mg/kg although the public health basis for that number was
never explained. The USEPA, USFDA, and USDA (1981) recommended a
maximum final concentration of lead in soils to be 800 mg/kg.
Again, the public health basis for their recommendation was not
given.
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This report recommends that 500 mg/kg DW lead be the maximum
acceptable level for lead in sludges or sludge compost destined
for sale/give—away programs. This recommendation is based on the
assumption that children could ingest small amounts of sludge
containing lead at these levels and based on the studies cited by
Logan and Chaney (1983), could therefore, take in unacceptably
high levels of lead. In reality, sludges used in the home are
likely to be mixed in garden soils or potting soil thereby
reducing the overall level of lead in soils that a child may have
access to. This factor appears to add an additional margin of
safety to the 500 mg/kg lead recommended. However, there was no
opportunity to review the studies from which the 500 to 1000
mg/kg values were derived for this study, so definitive support
for the applicability of the values to sludge regulations cannot
be established at this time.
The US EPA is developing a risk assessment methodology to
evaluate direct human ingestion of sludges as a route of exposure
to lead. Their evaluation of that route of exposure, as well as
their evaluation of direct animal ingestion of sludges and
subsequent human exposure, should provide valuable insight into
the level of protection provided by current guidelines and
recommendations for lead. For this study, the decision was made
not to conduct the same risk assessment independently and to
evaluate the peer—reviewed US EPA’s methodology when it becomes
available.
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Insufficient data were available to evaluate the public
health basis for limits on organic chemicals in municipal sludges
intended for general public use. As discussed in the organic
chemicals section of the report, only 10 chemicals were
identified for detailed risk evaluation by the U.S. EPA (1985).
Of those, most are pesticides whose prevalence in northeast
sludges could not be determined on the basis of data available at
the completion of this report. Even if present, their public
health or environmental significance needs more evaluation before
levels in sludge can be recommended.
PCB5 are a possible exception although reports on the basis
for the 10 mg/kg PCBs recommended in U.S. EPA’s 1979 regulations
are inconsistent and unclear. Hornick et al. (1984) suggest that
the PCB limits are based on the levels remaining on carrots grown
in sludge—amended soils following washing and peeling. The 1979
regulations, however, cite contamination of milk as the basis for
the limits. Until further risk analysis becomes available, the 3
mg/kg PCBS recommended by the EJSEPA, (JSFDA, and USDA (1981) for
sludges applied to surface soils should be used as a limit for
PCBs in sludges for general public use.
Sludges packaged or otherwise designated for general public
use should clearly state the maximum metal and organic chemical
concentrations permitted and those detected in the sludge so that
individuals know the characteristics of the material they choose
to use.
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As an additional factor of safety, it is recommended that
sludges packaged or otherwise designated for general public use
carry recommendations that sludges be applied at what most
investigators describe as agronomic rates, 10 to 20 mt/ha. For
general public information, this translates into 50 to 100 lbs of
sludge (dry weight basis) for every 250 square feet of garden.
These are rates which provide good soil conditioning but do not
necessarily meet all the nitrogen or phosphate requirements of
the crops grown, assuming typical levels of 1.5 percent N and
1.5 percent P in sludge compost (Hornick et al., 1984).
Application of sludges at these rates help assure that even if
the sludge contains 25 mg/kg cadmium DW, the annual cumulative
cadmium application rate will not exceed 0.5 kg/ha, the maximum
level allowed for growing leafy vegetables (U.S. EPA, 1979).
Finally, it is recommended that any packaging or
instructions provided with sludge carry recommendations that any
vegetables grown in sludge—amended soils be carefully washed
before eating.
Controlled Land Application of Sludges
Recommendations for regulation of cadmium, lead, and organic
chemicals (PCBs) in sludges are summarized in Table 28. Brief
explanations for the basis for these recommendations appear
below.
Acceptable Limits . For reasons given in the section on
general public use of composted sludges, 25 mg/kg cadmium in
sludge provides an adequate level of public health protection
from cadmium taken up in vegetable tissues. The level of
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TABLE 28. RECOMMENDATIONS FOR CADMIUM AND LEAD
CONTROLLED APPL I CAT ION
Regulations
Cadmium Lead PCBs
Acceptable Limits
25 mg/kg DW 500 mg/kg 10 mg/kg injected
DW 3 mg/kg surface
Application Rates
a. Use federal rates for cadmium to
establish upper limit.
b. Incorporate strong recommendations
that sludge be used only at agronomic
rates 10—20 Mt/ha for most
agricultural uses.
