EPA-670/2-73-064
August 1973
                       Environmental Protection Technology Series
    Pilot - Demonstration Project For
    Industrial  Reuse Of Renovated
    Municipal Wastewater
                                Office of Research and Development
                                U.S. Environmental Protection Agency
                                Washington, D.C. 20460

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                    RESEARCH REPORTING SERIES
Research reports of the Office of Research and Development,
Environmental Protection Agency, have been grouped into five
series.  These five broad categories were established to facili-
tate further development and application of environmental
technology.  Elimination of traditional grouping was consciously
planned to foster technology transfer and a maximum interface in
related fields.  The five series are:

     1.  Environmental Health Effects Research
     2.  Environmental Protection Technology
     3.  Ecological Research
     4.  Environmental Monitoring
     5.  Socioeconomic Environmental Studies

This report has been assigned to the ENVIRONMENTAL PROTECTION
TECHNOLOGY series.  This series describes research performed to
develop and demonstrate instrumentation, equipment and method-
ology to repair or prevent environmental degradation from
point and non-point sources of pollution.  This work provides
the new or improved technology required for the control and
treatment of pollution sources to meet environmental quality
standards.

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                                                    EPA-670/2-73-064
                                                    August  1973
             PILOT-DEMONSTRATION PROJECT FOR
   INDUSTRIAL REUSE  OF  RENOVATED MUNICIPAL WASTEWATER
                            By
                  G.  A.  Horstkotte, Jr.
           Contra Costa  County Water District
         Central Contra  Costa Sanitary District
             Walnut  Creek, California 94596
                  Project No. 17080 FSF
                      Project Officer

                      Carl A. Brunner
          U.S. Environmental Protection Agency
         National Environmental Research Center
                 Cincinnati, Ohio 45268
                       Prepared for

           OFFICE OF RESEARCH AND DEVELOPMENT
          U.S. ENVIRONMENTAL PROTECTION AGENCY
                 WASHINGTON, D. C. 20460
JTnr salaJiitJJui Snnnrlntr-ndent of Documents, U.S. Government Printing Office, Washington, D.C. 20402 - Price $1.
                                                              65

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              EPA REVIEW NOTICE
This report has been reviewed by the Office of
Research and Development, EPA, and approved for
publication.  Approval does not signify that the
contents necessarily reflect the views and
policies of the Environmental Protection Agency,
nor does mention of trade names or commercial
products constitute endorsement or recommendation
for use.

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                             ABSTRACT
Three pilot plant treatment sequences were operated during this study
to produce various grades of effluent for subsequent testing as industrial
water  sources.  The testing was conducted in pilot-sized test loops con-
sisting of small cooling towers and heat exchangers.  At  the same time
the renovated waters were tested,  Contra Costa Canal water, which is
presently used by industry in the study area, was  also investigated in a
test-loop identical to those used for the renovated water.

The study results illustrated that the wastewater investigated can be
treated satisfactorily for reuse in  industrial applications.  Corrosion
rates and fouling factors observed with renovated  water were equal to or
less than found with the canal water.  Precipitation of phosphorous •was
the major source  of scale formation •while using renovated water for
cooling purposes, thus indicating the need for phosphorous  removal.

Biological oxidation of organic materials and ammonia  in a multistage
treatment system resulted in renovated water suitable fcfr industrial re-
use.  Filtration and phosphorous removal in association with biologi cal
treatment were  also advantageous.   Physical-chemical treatment pro-
cesses can produce suitable renovated water provided that a suitable
method is developed to prevent the generation of noxious odors in the acti-
vated carbon process.

Costs  for the  alternative treatment systems  ranged from approximately
25^/1000 gal for conventional activated sludge treatment  to 50^/1000 gal
for a three-stage  biological treatment system with filtration and alum
addition  for phosphorous removal.  Physical-chemical  treatment costs,
including the cost for nitrogen removal,  ranged from about 38 to 45^/1000
gal.  The costs  for renovated water should be significantly less than the
above  costs in those cases •where high degrees of treatment are required
to discharge the treated effluent to  a receiving body of water.

This  report was  submitted  in fulfillment of Project  Number 17080 FSF,
by  the Contra Costa Water  District and  the Central Contra  Costa
Sanitary District, under  the partial sponsorship of  the Environmental
Protection Agency.
                                  111

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                             CONTENTS


Section                                                          Page

  I         INTRODUCTION                                          1

            Motivation                                               1

            Objectives                                               4

  II        CONCLUSIONS AND RECOMMENDATIONS                5

            Conclusions                                              7

            Recommendations                                       13

  III       EXPERIMENTAL PROGRAM                            15

            Description of Facilities                                 15

            Operating Program                                      ZZ

            Sampling and Analysis Program                         Z4

  IV        RESULTS OF WASTEWATER TREATMENT STUDIES    29

            Phase I :  Biological-Physical  Treatment System        Z9

            Phase II :  Biological Nitrification-Denitrification        39

            Phase III:  Chemical-Physical Treatment System         58

            Evaluation of Treatment Processes                      71

            Heavy Metals                                            79

 V          RESULTS AND DISCUSSION OF INDUSTRIAL
            TEST LOOP STUDIES                                   81

            Heat Exchanger Fouling Data                            81

            Corrosion Rates*                                       88

            Algal Growth Potential                                   92

            Toxicity Analysis                                       95

            Evaluation of Industrial Test Loop Results                98

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Section                                                           Page

  VI        ESTIMATED WASTEWATER TREATMENT COSTS      103

            Phase I:      Activated Sludge                          105

            Phase II:     Biological Nitrification                    105

            Phase II A:   Biological Nitrification-Denitrification    106

            Phase III:    Physical-Chemical Treatment             107

            Phase III A:  Combined Physical-Chemical-
                         Biological Treatment                      108

  VII       ACKNOWLEDGMENTS                                 111

  VIII      REFERENCES                                         113

  IX        APPENDICES                                          115

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                           ILLUSTRATIONS
Figure                                                           Page

 1-1        Geographic Location of Project Area                     2
 2-1        Process  Flow Diagram for the Pilot-Demonstration
            Facility                                                 6

 2-2        Approximate Treatment Costs'for  30-mgd Plants        12
 3-1        Perspective Drawing of Pilot-Demonstration
            Facilities                                              16

 3-2        Pilot-Plant Filtration Media                            18

 3-3        Pilot-Demonstration Plant Operating Schedule           21

 3-4        Sampling Points in the Pilot-Demonstration Facility     26

 4-1        Activated Sludge Process Operating Characteristics     30

 4-2        Activated Sludge Process  Quality Characteristics        31

 4-3        Filtration Data Using Activated Sludge Process
            Effluent                                                34

 4-4        Performance Data  of Activated Carbon Treatment
            of Activated Sludge and Nitrification Process Effluents  37
 4-5        Nitrification Process Data                             41

 4-6        Nitrification-Denitrification Process Data               44

 4-7        Denitrification Process Data                           47

 4-8        Filtration Data Using Denitrification Process
            Effluent                                                52

 4-9        Performance Data  of Activated Carbon Treatment
            of Nitrification and Denitrification Process  Effluents    54

4-10        Lime  Requirements for Chemical Treatment            59

4-11        Chemical Treatment Plant Lime. Requirement
            and pH Values                                          60

4-12        Hardness and Alkalinity of Raw Wastewater and
            First-Stage  and Second-Stage Chemical Treatment
            Effluents                                               62
                                 vn

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Figure                                                          Page

 4-13      Orthophosphate and Suspended Solids Removal
           in the Two-Stage Chemical Treatment Process         64

 4-14      Total and Soluble Organic Carbon Removals in
           the Two-Stage  Chemical Treatment Process            65

 4-15      Filtration Data Using Chemical Treatment Effluent     67

 4-16      Performance Data  of Activated Carbon on Chemical      _ ;
           Treatment Process Effluent                           69

  5-1      Average Fouling Factor Data                          86

  5-2      Algae Growth in Renovated Waters                     94

  6-1      Flow Diagrams  and Treatment Costs for 30-mgd
           Plants                                               104

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                               TABLES
Table                                                            Page

 3-1        Analytical Procedures                                 27
 4-1        Activated Sludge/Nitrification Data                     33
 4-2        Summary of Filtration Performance Using
            Activated Sludge Process Effluent                      35
 4-3        Summary of Activated Carbon Performance Data
            During Treatment of Filtered Activated Sludge
            Effluent                                               38
 4-4        Average  Monthly Suspended Solids Concentrations
            of the Biological Effluents (mg/1)                      45
 4-5        Phosphorous Removal Using Ferric and Aluminum
            Additions to the Denitrification System                 50
 4-6        Summary of Filtration Performance Using Denitri-
            fication Process Effluent                              53
 4-7        Summary of Activated Carbon Performance Data
            During Treatment of Filtered Nitrification and
            Denitrification  Process Effluents                       57

 4-8        Chemical Treatment Average Hardness and
            Alkalinity Data                                        6l
 4-9        Average  Performance Data of Activated Carbon
            on Chemical Treatment Process  Effluent                70
4-10        Pilot Plant Average Effluent Quality Compared to
            the Raw Wastewater                                   72
4-11        A Comparison of Single-Stage Activated Carbon
            Performance for Various Pilot Plant Effluents          77
4-12        Removal  of Heavy Metals                              80
 5-1        Fouling Factors and Scale Analyses                     82
 5-2        Typical Fouling Factors                               87
 5-3        Corrosion Rates and Circulating  Water Quality          89
                                 IX

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Table                                                             Page

 5-4        Comparison of Corrosion Rates                         91

 5-5        Sample Analysis for Algae Growth Potential Tests      93

 5-6        Summary of Toxicity Results                           96

 5-7        Industrial Test Loop  Toxicity Results                   97

 5-8        Typical Quality Characteristics of Wastewater
            and Canal Water                                       100

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                               Section I





                           INTRODUCTION








This report presents the results  of a pilot-demonstration investigation



on wastewater renovation conducted by Bechtel Corporation under a con-



tract dated July 27, 1970, with the Contra Costa County Water District



(CCCWD) and Central Contra Costa Sanitary District (CCCSD).  The in-



vestigation was partially funded by a  Class IV  Research and Development



Grant from the Environmental Protection Agency.  Figure 1-1 shows  the



project area location.  This location  is adjacent to industries  generally



located along the south shore of Suisun Bay.








MOTIVATION








In 1969, during a feasibility study conducted by Bechtel for the CCCWD,



it was  concluded that "it  is technically feasible to produce renovated water



for the  CCCWD for a wide range  of irrigational and industrial uses"



(Reference 1).  As a result, it was recommended that (1)  a sampling and



analysis program be established  to characterize local waters  and waste-



waters,  (2) a pilot-demonstration program be  initiated, and (3) a master



plan for water renovation be developed.   It was also recommeded that



an agreement be established for cooperation between the CCCWD and



CCCSD in undertaking additional wastewater renovation investigations.








The CCCWD and CCCSD, on December 3, 1969, entered into a memo-



randum of understanding which:

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                                  INTERSTATE   STATE 4
                                     680
       SAN FRANCISCO BAY
Figure 1-1.  Geographic Location

             of Project Area

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    •    Recognized the basic water supply function of the
         CCCWD and water pollution control  function of
         the CCCSD

    •    Established the intent of both Districts to cooperate
         in future water renovation and reuse activities
    •    Outlined the following six-phase program:

         Phase                     Activity

           I          Water Renovation Feasibility Study
                      (sponsored by CCCWD and complet-
                      ed September 1969)

           II          Solid Waste Disposal Investigation
                      (sponsored by CCCSD  and completed
                      March 1970)

          III          Sampling and Analysis Program
                      (jointly sponsored by CCCWD and
                      CCCSD and  completed  November
                      1971)

          IV          Pilot Plant Program (jointly spon-
                      sored by CCCWD and CCCSD)

           V          Demonstration Program (jointly
                      sponsored by CCCWD  and CCCSD)

          VI          Implementation Plan for waste -
                      water renovation and solid wastes
                      disposal
Because of the national significance associated with Phases IV and V,

the CCCWD and the CCCSD applied for, and were granted on  February

19, 1970,  a Class IV research and demonstration grant from the Fed-

eral Water Pollution Control Administration (now Environmental Protec.
tion Agency) to carry out the pilot-demonstration program.


The motivation for this investigation stems from the activities listed

above,  which reflect the  CCCWD's and the CCCSD's desire to conserve

our water resources by water reuse.

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OBJECTIVES
Objectives of the pilot-demonstration program using various wastewater

treatment process sequences were to;


    •    Allow investigation of the removal of various impurities
         in wastewaters by  certain treatment processes

    •    Produce various grades of renovated waters whose
         properties will be  tested for factors of importance in
         industrial water  use

    •    Provide process data that, along with other available
         information, will be used in orde r-of-magnitude cost
         comparisons of various water renovation processes

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                               Section II





              CONCLUSIONS AND RECOMMENDATIONS








Three pilot plant treatment sequences  were investigated during this  study



to determine the  suitability of various  grades of renovated wastewater



for industrial reuse (Figure 2-1).  In the Phase I treatment  sequence,



primary effluent  from the existing CCCSD treatment plant was given bio-



logical treatment in the pilot plant.  The biologically treated effluent,



before and after filtration,  was chlorinated  and used as cooling water



makeup for the industrial test loops.








In the Phase II pilot plant sequence,  primary and activated sludge treatment



was provided in the CCCSD treatment plant,  while ammonia was biolo-



gically oxidized to nitrate in the pilot plant nitrification process.   The



nitrate was subsequently removed biologically as nitrogen gas in  the



denitrification process (Figure  2-1).  Filtration and activated carbon



adsorption were used as additional treatment steps on a portion of the



effluents from the nitrification and the denitrification processes.   Ni-



trified, filtered nitrified, and activated-carbon-treated nitrified ef-



fluents were used as makeup water for the industrial test loops.   Simi-



lar combinations  of denitrified effluents were also used in the cooling



towers.








The Phase III treatment sequence incorporated only chemical and physical



processes.   Wastewater was given preliminary treatment for the removal



of grit, rags, and large suspended materials in the existing CCCSD  plant



before being conveyed to the pilot plant, where lime was  added to remove



suspended solids  and phosphorous in the first stage flocculation-sedi-



mentation processes.  Carbon dioxide was then added to reduce the pH

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PRIMARY EFFLUENT
(PHASE I) OR ACTIVATED
SLUDGE EFFLUENT
(PHASE II)
               rrrfrj
                             PILOT
                   BIOLOGICAL
                     STAGE
                                                                     CARBON
                                                                     ADSORPTION
                                                                     STAGES
                  SEDIMENTATION
RAW    — — J—
INFLUENT
PHASE III   FLOCCULATION
                                                                        CARBON
                                                                        ADSORPTION
                                                        WET             STAGES
                                                        WELL FILTRATION ^~~\   S~~\

                                                            f-^*l
                                                               +       ^
                        TEST LOOPS
                                                            LEGEND
        RENOVATED
          WATER
RENOVATED
  WATER
                                                                          PHASE
                                                             	   PHASE II
                                                             	PHASE III
                                             SLOWDOWN
                                            SLOWDOWN
                                 HEAT
                              EXCHANGER
                       CONDENSATE
                                            SLOWDOWN
           Figure  2-1.   Process Flow Diagram for the Pilot
                           Demonstration Facility

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prior to the removal of excess calcium in the  second stage flocculation-

sedimentation processes.  Filtration followed for the removal of the re-
maining suspended solids, and activated  carbon treatment was used to re-
duce the organic carbon content of the filtered effluent.  After chlorination,
a portion of the treated wastewater was used as makeup water for the in-

dustrial test loops.   Filtered chemically treated effluent was also used as
cooling water makeup.


In addition to testing various grades of renovated water  in the industrial
test loops, the Contra Costa Canal water that  is presently used by indus-
tries in the area was  also tested.   Such tests permitted  direct comparison
of the  renovated waters with the existing water source.


Conclusions regarding industrial  reuse and the various  treatment se-
quences investigated in this  study are discussed in this  section.  Re-
commendations based on the pilot-demonstration investigations are also
presented.


CONCLUSIONS


Industrial Reuse
         Based on the industrial test loop studies, wastewater
         can be treated satisfactorily for  reuse in industrial
         applications.   Major areas of concern for cooling
         water reuse are calcium, sulfate,  phosphate,  and
         silicate as they relate  to scaling, and the maximum
         cycles of concentration one  can maintain without
         excessive maintenance  costs.  Organics and total
         dissolved solids (TDS) are the most important
         factors affecting boiler feed water treatment costs.
         The  corrosion rate of carbon  steel as determined
         with corrosion coupons, for all renovated waters
         tested without  the use of corrosion inhibitors,
         ranged from 2.0 to 31  mils/year, which was less
         than that  for untreated canal "water ( 12. 5 to 37
         mils/year).  Canal water with the addition of a

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    corrosion inhibitor was observed to have a corrosion
    rate of 2. 7 mils/year.  Based on these  results, it
    can be concluded that renovated water can be pro-
    duced  that is substantially less corrosive than un-
    treated canal water.

•   Fouling of heat exchanger surfaces by renovated
    wastewater was approximately equal to  that of
    the untreated canal water.  The fouling  factors
    ranged from 0. 0005 to 0. 004 hr-°F-sq ft/Btu
    for. the renovated waters  and 0. 0005 to 0. 003
    hr-  F-sq ft/Btu  for the untreated canal water.
    Based on these results,  it can be concluded that
    renovated water  can be produced that will not
    cause  any greater fouling problems than un-
    treated canal water.

•   Precipitation of phosphorous was the major source
    of scale  formation while  using renovated wastewater
    for cooling purposes, thus indicating the need for
    phosphate removal.   The phosphorous concentration
    in the  renovated  water should be 0. 5 mg/1 as P or
    less in order to minimize scaling problems.
•   Where chlorine is used in cooling water systems for
    the control of biogrowth,  it would be desirable to
    remove ammonia from renovated water used for
    makeup purposes in order to reduce  chlorine re-
    quirements.  An effective removal procedure is
    the biological nitrification process in which ammonia
    is converted to nitrate.

•   Since nitrate does not limit the cycles of concentration
    attainable in the  operation of cooling towers, the need
    for denitrification cannot be justified on such a basis.
    However, lower  algal growth anticipated with denitri-
    'fied effluent compared to nitrified effluent suggests
    that denitrification may be helpful.

•   Filtration of renovated water not only improves the
    water  quality but also reduces potential problems
    arising from the deposition of suspended solids in
    industrial heat exchanger equipment.  With  filtered
    renovated water, this problem would not be as great
    as normally encountered during  the use of canal  water.

•   Activated carbon treatment would  not be required for
    biologically treated wastewater for its reuse as in-
    dustrial cooling water.    If renovated water  is to  be
    used for boiler feedwater, it may  be more economical
    for industry to provide any additional treatment,  such
    as activated carbon,  for  that portion of the  water used
    for such purposes.

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Biological Treatment
    •    Biological nitrification in a conventional single-
         stage activated sludge system, can be achieved
         provided the sludge age is greater than 10 days
         and the dissolved oxygen is maintained at greater
         than 2. 0  mg/1.  A two-stage biological system
         designed to  achieve nitrification is significantly
         more reliable and less difficult to control than
         a single-stage system.
    •    The presence of a limited concentration of organic
         materials in the nitrification reactor influent of a
         two-stage biological system is necessary to promote
         a required synergistic relationship between the nitri-
         fying bacteria and the heterotrophic bacteria.   These
         organic materials should have a total organic  carbon
         (TOC) concentration of approximately 30 to 50 mg/1.
         Reduction of organic  materials in typical municipal
         wastewaters to this level can be achieved with a high
         rate activated sludge system,  a  trickling filter,  or a
         chemical-primary treatment process.

    •    The pilot plant denitrification  data were quite  variable
         due to difficulties encountered with the methanol feed
         system and  solids separation.  Effluent nitrate con-
         centrations  ranged from less than 1 mg/1 to 20 mg/1
         and averaged about 3. 2 mg/1,  indicating an average
         removal  of  82 percent.  With an improved  methanol
         feeding system and an aeration step between the de-
         nitrification reactor and the final clarifier, as found
         necessary in subsequent studies to improve solid
         separation,  the denitrification process can be ex-
         pected to perform satisfactorily.
Physical-Chemical Treatment
         Chemical treatment resulted in the most consistent
         effluent quality of all the pilot plant processes in-
         vestigated during the study.  Total phosphorous re-
         movals averaged about 97 percent, and about 70
         percent of the total organic carbon (TOC) was  re-
         moved in the chemical  treatment system.

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e   Ferric chloride at a concentration of approximately
    15 mg/1 enhanced the coagulation of insoluble pre-
    cipitates formed in the  second-stage flocculation unit.
    In a large-scale treatment plant,  recycling lime sludge
    or using coagulant aids would be expected to perform
    as well as the ferric chloride for this purpose and would
    thus minimize potential sludge handling problems.

e   Because of the organic  carbon concentration remaining
    after chemical treatment,  either activated carbon or
    biological oxidation is  required to  lower the concentration
    of total organic carbon  in the effluent to about 10 mg/1.

•   The chemically treated effluent turbidity was approximately
    5 JTU.  This turbidity was  reduced by only 20 to 40 percent
    by filtration.  Improved filter performance may be expected
    if a polyelectrolyte or  alum is added to the  filter influent.

•   Filtration following biological treatment increases process
    reliability, improves effluent quality,  and  should  enhance
    disinfection as a result of significant decreases in the
    effluent suspended materials.

«   Chlorination  of the filtration process influent should be
    provided to prevent biological growths and subsequent
    clogging of the filter media.

»   The data obtained in this study indicate that if activated
    carbon treatment is  employed,  a carbon contact time of
    approximately 15 minutes would be suitable for biologically
    treated effluents and 30 minutes for chemically treated
    effluents.  Organic carbon  removals averaged only about
    2 or 3 mg/1 in the second stage of the activated carbon
    process when the contact time in each carbon stage was
    25  to 30 minutes.

«   The pilot plant data indicated that  approximately 410 pounds
    of activated carbon per million gallons  of water treated would
    be  required for biologically treated effluents,  and 690  pounds
    per million gallons would be required for chemically treated
    effluents.

•   While activated carbon  reduced the total organic carbon
    concentration of the  biological effluents to  values  as  low as
    2. 0 mg/1, the reduction generally represented less than 10
    percent of the total organic carbon removed from the raw
    wastewater.  Since only 70 percent'of the total organic carbon
    is removed by chemical treatment, activated carbon treatment
    of chemically treated effluents would be required.
                               10

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Related Studies
    •    Various units in the treatment sequences of the pilot
         plant were spiked with poliovirus and monitored to
         determine the degree  of inactivation resulting from
         each treatment step.  Essentially all of the poliovirus
         was inactivated within five minutes of exposure in the
         first-stage lime flocculation unit when  the pH was 11
         or above.  Contact with the lime  sludge at an operating
         pH between 10 and 11  and with biological sludges re-
         duced the active viral count by three to four orders of
         magnitude.  Activated carbon treatment removed about
         75 percent of the virus, whereas little  or no viral removal
         occurred  during filtration or sedimentation.

    •    Results of Provisional Algae Assay Procedure (PAAP)
         tests demonstrated that there was little or no growth of
         the test algae for  at least 15 days in the chemical treat-
         ment effluent,  indicating that algal growth can be mini-
         mized by  the removal of phosphorous.  Denitrified effluent
         resulted initially in a  logarithmic growth of algae, although
         after approximately five days the rapid growth stopped,
         thus  suggesting that nitrogen became the limiting nutrient.

    •    Cooling tower circulating water  which had approximately
         five cycles of concentration was not toxic to fish (stickle-
         back) after 96 hours of exposure, when canal water,  nitrified
         effluent, filtered nitrified effluent, filtered chemical treat-
         ment effluent,  and activated carbon chemical treatment
         effluent were  used as  cooling water makeup.

    •    Heavy metals and trace organics, including pesticides,
         phenols, and detergents, are generally reduced by 50 to
         99 percent in  the biological, chemical,  and physical
         treatment-renovation  processes.

    •    Treatment costs for the various sequences  investigated are
         summarized in Figure 2-2 for 30-mgd plants.  All of
         the costs  are based  on mid-1972 prices as discussed
         in Section 6.  The treatment costs range from approxi-
         mately 25^/1000 gal for conventional  activated sludge
         treatment to 50^/1000 gal for a three-stage biological
         treatment system  with filtration and  alum addition for
         phosphorous removal   Chemical treatment preceding
         biological nitrification, biological denitrification, and
         filtration  costs approximately 41^/1000 gal.  This treat-
         ment cost was within the range of costs associated with
         physical-chemical treatment including nitrogen removal
         (i.e., approximately 38 to 45^/1000  gal).
                                  11

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CENTS/1000 GAL
S 8 o S S
-

1
2
3
4


1
2
5
6
3
4


1
2
5
7
6
3
4


2
8
5
9
10


1
2
5
7
6
9
10
-
s § « §
DOLLARS/AC RE- FOOT
       PHASE I
PHASE II
PHASE IIA    PHASE HI   PHASE IIIA
1  - SLUDGE
2  - CI2
3  - ACTIVATED SLUDGE
4  - PRIMARY
5  - FILTRATION
           6 - NITRIFICATION
           7 - DENITRIFICATION
           8 - ACTIVATED CARBON
           9 - CHEMICAL TREATMENT CALCINATION
          10 - INFLUENT WORKS
Figure 2-2.  Approximate Treatment  Costs for 30-mgd Plants
                               12

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RECOMMENDATIONS
The following recommendations are offered for consideration:
         Additional investigations should be conducted on the
         biological denitrification process in order to develop:*

         —   Improved control of the methanol feed.  (A con-
             tinuous TOC analyzer or a selective nitrate probe
             may be satisfactorily used for this purpose. )

         —   Improved solids separation of mixed liquor sus-
             pended  solids.  (Intermediate aeration between
             the denitrification reactor  and the sedimentation
             basin may be desirable.  Dissolved air flotation
             may also be worthy of further study. )

         Further studies on the activated carbon process are
         recommended to:

         —   Optimize the  carbon contact times  required for
             biologically and chemically treated effluents

         —   Evaluate the necessity of filtration preceding
             activated carbon treatment

         —   Further investigate methods  to eliminate the
             generation of noxious odors in carbon columns

         —   Investigate  the advantages  and disadvantages of
             using two carbon  stages in series  versus a single
             stage, as well as the  expanded bed mode of operation
             versus  the packed bed

         Sludge disposal  methods should be evaluated to:

         —   Determine optimum dewatering methods such as
             vacuum filtration and centrifugation

         —   Ascertain fuel requirements  and product recovery
             values associated with incineration and recalcination

         —   Establish the market  value of digested sludge as a
             liquid fertilizer and,  after drying,  as a  soil condi-
             tioner
 Since the time the pilot plant results presented in this  report were
 completed,  CCCSD has conducted additional large-scale studies on
 the denitrification process.
                                 13

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                               Section III





                     EXPERIMENTAL PROGRAM








DESCRIPTION OF FACILITIES








A process flow diagram of the wastewater renovation pilot plant facili-



ties and the industrial test loops are presented in Figure 2-1.  The pilot



plant facilities consist of biological processes (activated sludge,  nitri-



fication,  and  denitrification), physical treatment processes  (filtration



and activated carbon adsorption), and the chemical treatment processes



of lime coagulation and flocculation.  The industrial  test loops  used during



this study were designed to simulate the use of cooling water in industrial



applications.   Figure 3-1 is a perspective drawing showing the relative



locations of the pilot plant facilities and  the industrial tests  loops.








Pilot Plant Facilities








In Figure  3-1, the rectangular basin labeled biological stage was 8 feet



wide,  16  feet long,  11  feet deep, and contained 32 submerged air diffusion



units (Chicago Pump).   This vessel was  initially used as a conventional



activated sludge basin treating primary effluent from the CCCSD plant.



Later the active volume of this  vessel was reduced by baffling, and  the



vessel was used as  a nitrification basin treating activated sludge effluent



from the  CCCSD 1 -mgd plant.








The biological denitrification basin was 5 feet 6 inches in diameter and



11 feet deep.   During the testing period on biological denitrification, this



basin was continuously  stirred with a submersible pump.  Methyl alcohol
                                  15

-------
    CLEAR WELL
SLUDGE STORAGE

  FLOCCULATION
                                                                                                 HEAT EXCHANGERS
                                                                                               AND COOLING TOWERS
                         BACKWASH WATER


                                    WET WELL
                                                                    PRIMARY OR ACTIVATED
                                                                       SLUDGE  EFFLUENT
                                      BIOLOGICAL
                                    DENITRIFICATION
                                                                                                                  SLUDGE
                                                                                                                  STORAGE
WET
WELL
                     Figure 3-1.   Perspective Drawing of Pilot-Demonstration Facilities

-------
was  added continuously to the denitrification basin using a variable-



speed diaphragm pump.  For a short period of time,  the denitrification



basin was used for biological nitrification since it was initially equipped



with air diffusers.








All sedimentation basins used in the pilot facilities were designed identi-



cally.   These basins were 6  feet in  diameter and 9 feet 11  inches deep with



an external peripheral effluent channel near the overflow weir.  A 60-de-



gree cone bottom,  constructed in each basin,  was connected to a horizon-



tal pipe located near the bottom of the basin for sludge withdrawal.








Lime addition  to the physical-chemical pilot plant influent (i. e. ,  partially



settled  raw wastewater) was regulated by a. preset pH controller (Uniloc



Model 1000).   The pH sensor was located in the first stage flocculation tank,



and  the pH was continuously  recorded in  the laboratory trailer.








The  flocculation tanks  in the physical-chemical system were each Z feet



6 inches in diameter and 3 feet 4 inches deep.  Three flocculation tanks



were provided for  each stage of treatment.  Inlet and outlet piping was



provided to facilitate removing any  one or all  of the flocculation tanks



from the operation.  Each operating flocculation tank was  equipped  with  a



clamp-mount variable-speed mixer  (Lighting Model ND-1YM)  with a flat



blade turbine impeller.








Recarbonation between the first and second  stage of the chemical treatment



system was provided in a tank Z feet 6 inches  in diameter  and  10 feet deep.



Bottled carbon dioxide gas was introduced through a diffuser into the  bottom



of the recarbonation tank,  countercurrent to the liquid flow.  Following re-



carbonation, precipitated calcium carbonate was flocculated with ferric



chloride used as a coagulant. The ferric chloride was  added continuously



(using a diaphragm pump) to the flocculator  in the second  stage of the



chemical treatment system.
                                  17

-------
The effluents from the biological processes  and the chemical treatment



process were given additional physical treatment of filtration follow-



ed by two stages of activated carbon adsorption.  The filtration equip-



ment  consisted of three 20-inch diameter pressure filters (Bruner,



Model AG20), each containing different media,  as illustrated in Figure 3-



Filters No. 1 and No.  2 contained anthracite coal (0. 68 to 0. 77 mm effec



tive size,  1.75 uniformity coefficient) and graded sand (0.45 to 0.55 mm



effective  size, 1. 50 uniformity coefficient).   Filter No.  3 contained mixec



media (Neptune Microfloc; MF-152) consisting  of anthracite, sand, and



garnet.  Each stage in the activated carbon  system included a pressurizec



36-inch diameter vessel (Bruner, Model AC36) containing granular carboi



(Filtrasorb 400,  Calgon Corporation) at a  depth of 2. 5 feet.  Graded grave



was used to support the filtration media as well as the activated carbon.



Backwash rates of approximately 20 gpm/sq ft  and 6 gpm/sq ft were used



for the filters and  the carbon columns, respectively.  Surface wash mecha



isms  were installed in each filter and carbon column.
FILTER
NO. 1
r 	 1

ANTHF
N
CN
CO
(ACITE
SAND
GRADED
GRAVEL
-JU
20"

. .
FILTER
NO. 2
r i
ANTHRACITE
n
^ SAND
GRADED
: GRAVEL
r^
20"

. .
FILTER
NO. 3

-------
Existing Treatment Plant








The  existing treatment plant at CCCSD provides primary treatment to the



incoming wastewater preceded by screening and grit removal.  Approxi-



mately 30 minutes detention time is provided in the  aerated grit chamber



thus providing pre-aeration as well as grit removal.  The design detention



time in the primary sedimentation tanks  for a 30-mgd average daily flow



is 1-1/2 hours.








Sludges from the primary sedimentation  tanks are anaerobically digested,



dewatered on drying beds,  and sold as a  soil conditioner.   The grit removed



from the  wastewater is  dewatered and buried on the plant site.  Gas pro-



duced  during anaerobic  digestion is used for fuel to  operate gas engines  used



for generation of electricity.  Digester supernatant  is returned to the plant



influent.








Pre-chlorination and post-chlorination of the wastewater is practiced, and



the chlorinated effluent is discharged to Suisun Bay  through an outfall pipe-



line.   The primary effluent used in the pilot plant study was pumped to the



pilot facilities before post-chlorination.








In addition to the 30-mgd primary treatment plant, a conventional activated



sludge plant having a nominal capacity of 1 mgd is located at CCCSD.  Pri-



mary effluent is treated in this plant and used for surface sprays and ir-



rigational needs at the plant site.  The activated sludge basin is rectangular



in shape and is aerated  using blowers connected to a diffused aeration



system.  A detention time  of approximately 6  to 8 hours is provided in this



basin.  The  sedimentation  basin  is also rectangular in shape providing a



detention time of about  2 hours.
                                  19

-------
 Industrial Test Loops







 Three industrial test loops, each consisting of a small cooling tower,



 heat exchanger,  and appurtenances, were included in the pilot-demon-



 stration facilities.  The cooling towers were 3 feet by 4 feet in plan with



 20 inches of packing,  which was constructed of  1 /4 inch by 1-1/2 inch



 redwood splash bars having 2 inch  horizontal spacing and 1-5/16 inch




 vertical spacing (Marley Model 4411).







 Each heat exchanger consisted of a steel shell,  with  1/2 inch steam inlet



 and outlet,  having an outside diameter of 4- 1 /2  inches (Schedule 40  pipe)




 and a length of 3 feet.  The heat exchanger  shell contained two 5/8 inch



 OD carbon  steel removable tubes,  each having a wall thickness of 0.065 inch



 (Calgon,  Model Test Heat Exchanger).








 The industrial test loops were  equipped with appropriate valves,  steam



 traps,  strainers,  rotometers,  pressure gauges, and  thermometers to



 facilitate their operation.   Also,  a  corrosion probe  (Magna) for instantaneous



 corrosion rate measurements and a corrosion test specimen bypass  loop



 (Betz, Model No.  35D000110) were located  in the circulating water on the



 heat exchanger tube outlet of each industrial test loop.








 Two sources of steam were used in the industrial test loops.  Excess steam



 available  at 15 psi from the CCCSD plant was piped  to the pilot plant area to



 serve as one source.  The  other source was produced at the pilot plant site



using  a  vertical firetube boiler (Eclipse, Type Z).  This boiler was rated



at 173 Ib steam/hour with a maximum operating pressure of 150 psig.



Boiler feed  water was filtered using cartridges  and  softened using ion ex-



change (Culligan Mark 5 Model CF-28-40).
                                 20

-------
PHASE
1
II
II
l&ll
III
III
TEST
LOOP
1
2
3
BOILER


1971
JAN


FEB
I I

MAR
I I

APR
1 |

MAY


ACTIVATED SLUDGE SYSTEM





JUNE
|

JULY
|

AUG
|

SEPT
| |

OCT
|

NOV


NITRIFICATION SYSTEM







DENITRIFICATION SYSTEM







FILTRATION^ACTIVATED FILTRATION & ACTIVATED CARBON
ACTIVATED SLUDGE EFFLUENT ^EFf?'




T




DENITRIFIED EFFLUENT





CHEMICAL TREATMENT SYSTEM (LIME)
REATME








FILTRATION & ACTIVATED CARBON
CHEMICAL TREATMENT EFFLUENT
ENT PLA

NT OPE

RATION

CANAL WATER






ACTIVATED SLUDGE EFFLUENT ^EFF""'






ACTIVATED SLUDGE w-i.pj.Ar
& FILTRATION IN-I-I-I-W,







SCHEDl

JLE





CANAL WATER _ iC 1
& Cl C +F I




DENITRIFIED EFFLUENT C+F+AC





DENITRIFICATION C+F+
& FILTRATION AC+CI





CANAL WATER PLANT STEAM CANAL PLANT D+F+AC PLANT STEAM


INDUSTRIAL TEST LOOP OPERATION SCHEDULE
1
LEGEND: NITRIF
Cl CORROSION INHIBITOR EFF.
C CHEMICAL TREATMENT (LIME) AC
F FILTRATION N
D
I I
I I I
_LJ_
1 1

_L_LJ
_L


NITRIFIED EFFLUENT
ACTIVATED CARBON
NITRIFICATION
DENITRIFICATION
m
1 I 1
J_
J_
Figure 3-3.  Pilot-Demonstration Plant Operating Schedule
                           21

-------
 OPERATING PROGRAM

 Operation of the pilot facilities was divided into three phases.  In addition
 to process evaluation, the major purpose of the experimental program was
 to test the use of the various renovated product waters in the  industrial test
 loops.  Activated sludge,  nitrification-denitrification,  and physical-
 chemical treatment processes were tested and evaluated, in Phases I
 through III,  as  discussed below.  Figure 3-3 summarizes the operating
 schedule for the entire period of the pilot plant study.  The upper portion
 of the figure refers to the operation of the treatment plants and the  lower
 portion refers to the periods when treated wastewaters were fed to  the
 industrial test loops.

 Phase I
 The treatment system adopted during Phase I consisted of activated
 sludge, filtration,  and activated carbon adsorption, as shown by the
 solid line in Figure 2-1.   The operation extended from January 6,  1971,
 through May 18, 1971.  On May 3,  1971,  effluent from the activated sludge
 process was used to start the second-stage biological (nitrification)
 culture.  At the same time, the detention time in the activated sludge
 aeration basin was reduced by approximately one-half.  The  test loop
 operation started on January 20,  1971, with Loop 1 receiving the
 Contra Costa Canal water, Loop 2 receiving activated sludge effluent,
 and Loop  3  receiving filtered activated sludge effluent.  The  canal
water was also used for boiler feed after  it was treated with  cartridge
filters and softened by zeolite resin.
                                 22

-------
Phase II







During the operation of Phase II, the CCCSD activated sludge effluent



was used as  the influent to the pilot plant facilities  (dotted line Figure



2-1).   The Phase I activated sludge basin was used for the biological



nitrification  basin,  and the denitrification reaction  was carried out in



the basin that was used for nitrification during Phase I.  Nitrified



effluent from the  Phase II treatment system was filtered and treated



with activated carbon from May 20 through June 30, 1971.  From July 1



until  November 4, 1971, the filters and activated carbon units were used



for treatment of the denitrified effluent.







Chemical addition for phosphate removal was  investigated during this



phase.  The  denitrification reactor was dosed with  ferric chloride  from



June  16 through September 2, 1971 and with alum from September  3



through October 26,  1971.   In addition, during the week of September 20,



polymer was added to the influent of the denitrification sedimentation



basin.









During this phase,  Loop 1  continued to receive Contra Costa Canal



water and, until June 30,  Loops 2 and  3 received nitrified effluent be-



fore filtration and after carbon adsorption,  respectively.   On July 1



and until October 29,  Loops 2 and 3 received  the denitrified effluent



before and after filtration,  respectively.  The boiler continued opera-



tion as in Phase I until June 15, at which time CCCSD plant service



steam was used in the industrial test loops.  From July 15 through



August 15, denitrified effluent after carbon adsorption was used as the



boiler feedwater.  The 15-psi CCCSD plant, service steam was utilized



during the remainder of the project.
                                 23

-------
 Phase III







 An evaluation of the physical-chemical treatment system was made    ,



 from March 15 through November 23, 1971.  After approximately 10



 minutes of sedimentation,  the partially  settled raw wastewater was



 flocculated with lime at a pH value of approximately  11.0 and recarbon-



 ated to pH 9 to 9. 5.  The calcium carbonate formed after  recarbonation



 was flocculated with approximately  30 to 40 mg/1 of  ferric chloride to



 improve floe formation before final sedimentation.  During the period



 from October 29 through November 23,  the industrial test loops were



 used to  investigate effluents from the physical-chemical treatment system.








 The filtered effluent from the two-stage chemical treatment plant was fed



 directly to Loop 1, whereas Loops 2 and 3 received the filtered water



 that had the additional benefit of treatment with activated, carbon.   An



 average of about 25.0  mg/1 of zinc-chromate (Nalco  370) was added to



 the influent water  of Loop  3 to determine its impact on any fouling  or



 corrosion that might develop.








 SAMPLING AND ANALYSIS PROGRAM








 A sample  collection and analysis program  was  established to monitor



 the performance of the pilot facilities.  Descriptions of the laboratory



 facilities,  sampling program,  and analytical methods are  presented below.







 Laboratory Facilities








A trailer laboratory located at the pilot plant site served as the center



for the sample preparation and analysis.  The  CCCSD Laboratory and



Bechtel Environmental Laboratory at Belmont  were used for  special



analyses such  as fish toxicity  studies and algae growth tests.   The  trailer



laboratory was equipped  to handle the routine analyses.
                                 24

-------
Sampling Program








Samples were  collected at several points in the treatment system during



each phase of the pilot plant studies,  as indicated in Figure 3-4.  The



composited samples  were collected daily and were analyzed for specific



constituents on a daily basis.  Additional analyses were performed



either three times a  week or weekly.  Appendix A summarizes the



sampling frequencies.  Automatic samplers,  which collected approxi-



mately 250 ml of sample each hour,  were generally used to provide the



daily composited sample for all analyses except for mixed-liquor solids



in the  biological units.  The latter samples were daily "grab" samples



since the concentration of these solids did not greatly change during a



24-hour period.