Maximum Cumulative
Same as 500
Concentrations
current kg/ha
federal
regulations
Application
Restrictions
1. General
Never to growing crops — for direct human
consumption (i.e., only to soil).
Injection or incorporation recommended
even for forage crops to be harvested for
animals intended for human consumption.
2. Crops
Never for —— -—
growing
tobacco
3. Grazing
a. Three months minimum should be
Restrictions
required between application and
grazing by animals intended for human
consumption. Otherwise, one month
or
b. One month minimum. Use of animal
products (meat or dairy) restricted
for 3 to 8 months from onset of
grazing.
Background Metal
Yes Yes --
Monitoring at
Soil Required
a. Annual basis if
sludge applied
more than
once/year.
b. Before application
otherwise.
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protection is particularly safe if soils are maintained at the
required pH 6.5 and other siting restrictions are met. As
explained in the body of the report, the primary route of
exposure considered is uptake in plants which then become part of
the human diet. Other limits for cadmium may be justifiable if
risk analyses of other routes of exposure (i.e., direct animal
ingestion of sludge or direct human ingestion of sludge) appear
to contribute significantly to human dietary intake of cadmium.
For lead, 500 mg/kg—DW/l000 mg/kg is recommended as a
maximum acceptable level in sludge. The public health basis for
allowing 1000 mg/kg lead, the value recommended in several
guidelines is not clear (USEPA, USFDA, USDA, 1981; Hornick et
al., 1984; Penn. State, 1985). Nor does it seem to be necessary
on the basis of reported mean concentrations of lead in sludge
(see Table 13). The recommended maximum concentration of lead in
sludge needs to be evaluated in light of the comprehensive risk
analysis under way by the U.S. EPA (1985).
Application Rates . The pH and CEC dependent cadmium appli-
cation rates provide protection of public health with an adequate
margin of safety. As discussed in the section on cadmium, these
rates were in part based on the “acid garden” scenario, a conser-
vative, worst case scenario. Therefore, although the federal
cadmium application rates are directed primarily to large—scale
agricultural users, they were designed to protect against
conditions of low pH in private gardens where individuals grow a
large percentage of their vegetables. Given the assumptions
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incorporated into the “acid garden” scenario, the federal
regulations provide adequate protection of public health for the
soil conditions more typically associated with the northeast.
One caveat is that the regulations address only plant uptake as a
route of human exposure; they may warrant revision or
modification if other routes of exposure to cadmium are also
significant.
New regulations should strongly recommend or possibly
require the use of sludges at agronomic rates (10 to 20 Mt/ha)
rather than on the basis of nitrogen requirements which can lead
to application of 2 to 10 times the volume of sludge (Hornick et
al., 1984). The recommendation should apply particularly to food
chain crops and exceptions would be suitable for horticultural
operations, dedicated, or reclamation sites. While the cadmium
and lead limits recommended provide public health protection,
application of sludge at agronomic rates provides an additional
factor of safety. Several investigators note that application
rates which provide good soil conditioning are more practical and
economical than the larger volumes that would be permitted on the
basis of maximum cadmium concentrations or nitrogen requirements
(Logan, 1986, personal communication; USEPA, USFDA, USDA, 1981;
Hornick et al., 1984).
Maximum Cumulative Application Rates . Maximum cumulative
application rates should also be established for metals other
than cadmium. On the basis of the “acid garden” scenario, the
maximum cumulative cadmium concentration is sufficiently protec—
154
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tive of public health. A maximum level should be set for lead
especially because of other environmental contributions to soil
lead levels (e.g., leaded gasoline). The USEPA, USFDA, USDA 1981
guidelines recommended a maximum cumulative value of 800 kg/ha DW
for lead in soil but the scientific basis for this recommendation
was not made clear. This value should be evaluated using the
risk assessment methodologies being completed currently by the
U.S. EPA (1985).