Because of clogging problems encountered with the automatic samplers



handling the influent  raw waste to the physical-chemical pilot plant,



samples were  taken manually  every  8 hours and composited for analyses



for this particular stream.








Analytical Procedures








Analytical methods used in the program generally followed References 2,



3, and 4 (the 12th Edition of Standard Methods and ASTM procedures).



Table  3-1  summarizes the methods used and the source references for



the procedures.  Some modification of certain methods was necessary



to assure thorough analytical coverage.  Appendix A gives  a detailed



description of the procedures  and instrumental methods used in this study



that are not available in the 12th Edition of Standard Methods.   Rigorous



sample preparation techniques stressing acid digestion and blending were



developed for the heavy metal  analyses.
                                  25

-------
PRIMARY EFFLUENT
(PHASE II OR ACTIVATED
SLUDGE EFFLUENT
[PHASE III         -
                               PILOT PLANTS
  CHEMICAL
  FEEDER
  BIOLOGICAL
    STAGE  V
                    AIR

                     RETURN SLUDGE
BIOLOGICAL DENITRIFICATION
T i


s


RETURN SLUDGE |
                                           	A	
                                          'SEDIMENTATION
                                                      CARBON
                                                      ADSORPTION
                                                      STAGES
                                                                          CARBON
                                                                          ADSORPTION
                                                                          STAGES
 RAW    	' —
 INFLUENT
 PHASE III   FLOCCULATION
                          TEST LOOPS
          RENOVATED
            WATER
 RENOVATED
                                                                              PHASE I
                                                           PHASE II
                                              — —	— —  PHASE III

                                              SAMPLING POINT
                             H     HEAT
                              *  EXCHANGER
                         CONDENSATE
   Figure  3-4.   Sampling Points in  the Pilot-Demonstration Facility
                                        26

-------
                                   Table 3-1

                         ANALYTICAL PROCEDURES
        Determination
                Method
Reference
Conductivity
pH
Turbidity
Total Solids
Dissolved Solids
Suspended Solids
Biochem Oxy.  Dem. (BOD)
Detergents  (MBAS)
Carbon Chloroform Extr.
Total Organic  Carbon (TOC)
Soluble Organic Carbon (SOC)
Organic Nitrogen
Phenol
Pesticides
Alkalinity
Ammonia
Boron
Calcium
Chloride
Chromium, Hexavalent
Copper
Hardness
Iron
Magnesium
Nitrate
Phosphate,  Ortho
Phosphate,  Total
Potassium
Silica,  Dissolved
Silica,  Total
Sodium
Sulfate
Trace Metals (Dissolved)*
Trace Metals (Total)*
Mercury
Selenium
Wheatstone Bridge
Glass Electrode
Photometric
Gravimetric
Gravimetric
Gravimetric
5-day Incubation
Methylene Blue
Direct CHC13 Extr.
Combustion-IR (Sample Unfiltered)
Combustion-IR (Sample Filtered)
Kjeldahl
Colorimetric - Distillation
Electron Capture G/l Chrom.
Titration
Nessler
Cur cumin
EDTA Titration
Mohr
Colorimetric
Cuprethol
EDTA Titration
o - Phenanth r oline
EDTA Titration
Reduction
Colorimetric
Colorimetric
Atomic Absorption
Colorimetric
Emiss, Spectrograph
Atomic Absorption
Gravimetric
Atomic Absorption
Emiss. Spectrograph
Colorimetric
Colorimetric
       2
       2
       2
       2
       2
       2
       2
       2
       2
       2
       2
       2
       2
       2
       2
       2
       2
       2
       2
       2
       2
       2
       2
       2
       2
       2
       2
       2
       2
       4
       3
       2
       4
       4
       2
       2
*Trace Metals include aluminum, arsenic, barium, boron, cadmium,  chromium (tot;
chromium (hex. ),  cobalt, copper, iron, lead, lithium,  manganese, mercury, molyb-
denum, nickel,  silver,  strontium,  tin, titanium, vanadium, zinc,  and zirconium.
                                      27

-------
                               Section IV





         RESULTS OF WASTEWATER TREATMENT STUDIES








The results from Phases I, II, and III of the pilot plant studies at the



CCCSD treatment plant are presented and evaluated in this Section.  A



description of the experimental results from the industrial test loops is



presented in the following section.








PHASE I:  BIOLOGICAL-PHYSICAL  TREATMENT SYSTEM








The biological treatment  system was operated initially as  a conventional



activated sludge plant and later as a  multistage  plant for biological



nitrification and denitrification (Figure 2-1).  Physical treatment con-



sisted of filtration through dual or mixed-media filters followed by activa



ted carbon adsorption.  At different times during the study, the  effluent



from the various biological-physical process steps was conveyed to the



industrial test loops  for  evaluation of its suitability for industrial use.








Pilot Plant Activated Sludge








The activated sludge process  was in  operation from January 6 through



May 18, 1971.  Figure 4-1 indicates  the  flow and general  characteris-



tics of the activated  sludge system.  The mixed-liquor  suspended-solids



concentration during the first month  was approximately 2000 mg/1 and



then increased to a steady-state  concentration of about 3000 mg/1 during



the remaining periods.   The volatile  suspended  solids (VSS) in the



mixed liquor averaged 80 percent, whereas the  sludge volume index



(SVI) averaged 250 ml/gm during the test period.
                                 29

-------
The net growth rate in the system,  defined as the mass of solids pro-



duced per unit time per  unit mass of solids in the reactor,  was quite



variable during the first part of January and then remained at a steady-



state value of approximately 0. 04 day    dujring the latter part of



January and  February (Figure 4-1). Although the net growth rate was



relatively low for activated sludge (typical values are 0. 05 to  0. Z day  )



during this period, the degree of nitrification was also low, as indicated



by the  influent and effluent ammonia concentrations shown in Figure 4-2.



This is believed to have resulted from the 0. 5 mg/1  minimum DO con-



centration maintained in the activated sludge mixed liquor.
                     NET GROWTH RATE






                        SUBSTRATE REMOVAL RATE
    •o8
    - >

60
40
0
%vs§__~^_^-v-

' MLSS



. 	 ."'


%A_
'"' '"-''' " 	 '" '•-.„...

L. _^-


*~"
                 JAN
                               FEB
                                             MAR
                                      1971
                                                            APR
                Figure 4-1.
Activated Sludge Process


Operating Characteristics
                                  30

-------
As indicated in Figure 4-2,  the  activated sludge influent ammonia con-
centration was usually between 20 and 30 mg N/l.  Some nitrification
did occur in the activated sludge unit as indicated by the increase in
nitra'te-N during January and again in March.   However, this single-
stage system was not consistently nitrifying, and thus rather high efflu-
ent ammonia concentrations were observed for a significant  amount of
the time.  During the latter part of March and early April, the DO was
increased to 2. 0 mg/1 and the effluent ammonia-N concentration was very
low.  However, the concentration increased somewhat by early April
and remained at approximately  10 mg/1 N thereafter.  The data plotted
in Figure 4-2 suggest that by maintaining a DO of about 2. 0 mg/1,  in
   Su  "°
   § S  30
   h- ?  M
   2    10
        0
       120
   2 > 100
   O E
   5 §  80
   a. —  60
   
-------
 conjunction with a net growth rate of about 0. 1 days   (Figure 4-1), it



 is possible to obtain consistently a 50 percent reduction in the influent



 ammonia-N concentration with the activated sludge process.
 The effluent suspended  solids concentrations were found to be quite



 variable, primarily because of floating materials in the secondary sedi-



 mentation tanks.  These materials did not appear to be typical floating



 activated sludge.  Instead, the materials appeared to consist of small



 globules with attached activated sludge floe  and filimentous organisms.



 This problem indicated  the need for permanent skimming equipment on



 the secondary sedimentation tanks.   The influent suspended solids  aver-



 aged 80 mg/1 and the  effluent 33 mg/1 during this testing period.








 The activated sludge influent TOC concentration averaged  about 80 mg/1



 with a minimum of  55 mg/1 and a maximum of  130 mg/1 (Figure 4-2).



 While  the SOC concentrations in the activated sludge effluent were  nearly



 constant at  about  9  mg/1, the effluent TOC varied in relationship to the



 effluent suspended solids and averaged about 26 mg/1.








 In May, the loading on the activated sludge system was increased by block-



 ing off a portion of  the aeration basin volume.  The effluent was then split



 with one stream going to the filtration and activated carbon systems and



 the other  stream  to a separate nitrification  basin.  A nitrifying culture



 had been  established a few weeks earlier.








 The activated sludge and nitrification proces s data for this operating period



 are summarized in  Table 4-1.  The degree  of nitrification obtained during



 this short period  of time indeed suggested that multistage  biological treat-



ment had  much greater  potential  of nitrification than a single-stage biologi-



 cal process.  The pilot  plant operation was  thus modified to a three-stage



 system to provide carbonaceous BOD removal  in the first  stage,  nitrifica-



tion in the second stage, and denitrification in  the third stage,  as des-



 cribed in  Section  3  for the Phase II operation.
                                  32

-------
                       Table 4-1
PRELIMINARY ACTIVATED SLUDGE/NITRIFICATION DATA



Flow, gpm
Activated Sludge
Influent
SS, mg/1
TOC, mg C/l
SOC, mg C/l
Ammonia, mg N/l
MLSS, mg/1
Effluent
SS, mg/1
TOC, mg C/l
SOC, mg C/l
Ammonia, mg N/l
Nitrate, mg N/l
Nitrification Effluent
TOC, mg C/l
SOC, mg C/l
Ammonia, mg N/l
Nitrate, mg N/l
May
10,
1971
16


163
102
22
21
1840

12. 8
16
9.5
13
3



4
23
May
12,
1971
16


128
82. 5
20. 3
26
1750

120 6
20
11.6
20
4

15
7.2
0. 6
24
May
13,
1971
16


148
'92
20
20
1980

62. 5
35
7.0
11
8

17
5. 3
1. 5
30
May
14,
1971
16


118
80
16
23
2180

51.0
29
6,2
9
9

11
4.6
0.6
31
May
17,
1971
16


77
64
16
29
1930

35.6
33
24
24
2

13
5
8
23
May
18,
1971
9. 3






2230







10
4.8
5
21
                           33

-------
Filtration




Effluent from the biological treatment processes  generally contained 10 to

30 mg/1 of suspended solids.   These solids contributed significantly to the

effluent total organic content.  Filtration of this effluent can, however,  in-

crease the plant reliability and result  in a much more consistent effluent

quality.   Figure 4-3 summarizes the influent and effluent TOG and turbidity

data for the three types of filter media investigated during this  study at a


filtration rate  of 5. 0 gpm/sq ft.   The TOG concentration of the  filtered ef-

fluent approached that of the SOC (10 to 20 mg/1),  indicating that the filters


were removing most of the suspended  organic material.  The filtered ef-

fluent turbidity was generally less than Z JTU,  and it was  much better in

quality than the unfiltered  activated sludge effluent.
  Z
  O
  m
  DC
  O S
  Z^
  < ?
  O *-
  QC
  O
H
Q
m
o:
D
I-
    50


    40

    30

    20

    10

    0
40


30

20


10

 0
                    INFLUENT TOC
                           EFFLUENT TOG
                              FILTER IN OPERATION
                   ^INFLUENT
                             EFFLUENT
              JAN
                             FEB
                                            MAR
                                                            APR
              Figure 4-3.  Filtration Data Using Activated

                           Sludge Process Effluent



 The average percent  removals  of TOC and turbidity are summarized

 in Table 4-2.  The removals observed indicate very small  difference

 in the three types  of filter media tested.   Filter No.  3,  the mixed media,

 appeared to have somewhat higher removal efficiencies than  Filter Nos.

 1 and 2.  However, the influent TOC and turbidity concentrations to
                                   34

-------
                              Table 4-2

        SUMMARY OF FILTRATION PERFORMANCE USING
            ACTIVATED SLUDGE PROCESS EFFLUENT
Filter
No. 1 (Dual Media)
20 Percent Sand
80 Percent Anthracite
No. 2 (Dual Media)
45 Percent Sand
55 Percent Anthracite
No. 3 (Mixed Media)
25 Percent Garnet
30 Percent Sand
45 Percent Anthracite
Average Percent Removal
TOC
35
39
50
Turbidity
JTU
75
73
79
Filter No. 3 during the testing period were generally higher than for

Filter Nos. 1 and 2.  Thus, one would anticipate somewhat higher re-

movals.  The cycle time between backwashings for a 20 psi pressure

drop was approximately the same for Filter Nos.  1  and 3, with shorter

times  observed for Filter No.  2.  For an influent suspended solids

concentration of about 100 mg/1, the  time between backwashings was

only one to three hours.  At an influent suspended solids concentrations

of about 40 mg/1, filter  runs were 10 to 15  hours, and,  with an in-

fluent  suspended solids of 10 mg/1, filter runs of approximately 30 hours

were observed.  Based on this information,  normal filter runs for a

typical plant may be in the  range of 12 to 24 hours.   However, during

periods of relatively high solids in the filter influent (i.e., approxi-

mately 50 mg/1), filter runs  as low as four hours may be expected.
                                 35

-------
Although the filtration process generally worked satisfactorily,  prob-
lems were encountered with biological growth in the filter media.   This
growth resulted in what appeared to be channeling through the filter
along with excessive head losses.   Extended backwashing and the addi-
tion of heavy doses of chlorine did not eliminate the problem, and,  con-
sequently, the filter media were replaced.  As  a result,  facilities were
installed to chlorinate the feedwater to the filtration process.  This proce-
dure eliminated biological growth problems.  Approximately 5 mg/1 of
chlorine was fed into the water before filtration, resulting in a post-
filtration residual of approximately 0. 5 mg/1 Cl_.  Based on these ob-
                                               Lf
servations, the ability to chlorinate the filter influent in  a full-scale
filter plant would be advantageous.

Activated Carbon

Two identical activated carbon columns were operated in series to  treat
the filtered effluent from the activated sludge units from January 6
through May 25,  1971.  The empty-bed contact  time for  each column,
calculated from the total bed volume and the volumetric flow rate,  was
about 11 minutes.  Backwashing every four or five days at about 6.5
gpm/sq ft was  required to keep the head loss below 10 psi.   Figure 4-4
indicates the TOC and SOC concentrations for the first-stage influent
and effluent and the second-stage effluent.  The average  activated car-
bon influent TOC was  about  14 mg/1,  while the activated  carbon effluent
TOC averaged  about 8 mg/1. The data plotted in Figure  4-4 indicate
that the first stage of the activated  carbon system was removing the
bulk of the material during most of the treatment period. The higher
TOC removals observed in the first stage  can be attributed  partly to
the filtration of suspended materials remaining in the filtered influent
feed.

By May,  the removal efficiency of the first stage in the activated carbon
process had decreased significantly.   Its effluent concentrations of TOC
                                 36

-------
                                                                                              INFLUENT - tft STAGE
                                                                                              EFFLUENT- t« STAGE
                                                                                              EFFLUENT - 2nd STAGE
                               700      800      900     1000

                               CUMULATIVE VOLUME TREATED - lOOO'i gal
                                                              1100      1200
                                                                                              1500     1600
                                                                  JANUARY 6 - MAY 17   ACTIVATED SLUDGE EFFLUENT
                                                                  MAY 18-MAY 26      NITRIFIED EFFLUENT
                                                                                             INFLUENT- 1ft STAGE
                                                                                             EFFLUENT- 1st STAGE
                                                                                             EFF LUENT - 2nd STAGE
                               700      BOO      900     1000
                               CUMULATIVE VOLUME TREATED - loco's gal
                                                                              1300     1400     1500     1600
Figure  4-4.  Performance Data of Activated Carbon  Treatment of
                 Activated Sludge  and Nitrification Process Effluents

-------
and SOC were nearly the same as  the influent concentrations.   On.May
25, 1971,  the first-stage column was replaced with fresh carbon and re-
installed as the second stage of treatment.

Approximately 1.7 x 10  gallons of filtered activated sludge effluent
were treated by activated carbon before the first stage approached ex-
haustion.  At this point,  the activated carbon removed O.cl7 Ib  TOC/
Ib activated carbon in the first stage.   Based on an influent TOC con-
centration of 14 mg/1,  a 60 percent removal, and a removal of 0. 17
Ib TOC/lb carbon, approximately 410 Ib of activated  carbon would
be  required for each million gallons of water treated.

Average performance data for the carbon units are summarized in
Table 4-3.  The first-stage  carbon unit removed approximately 40

                                Table 4-3
SUMMARY OF ACTIVATED CARBON PERFORMANCE DATA DURING
    TREATMENT  OF FILTERED ACTIVATED SLUDGE EFFLUENT
.Item
Average Influent mg/1
Average Effluent mg/1
Total Pounds Applied Ibs
Total Pounds Removed Ibs
Ibs OC removed
Ibs act. carbon
Average Removal percent
Average Flow gpm/sq ft
Total Throughput Volume gal
Average Empty Bed
Contact Time min
First .Stage
Organic- Carbon
Total
14, 0
8. 3
192
77
0. 17
40
1.4
1.7 x I0(>
11.2
Soluble
8, (i
5.8
120
40
0.07
33



Second Stage
Organ if C;t rbnn
Total [Soluble
8 3
5, 7
1 H.
3(.
0.081-
31
14
17
11.2
T. «
3 (,
81
30
0.068
37



Overall
Carbon Removal
Total 1 Soluble
_._ j

192
111

59





120
I''1.'

5K



*Carbon adsorption was terminated before breakthrough of the activated carbon column.
 Operation of the first stage: January 6 - May 25, 1971
 Activated carbon bed repacked:  May 25, 1971
                                   38

-------
and 33 percent of the influent TOC and SOC,  respectively, whereas the



second stage removed 31 and 37 percent of the remaining TOC and SOC.



Removal percentages of the organic carbon were nearly identical in



each stage of carbon treatment, indicating that the organic carbon which



passed through the first stage was readily adsorbed by the second car-



bon column.   The combined two-stage activated carbon treatment process



achieved a 59 percent reduction in the organic carbon concentration of



the activated sludge effluent during the five months of operation.  These



removals,  combined with those  resulting from the activated sludge pro-



cess resulted in  an overall TOC removal of 93 percent,  82 percent of



which occxirred in the conventional  activated sludge  stage.  Although



the activated carbon treatment removed  almost 60 percent of the organ-



ic carbon in the activated sludge effluent, this only amounted to  about



7. 5 percent of the TOC in the  raw wastewater.  This small but significant



increase in effluent quality resulted in an appreciable increase in the



complexity and expense of the treatment process.  Thus, in cases where



biological systems are able to operate at high efficiencies, it may not



be necessary to utilize activated carbon  treatment unless very high quality



effluents are required.








PHASE II:  BIOLOGICAL NITRIFICATION-DENITRIFICATION








Phase II of this study started on May 20, 1971,  at which time activated



sludge effluent from the CCCSD 1 -mgd plant was used as the influent to



the pilot plant nitrification  reactor.   The average influent flow rate into



the treatment process was  approximately 17 gpm, resulting in a four-



hour detention time in the nitrification basin followed by two hours of



sedimentation.  The settled nitrified effluent was then fed into a hydrau-



lically mixed  reactor where methanol was added in a 3:1 methanol:



nitrate-N weight ratio for biological denitrification under anaerobic
                                 39

-------
conditions.   Flow in this basin averaged 10 gprn initially for a deten-



tion time of about three hours and a settling time of two and a half hours.



This overall operation resulted in a three-stage biological system which



provided carbonaceous BOD removal in the activated sludge, ammonia



oxidation in the nitrification basin, and  nitrate removal in the denitrifi-




cation basin.







The main emphasis during this phase of the work was on the nitrifica-



tion and denitrification studies.  However,  additional investigations



were conducted using the physical treatment processes of filtration



and activated carbon adsorption.  Nitrified effluent was fed to the



filtration and activated carbon units from May 20 until  June 30.   From



July 1 until project complation on November 4, the denitrified efflu-



ent was  filtrated and treated with activated carbon.








Nitrification








The influent and effluent ammonia concentrations, nitrification mixed



liquor suspended solids (ML.SS) concentrations,  and the ammonia re-



moval rates are presented in  Figure 4-5.








The ammonia content in the nitrification process influent was usually 10



to ZO mg/1; however,  at times,  lower ammonia values  were observed.