Soil Monitoring for Background Metal Levels . Monitoring for
background levels of metals should be required before sludge is
accepted for a site to assure that maximum cumulative metal
levels, including background levels, are not exceeded.
Application Restrictions . Sludge should never be directly
applied to growing crops destined for direct human consumption.
Sludges can adhere strongly to leafy or vegetative parts of the
plant and may contribute to human exposure especially for
contaminants like lead which are not significantly incorporated
into plant tissues. This restriction is also recommended to
limit human exposure to sludge pathogens.
A recent USDA bulletin recommends that sludges never be
applied to land used for growing tobacco (Hornick et al., 1984).
Tobacco prefers acidic soils, incorporates cadmium readily, and
already contributes to the body burden of cadmium in smokers.
Grazing restrictions should also be required on lands used
for grazing of animals intended for human consumption (meat and
dairy products). Reddy et al. (1985) reported elevated fecal
155
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cadmium levels in cattle grazed on sludge amended pastures but
the levels dropped to pre—sludge levels 3 to 8 months after
sludge application. Unfortunately, fecal metal levels could not
be correlated with tissue metal levels over time so the public
health implications of the fecal cadmium levels are not clear.
However, at the termination of the study, Reddy et al. did report
elevated cadmium and lead levels in some tissues although not in
muscle. Although not conclusive about the public health impact
of metal uptake by grazing animals, the study indicates that the
one month typically required between application and grazing
instituted because of pathogen concerns, may not be sufficient to
prevent excess metal exposures.
Recommendations for Pathogens in Composted Sludge .
Assessment of the public health and environmental risks
associated with pathogens in composted sludge requires under-
standing of the several steps lying between the presence of a
given pathogen in unstabilized sludge and the infection of a
human being or domestic animal. The type of pathogens present,
their ability to survive various levels of stabilization, their
survival and transport in the environment, and their subsequent
infection of human or animal hosts affect the level of risk
associated with different uses of or exposure to composted
sludge. In this report, each of these steps has been evaluated
in order to gain insight into the overall level of hazards from
pathogens in composted sludges applied to land.
156
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While the pathogen content of various sludges has been
reasonably well characterized, the fate of pathogens in
composting processes and in the environment, the routes of
exposure by which they pose the greatest hazard to man or
animals, and the actual level of infection and disease associated
with their presence in composted sludges applied to land, have
not. Epidemiologic evidence showing a problem associated with
pathogens in composted sludge in human infection and disease is
essentially absent.
Despite these limitations, the research conducted for this
report supports several general recommendations. They have been
divided into two broad sections: recommendations for composted
sludges intended for general public use and recommendations for
composted sludges for use in controlled land application
programs.
General public use of composted sludge . Table 29 lists for
regulation of composted sludge intended for general distribution,
sale, or give away to the public. The recommendations assume
that a minimum of control can be exerted over how and where the
sludge is used.
The primary recommendation is that the sludge should undergo
a process to further reduce pathogens (PFRP) prior to release to
the public. As discussions in the body of the report indicated,
processes to significantly reduce pathogens (PSRP) are not as
effective at reducing numbers of pathogens as PFRP. If suffi-
cient numbers of bacteria remain, regrowth can occur leading to
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TABLE 29. RECOMMENDATIONS FOR PATHOGENS IN COMPOSTED
SLUDGE: GENERAL PUBLIC USE
Regulation or Guideline Recommendation
Degree of Stabilization PFRP (See Appendix II)
Labeling Requirements 1. Recommended sludge
application rate based on
soil conditioning
requirements 10—20 Mt/ha —
50—100 lbs/250 sq ft.
2. Recommend immediate
incorporation into soil.
3. Recommended washing of all
fruits and vegetables grown
on sludge—amended soils.
infectious levels of such organisms as salmonella. The ova of
several parasites, Ascaris sp. in particular are highly resistant
to treatment and it is not clear that the PSRP specifications for
composting reach sufficient temperatures for long enough periods
of time to achieve ova destruction. One study reported the
threshold for the destruction of helminth ova to be 51°C;
composting to meet PSRP requires that 55°C be achieved for only
4 hours.