These lower values resulted from varying degrees  of nitrification occur-



ring in the activated sludge stage preceding the nitrification stage.  Often,



the ammonia concentration in  the nitrification-stage effluent was less



than 1 mg N/l.  Ammonia concentrations greater than this value  gener-



ally corresponded to periods when the MLSS in the  nitrification reactor



were  significantly reduced in  concentration.
                                 40

-------
            INFLUENT
z
01

I
Z
o
20







10







 0



-5
            EFFLUENT
  2,000 -
  1,000 -
       MAY
             JUN
                            JUL
                                        AUG
                                                    SEP
                                                               OCT
                                                                   NOV
            Figure 4-5,  Nitrification Proces s Data
                                  41

-------
During about the first three months of operation of the nitrification



stage, as shown in Figure 4-5, the MLSS concentration was quite



variable.  The sudden increases in MLSS resulted from the  addition



of settled activated sludge solids from the activated  sludge mixed



liquor.   Following each addition of solids, however, the nitrification



MLSS decreased with time until the nitrification efficiency decreased,



and,  consequently, the effluent ammonia concentration increased.








During the latter three months of operation, activated sludge solids



were added to the nitrification reactor at more frequent  intervals so



that the MLSS did not decrease below about 500 to 1000 mg/1.  The



effluent ammonia concentrations observed during this period were



consistently quite low.   However,  in October,  the effluent ammonia



concentrations increased to values around 10 mg/1.   For about one



week prior to this period, the influent ammonia concentrations to



the nitrification stage were quite low since the  ammonia was being



oxidized in the activated sludge stage.  It is possible that because



of the low  influent ammonia,  the viability of the nitrifying culture



decreased  resulting in the reduction of nitrification efficiency.








The ammonia removal rates,  expressed as the mass of ammonia re-



moved per unit time per unit mass of suspended solids in the nitrifica-



tion reactor (Figure 4-5), were initially quite  variable as a  result of



the changing MLSS concentrations.  These rates, however,  were more



stable during the latter  two months of operation.   The data indicate



that,  with  an ammonia removal rate of 0.05 mg NH  -N/mg MLSS-day,



a MLSS of  3000  mg/1, and 20 mg/1 of ammonia oxidized, a detention



time of 3. 2 hours would be required in the nitrification reactor.   It



should be noted  that this ammonia removal rate is based on pH values
                                 42

-------
of about 7. 0.   If somewhat higher pH values of around 8. 0 to 8. 5 could



be maintained in the nitrification reactor,  then a higher ammonia re-



moval rate would be expected, providing the potential of reducing the



required detention time.








The results obtained during this study  suggest that high removal efficien-



cies of organic materials and suspended solids in the first biological



stage preceding the nitrification stage  are  not required, and indeed are



not desireable.  If relatively high removal efficiencies are obtained in



the first biological  stage, then, at times,  some nitrification may occur



which could be detrimental to the nitrifying culture in the  second stage.



Also,  in order to maintain a desireable MLSS concentration in the



nitrification reactor,  the data indicate that it  is necessary to have  some



carbonaceous  oxidation in the nitrification  reactor in conjunction with



the oxidation  of ammonia to nitrate,  thus establishing a synergistic



effect between the heterotrophic and autotrophic microorganisms.
The average and range of suspended solids observed monthly in the



CCCSD 1-mgd activated sludge effluent and the effluents from the pilot



plant nitrification and  denitrification stages are summarized in Table 4-4.



The TOC and SOC  concentrations for these effluents are illustrated in



Figure 4-6.  Suspended solids in the activated sludge effluent averaged



9 mg/1 less than observed in  the nitrified effluent.  The decrease in nitri-



fied MLSS discussed earlier can be largely attributed to this increase in



solids concentration.








In the denitrified effluent,  the suspended solids averaged approximately



ZO mg/1 higher than the nitrified effluent.  This increase resulted from



problems encountered with the denitrification stage MLSS floating in  the



sedimentation tank.  At times,  a layer  of solids  several inches thick would



accumulate on the  surface of  the sedimentation tank.  The floating nature



of these solids  is discussed in more detail later.
                                  43

-------
  55
  50
  45
-40
OJ
                          ~~— ACTIVATED SLUDGE EFFLUENT
                          	NITRIFICATION EFFLUENT
                               DENITRIFICATION EFFLUENT
  35
  30
03
  20
  15
  10
                                             i   i  i
                                                                      j	i
  25

E
 I 20
z
O
CO
QC
< 15
o
o

§10
(T
O
ao
D
O
CO
                                                ACTIVATED SLUDGE EFFLUENT
                                                NITRIFICATION EFFLUENT
                                                DENITRIFICATION EFFLUENT
                        J—i—i	1	1—i   I   i  i   i
    MAY
                JUN
                               JUL
                                              AUG
                                                              SEPT
                                                                         OCT
                                      1971
          Figure 4-6.  Nitrification-Denitrification Process Data
                                     44

-------
                                 Table 4-4

     AVERAGE MONTHLY SUSPENDED SOLIDS CONCENTRATIONS
                OF THE BIOLOGICAL EFFLUENTS (mg/1)
Month
June
July
August
September
October
Average
Activated Sludge '
Average
10
7
6
14
29
14
Range
8-13
2-10
2-12
4-50
6-87

Nitrification
Average
34
23
18
19
25
23
Range
22-42
12-50
8-26
11-37
8-56

Denitrification
Average
45
35
25
56
61
42
Range
30-70
21-62
5-37
33-95
13-116

  CCCSD 1 mgd plant



Effluent TOC concentrations, as shown in Figure 4-6, averaged 14 mg/1

in the activated  sludge effluent  and 15 mg/1 in the nitrified effluent.  In

the denitrified effluent, the TOC averaged 20 mg/1  with this higher value,

compared to the nitrified effluent,  resulting primarily from the loss of

floating solids mentioned above.


The  SOC  concentrations  shown  in Figure  4-6  for the activated sludge and

nitrification-stage effluents indicate slightly lower  values for the latter.

Generally,  the denitrified effluent SOC  concentration was nearly the

same as the nitrified effluent except for three peak concentrations.

These peaks probably  resulted  from the methyl alcohol which was not

completely metabolized in the denitrification reactor.
                                  45

-------
De nitrification








Nitrate removal rates expressed as the mass of nitrate-nitrogen re-



moved per unit  time per unit mass of suspended solids in the denitrifi-



cation reactor,  influent and effluent nitrate-nitrogen concentrations,



and denitrification MLSS  concentrations are presented in Figure 4-7.








The nitrate removal rates were quite variable during the first two



months of operation, but,  during the latter three months, the rates



were  more  stable.  The removal rates were quite  high during the



month of July, primarily as a result of low concentrations of MLSS



(Figure 4-7).  Very good removals were  observed at rates up to about



0. 15  mg nitrate removed/mg MLSS-day,  indicating that  the detention



time  in the  denitrification reactor could be as low  as approximately



one hour.   The  residence  time in the denitrification reactor  may,  how-



ever,  need  to be longer in order to assure  that sufficient time is avail-



able for the denitrification reaction to be completed,  thus minimizing



any additional denitrification in the final sedimentation tank.








During the pilot plant  denitrification studies, problems were  encounter-



ed with poor settling of the denitrification MLSS. Apparently, either the



denitrifying organisms were continuing to produce nitrogen gas in  the



sedimentation basins or the suspended solids from the denitrification



basin were  carrying entrained nitrogen gas bubbles into  the sedimen-r



tation basin, thereby buoying up the settled solids  and causing them to



float  on the surface of the sedimentation tank.   The inlet to the  sedimen-



tation tank  was modified  so the mixed liquor would be exposed
                                 46

-------

0.7


0.6


0.5

0.4


0.3

i
0.2


 0.1

  0
 40
 !  30
  I
 gE  20
 uu
 o
                                    -.868
    10
 <
 H
 Z
  4000
t/J
Q
Q
LLI
Q
Z
LU
Q.
  2000
  1000
                           .801
     0 I  '  '   I  I  i  i—I  I I—I—l_l—I—I—I	1—I—I—L
     MAY        JUN         JUL         AUG
                                               I  i  i  i  i  i I  i  i  i  |  i  I
                                                    SEP        OCT     NOV
              Figure 4-7.  Denitrification Process  Data
                                     47

-------
to atmospheric pressure for a  short time before entering the settling



zone.  This modification was employed to release the nitrogen gas  en-



trapped in the biological floe.  Some  reduction in suspended solids  losses



was  achieved by this technique, but the problem was  not eliminated.  Air



agitation for 3 to 5 minutes  in the center of the sedimentation tank inlet



was  also tested as a means  of stripping  out excess nitrogen gas  and meth-



anol and to provide a residual  DO in  the sedimentation tank.  Since  there



was  no apparent improvement in the effluent quality,  this procedure



was  discontinued.  Recent information,  from  the EPA District of Colum-



bia pilot  plant,  indicates that  aeration  of the mixed liquor for  about 30



minutes prior to settling reduces the solids  separation problems and,  at



the same  time,  reduces the excess methanol carried over from  the  deni-



trification reaction.  Similarly, results obtained from the CCCSD plant,



which was modified to further investigate the problems with denitrifica-



tion discussed above at  a scale of about  0. 5 mgd,  indicate that aeration  oi



the denitrification mixed liquor for approximately one hour prior to sedi-



mentation significantly improves solids  separation and effluent quality.








The  effluent nitrate concentrations, as shown  in Figure 4-7,  were quite



variable.   However, the rather high nitrate  concentrations observed dur-



ing part of July resulted from problems encountered  with the methanol



feed pump.  The effluent nitrate increases observed in August and the



first part of September  are  believed to have resulted from the ferric



chloride additions  being made to the denitrification reactor during this



time, which caused a decrease in the pH of the mixed liquor.  When all



plant functions were properly operating  and  the denitrification MLSS con-



centration was sufficiently high,  effluent nitrate-nitrogen  concentrations



of 1  mg/1 or less  could  be maintained.








Although the denitrification results obtained during this study generally



placed doubt on the adequacy of this process,  enough good results were
                                  48

-------
obtained to indicate that, with additional time and development, the pro-



cess can be made to perform satisfactorily.  The results from the EPA



District of Columbia pilot plant and the CCCSD "Advanced Treatment



Test Facility, " reported after  the data in this  report were obtained, illus



trate  that the denitrification process can be designed to perform satis-



factorily.   Perhaps the most significant finding in these more  recent in-



vestigations was the required aeration of the denitrification MLSS for



30 to  60 minutes prior to final  sedimentation.








Phosphorus Removal








Ferric  chloride and  alum were added during different periods of time



to the denitrification system to observe the effect on phosphorus  re-



moval.  Table 4-5 is a summary of the results.








Ferric  chloride was  added in three different ratios  of iron to phos-



phorus.  Removals of phosphorus  for Fe/P weight ratios  of 1.9 and



5.6 were  57 percent and 63  percent,  respectively.  Results during



the testing period from June 16 to June 24 indicated only 43 percent



phosphorus removal  at an Fe/P ratio of 2. 5.  This  lower removal  re-



sulted in part from problems encountered with the chemical feeding



system.  Also,  the addition of  ferric chloride periodically reduced



the pH of  the denitrification MLSS to the extent that the denitrifica-




tion reaction was inhibited.








Alum additions during periods  in September and October were  main-



tained at an aluminum-to-phosphorus weight ratio of about 1. 2 to



1.3.  These ratios resulted in  average phosphorus removals of 52



percent across the denitrification  system.  Based on these results,



it appears that alum would be preferred over ferric chloride for the
                                 49

-------
removal of phosphorus in combination with biological treatment.   How-

ever, to obtain a high degree of removal, multiple addition points

would be required.
                              Table 4-5

              PHOSPHOROUS REMOVAL USING FERRIC
                AND ALUMINUM ADDITIONS TO THE
                     DENITRIFICATION SYSTEM
Date
6/16 6/24
7/30 8/20
8/21 - 9/2
9/3 - 9/17
9/20 - 9/27
9/28 - 10/26
Dosage
(Weight Ratio)
Fe/P
2. 5
1.9
5.6
—
—
—
Al/P
—
—
—
1. 2
1. 3
1. 2
Effluent
mg/1 as P
5.2
4. 2
3.6
4.2
4. 2
4.9
Removal
%
43
57
63
55
52
50
                                 50

-------
Filtration








The filtration process data shown in Figure 4-8 for filtration rates of



5. 0 gpm/sq ft indicate that,  during the time that nitrified effluent was



being filtered, there was a very good removal of the suspended organic



materials.  Effluent turbidities were quite low and showed only minor



variations over the six weeks of operation.  Influent turbidities ranged



from Z to 30 JTU, averaging about  14 JTU; whereas effluent turbidities



averaged about Z JTU, for a mean turbidity removal of 85 percent.  TOC



removals averaged 70 percent through the filtration process resulting in



an effluent concentration of about 6 to 7 mg/1.  Apparently,  the effluent



suspended solids in the nitrified effluent formed a strong floe with fil-



terability similar to typical  activated sludge floe.








The quality of the filtered,  denitrified effluent was considerably more



variable than that of the nitrified effluent. In July and early August,



when the influent turbidity-was  relatively low,  there was very little



removal of turbidity occurring  with Filter No. Z.   Removals were



somewhat better in late  August and September, when Filter No. 1 was



in operation.   This may have been due to the higher  solids loading



during this period, since turbidity removals of Filter No.  Z appeared



to improve somewhat between August 5 and 15 as  the loading increased.



Effluent turbidities from Filter No.  3 appeared to be consistently lower



than observed with Filter Nos.  1 and 2.   Table 4-6  summarizes the



average removals for the various filters  employed.








The highly variable turbidities  of the filter influent attest to the difficul-



ty of attaining consistent solids removals in the denitrification sedimen-



tation tank.  The lower quality  of the filtered,  denitrified effluent may



have been due to the nature of the floe.   It appears from the filtration
                                   51

-------
  45



  40



^ 35
O>


 1 30
z
o
m
o: 25

o

^20
  10



   5



   0
NITRIFICATION-*
 EFFLUENT



Fl
                                  *••«	1
                        FILTER IN OPERATION
MAY
         JUN
                     JUL
                                       AUG
SEPT
OCT
                                                                 NOV
          Figure 4-8.   Filtration Data Using Denitri-

                        fication Process Effluent
                              52

-------
                               Table 4-6

         SUMMARY OF FILTRATION PERFORMANCE USING
              DENITRIFICATION PROCESS EFFLUENT
Filter
No. 1 (Dual Media)
20 Percent Sand
80 Percent Anthracite
No. 2 (Dual Media)
45 Percent Sand
55 Percent Anthracite
No. 3 (Mixed Media)
25 Percent Garnet
30 Percent Sand
45 Percent Anthracite
Average Percent Removals
TOC

58*
37

27

38
Turbidity
JTU

84*
53

37

61
    *    Nitrified Effluent

data that this floe was more fragile than that developed in the first two

biological  stages.  If this is the case, it may be necessary to reduce the

filtration rate when filtering denitrified effluent.   Also,  aeration of the

denitrification MLSS prior to  sedimentation,  as discussed earlier, may

improve the filterability; however,  this was not studied.


Activated Carbon


The results of the two-stage carbon adsorption studies for the Phase II

pilot plant are shown in Figure 4-9.  Nitrified effluent was filtered and

passed through the columns from May 20 until June 30,  1971.   From July

1 until November 4,  the  denitrified effluent was used as the influent to

the activated  carbon adsorption system.  The 1.7  million gallons which

the first-stage carbon column had been  exposed to at the start of the study
                                  53

-------
NITRIFIED EFFl UENT
                                                    DENITRIFIED EFFLUENT
                                  2300 0      100      200

                                CUMULATIVE VOLUME TREATED - lOOCTsgal
     Figure 4-9.  Performance Data of Activated Carbon Treatment of
                    Nitrification and Denitrification Process Effluents

-------
represents the amount of water treated during Phase I, when this column
acted as the second-stage for the activated sludge effluent.   The new
second-stage  column was freshly repacked activated carbon.

The  TOG concentration in the first-stage effluent as shown in Figure 4-9
was  generally Z to 4 mg/1 less than the influent TOG,  representing about
a 30 percent reduction in the TOG concentration.  The very high TOG con-
centrations resulting when the denitrified effluents was fed to the carbon
columns were due to  suspended solids from the denitrification process.
However,, these materials were  effectively removed in the carbon column.
The  second stage of the  activated carbon system was operating more ef-
fectively than the first during this period, as is evident from Figure 4-9,
This column was generally removing 3 to 5 mg/1 of  TOG, or about 50 per-
cent of the influent TOG.

SOC concentrations in the activated carbon influent were usually between
5 and 10 mg/1, while the second-stage effluent was generally between 1
and  2 mg/1.   This reduction represented approximately 80 percent re-
moval of the SOC through the activated carbon process.

During much  of July and early August, the organic carbon content of the
first-stage effluent was  nearly the same as. the influent.  On August 17,  the
first-stage was removed from service after treating approximately 2. 2  miL
lion gallons,  repacked with fresh activated carbon and reinserted as the
 second  stage of the carbon treatment  system.  The  former second stage
 was installed as the first stage.  (Note in Figure 4-9 the discontinuity
 in the abscissa on August 17,  when the treated volume of the first stage
 changes from 2.2 million gallons to about 500,000 gallons,  signifying the
 interchange of columns).  Removal efficiencies improved appreciably.
 Except  for two high TOC concentrations in the first-stage effluent in late
 September,  each column appeared to  remove about the same amount of
 TOC and SOC,  resulting in  a treated effluent having a TOC concentration
 of 2 to 3 mg/1.
                                  55

-------
The activated carbon adsorptive capacity was determined from, the time



freah carbon was initially contacted with the influent until the time the car-



bon was exhausted.  This was done by calculating the masses of  TOC  and



SOC removed and relating them to the mass of activated carbon  contacted.



A summary of the data is shown in Table 4-7 for the period between January



6 and August 16,  1971.   The average removal efficiency during this period



was 30 percent and the average carbon loading,  through exhaustion, was



0. 11 Ib total organic carbon removed per pound of activated  carbon.








Also shown in Table 4-7 are performance data for the activated carbon



column that served as the second  stage in the process from May  26 to



August  17 and then the first stage  from August  17 through October  31,  1971.



The data, as shown in Figure 4-9, indicate that this carbon column was not



completely exhausted through the  end of October.  The average TOC re-



moval efficiency for this column was 50 percent and the carbon loading



was  0. 13 Ib TOC removed per pound of activated carbon. Since the carbon



"was not exhausted, this removal efficiency  was greater than observed with



the column operated between January 6 and August 16.  However, the  car-




bon loading  on the column operated from May 26 through October 31, with-



out being exhausted, was actually  higher than that of the previous observa-



tions.  This difference in carbon loading was due to the differences in the



influent suspended TOC concentrations.  The activated sludge and nitri-



fication proces s effluents,  which were readily filtered, resulted  in lower



TOC concentrations than the denitrification process effluent.








TOC removals in the activated carbon columns  generally ranged  between



6 and 12 mg/1.  Based on an average TOC concentration of about 80 mg/1



in the treatment plant influent, the activated carbon system removed only
                                 56

-------
                        Table 4-7

SUMMARY OF ACTIVATED CARBON PERFORMANCE DATA
DURING TREATMENT OF THE FILTERED NITRIFICATION
     AND DENITRIFICATION PROCESS EFFLUENTS

Jan 6 - Aug 16, 1971
Total Applied
Total Removed
Average Removal
Carbon Loading
.Average Flow
Detention Time
May 26 - Oct 31, 1971
Total Applied
Total Removed
Average Removal
Carbon Loading
Average Flow
Detention Time

Ibs
Ibs
percent
Ibs TOC removed
Ibs act. carbon
gpm/sq ft
min

Ibs
Ibs
percent
Ibs TOC removed
Ibs act. carbon
gpm/sq ft
min
Organic Carbon
Total Soluble

166 109
49 36
30 33
0.11 0.08
0. 7
27

112 63
56 38
50 60
0.13 0.086
0.9
21
                          57

-------
about 10 percent of the organic materials.   Thus, although the  activated



carbon treatment resulted in very low effluent organic  carbon concentra-



tions, the preceding biological treatment processes were  responsible for



the removal of the bulk of the  organic materials.








PHASE  III:  CHEMICAL-PHYSICAL  TREATMENT SYSTEM








The two-stage chemical treatment system which began operation in late



April and continued until November consisted of lime coagulation and



settling in the first stage followed by recarbonation and settling of the



calcium carbonate precipitate  in the second stage.  The effluent from



this treatment process was then filtered and treated with activated



carbon.







Lime Treatment








Preliminary laboratory data were obtained on the chemical treatment of



wastewater  to determine the approximate operating pH to  use in the pilot



plant studies.  As shown in Figure 4-10, apHof  10.5 to 11.0 appeared to



be near the  optimum value with regard to minimizing the lime  require-



ments and obtaining appreciable reductions  in  TOC, phosphorus, and tur-



bidity.  Approximately 350 to  500 mg/1 of lime (as  CaO) were  required to



maintain a pH of 10. 5 to  11.0, while only 250 mg/1 of lime were required



to obtain an operating pH of 10. 0.








The lime dosage requirements, and the operating influent  and effluent



pH values for the chemical treatment system are  shown in Figure 4-11.