While it is unclear whether or not sufficient numbers of
pathogens remain to make human or animal infection likely, end
use of composted sludge by the general public cannot be easily
controlled. Prudent public policy requires worst case assump-
tions about human exposure and infection. Children may come into
contact with or ingest small quantities of sludge or sludge
amended soils which have a sufficient number of organisms to
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cause disease, Vegetables grown in sludge—amended soils in
private gardens could carry sufficient organisms to cause
infection. Requiring the use of PFRP for sludges intended for
distribution to the public does not eliminate, but substantially
reduces, the likelihood that such infections could occur.
The second recommendation is for labeling or notification
requirements to promote practices which further reduce the
likelihood of infection or disease, such as immediate incorpor-
ation into soil in order to avoid accidental contact. The
requirements are essentially those recommended for cadmium and
lead. Labels or information distributed with the sludge should
include recommendations on maximum loading rates, incorporation
of sludge into the soil, and on washing of produce grown on
sludge amended soils.
Controlled land application of composted sludges .
Recommendations for controlling pathogens from land application
of composted sludge are in Table 30. When use of composted
sludges can be controlled through site selection, permitting, and
other requirements, processes to significantly reduce pathogens
(PSRP) appear to provide adequate protection of the public,
domestic animals and water supplies from sewage pathogens.
Application of sludges to agricultural lands, dedicated sites, or
to reclamation sites are more readily made subject to land
management requirements than smaller scale, private uses. This
report found little evidence in recent scientific literature of
increased human or animal risk of infection when sound land and
sludge management practices have been used.
159
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TABLE 30. RECOMMENDATIONS FOR PATHOGENS IN COMPOSTED
SLUDGE: CONTROLLED LAND APPLICATION
Regulations or Guidelines Recommendation
Degree of Stabilization PSRP
Application Rates 1. Establish upper limit on the
basis of maximum annual
loading rate for cadmium or
other limiting contaminant.
2. Incorporate strong recommenda-
tions that sludge be used only
at agronomic rates, 10—20
Mt/ha, for most agricultural
uses.
Application Restrictions
1. General Never directly to crops grown for
direct human consumption.
2. Between Hay Crops Apply within 1 week of first
harvest to minimize sludge
adherence to vegetation. One
month minimum required between hay
crops.
Grazing Restrictions Establish a waiting period of 2—3
months after application.
The epidemiologic study recently completed by investigators
at Ohio State University provides some of the most convincing
evidence. Despite limitations in the study, the investigators
found no increase in disease or infection in 40 farm families or
their animals on farms receiving 2 to 10 Mt/ha of digested sludge
compared to their counterparts on farms receiving no sludge
(Brown, 1985). While these application rates are lower than
those that can theoretically be permitted for agricultural lands
160
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(depending on sludge metal content), other factors could have
increased the likelihood of infection. Human access to the
pastures or fields receiving sludges was not necessarily re-
stricted and it appears that animals were permitted to graze on
the pastures not long after sludge was applied.
Assuming that sludges meet only PSRP requirements, the
remaining recommendations address land and sludge management
practices. First, application of sludges to agricultural lands
should be restricted to agronomic rates, rates which provide
basic soil conditioning and some fertilizer value. Rates between
10 and 20 Mt/ha have been recommended by several authors (Hornick
et al., 1984, Logan, 1986, personal communication).
There are two recommendations regarding application
restrictions. One confirms current federal regulations and the
other addresses an issue raised in the scope of work. First,
sludge should never be applied directly to crops grown for human
consumption. Various pathogens can live for up to two months on
plant surfaces and therefore could persist through harvest.
Since some organisms, like salmonella, can survive in soil ifor up
to a year or more, root crops in particular should not be grown
in sludge amended soil for the 18 months recommended by the
federal regulations (USEPA, 1979) at a minimum. Some parasite
ova can remain viable and infective for five or more years,
although they are typically found in much lower concentrations in
sludges and soils than bacteria or viruses.
161
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The second recommendation is that application between hay
crops of sludge that has undergone only PSRP, whether by
composting or any other means, can be permitted provided that the
sludge is applied within a week or less after the harvest.