The amount of lime used in the chemical process  was  controlled by a pH



feedback controller to maintain a predetermined pH value.  Daily lime



requirements ranged from 200 to 500 mg/1 CaO, averaging about 390 mg/1,



From mid-September until the end of November,  the lime dose was  about
                                 58

-------
12
11
10
                                                  TOC
                                                          30     -
                                                          25     -
                                                              I
                                                          20  -
o
URB
60
                                                                  50
                                                                     01
40 g
                                                                     O
                                                                     O


                                                                  30  <
                                                                     O
                                                                     cc
                                                                     O
                                                                     _!
                                                                     <

                                                                  20  £
                                                                     K
                                                                  10
                                                                         10
       8  _
          Q.
       6  I
          O


       5  I
          O
          X
          Q.
         200      400      600      800     1000     1200

                       LIME CONCENTRATION - mg CaO/l



                Figure 4-10.  Lime Requirements  for

                              Chemical Treatment
 450 mg/1, resulting in an operating pH of about 11.0.  Initial studies

 indicated little  difference in the quality of the treated  effluent between

 flocculation times of 30  and 20 minutes,  so the shorter flocculation time

 was  adopted throughout the study.  After recarbonation and  second stage

 flocculation and sedimentation,  the pH of the lime treated effluent was

 about 9. 5.  It was observed that the dispersed nature  of the calcium car-

 bonate precipitate formed after recarbonation made it difficult to  separate


 by gravity settling.   The addition of ferric  chloride to coagulate the dis-

 persed material resulted in better  separation, but light flocculant materials
                                    59

-------
were observed in the  effluent.  By returning a portion of the  calcium

carbonate sludge to the second-stage flocculator,  the effluent quality

was improved, most likely as a result of improved particle growth.

However,  recycling of lime sludge to the first-stage flocculator did not

appear to significantly improve the performance of that stage.
  700

  600

  500

  400
SE 300
a
£ 200
UJ
1 100
             ,st,
        	  1SI STAGE EFFLUENT
        	  RAWWASTEWATER
        	  2^ STAGE EFFLUENT
        	I	I
        MAY
                  JUN
                           JUL
                                     AUG
                                              SEPT
OCT
NOV
                Figure 4-11.  Chemical Treatment Plant
                              Lime Requirements and pH
                              Values
                                  60

-------
Hardness and Alkalinity


The hardness and alkalinity data for the chemical treatment system are

shown in Figure 4-12.  Average influent and effluent data are  summarized

in Table 4-8.  Generally,  the alkalinity of the  second stage effluent was

less than in the raw wastewater, its decrease  averaged 18 mg/1 as CaCO

or 9. 1 percent.  The total hardness of the treated effluent was not  signif-

icantly changed.  An average increase in hardness of 6 mg/1 as  CaCO  or

3. 3 percent was observed.
                               Table 4-8

           CHEMICAL TREATMENT AVERAGE HARDNESS
                       AND ALKALINITY DATA
First Stage Influent, mg/1
Second Stage Effluent, mg/1
Concentration Change, mg/1
Concentration Change (%)
Alkalinity
198
179
18
9. 1
(Decrease)
Hardness
152
158
+ 6
3. 3
(Increase)
     Concentrations expressed as CaCO



 The increase in hardness most likely resulted from incomplete precipi-

 tation of calcium  carbonate following the recarbonation step.  The typical

 chemical reactions associated with water softening were not directly ap-

 plicable because of the likely interference of organic materials in the raw

 wastewater with the calcium. Improved performance of the  chemical

 treatment system may have been obtained if sludge recycling was effec-

 tively used.
                                  61

-------
  350
^300
<3 250
O)

, 200
Z  150
_i
<
j  100
<

   50

    0
             RAW WASTE WATER
             RECARBONATED EFFLUENT
             SETTLED RECARBONATED EFFLUENT
/r
210

190




150

130

110

 90

 70
                           1 WASTEWATER
                       RECARBONATED EFFLUENT
                       SETTLED RECARBONATED EFFLUENT
         JUN
                 JUL
                             AUG
                                          SEPT
   OCT
NOV
     Figure 4-12.  Hardness and Alkalinity of Raw Wastewater and
                   First-Stage and Second-Stage Chemical Treat-
                   ment Effluents
                                  62

-------
Suspended Solids








The suspended solids concentrations for the various stages in the chemical



treatment plant are  shown in the upper portion of Figure 4-13.  Although



the suspended solids concentration in the influent to the first-stage floccu-



lation basin varied from about 100 mg/1 to as  high as 350 mg/1, the sus-



pended solids content of the  effluent from  the  second stage of the process



was nearly constant.  The variability in the suspended solids content of



the raw wastewater  was largely removed in the first stage of the chemi-



cal treatment process.  During the 7 months of operation of the chemi-



cal treatment plant, the suspended solids  removal averaged 87 percent.



The chemically treated effluent suspended solids ranged from 5 to 40



mg/1, with an average concentration of 19  mg/1.







Phosphorus







The total phosphorus contents  of the  influent,  first-stage effluent, and



second-stage effluent of the  chemical treatment plant are shown in the



lower portion of Figure 4-13.  The total phosphorus content of the influent



water was generally about 7.4 mg P/l, whereas after the first stage of



lime treatment, the total phosphorus was  reduced to an average value of



about 1.6 mg/1.  This reduction represented about 80-percent removal



of the total phosphorus content of the raw  wastewater.  The total phos-



phorus concentration in the  effluent from the first-stage flocculation ba-



sin was higher during August due to the decrease in operating pH from



10. 7 to  10.'2 (Figure 4-11).







The phosphorus concentrations in the first-stage effluent were further



reduced  in the  second stage  of the chemical treatment process.  Effluent



from the second stage contained approximately 0.4 mg/1 of total phos-



phorus,  making the  overall phosphorus reduction in the  chemical treatment
                                 63

-------
  300
  250
  200
  150
Q
01
Q
Z
LU
Q.
C/3
  100
                                    RAW WASTEWATER
                                    RECARBONATED EFFLUENT
                                    SETTLED RECARBONATED EFFLUENT
         JUN
                           /      \  '   \                * ^
                           /       \ '   *     A          * *
                                    "   X   A A   -  / V'
                         ,'   ^  ^	^  AV  v  V-\/__.
                    JUL
                              AUG
                                          SEPT
                                                    OCT
                                                               NOV
   35
   30
E  25
I
C/3
i  20
O
O
Q_
O
   15
   10
                                         RAW WASTEWATER
                                         RECARBONATED EFFLUENT
                                         SETTLED RECARBONATED EFFLUENT
                  A
            x   ;  \

  Figure 4-13.  Orthophosphate and Chemical Suspended Solids  Re-
                moval in the Two-Stage Chemical Treatment Process
process approximately 95 percent.  During October and November, when

the pH of the first stage was between  11 and 11. 5,  the total phosphorus

concentration of the effluent was generally about 0. 16 mg/1, indicating a

98-percent removal.


Organic Carbon


Figure 4-14 illustrates the  TOG contents  of the influent wastewater, which

had been settled for about 10 minutes  in the CCCSD primary sedimentation
                                 64

-------
  140
^120
E
I
Z100
o
00
cc
< 80
o

  60
   20
              	RAW WASTE WATER
              	RECARBONATED EFFLUENT
                  SETTLED RECARBONATED
                  EFFLUENT
   50
   40
  30
  20
   1.0
CO
                  RAWWASTEWATER
                  •RECARBONATED EFFLUENT
                  SETTLED RECARBONATED
                  EFFLUENT
         JUN
JUL
                               AUG
                                          SEPT
OCT
                                           NOV
        Figure 4-14.  Total and Soluble Organic Carbon Removals
                      in the Two-Stage Chemical Treatment Process
 basin to remove large suspended materials and rags,  the first-stage  ef-

 fluent, and the second-stage effluent of the chemical treatment plant.

 The influent TOC varied from a low of 60 mg/1 to a maximum value of

 125 mg/1.  The average influent TOC was approximately 90 mg/1 dur-

 ing this study, whereas the concentration of TOC in the recarbonated

 effluent was usually between 25 and 30 mg/1, indicating that nearly

 70 percent of  the TOC was removed in the chemical treatment process.
                                   65

-------
There was very little  change in the SOC concentration as & result of the



chemical treatment, as  is apparent from th6 data plotted in the lower



half of Figure 4-14.  The SOC concentration in the effluent from the first-



stage flocculation basin  was usually greater than that in the influent



water.  Apparently, the high pH of the first stage was causing the TOG



to undergo alkaline hydrolysis, converting some particulate organic



carbon to soluble  organic material.  Some of the SOC was removed during



the second-stage flocculation reaction so there was little or no net in-



crease in SOC,  and at times the SOC  showed a moderate decrease1 through



the system.  Overall,  SOC removals  averaged about 5. 0 percent for the



7-month operation of the two-stage system.








Filtration








Figure 4-15  summarizes the turbidity data  from the influent and effluent



of the filtration process.  The settled effluent from the second stage of



the chemical treatment plant was filtered at a rate of 2. 5 gprn/sq ft, and



the filters  were backwashed at a rate of 20  gpm/sq ft.








The effluent turbidity  from the chemical treatment process was generally



about 5 JTU  (Figure 4-15), but there  were periods when much higher tur-



bidity resulted.  Filtration reduced the average turbidity by about 50 per-



cent,  producing a filtered effluent having a  turbidity of 2 to  3  JTU.  How-



ever,  when the turbidity of the filter influent increased substantially above



5 JTU, the filters usually were able to  control the turbidity, indicating



that for the most part the chemical floe was readily filterable.  The TOC



data shown in Figure 4-15 from the filter influent and effluent  indicate



that there was  very little removal of  TOC in the filters.  This was not



surprising since about 70 percent of the TOC was in the soluble form



(SOC).  Filter  No. 1 appeared to  show the best performance during



these tests.
                                  66

-------
  25
  15
9 10
CQ
CC
                                                      FILTER INFLUENT

                                                      FILTER EFFLUENT



2 *~
FILT

^ 1 ••
ER IN OPERATION


 35



, 30



 25



 20



 15
o
o
cc
o 10
O  5



   0
                                                      FILTER INFLUENT

                                                      FILTER EFFLUENT
         JUN
                    JUL
                                AUG
                                           SEPT
                                                       OCT
                                                                NOV
   Figure 4-15.  Filtration Data Using Chemical Treatment Effluent
                                   67

-------
Activated Carbon







The results of the activated carbon adsorption studies are shown in



Figure 4-16.  For the two stages of carbon treatment,  the average



empty bed contact time was about 25  minutes per stage with an average



How of 0. 76 gpm/sq ft.  Influent TOC concentrations averaged about



24 mg/1,  whereas the first-stage effluent averaged about 13 mg/1 and the



second-stage  about 11 mg/1.  The second stage of carbon treatment



appeared to have little influence on the organic carbon removal,  indi-



cating that these materials could not be readily adsorbed with activated




carbon.







In early  September, the effluent TOC and SOC from the carbon adsorp-



tion system began to  approach the influent concentration,  signifying



that the columns were approaching exhaustion.  Surprisingly,  it was the



second stage which had the greatest effluent concentration at this time,



even though it had only received a very light loading of organic carbon



compared to the first stage.   This apparent inefficiency of the second



stage may have  been  due to anaerobic conditions interfering with the



organic carbon adsorption process.   On September 9, the two  carbon



columns  were interchanged,  and the former first-stage carbon column



was repacked  and replaced as the second stage.  After this interchange,



the TOC  and SOC of the effluent generally remained below 10 and 6



mg/1, respectively.








The overall performance of the activated carbon columns is  summarized



in Table  4-9,  showing approximately 52 and 60 percent removal of TOC



and SOC  for the  two-stage system.  At the time the first stage became



exhausted, 0.  14 Ibs of organic carbon had been removed per pound of



activated carbon, and this occurred after a volume of 640, 000 gallons



had been treated.  Based on the  observed loading rates for the first stage,
                                 68

-------
                                                                                           INFLUENT - 1st STAGE
                                                                                           EFFLUENT - 1st STAGE
                                                                                           EFFLUENT - 2nd STAGE
|700    [750    [BOO    860    |900    |950    1000 in STAGE
50     100    150    200    260    300    350   2nd STAGE
   NOTE
   FIRST STAGE REMOVED ON SEPT 7. 1971, REPACKED AND REPLACED
   AS NEW STAGE 2.  OLD STAGE 2 BECOMES NEW STAGE 1
                                   CUMULATIVE VOLUME TREATED - lOOO'i 93
                                   CUMULATIVE VOLUME TREATED - 1000*1 g«l
                                                                                                    llOOO 1st STAGE
                                                                                                   360   2nd STAGE
Figure 4-16.   Performance Data of Activated  Carbon on Chemical
                    Treatment  Process  Effluent

-------
it would require about 690 Ib of activated carbon to treat one million
gallons of chemically treated wastewater for the removal of about 50
percent of the influent TOG at a concentration of 24 mg/1.

                             Table 4-9
      AVERAGE PERFORMANCE DATA OF ACTIVATED CARBON
           CHEMICAL TREATMENT PROCESS EFFLUENT
Item
Influent Carbon mg/1
F'ffluent Carbon mg/1
Total Applied Ibs
I'otal Removed Ibs
1 b '! OC removed
Ib af t. ea rbon
Avrraur Removal percent
Avorauc Flow gpm/.sq ft
[oial Ihrouuhput Volume gallon*
Average Kmpty Bed
Contact Time minutes
First Stage
Organic Carbon
Total
23.8
12.6
131
62
0. 14
47
0. 76
0. 64 v 10(>
24 5
Soluble
15. 2
7.2
82
43
0. 10
52
. 76


Second Stage
Organic Carbon
Total
12,6"
11.0
69
8
0.019
12
0. 76
0.64 x 10f'
24, 5
Soluble
7. 2
6. 1
40
(,
0. 014
15
0. 76


Overall
Organic Carbon
Total


131
70

52



Soluble


82
49

60



                                 70

-------
One major difficulty that arose during the activated carbon processing of



the chemically treated wastewaters was the noxious odors that were gen-



erated in the carbon columns.  Since  little or no aeration occurred dur-



ing chemical treatment, the influent to the carbon columns was devoid



of oxygen.   As the amount of adsorbed organics increased, bacteria be-



gan to attack these materials, producing odors through putrefaction



(production of hydrogen  sulfide).  Injection of oxygen and chlorine ahead



of the filters was  not sufficient to overcome the anerobic conditions that



had developed in the filters and the carbon columns.  It is possible that



if aeration and chlorination had been practiced from the  start of the ex-



perimental runs,  the anerobic conditions might never have developed.



The use  of diffused air aeration ahead of activated carbon treatment



would most likely be impracticable; it would undoubtedly result in con-



siderable foaming due to the high concentrations of MBAS  (Methylene



Blue Active Substances, surfactants)  that had not been removed by chem-



ical treatment alone.  Additional studies are required to develop a suit-



able means  of eliminating these problems.







EVALUATION OF TREATMENT PROCESSES







The average physical  and chemical quality parameters  of the treated ef-



fluents from the various pilot plant studies are summarized in  Table 4-10,



Where applicable, average removal efficiencies are  also presented.  In



this section, these parameters are discussed along with a comparison of



the results  from the filtration and activated carbon adsorption studies.



Also,  results from separate virus and trace metal removal investiga-



tions  are presented.







Organic Carbon







The average TOC and SOC of the various effluents differed only moder-



ately during the study.  Nitrification  reduced the TOC and SOC of  the
                                  71

-------
                  Table 4-10

PILOT PLANT AVERAGE EFFLUENT QUALITY
   COMPARED TO THE RAW WASTEWATER
Parameter
TOG
mg/1
% removal
SOC
mg/1
% removal
Suspended Solids
mg/1
% removal
pH
mg/1
Conductivity
jumhos /cm
Ammonia -N
mg/1
% removal
Nitrate-N
mg/1
% removal
Or tho- Phosphate
mg/1 P
% removal
Total Phosphate
mg/1 P
% removal
Activated
Sludge
(1 Stage)

26
82

9
61

33
86

7.4

982

7.4
70

16. 5
—

7. 7
—

8.6
—
Nitrified
Effluent
(2 Stage)

15
89

6. 0
83

23
90

7. 1

846

2.9
88

19. 3
—

9.3
—

9. 7
—
Denitrified
Effluent
(3 Stage)

20
85

7. 2
79

42
82

7. 0

767

2. 1
—

3. 5
82

7. 3
—

7.4
—
Chemical
Effluent
(2 Stage)

26
70

18
5

19
87

9.2

827

16
20

0. 1
—

0.2
98

0.4
95
                     72

-------
activated sludge effluent by 11 mg/1 and 3 rng/1,  respectively.  Following



denitrification, both the  TOG and the SOC increased, the former due pri-



marily to the carryover  of suspended solids from the settling basin and



the latter probably from excess methanol in the treated effluent.








The average TOC and SOC of the chemically treated effluent (without ac-



tivated carbon treatment) was somewhat  greater than that resulting from



biological treatment, primarily due to the poor  removal of  soluble organic



material in the lime treatment operation. Alkaline hydrolysis of particu-



late organic carbon apparently released as much as  new soluble organic



material as was adsorbed by the insoluble calcium floe formed during the



chemical treatment process,  leading to an average SOC reduction of less



than 5 percent.  Although the quality of the chemically treated effluent was



poorer than that of the biological process, chemical  treatment demonstrated



less variability than was observed with the biological processes.








Suspended Solids








The average suspended solids  concentrations for the biologically treated



settled effluents in the pilot plant decreased in proceeding from activated



sludge through nitrification and then increased through the denitrification



process. The activated sludge effluent observed in the pilot plant,  with a



suspended solids concentration of 33 mg/1, was  significantly higher than



observed in the CCCSD 1-mgd plant, which had  an average  concentration



of 8. 7 mg/1.  This difference can be attributed to (1) poorer efficiencies



normally associated with small scale  sedimentation  basins  and (Z)  the



relatively low overflow rates in the  CCCSD plant. Also,  problems were



encountered in the activated  sludge pilot plant with floating  sludge that



significantly increased the effluent suspended  solids  concentration.  The



effluent  suspended solids from the nitrification proces s at Z3  mg/1 were



generally lower  than observed with the activated sludge pilot plant  but were



higher than observed with the CCCSD  1-mgd activated sludge  plant.
                                  73

-------
The nitrified effluent quality further degenerated after denitrification,



primarily due to the buoying of settled solids by nitrogen gas bubbles.



Thus,  the combined treatment of activated sludge,  nitrification, and de-



nitrification removed  only about 82 percent of the suspended solids with



respect to the raw wastewater.  As noted earlier,  recent information



illustrates that  significant improvement in denitrification MLSS separation



can be achieved by aerating these solids for 30 to 60 minutes prior to fi-



nal sedimentation.







Chemical treatment of the partially settled raw wastewater removed 87



percent of the suspended material, producing  an  effluent having 19 mg/1.



Since the chemical treatment process  resulted in the precipitation of



soluble materials during the flocculation reaction,  a significant portion



of the  19 mg/1 suspended  solids in the effluent was calcium carbonate



rather than suspended organic materials.   Contrary to the biological pro-



cesses,  chemical treatment consistently produced  a moderately low sus-



pended solids concentration in the effluent.








Inorganic Nitrogen








The data listed  in Table 4-10 indicate  that the activated  sludge process



oxidized 70 percent of the ammonia -N to nitrate.  However,  this  did not



represent the conversion  efficiency desired,  particularly since only



about 50 percent of the ammonia could be  consistently oxidized in  this



single-stage system.   By using  a  two-stage biological treatment system,



the average ammonia  concentration was reduced  to 2. 9 mg/1 for an over-



all ammonia conversion of 88 percent.  This higher efficiency was attained



despite the  difficulties of  maintaining  an adequate MLSS in the second-



stage nitrification basin.  Although the average effluent  ammonia  -N was



2.9 mg/1, much of the time concentrations of 1 mg/1 or less of ammonia



-N were observed.  The data indicate that by maintaining an adequate
                                  74

-------
MLSS concentration in the nitrification reactor very low effluent am-



monia concentrations can be consistently obtained.








On the average,  82 percent of the influent nitrate  -N was reduced to ni-



trogen gas in the denitrification reaction,  resulting in an average effluenl



concentration during the study period of 3. 5 mg/1 nitrate -N (Table 4-10)



As with the nitrification process,  the major difficulty  encountered during



the operation of  the denitrification process was in maintaining the MLSS



at a desired level.








A  small amount  of ammonia was lost during chemical  treatment,  re-



ducing the ammonia -N content by  approximately 20 percent.   These



losses probably  resulted from the  high surface-area-to-volume ratio in



the pilot plant in conjunction with the high pH.  It is doubtful that the



ammonia removal  would be this great in a full-scale plant.








Phosphorus Removal








Between 95 and 98 percent of the phosphorus was removed in the chemi-



cal treatment system,  resulting in effluent concentrations of about



0.4 mg/1 of phosphorus.  While this  is enough phosphorus to stimulate



algal growths, potential problems  in industrial cooling towers could be



controlled by periodic  shock doses of chlorine.