Sludges containing pathogens can adhere strongly to plant
surfaces and can make up a substantial percentage of the dry
weight of the forages if applied too soon before harvest. If
sludges are applied shortly after the first hay crop, one to two
months or more (depending on geographical location) will elapse
before the second hay crop. The survival times reported for most
organisms on grass and clover ranged from a few days to just over
a month in the literature reviewed. Dry conditions and sunlight
decrease the survival time of organisms and account for the
shorter survival time of organisms on plants than in soils.
Grazing restrictions on sludge amended pastures need to be
more stringent because animals tend to ingest sludges from both
vegetation and soils. Current federal regulations require a
waiting period of only a month but three months may be more
appropriate. One paper reviewed reported a case in which calves
grazing on pastures 9 to 10 weeks after they were treated with
sludge containing ova of Taenia saginata (beef tapeworm) became
infected (Little, 1985).
In conclusion, the public health and environmental impact of
land application of sludges is the subject of ongoing debate.
The various toxic metals, organic compounds, and pathogenic
organisms that have been identified in sludges can pose a hazard
162
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to public health and the environment if sufficient exposure to
these contaminants occur. The current debate focusses on the
most effective means of reducing the likelihood of exposure and
impact. The consensus emerging from this review of recent
scientific literature is that a combination of scientifically
based limits on toxic and pathogenic constituents of sludge and
sound land management practices can effectively protect both
public health and the environment.
163
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REFERENCES
Bitton, Gabriel, and Charles P. Gerba, 1984. “ Groundwater
Pollution Microbiology , Chapter 4.
Brown, Robert E., 1985. “Demonstration of Acceptable Systems for
Land Disposal of Sewage Sludge.” EPA—600/2—85—062, U.S.
Environmental Protection Agency, Cincinnati, OH (April).
Burge, W.D. et. al., 1977. “Occurance of Pathogens and Microbial
Allergins in the Sewage Sludge Composting Environment.” 1977
National Conference on Composting of Municipal Residues and
Sludges, August 23—25.
Chaney, R.L. 1986. U.S. Department of Agriculture, Personal
Communication to K.D. Walker, Metcalf & Eddy, April.
Chaney, R.L. and P.M. Giordanco, 1977. Microelements as Related
to Plant Deficiencies and Toxicities. In: Soils for the
Management of Organic Wastes and Wastewaters , L.F. Elliot and
F.J. Stevenson (eds) Am. Soc. Agronomy. Madison, WI.
Chaney, R.L., Smith, Baker et al., 1986. Unpublished.
Chaney, R.L., S.B. Sterrett, M.C. Morella, and C.A. Lloyd,
1982. “Effect of Sludge Quality and Rate, Soil pH and Time
on Heavy Metal Residues in Leafy Vegetables” In: Proceedings
of the Fifth Annual Madison Conference on Applied Research
and Practice on Municipal and Industrial Waste , Univ. of
Wisconsin, Madison.
Clark, C.S., et. al., 1984. “Biological Health Risks Associated
with Composting of Wastewater Treatment Plant Sludge.” J.
Water Pollut. Control Fed . 56, 1269—1276.
Foth, H.D., et al., 1971. Laboratory manual for Introductory
Soil Science , Third Edition, Chapter 4.
Gerba, C.P., 1983. “Utilization of Minicipal Wastewater and
Sludge on Land — Pathogens”, In: Proceedings of the 1983
Workshop on Utilization of Municipal Wastewater and Sludge on
Land . (eds A.L. Page, T.L. Gleason, J.R. Smith et al.)
University of California, Riverside.
Goldstein, 1985. “Sewage Sludge Composting Facilities on the
Rise”. Biocycle , November—December
Grasso, D. et. al., 1984. “Sludge Disinfection: A Review of the
Literature.” Water—Pollution Control Federation, Washington
D.C.
Hay, J.C.et al., 1985. “Sewage Sludge Disinfection by Windrow
Composting.” Precoriference, The Workshop on Municipal
Wastewater Sludge Disinfection, October.
164
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REFERENCES (Continued)
Hornick, S.B., L.J. Sikera, S.B. Sterrett et. a].., 1984.
Utilization of Sewage Sludge Compost a i1 Conditioner at
Fertilizer for Plant Growth . U.S. Dept. of Agriculture,
Agriculture Information Bulletin No. 464.
Jakubowski, W., 1985. “The Epidemiological Approach for
Determining the Significance of Pathogens in Sewage
Sludge.” Preconference, The Workshop on Municipal Wastewater
Sludge Disinfection, Oct.
Little, M.D., 1985. “The Detection and Significance of Pathogens
in Sludges: Parasites.” Preconference, The Workshop on
Municipal Wastewater Sludge Disinfection, Oct.
Logan, T.J. and R.L. Chaney, 1983. “Utilization of Municipal
Wastewater and Sludge on Land-Metals”, In: Proceedings of the
1983 Workshop on Utilization of Municipal Wastewater and
Sludge on Land . (ed: Page, A.L., Gleason, T.L. Smith, J.R.
et. al.,) University of California, Riverside.
Logan, T.J., 1986. Agronomy Department, Ohio State University.
Personal Communication to K. Walker, Metcalf & Eddy, Inc.
April 18.
Lomnitz, E., 1986. Office of Criteria & Standards, US EPA.
Personal Communication to K. Walker, Metcalf & Eddy,
February 14.
Moore, B.E. and C.A. Sorber, 1985. “The Detection and
Significance of Human Virses in Sludges.” Preconference, The
Workshop on Municipal Wastewater Sludge Disinfection, Oct.
Needleman, H.L., C.E. Gunnoe, A. Leviton, et. al., 1979.
Deficits in Psychologic and Classroom Performance of Children
with Elevated Lead Levels. N. Engl . J. Med . 300:689—695.
Needleman, H.L., 1980. “Lead and Neuropsychological Deficit:
Finding a threshold.” In: H.L. Needleman (ed.) Low Level
Lead Exposure: The Clinical Implications of Current
Research , Raven Press, New York.
Overcash, M.R., ed. 1981. Decomposition of Toxic and Nontoxic
Organic Compounds in Soils . Ann Arbor Science, Ann Arbor,
Michigan.
Overcash, M.R. 1983. “Land Treatment of Municipal Effluent and
Sludge: Specific Organic Compounds” In: Proceedings of the
1983 Workshop on Utilization of Municipal Wastewater and
Sludge on Land .
165
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REFERENCES (Continued)
Page, A.L. et.al. Workshop on Effects of Sludge Quality and Soil
Properties on Plant Uptake of Sludge-Applied Trace
Constituents 1986. Workshop sponsored by US EPA in Las
Vegas, NV with a final report scheduled for Fall 1986 .
Passman, F.J., 1978. “Fate and Occurance of Pathogens.” Workshop
on Health and legal Implications of Sewage Sludge Composting,
December 18, 19, 20.
Pennsylvania State University, 1985. Criteria and
Recommendations for Land Applications of Sludges in
the Northeast . Bulletin 851, March.
Reddy et. al., 1985. In: Brown R.E., “Demonstration of
Acceptable Systems for Land Disposal of Sewage Sludge”
EPA/600/2—85/062. April.
Reimers, R.S. et. a].., 1985. “Chemical Inactivation of Pathogens
in Municipal Sludges.” Preconference, The Workshop on
Municipal Wastewater Sludge Disinfection, Oct.
Ryan, J. 1986. U.S. EPA, Cincinnati: Personal Communication to
K. Walker, Metcalf and Eddy, Inc. April.
Ryan, Pahren, and Lucas, 1982. “Controlling cadmium in the human
food chain: A review and rationale based on health
effects”, Environ. Res . 28:251—302.
State of Colorado, Department of Health, 1985. Domestic Sewage
Sludge Regulations — Statement of Basis arid Purpose .
Taffel, William, 1978. “Health Risk Assessment.” In: Workshop
on Health and Legal Implications of Sewage Sludge
Composting, December 18, 19, and 20 . Energy Resources Co.
Inc., Cambridge, MA.
U.S. EPA, U.S. FDA, USDA 1981. Land Application of Municipal
Sewage Sludge for the Production of Fruits and Vegetables; A
Statement of Federal Policy and Guidance .
U.S. EPA, 1979. Criteria for Classification of Solid Waste
Disposal Facilities and Practices; Final, Interim Final, and
Proposed Regulations. FR44 (179): 53438—53464.
U.S. EPA. 1983. Process Design Manual for the Land Application
of Municipal Sludge . EPA—625/l—83—016. October.