Filtration








Results of the filtration studies indicated that the average turbidity  of



the effluents from  the activated sludge, nitrification, and chemical  treat-



ment proces ses  could be maintained  at 5  JTU or less.   Apparently, the



floe formed during these operations had a high shear strength and was



readily removed during filtration.
                                 75

-------
Floe from the denitrification basin did not exhibit the same filterability



characteristics.  Solids frequently broke through the filters during opera-



tion with this effluent.  Thus, the denitrification process floe was either



finer  than floe from the other processes or had a lower shear  strength.



In either case,  filtration of denitrification process effluent most likely



will require the use of filter aids (polyelectrolyte) in order to  produce a



desirable effluent quality.  Aeration of the denitrification MLSS prior to




settling may also be  expected to improve the solids filterability.








Since the filters were not operated in parallel on the same effluents, it is



very difficult to compare their performance.  There was no significant



difference in the effluent quality from the three filters during all  operations



except that of denitrification,  where there appeared  to be a reduction in



the variability of the effluent turbidity when the mixed media filter was



used instead of the dual media.   Further evaluations of filterability would



be necessary before  the optimum media  could be selected.








During the operation of the filtration process,  biological growths  developed



in the filter media.   To prevent this problem from occurring,  a suitable



means of disinfection should be provided ahead  of the filters.  In  general,



filtration significantly improved the effluent quality and process reliability



of all the pilot plant systems investigated.








Activated Carbon
The  results for the  first stage of carbon adsorption of filtered activated



sludge, denitrification, and chemical effluents are summarized in Table



4-11.  The carbon used with the activated-sludge-treated wastewater had
                                  76

-------
a slightly greater adsorption capacity than that determined with the other

two effluents.  Carbon adsorption of the denitrified effluent produced the

lowest organic carbon concentrations in the treated effluent,  despite  the

fact that the influent TOC was greater than that from the activated sludge

unit.  These lower concentrations in the denitrified effluent were probably

due to the increased detention time  in the  carbon column which was neces-

sitated by the need for a lower hydraulic loading  in the denitrification re-

actor and settling basin.  The chemically-treated wastewater, which  had

the highest  influent TOC and SOC, also had the highest effluent organic

carbon concentration.  Removal efficiencies in the first-stage treatment

of the chemical effluent were nearly equivalent to those in the denitrified

effluent and somewhat better than those for activated sludge,  although

increased contact time for the  activated sludge effluent would be expected

to improve  the removal efficiency.
                              Table 4-11

       COMPARISON OF SINGLE-STAGE ACTIVATED CARBON
     PERFORMANCE FOR VARIOUS PILOT PLANT EFFLUENTS
Parameter
Effluent
TOC mg/1
SOC mg/1
Ibs TOC Removed
Ib Activated Carbon
Average Removal
TOC %
SOC %
Contact Time (min)
Ibs Carbon required
to treat 1 mg
Activated
Sludge
8. 3
5.8
0. 17
40
33
11
410
Denitrified
Effluent
7.2
3.4
0. 13
50
60
21
—
Chemical
Effluent
12. 6
7.2
0. 14
47
52
24. 5
690
                                  77

-------
Because of the higher influent TOC and SOC concentrations to the acti-



vated carbon columns in the chemical treatment plant effluent,  more



activated carbon per  unit volume treated was required to adsorb the



organic carbon.  Thus, it would require 690 pounds of activated carbon to



treat 1 mg chemically treated effluent,  about 1.7 times  the amount required



to treat the  activated sludge effleunt.








While having two activated carbon  columns in series  increased the re-



liability  of the adsorption system during the pilot plant studies, the



second carbon stage generally removed no more than 2 to 4 mg/1 of  or-



ganic carbon.  It is possible that the activated carbon treatment could



be optimized either by decreasing  the carbon contact time in  each stage



or by having only a single-stage treatment system to provide sufficient



contact time.   The type of system  which would  actually be employed



would depend  on the water quality requirements for each specific reuse ap-



plication and the relative cost of the two-stage  versus single-stage system.








Virus Removal








The  viral content of the treated wastewater is important from a public



health point of view,  especially if the water is to be reused or dis-



charged  to a waterway which may be used for body contact recreation.



Because of the potential hazards of virus in the treated waters, a



separate study was sponsored by CCCSD/CCCWD and Bechtel Corporation



to determine virus removals in the pilot plant processes.  A  brief sum-



mary of the results of the study conducted  by Cooper et  al.   (Reference 5)



is presented here.








Since the viral content of treated wastewater was anticipated  to be at or



near the detection limit of available analytical procedures,  it was deemed



necessary to add a known amount of attenuated  virus  (poliovirus type 1,



strain LSc)  to the wastewater and then measure the concentration of
                                  78

-------
virus after various steps in the treatment process.  Tracer studies
through the various processes were made so that effluent concentrations
with respect to time could be predicted and compared with actual mea-
surements.

Results of experiments in the biological treatment systems indicated
that the viral concentration was  reduced from one-one hundreth to one-
one thousandth of its initial concentration in the treatment units contain-
ing high MLSS concentrations.  When the pH of the  chemical treatment
system was maintained at 11 or  above,  there was no virus found in the
effluent.   The results  indicated a very rapid reduction in the viral con-
centration in the lime  reactor so that after just three  minutes, the viral
concentration was reduced to about one-five hundredth of its original
concentration.  Limited removal of virus occurred in the filtration pro-
cess, while the  activated carbon reduced the influent viral concentra-
tions by about 75 percent.

HEAVY METALS

Table 4-12 illustrates the removal of heavy metals in the activated sludge,
filtration, activated carbon, and chemical  treatment processes.   Atomic
absorption spectroscopy and emission spectrography analyses were made
on 24-hour composites of the influent and effluent streams.  Removal
efficiencies were generally better in the chemical treatment process than
they were in the  activated sludge process,  except for  copper and nickel.
However, since the influent concentrations were generally quite low,  ana-
lytical variance makes it difficult to compare the results directly.

Appendix B contains a summary of data from a series of experimental
runs using the chemical treatment plant in which a  solution of soluble
metal salts was added to the influent stream.   Removals ranged between
                                  79

-------
85 and 99 percent for all metals except hexavalent chromium, which was



reduced by an average of only about ZO percent.  Filtration generally re-



moved between 60 and 99 percent of the metals, indicating that most of



the metals were associated with the particulate material in the waste



streams.  Similar results were achieved using activated carbon,  where



adsorption of organometallic  compounds as well as straining  of particu-



late metallic materials were  undoubtedly taking place.







                             Table 4-12





                  REMOVAL OF HEAVY METALS

Ha riLim
Chromium
Copper
I. pad
\Unjjanoic
\UkH
SiKer
Titanium
/inc
Biological-Physical Treatment
Activated Sludce
Pi
In
rnn/1
Nil
0. 12
1). 12
0. 09
11. 21
a. 07
0. 012
0. 035
Nil
ot Plant
Out
mg/1
Nil
0. Of,
0 03
0 02
0. 24
i). 02
0. 006
0. Old
Nil
rem

50
73
78
11
7 1
50
54

CCCSD 1 mgd
In
mg/1
0, 50
0. 05
0.8
0. 1 15
0. 39
0. 085
0. 007
0. 27
0. 33
Out
mg/1
Nil
0. 01
0. 19
0. 008
0. 32
0 021
0. 001
0. 01
0. 10
rem
99 i
SO
70
93
18
75
85
9B
70
Filtration
In
mg/1
Nil
0.42
0.033
Nil
0. 017
0. 01
Nil
0. 01
Nil
Out
mg/1
Nil
0. 01
0, 023
Nil
0. 015
0. 006
Nil
Nil
Nil
rem
_
98
30
-
12
dO
-
99 t

Activated Carbon
In
mg/1
Nil
Nil
0. 023
0. 040
0. 060
0. 010
Nil
0. 34
0. 020
Out
me /I
Nil
Nil
0. 015
0. 001
0. 001
0. 005
Nil
0. 01
0. 001
rem
.
-
35
98
9?
50
-
98
98
Chemical Treatment
mg/1
0.43
0. 17
0. 14
0. 13
0. 33
0. 015
0. 013
Nil
Nil
Out
mg/1
Nil
0. 07
0. 05
Nil
0.02
0. 004
0. 002
Nil
Nil
Rem
99^
59
64
99.
94
67
85
-
-
                                 80

-------
                              Section V

                   RESULTS AND  DISCUSSION OF
                 INDUSTRIAL TEST LOOP STUDIES
Three industrial test loops and a test boiler received Contra Costa Canal

water and various grades  of renovated water during the pilot-demonstra-

tion project to evaluate the feasibility of using renovated wastewater for

industrial purposes in relationship to the present water source.   Data

on the scaling potential, corrosion rate, algal growth potential,  and

toxicity of the circulating  water in the test loops are presented and dis-

cussed in this section.


HEAT EXCHANGER FOULING DATA


During the normal operation of heat exchangers, there may be scale

formed on the walls of the heat exchanger tubes.  This scale may reduce

corrosion, but, if it becomes  excessive,  a significant loss in heat trans-

fer occurs.  During this study,  reduction in the rates  of heat transfer

and the related fouling factors were used as one means of evaluating

the various renovated waters and canal water.  Knowing the temperature

of the water  and steam at  the inlet and outlet of the  heat exchanger, the

flow (contact time), surface area, and type of  heat exchanger tubes, it

was possible to calculate the heat transfer coefficient,,  Any reduction

from the original value indicated that fouling was occurring and a fouling

factor could  be calculated.


Heat exchanger tube fouling may result from precipitation of calcium

phosphate or carbonate, corrosion products (rust),  dirt, and other for-

eign materials which accumulate on the heat exchanger surfaces. Table 5
                                  81

-------
                 Table 5-1




FOULING FACTORS AND SCALE ANALYSES


Exchanger Tube Exposure Period
Corrosion Inhibitor
Phosphorus Removal
Fouling Faclor lhr-°F-sq ft/Btu]
pll
Cy. les of Concentration
rempi-ralure IHeal Exchange
Oiitlell I°F)
Aluminum
Huron
Gallium
Chromium
Cobalt
Copper

Lead
Magnesium
Manganese
Molybdenum
N'u-kel
Phosphorous
Si lii-on
Silver
Strom ium
Tin
Titanium
\anaclium
/ mi
Other Hindis
Contra Costa Canal
5/18-6/8
6/9-7/1
No No
No I No
0.001 0.003
8.5
8.0
9.8 ! 7.0

125
0.08

140
O.I-
Nil , Nil
7't-7/30 's/1-8/31
No 1 Yes
No 1 No
0.0005 0.002
H. 5 7. 5
8.9 ' 6.5

IOS I 134
Nitrification
Effluent
5/18-6/8
No
No
0.0005
6/9-7/1
No
No
0.0005
8.4 7.8
5.6 6.7

100
I 1 5
0. 3 i 0.6 0. 03 0. 02
Nil Nil Nil 0.03
0.01 0.3 0. 06 ; 0.2 16' 30
0.01 ' 0 . 0 1
0.002 0.003
0. 08 0.10
65 60
Nil ! 0.01
0. 3
0.2
0.01
0.002
Nil
Nil
Nil
0.002
Nil
0. 7
0.2
0. 59 j 1.5 0. 0 1 | 0. 005
Nil ' Nil Nil Nil
0.09 ! 0.009 0.01
62 54 4. 3
0. 03 0. 2 0. 06
0.2, 1.2 6.1
0. 1 0. 20 0. 5
0.01 j 0.09 : 0.2 Nil
0.007 Nil 0.02 0.006
Nil
^
"Nil Nil ' 22
2.4 3.6 Nil
Nil Nil . Nil Nil
0. 0]
Nil
0.002 Nil
Nil
Nil
3 . n 6.0
Nil
Nil
Nil ' Nil 0. 50
Nil ! Nil Nil
O.OOi. i 0.01 0.01
Nil Nil ! Nil
2.01 7.5' 6.2
:->il I Nil i Nil
0.03
0. 4
0.005
2.0
0. 2
Nil
0.003
1 5
0.05
Nil
0. 1
Nil
Nil
Nil
5.0
Nil
Activated
Carbon/
Nitrification
Effluent
5/18-6/8
No
No
0. 0005
8.0
4. 4

6/9-7/1
No
No
0. 003
7.8
6.2

100 108
0.02 0.01
Nil 0.03
15
0.002
Nil
0. 01
2.4
0.05
4. 3
0.4
Nil
0.001
26
Nil
Nit
0. 30
Nil
Nil
Nil
6. 9
Nil
35
0.008
Nil
0. 04
0.7
0.005
1. 5
0.08
Nil
0.003
15
0.04
Nil
0. 1
Nil
Nil
Nil
6.0
Nil

Effluent
7/6-7/30
No
No
0.002
8. 5
8.0

102
0.02
0. 05
20
0.01
8/1-8/31
No
Yes
0.001
7.9
a. 4

134
0.04
0. 02
4.2
0.024
Nil Nil
Nil
0. 36
0. 1
3. 9
0.4
Nil
0.006
25
0. 7
0. 0007
0. 1
0.011
Nil
Nil
1.7
Nil
0.09
48
0.05
1 . 4
0. 3
0.02
0.01
2.8
2.7
0. 0006
0. 04
Nil
Nil
Nil
6. 3
Nil
Filtered
Effluent
7/6-7/30
No
No
0.004
8. 4
5.7

106
0.6
0.01
23
0.015
Nil
0.006
15
0. 06
2. 5
0. 4
Nil
0.008
6. 1
0.06
0.0009
0. 2
Nil
Nil
Nil
3. 1
Nil
8/1-8/31
No
Yes
0.002
7.4
5.4

134
0.03
0. 009
5. 3
0.02
Nil
0.09
29
0. I
1.0
0.2
0. 01
0.009
I 1
0. 7
0. 0003
0. 04
Nil
Nil
Nil
Filtered
C emica
Effluent
10/29-11/24
No
Yes
0.001
8. 6
10.4

126
0. 15
0.002
0.08
0. 66
Nil
0.08
20
0.02
0. 6
0. 08
0.04
0.005
Nil
0.40
Nil
0. 0 1
Nil
0.003
Nil
16 2.S
Nil Nil

Chemical Treatment
Effluent
10/29-1 1 /24
No
Yes
0.002
8. 1
5. 4

1 17
0. 2
10/29-11/24
Yes
Yes
0.003
8.4
7.4

120
0.2
0.004 , 0.002
0. 5 , 0. 30
0.05 0.009
Nil
0.06
0.002
0.05
17 19
0.06 0.05
0.6
0. 10
0.007
0.4
0. 08
0.006
0.005 ! 0.007
1.6 | 1.0
0. 3
Nil
0.02
Nil
Nil
Nil
5. 2
Nil
0. 3
Nil
0.02
Nil
Nil
Nil
5.0
Nil

-------
summarizes the data for the chemical composition of the scale that



formed during the various  test periods of this study.  Fouling factors



(see Reference 6 for calculation procedure) and operating data for



each test period are included in the table.  Analyses of the scale formed



in the heat exchanger tubes where canal water was used in the test loops



indicated that it consisted primarily of corrosion products (iron)



with some deposition of silica.  There was  no significant calcium or  phos-



phorous scale formed during use of the canal water.   The addition of a



corrosion inhibitor  (NALCO 370) to the canal water caused a moderate



increase in the  amount of zinc-chromate in the scale but had little effect



on the magnitude  of the fouling factor.  The relatively high levels of zinc



in the scale formed by all of the samples listed in Table 5-1  most likely



resulted from the dissolution of the galvanized coating on the bottom  pans



of the cooling towers, since analysis of the influent waters indicated  re-



latively low zinc levels.








In contrast to the canal water,  the renovated  waters that had received bio-



logical-physical treatment generally  resulted in scale formation composed



largely of calcium and phosphate. When ferric chloride was added to the



denitrification basin to reduce the phosphorous concentrations in late July



and August, the iron content of the scale formed in using this water in-



creased sharply,  whereas  the phosphate was  appreciably reduced.  This



reduction in phosphorous scale was observed even though only about 50



percent of the phosphorous had been removed from the makeup water.








The significance of  this scale is further illustrated by the results obtained



with the effluents from the  chemical treatment process.  With these ef-



fluents,  the phosphorous and calcium scale formed in the heat exchanger



tubes was greatly reduced,  resulting in a scale composition nearly the



same as found with  the canal water.   Also,  the silicon in the scale was



generally less  when using the renovated waters than when using the canal
                                  83

-------
water.  Based on these observations, it must be concluded that a high



degree of phosphorous removal is desirable for the use of renovated



water for industrial cooling purposes.








The fouling factors, shown in Table 5.1, ranged from 0.0005 to 0.004



hr-°F-sq ft/Btu for the canal water and the renovated waters.  These



factors represent the values observed after 18 days  from the time new



heat exchanger tubes were placed in operation for each exposure period.








The nitrified effluents consistently resulted in the lowest fouling factors



observed (i.e.,  0.0005 hr-°F-sq ft/Btu).  However,  nitrified effluent



that was filtered  and treated with activated carbon resulted in fouling



factors ranging from 0. 0005 to  0. 003 hr-°F-sq  ft/Btu.  There is no



apparent reason for the lower fouling factors  observed with the nitrified



effluent.








The fouling factor observed for the  filtered chemically treated effluent



was 0. 001 hr-  F-sq ft/Btu, whereas this effluent that had activated car-



bon treatment resulted in a fouling factor of 0. OOZ hr- F-sq ft/Btu.  The



addition of corrosion inhibitor to the carbon-treated effluent further in-



creased the fouling factor  to 0.003 hr-°F-sq ft/Btu.








An interesting observation from the tests conducted  is that the renovated



waters that were filtered or treated with activated carbon generally had



somewhat higher fouling factors than the same waters without these addi-



tional treatment steps.  The scale  formed  with the filtered and carbon-



treated waters appeared to be considerably harder and adhered to the



heat exchanger surface more  tenaciously.  It  is possible  that when organic



and particulate materials were  present (i.e. , no filtration or activated



carbon treatment),  the scale formed on the heat exchanger tubes was



partially removed because of scouring action  of the circulating water.
                                 84

-------
Visual observations made during operation of the test loops indicated



that the rather turbid canal waters and the  unfiltered renovated waters



deposited a significantly greater amount of solids in the bottoms of the



cooling towers than the filtered effluents.   Although the solids deposition



did not adversely affect the operation of the test loop equipment, such



deposition in heat exchange components used by industry could result



in significant operational problems.  These difficulties would be expec-



ted to  offset any benefits derived from  the  softer scale formed without



filtration.








Figure 5-1 summarizes  the fouling factor  data  described above.  The



data plotted for the canal water and various process waters represent



average values.   The data  indicate that the fouling potential of the reno-



vated waters is nearly the  same as observed with the canal waters.



Filtered,  chemically treated effluent and nitrified effluent had the  low-



est fouling potentials.








Control of the pH in the pilot plant treatment processes and the industrial



test loops  was limited so that on occasion  pH values in the makeup and cir-



culating waters were  higher than desired.   During these periods,  in-



creased precipitation of calcium salts most likely occurred,  resulting



in an accelerated decrease in the heat transfer  rate over a very short



time period.  Although the process difficulties  were generally corrected



within a day,  the precipitated materials probably remained,  thus keep-



ing the heat transfer at a low rate.  Because of this, it is felt that  the



data presented for the fouling factors represent conservative  (high)



values for  fouling.  In a  full-scale treatment plant,  operating conditions



would be more closely controlled, thereby  eliminating some  of the prob-



lems resulting from abnormally high pH values.