U.S. EPA, 1985. Summary of Environmental Profiles and Hazard
Indices for Constituents of Municipal Sludge . Office of
Water Regulation and Standards, July.
166
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REFERENCES (Continued)
Venosa, Albert D., 1985. “Detection and Significance of
Pathogens in Sludges.” Preconference, The Workshop on
Municipal Wastewater Sludge Disinfection, Oct.
Winneke, G., A. Brockhaus, U. Kramer, et. al., 1981.
“Neuropsychological Comparison of Children with Different
Tooth Lead Levels.” Preliminary report. In: Proc. mt.
Conf. Heavy Metals in the Environment. CEP Consultants,
Edinburgh, Scotland.
167
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APPENDIX I
REGULATIONS AND GUDELINES FOR LAND APPLICATION AND USE OF
SLUDGE IN THE UNITED STATES
-------
APPENDIX I
REGULATIONS AND GUIDELINES FOR LAND APPLICATION AND USE OF
SLUDGE IN THE UNITED STATES
This appendix is contained on the accompanying computer diskette.
This is a high density diskette and must be used in the high
density disk drive of an IBM Personal Computer AT or compatible
machine. Information on the regulations and guidelines of 40
states plus the District of Columbia and Federal regulations is
contained in four Lotus 1-2-3 (release 1) files. These may be
read on a computer containing either Release 3. or Release 2 of
Lotus 1-2-3. The following table indicates which states’
information is contained on each of the four files.
SLUDREG1 SLUDREG2 SLUDREG3 SLUDREG4
Federal New Jersey Tennessee Nebraska
Connecticut New York Illinois Michigan
Florida Oregon Pennsylvania Hawaii
Iowa Rhode Island Ohio Indiana
Maine Texas South Carolina Nevada
Maryland Vermont North Carolina Arizona
Massachusetts Wisconsin Georgia Virginia
New Hampshire Kansas Distr. of Columbia
Colorado Montana
California Mississippi
Wyoming
Alabama
Utah
Alaska
Minnesota
Washington
Delaware
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APPENDIX II
PROCESSES TO SIGNIFICANTLY REDUCE PATHOGENS
PROCESSES TO FUTHER REDUCE PATHOGENS
-------
APPENDIX II
(From 40 CFR Part 257)
A. Processes to Significantly Reduce Pathogens
Aerobic digestion : The process is conducted by agitating
sludge with air or oxygen to maintain aerobic conditions at
residence times ranging from 60 days at 15° C to 40 days at
20° C, with a volatile solids reduction of at least 38 percent.
Air drying : Liquid sludge is allowed to drain and/or dry on
under—drained sand beds, or paved or unpaved basins in which the
sludge is at a depth of nine inches. A minimum of three months
is needed, two months of which temperatures average on a daily
basis above 0° C.
Anaerobic digestion : The process is conducted in the
absence of air at residence times ranging from 60 days at 20° C
to 15 days at 35° to 550 C, with a volatile solids reduction of
at least 38 percent.
Composting : Using the within—vessel, static aerated pile or
windrow composting methods, the solid waste is maintained at
minimum operating conditions of 40° C for five days. For four
hours during this period the temperature exceeds 55° C.
Lime stabilization : Sufficient lime is added to produce a
pH of 12 after two hours of contact.
Other methods : Other methods or operating conditions may be
acceptable if pathogens and vector attraction of the waste
A—II—l
-------
(volatile solids) are reduced to an extent equivalent to the
reduction achieved by any of the above methods.
B. Processes to Further Reduce Pathogens
Composting : Using the within-vessel composting method, the
solid waste is maintained at operating conditions of 55° C or
greater for three days. Using the static aerated pile composting
method, the solid waste is maintained at operating conditions of
55° C or greater for three days. Using the windrow composting
method, the solid waste attains a temperature of 55° C or greater
for at least 15 days during the composting period. Also, during
the high temperature period, there will be a minimum of five
turnings of the windrow.
Heat drying : Dewatered sludge cake is dried by direct or
indirect contact with hot gases, and moisture content is reduced
to 10 percent or lower. Sludge particles reach temperatures well
in excess of 80° C, or the wet bulb temperature of the gas stream
in contact with the sludge at the point where it leaves the dryer
is in excess of 80° C.