Representative fouling factors  for various types of  waters  used in indus-



trial applications are listed in  Table  5-2.   The  fouling factors (corrected
                                  85

-------
                    FOULING FACTOR
                                                 Hr °F ^ Ft
                                                    Btu
00
              oq
               £
               i-i
               CD
               m
               I
OQ
n>
               o
               P
               O
               r-t-
               O
               I-t


               d
                                 O
                                 8
                               p
                               §
                               ro
p
8
p
8
                                         CANAL WATER
                                             ' CANAL WATER (WITH CORROSION INHIBITOR)
              NITRIFIED EFFLUENT
                                           CARBON TREATED NITRIFIED EFFLUENT
                                              DENITRIFIED EFFLUENT
                                                                       FILTERED DENITRIFIED EFFLUENT
                                  DENITRIFIED EFFLUENT (WITH PHOSPHATE REDUCTION)
                                FILTERED DENITRIFIED EFFLUENT
                                (WITH PHOSPHATE REDUCTION)
                                   FILTERED CHEMICAL TREATMENT EFFLUENT
                                            J FILTERED AND CARBON-TREATED CHEMICAL EFFLUENT
                                                           FILTERED, CARBON TREATED CHEMICAL
                                                           EFFLUENT (WITH CORROSION INHIBITOR)

-------
                               Table 5-2
                    TYPICAL FOULING  FACTORS"
Temperature of Heating Medium
Temperature of Water
Types of Water
Sea Water
Brackish Water
Cooling Tower and Artificial Spray Pond:
Treated Makeup
Untreated
City or Well Water (Such as Great
Lakes )
Great Lakes
River Water:
Minimum
Mississippi
Delaware, Schuylkill
East River Iv New York Bay
Chicago Sanitary Canal
Muddy or Silty
Hard (Over 15 grains/gal)
Engine Jacket
Distilled
Treated Boiler Feedwater
Boiler Blowdown
Up to 240°F
125°F or Less
Water Velocity
3 ft/sec
and Less
. 0005
. 002

. 001
. 003
. 001
. 001

„ 002
. 003
. 003
. 003
. 008
. 003
. 003
. 001
. 0005
. 001
. 002
Over
3 ft/sec
. 0005
. 001

. 001
. 003
. 001
. 001

. 001
. 002
. 002
. 002
. 006
. 002
. 003
.001
. 0005
. 0005
, 002
240°F to 400°F
Over 125°F
Water Velocity
3 ft/sec
and Less
. 001
. 003

. 002
. 005
. 002
. 002

. 003
. 004
. 004
. 004
. 010
. 004
, 005
. 001
, 0005
. 001
. 002
Over
3 ft/ser
. 001
.002

. 002
. 004
. 002
. 002

. 002
. 003
. 003
. 003
. 008
. 003
. 005
. 001
. 0005
. 001
.002
Reference 6
                                   87

-------
to a velocity of 2 ft/sec), observed during this study for various reno-



vated waters compare favorably with the published data.  This informa-



tion supports the results obtained and indicates that on the basis of foul-



ing,  renovated waters are comparable to many other sources of indus-



trial cooling water being used throughout the United States.







CORROSION RATES








Corrosion rates associated with the use of Contra Costa Canal water and



various grades of renovated •water in industrial applications  were deter-



mined using two procedures. The first procedure involved the use of a



portable corrosion meter (Magna  Corporation) in conjunction with  a cor-



rosion probe inserted in the circulating water of each  industrial test loop.



Corrosion rates using this procedure  could be determined immediately.



The second procedure utilized standard corrosion coupons made from car-



bon steel.  Four of these coupons were inserted in a circulating  water  by-



pass loop during each testing period.   Coupon weight loss was determined



after  each testing period using ASTM procedures, and a corrosion rate



was calculated.   The corrosion probes and the corrosion coupons were  lo-



cated on the discharge side of the heat exchangers.








Table 5-3 summarizes the corrosion rates obtained with the corrosion



probes and meter for  the various  renovated  waters and canal water in the



industrial test loops.  Chemical characteristics of the circulating  waters



are also shown in Table  5-3.








The observed corrosion  rates,  as  determined with the corrosion probes



and meter,  for the untreated canal water ranged from  23 to  106 mils/yr



while the  corrosion rates for the renovated waters that received biological



treatment ranged from 6. 3  to 14 mils/yr.  A corrosion  rate of  3 mils/yr



was observed for the filtered chemical treatment effluent.  However,  a

-------
                                                               Table  5-3

                             CORROSION RATES AND CIRCULATING  WATER QUALITY



Source of Water

Exchanger Tube Exposure Period
Corrosion Inhibitor
Phosphorous Removal
Corrosion Rate* mils/yr
Cycles of Concentration
Langelier Index





3/5-
5/4
No
No
106
4. 7
0. 27
Calcium niR/1 CaCO( 1 (,8
Alkalinity nip/I CaCO, 69
pll 8.0
Total Phosphate mc/l PO 0.08
Conductivity Mmhos /cm 1263
o
Kxit Temperature F 104
Suspended Solids mg/I 15.2



Act
Contra Costa Canal Sludge
Eff
5/18-
6/8
No
No
6/9- 7/f>-
7/1 7/30
No
No
68 41
9. 8 7.0
,.42 ,0.83
267 215
88 70
8/1- . 3/5-
8/31 5/4
No Yes l No
No No
23 5.4
8. 0
1.74
6. 5
3.05
No
10
4.0
1. 31
316 230 ' 424
230 .52 112
8.5 K. 0 8.5 7.5
0. 60 0.70 | 1.5
2143
1 19
18
1415 ! 1780
1 14
14
102
48
1.8
1323
123
•I. 0
8.0
Filt-
ered
Act
Sludge
Eff



Nitrification
Err
3/5- J5/18-
5/4 6/8
No
No
No
No
6. 3 ; 14
4.7
0.98
496
6/9-
7/1
No
No
7.8
5. 6 6. 7
1.47 0.82
395 ; 471
87 111, 64


At t Carbon
Nitrification
Eff
5/18-
6/8
No
No
10.7
4.4
0.68
6/9-
7/1
No
No
6. 3
6.2
0.77


Dentrifica-
tion
Eff
7/6,
7/30
No
No
12
8.0
,.75
289 426 366
59 52 258
8/1-
8/31
No
Yes
9.2
8.4
0.89
542
74

Filtered
Dentrifica-
tion
Eff
7/6-
7/30
No
No
7.9
5.7
1. 53
338
207
7.9 ' 8.4 ' 7. 8 8.0 . 7. 8 8.5 ' 7.9 8.4
18 15 1 0 ' 24 : 9 11 13 13
3063 4740
1 10
6. 3
107
35
5180 5855
121
1 •
1 18
3. 6
3944 j 5406 5780 5242
,22
4.7
128 105
2.4 ; „. 3
12
5100
127 , 104
13 5.8
8/1-
8/31
No
Yes
11
5.4
0.27
496
49
7.4
Filt-
ered
Chem
Treat-
ment
10/29-
11/24
No
Yes
3.0
10.4
2.7
580
230

Act Carbon
Chemical
Treatment
Eff
10/29-
11/24
No
Yes
72
6. 1
0. 5
260
40
8. 6 8. 1
20 1 1.2 j 1.5
4929
130
11
7610 ' 4400
130 130
7.5 '• 4.0
10/29-
11/24
Yes
Yes
26
7.4
0.93
396
60
8. 3
1. 9
5420
119
3.7
 Data obtained from corrosion probes
Noli-: Art  Activated
     KIT  Klfluenl

-------
rate of 72 mils /yr was determined for the chemical treatment effluent that



was also treated with activated  carbon.   These latter values suggest that



the 3 mils/yr corrosion rate observed with the filtered chemical treatment



effluent may be  erroneously low.  The addition of a  corrosion inhibitor to



the canal water  decreased the corrosion rate from an average of 60 mils/



yr to 5.4 mils/yr.  A  decrease in the corrosion rate from 72 mils/yr to



26 mils/yr was  observed when corrosion inhibitor was added to renovated



water having chemical and activated carbon treatment.








Shown in Table 5-4 are the  corrosion rates obtained from the corrosion



coupons inserted in the industrial test loop circulating waters.  Also shown



in this  table are the corresponding corrosion rates  observed with the cor-



rosion probes and meter.  In all cases the corrosion coupons indicated



lower corrosion rates  than  determined with the corrosion probes and



meter.  Biologically treated renovated waters resulted in corrosion  rates



ranging from 2.  0 to 6. 6 mils/yr as  determined with the corrosion coupons,



while untreated  canal water had corrosion rates of  12. 5 to 37. 2 mils/yr.



The canal water corrosion rate was reduced to 2. 7  mils/yr by the addition



of a corrosion inhibitor.  The renovated water receiving chemical and  ac-



tivated carbon treatment resulted in a corrosion rate,  as determined with



the coupons, of  31.0 mils/yr; this rate  was reduced to  11.9  mils/yr with



the use  of a corrosion inhibitor.








The data generally indicated that the renovated waters receiving treatment



for the reduction of phosphorous had higher corrosion rates  than when



phosphorous was not removed.  This  observation suggests that either the



phosphorous in the water inhibited corrosion  or the phosphate scale that



was formed on the heat exchanger tubes provided a protective coating.



Visual observation of the heat exchanger tubes suggested that the scale



formation most  likely  was the primary mechanism  associated with the re-



duction in the corrosion rate.  Also,  solubility coefficients for various



calcium and phosphorous compounds indicate that scale formation  could



continue to the point that heat exchanger tubes would be severely restricted.
                                90

-------
                             Table 5-4

               COMPARISON OF CORROSION RATES
Type of Water
Canal Water
Canal Water
Canal Water with Corrosion
Inhibition
Nitrified Effluent
Denitrified Effluent
Denitrified Effluent with Phos-
phorous Reduction
Filtered Denitrified Effluent
Filtered Denitrified Effluent
with Phosphorous Reduction
Chemical and Activated Carbon
Treated Effluent
Chemical and Activated Carbon
Treated Effluent with Corrosion
Inhibitor
Date
6/9 7/1
7/6 7/30
8/1 8/31
6/9 7/1
7/6 - 7/30
8/1 - 8/31
7/6 7/30
8/1 8/31
10/29 11/24
10/29 - 11/24
Corrosion Rate
mils/yr
Coupons
37. 2
12. 5
2. 7
2.9
2. 0
6. 6
2. 2
4.9
31. 0
11.9
Probe""
41. 0
23. 0
5.4
7.8
12. 0
9.2
7.9
11.0
72. 0
26. 0
  Data obtained with corrosion coupons
##Data obtained with corrosion probes
                                 91

-------
For the canal water and the renovated waters,  the L/angelier Index did not



provide an accurate assessment of the potential for scaling or corrosion.



The chemical characteristics of these waters must have been responsible



for these inaccuracies.








ALGAL GROWTH POTENTIAL







Since many of the problems which arise from the discharge of nutrients



into the environment are associated with the response of algae to the in-



creased nutrient levels, a means of assessing this potential growth would



be useful in evaluating the efficacy of various treatment procedures.  The



Provisional Algae Assay Procedure (PAAP) was used for this purpose dur-



ing this investigation in accordance with the methods  developed by the



University of California Sanitary Engineering Research Laboratory.   This



procedure  utilized algae to measure the growth potential of a  given sample



of water in much the same way that BOD is used to assess the oxygen con-



suming capacity of a given waste by bacteria.  Growth of the test species of



algae Selenastrum capricornutum was assessed using a standard solution



which had all of the  nutrients  required for the  growth of the algae.   The



growth of the algae in this standard solution was then compared to the



growth in the sample solutions.








Table 5-5 indicates  the phosphorous and inorganic nitrogen concentrations



in the sample waters which were used for the Provisional Algae Assay



Procedure.  The denitrified effluent had a high poshphorous content but



relatively low concentrations  of nitrate  and ammonia, whereas  the acti-



vated sludge effluent had both high phosphorous and high inorganic nitro-



gen concentrations.  The chemically treated effluent  had a very low phos-



phorous concentration and almost all of the nitrogen present was in the



ammonia form.   When these process waters were used as the algal growth
                                 9Z

-------
                               Table 5-5





 SAMPLE ANALYSIS FOR ALGAE  GROWTH POTENTIAL  TESTS
Measured Parameter

pH
Conductivity /j. mho
Orthopho sphate
as P mg /I
Nitrate, as N nig /I
Ammonia, as N nig /I
Process Water
Deni-
trified
Effluent
7.4
630
8. 5
0. 3
0.6
Activated
Sludge
Effluent
7. 5
610
9. 1
9.0
9.0
Lime-
Treated
Effluent
7.8
895
Nil
Nil
17.0
medium,  the response curves shown in Figure 5-2 were obtained.   The



algae grew rapidly in the standard test medium and,  even after six days,



were still in the log  growth phase in this medium.  There was a lag of about



three to five days in the growth of the algae in the denitrified medium and



the activated sludge  medium.  The log growth phase  in the denitrified effluent



lasted for approximately three days, and after aboutnine days it appeared as



if nitrogen limited further growth of the algae in this medium. Growth in the acti-




vated sludge medium continued for the duration of the experiment after



the initial lag period.  Apparently,  there was some material in the acti-



vated sludge effluent which inhibited the growth of the algae initially, but,



once the algae became acclimated to the activated sludge effluent,  they be-



gan to grow rapidly since they were not nutrient limited.  The chemically



treated effluent apparently had a low enough phosphorous concentration so



as to limit the growth of algae in  this medium.  The  data plotted in Figure



5-2 indicated that lime  treatment produced  an effluent which permitted



little or no growth of the algae, whereas denitrification permitted a limited
                                  93

-------
    1.00-
to
fa
 o
 UI
     0.10-
    0.01-
                STANDARD
                               ACTIVATED SLUDGE
                                   EFFLUENT
                            DENITRIFICATION
                              EFFLUENT—,     /
                                         LIME-TREATED
                                          EFFLUENT
                                 8

                               DAYS
—i—
 10
12
—I—
 14
                   16
      Figure 5-2.  Algae Growth in Renovated Waters
                              94

-------
growth of the algae.  The high nutrient concentrations  in the activated

sludge effluent permitted a rapid and continuous growth of algae for at

least a 15-day period.


With nutrient removals in excess of 95 percent,  there  will be sufficient

nutrients  remaining to  support  some growth of algae.  However,  it is an-

ticipated that such growth can be readily controlled in  cooling towers using

established techniques.


TOXICITY ANALYSIS


The toxicities of effluent streams receiving primary and activated sludge
                                                                         •j<
treatment and primary with lime treatment are summarized in Table 5-6. ""

The  results indicated that primary  treatment produced an effluent which,

when diluted to an average value of 47. 5 percent of its  initial concentra-
tion with dechlorinated tap water, killed 50 percent of  the test species

(stickleback) in 96 hours (96 hr  LC-50% =  47. 5).  Undiluted effluent from

the activated sludge plant killed less than 50 percent of the test species in

96 hours.  Lime precipitation,  on the  other hand, produced an effluent

which was only slightly less toxic than that resulting from primary treat-

ment alone,  so that diluting to 61 and  81 percent of the initial concentra-

tion produced a 50-percent kill after 96 hours in the chemical effluent.   By

providing activated carbon adsorption after chemical treatment, the toxi-

city  of the effluent was reduced  to the  point that less than half of the fish

were killed in the undiluted waste after 96 hours.  Since the ammonia con-

centration did not change appreciably  due to the carbon treatment,  some-

thing other than just  ammonia must have been contributing to the toxicity.

When the  ammonia was removed from the  chemical treatment effluent by

ion exchange (clinoptilolite),  the survival was again greater than 50 per-

cent after 96 hours in the undiluted waste.
*Toxicity analyses performed by Sanitary Engineering Research Laboratory,
 College of Engineering and School of Public  Health,  University of Cali-
 fornia, Berkeley.
                                  95

-------
                                Table 5-6


                   SUMMARY OF TOXICITY RESULTS*
                  (Central Contra Costa oanltary District)

Constituent
Week 1
(April 23-27)
COD v
BOD j
SS >mg/l
NH3-N I
Total P/
pH
96 hour LC-50,
percent
Week 2
(April 27-May 1)
COD \
BOD
SS Trig /I
NH3-N
Total P/
PH
96 hour LC-50,
percent
72 hour LC-50,
percent
Biological Treatment
Primary
Effluent


208
112
96
22. 7
9.3
7. 3

45


217
80
88
24. 8
9.2
7.4

50


Activated
Sludge
Effluent


86
42
37
7. 2
10, 5
7. 2

•':-.':'


110
30
32
7. 8
9. 7
7. 3




Physical-Chemical Treatment
Partially
Settled
Sewage


260
112
178
22. 2
12. 8
7. 1

58


299
130
129
20. 9
13. 3
7. 4



71
Chemical
Treat
ment
Effluent


83
29
13
18. 5
1.6
6.8

61


78
20
15
20. 9
1.0
7. 2



81
Chemical Treatment
Effluent After
Activated
Carbon


43
19
11
19. 0
1, 5
6.9




44
13
9
21. 0
1.0
6, 7



'!' '!^
Ammonia
Removal


69
29
13
3. 1
1. 5
7. 0

sV -'-•


55
14
8
1. 9
0. 7
7. 6



;!' ;!'
*   Average of daily composites

**  Less than 50 percent kill in  100 percent waste at 96 hours


Note:  The above data were obtained by the Sanitary Engineering Research
       Laboratory at the University of California, Berkeley
                                    96

-------
Table 5-7 presents a comparison of the toxicity of activated sludge, nitri-

fied,  and filtered nitrified effluents from the pilot plant.  After 96  hours

of contact, two of the test species were dead in the undiluted activated

sludge effluent,  whereas there was  complete survival of the test species

in the nitrified effluents.  All of the test species survived after 96  hours

exposure to the  circulating waters  in the industrial test loops which had

been  concentrated by approximately five times.  These data indicated that

blowdown from cooling towers using renovated water should not result in

toxicity problems if adequate treatment is provided.



                                Table 5-7


            INDUSTRIAL TEST LOOP  TOXICITY RESULTS

CCSD Activated
Sludge Effluent
Pilot Nitrified
Effluent
Pilot Filtered
Nitrified Effluent
Cooling Tower
Circulating Water
Canal
Nitrified
Effluent
Filtered Nitri-
fied Effluent
Filtered Chemically
Treated
Effluent
Filtered Acti-
vated Carbon
Chemically Treated
Effluent
Dilu-
tion
None
None
None

None
None
None
None
None
DO
mg/1
8.2
8. b
9.0

8.6
8. 0
8.8
7.9
9. 5
pH
7. 95
7. 45
7. 55

7. 15
7. 70
7. 60
8. 4
7. 0
Numbor Sur\ ving/Prrrent Survival
Start
10/100
10/100
10/100

10/100
10/100
10/100
10/100
10/100
24 hr
10/100
10/100
10/100

10/100
10/100
10/100
10/100
10/100
4K hr
10/100
10/100
10/100

10/100
10/100
10/100
10/100
10/100
72 hr
8/80
10/100
10/100

10/100
10/100
10/100
10/100
10/100
c'6 hr
8/80
10/100
10/100

10/100
10/100
10/100
10/100
10/100
 jr,Temperature  71 F  Test Species  stickleback  Number of fish per test  10
 'Slowdown from the cooling towers was about five times the concentration
  of the cooling tower feed.
                                    97

-------
EVALUATION OF INDUSTRIAL TEST LOOP RESULTS








The most significant finding during the investigation of fouling factors and



corrosion rates was  that renovated water used as cooling tower makeup



performed at least as well as the Contra Costa  Canal water.  Precipitation



of phosphorous in the test heat  exchanger tubes was observed for  the reno-



vated waters not receiving treatment for phosphorous removal.   Calcium



precipitation was associated with the precipitated phosphorous.   However,



scale formed from the use of lime-treated renovated water with very low



phosphorous concentrations had very small contents  of calcium and phos-



phorous.  Since the calcium concentrations and pH of the lime-treated



waters were approximately the same as in the biologically treated effluents



not receiving treatment  for phosphorous removal,  it appears  that little



precipitation of calcium carbonate or calcium sulfate would be expected



when the renovated water  tested in this study is used as cooling water.



Thus,  the chemical constituent in these wastewaters most directly in-



fluencing the scaling of heat exchanger tubes was phosphorous.  Removing



the phosphorous increased the corrosion rate of the renovated water, but



this was satisfactorily reduced by the addition  of a corrosion  inhibitor.








When the above considerations  are taken into account,  the  potential fallacy



of considering only the total dissolved solids content when evaluating a



water's utility for reuse becomes apparent.  Water having a high  TDS but



a low phosphorous or  calcium content generally would not be expected to



result in problems associated  with scaling from precipitation. Similarly,



chlorides,  which are important with respect to  the stresses imposed on



stainless steel heat exchanger tubes, may be relatively low in waters hav-



ing a  high TDS if these waters are derived primarily from the dissolution



of calcareous sediments.   Thus,  TDS concentrations can be used  to provide



a preliminary indication of the  potential utility of a given water for reuse,



but should not be relied  upon as the  sole criterion  for a given water.
                                 98

-------
The fouling factor results, summarized in Figure 5-1,  indicate that nitri-



fied effluent,  denitrified effluent with phosphorous reduction, and filtered



lime-treated  effluent with and without carbon adsorption have fouling ten-



dencies comparable  to canal waters treated with a corrosion inhibitor.



Corrosion rates for  these waters were also approximately the same as



canal water with a  corrosion inhibitor added.  The only exception to this



was the filtered, activated carbon, lime-treated effluent which had  a rela-



tively high corrosion rate of 31  mils/yr. When the corrosion  rate was



reduced to about 12 mils/yr with a corrosion inhibitor, the fouling in-



creased appreciably.  These results indicate that a balance between cor-



rosion and fouling can  be achieved by the treatment processes of activated



sludge and nitrification.  Denitrification did not appear to improve the



fouling  or corrosion rates,  so this added process would not be expected



to significantly improve  the industrial usability of the treated wastewater.



While it is likely that adding a corrosion inhibitor to the filtered,  lime-



treated effluent •would produce a water which would have a  lower corrosion



rate than  the  same water receiving activated  carbon treatment, there  is



no way of knowing  how this would affect the fouling factor,  since experi-



mental results  for this particular test were not obtained.