Heat treatment : Liquid sludge is heated to temperatures of
180° C for 30 minutes.
Thermophilic aerobic digestion : Liquid sludge is agitated
with air or oxygen to maintain aerobic conditions at residence
times of 10 days at 55—60° C, with a volatile solids reduction of
at least 38 percent.
Other methods : Other methods or operating conditions may be
acceptable if pathogens and vector attraction of the waste
A—II—2
-------
(volatile solids) are reduced to an extent equivalent to the
reduction achieved by any of the above methods.
Any of the processes listed below, if added to the process
described in Section A above, further reduce pathogens. Because
the processes listed below, on their own, do not reduce the
attraction of disease vectors, they are only add—on in nature.
Beta ray irradiation : Sludge is irradiated with beta rays
from an accelerator at dosages of at least 1.0 megarad at room
temperature (Ca. 20° C).
Gamma ray irradiation : Sludge is irradiated with gamma rays
from certain isotopes, such as 60 cobalt and 137 cesium, at dosages
of at least 1.0 megarad at room temperature (Ca. 20° C).
Pasteurization : Sludge is maintained for at least 30
minutes at a minimum temperature of 70° C.
Other methods : Other methods or operating conditions may be
acceptable if pathogens are reduced to an extent equivalent to
the reduction achieved by any of the above add-on methods.
A—II—3
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APPENDIX III
SUMMARY OF STATE CONTACTS
AND BASIS FOR STATE REGULATIONS
AND GUIDELINES IN THE NORTHEAST
-------
APPENDIX III
Basis
for
Background
Documents
State Contact Regulations Cited Developed
Connecticut Brian Curtis Penn State (1985) No
203—566—3654
Maine Karen Townsend Uncertain; No
Department of Other U.S. State Regs.,
Environmental European Guidelines,
Protection U.S EPA (1979)
207—289—3901 Penn. State, (1985)
Maryland Ernest Spencer U.S. EPA, (1983) No
Department of Other state regs.
Health and
Mental Hygiene
310—225—5664
Massachusetts Fifi Nessen U.S. EPA, (1979) Yes
DEQE Sludge Task Force
617—292—5590 recommendations
New Hampshire Carl Woodbury Uncertain; No
NH Office of U.S. EPA, U.S. FDA,
Waste Management U.S. DA, (1981)
603—271—4672 U.S. EPA, (1979)
New Jersey
New York Thomas Easterly U.S. EPA, 1979 No
Residuals Mgmt.
Director
Division of
Solid waste,
NY State DEC
518—457—2051
Ohio S.M. Blyndenburgh Brown, Robert E. No
Engin. Unit Spvsr. (1985)
Public WW Section
Ohio EPA
614—466—2328
Pennsylvania Jay Ort Penn State (1985) No
PA Department of (Dr. Dale Baker)
Environmental
Residuals
Bureau of Waste
Management
717—787—7381
3—111—1
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Basis
for
Background
Documents
State Contact Regulations Cited Developed
Rhode Island Chris Campbell Uncertain; No
401—277—2234 U.S. EPA, (1979)
U.S. EPA, (1983)
Vermont Katie Gehr U.S. EPA, (1979) No
Hydrologist, U.S. EPA, U.S. FDA,
State of Vermont U.S. DA, (1981)
802—828—3395
B—III—2
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REFERENCES
Brown, Robert E., 1985. Demostration of Acceptable Systems for
Land disposal of Sewage Sludge . EPA/600/285/062. April
Pensy].vania State University, 1985. Criteria and Recommendations
for Land Application of sludges in the Northeast . Bulletin
851. March.
U.S. EPA, 1979. Criteria for Classification of Solid Waste
Disposal Facilities and Practices; Final, Interim Final, and
Proposed Regulaions. FR 44(179): 53438—53464.
U.S. EPA, U.S. FDA, U.S. DA, 1981. Land Application of Municipal
Sewage Sludge for the Production of Fruits and Vegetables; A
Statement of Federal Policy and Guidance .
U.S. EPA, 1983. Process Design Manual; Land Application of
Municipal Sludge . EPA—625/1—83—016. October.
B—III—3
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