Table 5-8 summarizes typical concentrations of chemical constituents in the



Contra  Costa Canal water and CCCSD primary influent.  As  is apparent



from  this table, there  is an appreciable increase in the concentration  of



dissolved salts in the wastewater in relationship to the canal water.  How-



ever, of major concern in the reuse  of this wastewater for cooling water



purposes  is the calcium, carbonate,  and sulfate concentrations.   These



constituents as well  as phosphorous are important since they may enter



into precipitation reactions  in a cooling  water system as the number of




cycles of  concentration and  the temperature increase.   Studies concern-



ing the  fouling tendencies of the renovated waters indicated that no signifi-



cant precipitation of calcium salts occurred during the industrial  test



loop studies other than that  due  to precipitation with phosphorous.
                                  99

-------
                              Table 5-8

                TYPICAL QUALITY CHARACTERISTICS
                OF WASTEWATER  AND CANAL WATER
Chemical Parameters
Na+
K+
Ca++
Mg++
Cl"
S°4
HC03
TDS
Alkalinity (as CaCO )
Hardness (as CaCO )
CCCSD Primary
Influent (mg/1)
106
12
51
17
123
116
205
860
179
197
Canal
Water
(mg/1)
57
2.4
26
15
78
56
103
310
84
129
Thus,  no trouble with precipitatioh of calcium salts is expected in using

renovated water for cooling purposes at cycled of concentration of approxi

mately five  to eight,  if the total phosphorous  concentrations are reduced

to 0. 5  mg/1 as P or less.


Chloride concentrations  are of concern with regard to stress corrosion

in the heat exchanger tubes fabricated from stainless steel.  However,

the chloride concentrations which cause such problems with Stainless

Steel 316 are in excess of those in the renovated wastewater  even at

cycles  of concentration above ten.  Therefore,  chlorides are not expected

to be a major problem during the  use of renovated water for  cooling

purposes.
                                100

-------
In using renovated water for industrial purposes, limitations on the dis-



charge  of blowdown waters to receiving waters must be considered.  Of



prime concern is the toxicity of the discharge, to established fish species



and the tendency for the discharge to stimulate algal growths.  Fish bio-



assay studies using the blowdown from.the industrial test loops indicated



that  100 percent  of the test organisms survived after 96 hours of exposure



to the concentrated canal water, unfiltered and filtered nitrified effluent,



and filtered chemically treated effluent with and  without activated carbon



treatment.  However, it  should be noted that the bioassay studies were



made on the blowdown waters after they had been aerated sufficiently to



increase the DO  to greater than 7 mg/1 and cooled to ambient temperatures.








Zinc, •which may be toxic to fish at concentrations of 1 mg/1 or less, was



one of the relatively high constituents of the  scale formed in the industrial



test  loop studies.  Although zinc was probably present in the blowdown



water as well as the scale, there was no apparent effect of this toxic



metal on the test organisms during the bioassay  studies.  As discussed



earlier, the high zinc concentrations were probably due to leaching of



zinc from the galvanized coating on the cooling tower bottom pans.  This



source  of zinc •would be greatly reduced or eliminated in a commercial-



scale cooling  tower.








The  use of zinc chromate as a  corrosion inhibitor in cooling towers, how-



ever, may cause toxicity to fish or other sensitive organisms if they are



exposed to the blowdown water. This effect was not evaluated during this



study but  should  be reviewed before such water is discharged to receiving



bodies of water.   In this  respect, the use of renovated wastewaters is



not expected to cause  any greater problems than encountered in the use




of canal water.
                                 101

-------
Based on the findings of the industrial test loop studies, the nitrified ef-



fluent produced the most satisfactory water for industrial reuse except



with respect to algal growth potential.  This growth potential was signifi-



cant because neither nitrogen nor phosphorous was reduced by this treat-




ment sequence.   The nitrified effluent did have a relatively high potential



for phosphorous precipitation, and the scale analysis did show appreciable



amounts of calcium  and phosphorous.  Despite this scaling, the fouling



factor was surprisingly low for the nitrified effluent.  With phosphorous



removal to minimize algae growth and scaling problems,  biological



oxidation and nitrification to remove organics and ammonia, and fil-



tration following nitrification to reduce suspended solids  and improve



process reliability,  a suitable renovated water can be produced for in-



dustrial cooling purposes.  In the event that total nitrogen is limited  to



receiving bodies  of water, biological denitrification may also be necessary,








Activated carbon treatment tended to increase the fouling  factors but had



little or no effect on decreasing the corrosion rates of  the renovated



waters.  Since it did not appear necessary to  remove organic materials



to reduce toxicity,  the  use of activated  carbon treatment for general  in-



dustrial water supply does not appear to be necessary.   Where specific



uses call for low organic carbon in the  water,  such as  may  be required



for boiler feedwater, it would probably be  most economical for  the indus-



try concerned to  supply the additional treatment necessary.  Biological



denitrification and activated carbon treatment may also be important if



the renovated water is  to be demineralized  and used for boiler feed or



process purposes.
                                 102

-------
                              Section VI




          ESTIMATED WASTEWATER TREATMENT COSTS







This section presents cost estimates for 30-mgd plants using the treat-



ment processes investigated during the pilot-demonstration studies.



These  cost estimates can serve  as an aid in the comparison of alternative



treatment procedures; they are based on assumed average conditions for



land, easements,  site preparation, and engineering.  Actual costs for



specific treatment facilities,  such as those for the Central Contra Costa



Sanitary District, will differ  somewhat because of factors peculiar to



the individual construction site.   The costs discussed below are  for treat-



ment facilities only;  they do not  include the cost of administration and



maintenance buildings, utility tunnels and discharge lines, or storm



water treatment,  since these facilities would be common  to all of the



treatment systems.







Figure  6-1 indicates  the  estimated treatment costs, in 1972 dollars,  for



each of the three phases  of the study.  A cost index of 185. 0,  as  published



by the  EPA  for wastewater treatment plants, was  used to adjust  cost data



presented by others (References 7, 8, 9,  and 10).  Amortization costs



were based  on capital recovery at 6-percent  interest over a 25-year



period.  For the purpose of cost comparison, no federal or state grants



were assumed.  It is emphasized that the costs presented in this section



may not be directly related to  water  renovation costs because in  many



cases considerable treatment is  required simply to discharge the efflu-



ent to receiving bodies of water.  In  such cases,  the  costs associated
                                 103

-------
PHASE NUMBER
1
	 •"JPRIMARY
~\ 	

2 3
1 IU2
ACTIVATED *
~~T SLUDGE


SLUDGE
DISPOSAL
I-CONVENTIONAL TREATMENT
1
	 *• PRIMARY

ii-BIOLOGICAL
NITRIFICATIO
I
	 *• PRIMARY

IIA-B OLOGICAL
NITRIFICAT
DENITRIFY
III - PHYSICAL-
CHEMICAL
TREATMENT
1
	 ^.INFLUENT
WORKS

ALUM (OPTIONAL)
|~ 2 3 ~J 4 5
1 1 1 1
-1*. A(1TIV*J|D 	 P.NITRIFICATlONk-i*-FILTRATlON 	 !-»•
_. SLUDGE -.
r ii i

i
6
N SLUDGE DISPOSAL 	 *-

ALUM (OPTIONAL
r~ "5 3—14 5
i 	 * 	 	 * 	 1 	 	
— 1*. ACTIVATED — ^ NITR1F CATION -J^DENITR FICATION 	 ^FILTRATION
p, SLUDGE ^ p.
1 II 1 1 1
1 1 1
1
SLUDGE DISPOSAL 	 »-
mnN

L|M£ NH3 REMOVAL IOPTIONALI 3-11V/1C
1 34
1 CHEMICAL ACTIVATED
CALCINATION ^nou«

LIME
1 | 2 3 4 5
INFLUENT
WORKS

1 CHEMICAL
•i*- TREATMENT* — »- NITRIFICATION — *• DEN ITRI FICATION — «- FILTRATION
CALCINATION
1
I

6
J±
	 1— »-

WO GAL
_b
J*.
MIA- COMBINATION BIOLOGICAL SLUDGE
DISPOSAL



TREATMENT COSTS {i n 000 gal)
0 & M
1
2
3
4
1
2
3
4
5
6
OPTIONAL
I
2
3
4
5
6
7
OPTIONAL
1
2
3
4
5
1
2
3
4
5
6
7
1.6
6.5
1.7
3.7
13.5
1 6
6 3
35
36
1 7
38
205
267
1 6
63
35
3.5
36
1 7
3.8
24.0
30.2
1.3
101
3.6
3.4
1.7
20.1
1 3
10 1
3 5
35
36
1.7
1.6
253
AMORTIZATION
2 7
4 6
0 1
3 8
1 1 2
2 7
3 8
3 4
1 4
0 1
4.5
15 9
16 5
2 7
3 8
3 4
3 1
1 4
0 1
4 7
19 2
19 8
2.2
4 4
1 .4
6 4
0.1
14.5
2 2
4 4
3 4
3 1
1 4
0 1
0.9
15 5
TOTAL
4 3
I 1 1
1 8
7 5
24 7
4 3
10 1
6 9
5 0
1 8
8.3
36 4
43 2
t 3
10.1
6 9
6 6
5 0
1 8
8.5
43 2
50 0
3 5
14 5
5 0
9 8
1 8
34 6
3 5
14 5
6.9
6.6
5.0
1 8
2.5
40.8
COMMENTS
• Least cost solution
• Waslewater may be toxic and require more treatment lor
ditcharge
• Limited reduction in nutrient content ol wastewater
• Additional costs are excessive if nutrient removal is required (see option
Phase II A)
• Limited reuse potential tor industrial purposes due to phosphorus and
• Undiluted effluent is apparently not toxic
• Nitrification reduces the qxygen demand of the effluent
• Phosphorus removal coukj be achieved by adding alum at an annual
cost of 634/1000 gal
• Limited reuse potential for industrial purposes due to potential
phosphorus precipitation
• Filtration will increase the plant reliability and improve effluent
quality
• Undiluted effluent is apparently not toxic
• Demtnfication may limit the algal growth in the effluent
improve effluent quality
• Industrial reuse would be limited by the high phosphorus
• If nitrogen and phosphorus removal are required, this is the most expen
• Lime treatment was most reliable of the pilot plant systems
• About 95 percent phosphorus removal in the lime stages
• Requites additional step for SOC reduction
• Effluent is apparently not toxic and may be suitable toi industrial use
if odors are controlled
• Filtration may not be necessary if activated carbon is used
• Ammonia removal could be accomplished with clinoptilolite ( 8 to
lOrf/lOOOgall
• Nitrification reduces the organic carbon and oxidizes the ammonia to
nitrate
• Filtration increases reliability of treatment and effluent quality
• Nitrified lime-treated effluent is probably nontoxic and should be good
for industrial purposes
• Demtnfication could be deleted if nitrogen removal is not
required fot discharge into receiving waters
Figure 6-1.  Flow Diagrams and Treatment Costs for 30-mgd Plants

-------
with wastewater treatment should be deducted from the water renovation



co.sts.








General process descriptions of the alternatives considered in the cost



estimates are presented below.  Advantages and disadvantages of the



various alternatives are also discussed.








PHASE I: ACTIVATED SLUDGE








The first alternative considered was a conventional activated sludge plant



consisting  of primary and activated sludge  treatment along with sludge



dewatering  and  incineration.  This alternative was the least expensive



treatment sequence having water costs for  a 30-mgd plant of approxim-



ately 24. 7  cents per thousand gallons at capacity.  Although this  plant



should remove approximately 90  percent of the suspended solids  and BOD,



the nutrient content of the effluent, especially  ammonia and  phosphorous,




\vould support appreciable  algal growth.  Because of the chlorine demands



associated with the ammonia, the potential for algal growth, and the



likelihood of precipitation of calcium phosphate, additional treatment



processes would be required to produce an effluent  suitable for direct



industrial cooling water  use.  It is possible, however, that  an industrial



user  could provide the additional treatment necessary.








PHASE II:   BIOLOGICAL NITRIFICATION








This  system includes the basic plant considered in Phase I with the addi-



tion of a nitrification stage to oxidize the ammonia to nitrate, followed by
                                105

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filtration to increase the overall reliability of the plant and improve the




renovated water quality.  The detention time  in the activated sludge unit



(i. e. , the first stage) would be reduced so there would be a higher organic



carbon concentration in the nitrification reactor influent and the treatment



costs for -this stage can be reduced.   As with the  Phase I alternative,



sludge disposal would consist of dewatering and incineration.   Costs  for



this treatment system were  estimated at 36. 4 cents per thousand  gallons.








For phosphorous removal,  it would be possible to use alum in  conjunction



with the biological  treatment processes, as indicated in Figure 6-1,



Phase II.  Annual operating  costs for this treatment would be approxim-



ately 6. 8 cents per thousand gallons in addition to the above mentioned



costs, resulting in a total cost of 43. 2 cents per thousand gallons. This



additional cost represents the cost for the alum feeding system as well



as the additional sludge disposal costs.








With phosphorus  removal, the effluent produced with this treatment sys-



tem  should,  in most cases,  be suitable for direct reuse by industry for



cooling  water makeup.  Consideration must be  given, however, to the



increase in TDS, specifically sulfate, resulting from the use of alum for



phosphorus removal.








PHASE  II A:  BIOLOGICAL NITRIFICATION-DENITRIFICATION








This option is identical to that discussed under  Phase II except the addi-



tional step of denitrification has been added to remove inorganic  nitrogen



from the effluent.  The additional cost for this  option would be about 6. 6



cents per thousand gallons.   Included in these costs would be the denitri-



fication reactor,  an aeration basin,  and a settling basin.  Aeration is pro-



vided to aid in the sedimentation of the denitrification solids and to bio-



logically oxidize any excess methanol.
                                  106

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Sludge disposal costs for this three-stage system were increased to
account for the additional sludge produced during the denitrification
reaction.  The total cost for this system was estimated to be 43. 2 cents
per thousand  gallons.  As discussed for biological nitrification,  alum
could be added to the treatment system for phosphorous removal at an
additional cost of about 6. 8 cents per  thousand gallons.

As with the Phase II alternative, the effluent produced with the treatment
system including biological denitrification should be suitable  for indus-
trial reuse.   The nitrogen removal step should reduce the algae  growth
potential in industrial cooling towers.  However, with phosphorous  re-
moval and typical industrial cooling water treatment, the need for bio-
logical denitrification does  not appear justified.  This treatment step
may be necessary in some cases when the effluent is discharged to  a re-
ceiving body of water.

PHASE III:  PHYSICAL-CHEMICAL TREATMENT

The physical-chemical treatment system considered for the Phase III
alternative  consisted of two-stage chemical treatment followed by filtra-
tion and activated carbon adsorption.  Lime would be added to the first
chemical treatment stage, the effluent recarbonated, and the  precipitated
calcium carbonate removed in the second stage.  The sludges produced
would be dewatered, classified, and recalcined or incinerated.  Recal-
cined materials would be reused in the first stage of the chemical treat-
ment process.

This treatment sequence has been estimated to cost 34.6  cents per
thousand gallons.  For an additional 8 to  10 cents per thousand gallons,
clinoptilolite  could be used to remove ammonia, while ammonia strip-
ping would cost between  3 and 5 cents per thousand gallons treated.
Ammonia removal would be very desirable  in conjunction with the in-
dustrial reuse of the water produced.
                                  107

-------
Based on the observed limited removals of turbidity and TOG in the

filtration process during the pilot plant studies,  it might '    ossible

to eliminate this process step and use the  activated carbon Columns to

remove the small amounts  of suspended material carried over from

the chemical treatment process.  Also,  a  single-stage chemical treat-

ment process may be  satisfactory for wastewater having relatively high

hardness concentrations.  If either the filtration process, second-stage

chemical treatment process,  or both could be  eliminated, the treatment

cost would be significantly  reduced.


Noxious odors that developed in the pilot plant activated carbon columns

indicated the need to develop a satisfactory odor control procedure.

The costs  for such a procedure would be expected to be less than 1. 0

cent per thousand gallons,  but  the procedure must be satisfactorily

developed  before this  alternative becomes suitable.
 PHASE III A:  COMBINED PHYSICAL-CHEMICAL-BIOLOGICAL
 TREATMENT
An alternative to the independent physical-chemical treatment sequence

described for Phase III would be the use of a  combined physical-chemical

biological treatment sequence.  Based on the results of the pilot plant

and industrial test loop studies, chemical  treatment,  as described for

the Phase III alternative,  preceding biological treatment, could provide

definite advantages.  Since chemically treated wastewater is too high

in organic carbon content (BOD) for reuse or discharge, either activated

carbon or biological oxidation is required  to reduce the organic carbon

concentration.  Biological nitrification in conjunction with oxidation of

 the remaining organic materials could be used.   Such a system would

also provide  the advantage of phosphorous removal.  If discharge lim-

itations  require inorganic nitrogen removal, this could be  accomp-

lished by biological denitrification, as described under Phase  II A.  To
                                  108

-------
assure effluent quality and increase process reliability,  filtration would



also be desirable.   Sludge disposal consisting of dewatering,  recalcina-



tion,  and incineration would also be included.








The cost for the Phase III A alternative described above and shown in



Figure 6-1,  is approximately 40.8 cents per thousand gallons.  This



cost is nearly the same as that for the Phase III alternative with ammonia




removal included.   As discussed for the Phase III alternative, if a single-



stage chemical treatment system can be used,  the cost will be reduced.



The effluent produced with this treatment sequence — in which phosphorous



nitrogen, organics, and  suspended solids are removed — should be suit-



able for  direct reuse  by  industry for cooling water makeup.
                                  109

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                              Section VII





                       ACKNOWLEDGEMENTS







The assistance and cooperation provided by the Boards of Directors and



staffs of the Central Contra Costa Sanitary District and the Contra



Costa County Water District are gratefully acknowledged.  The support



of the Environmental Protection Agency and the help provided by Dr.



Carl Brunner,  Project Officer, were  sincerely appreciated.
                                 Ill

-------
                             Section VIII





                           REFERENCES








1-      Feasibility Investigation of Water Renovation in Central Contra



        Costa County, prepared for Contra Costa County Water District



        by Bechtel Corporation, September 17,  1969.



2.      Standard Methods for the Examination of Water  and Wastewater,



        APHA, AWWA,  WPCF,  12th Edition, 1965.



3.      Annual Book of ASTM Standards, General Test Methods, Part



        30,  American Society for Testing Materials, 1970.



4.      Instruction and Operational Manual,  Model 915,  Total Organic



        Carbon Analyzer, Beckman Instruments, 1969.



5.      R. C. Cooper, R. C. Spear, and F.  L.  Schaffer,  Virus Sur-



        vival in the  Central Contra  Costa County Waste Water Renovation



        Plant,  University of California at Berkeley, School of Public



        Health,  The Environmental Health  Services Division,  January



        1972.



6.      Standards of Tubular Exchanges, Manufacturers Association,  Fifth



        Edition, New York,  1968.



7.      Estimating Costs and Manpower Requirements for Conventional



        Wastewater Treatment Facilities,  EPA,  Water Pollution Control



        Research  Series, Project No.  17090  DAN,  October 1971.



8.      R. Smith, "Cost of Conventional and  Advanced Treatment of



        Wastewater," Journal WPGF, Vol 40, No. 9,  pp 1546-1574,




        September 1968.



9.      Cost and Performance Estimates for Tertiary Wastewater



        Treating Process, Robert A. Taft  Water Research Center,



        Report No.  TWRC-D, June 1969.
                                113

-------
10.      Preliminary Cost Estimates  for a Blue Plains Advanced Water



        Treatment Plant, prepared for FWQA by Bechtel Corporation,



        July 10, 1970.



11.      Annual Book of ASTM Standards, Volume 23, American Society



        of Testing Materials,  1968.



12.      Y. Argaman and C. L. Weddle, "The Fate of Heavy Metals in



        Physical-Chemical Treatment Processes, " to be published by



        AIChE in 1973).
                                 114

-------
                               Section IX

                            APPENDICES


Appendix                                                        Page

    A       ANALYTICAL PROCEDURES                           117

            Determination of Mercury                              117

            Determination of Selenium in Wastewater               122

            Determination of Trace Metal Emission
               Spectroscopy                                        123

            Table A-l;  Recovery of Mercury from
                        100  ml of Wastewater                       121

            Table A-2:  Sampling and Analysis Schedule,
                        Activated Sludge Process                   125

            Table A-3:  Sampling and Analysis Schedule,
                        Nitrification/Denitrification Processes      126

            Table A-4:  Sampling and Analysis Schedule,
                        Physical-Chemical  Processes               127

            Table A-5:  Sampling and Analysis Schedule,
                        Industrial Test Loops                      128

    B       TRACE METALS                                      129

            Table B-l:  Summary of Heavy Metals Testing
                       Program                                   130

            Table B-2:  Removal  of Heavy Metals by  Lime
                        Coagulation, Settling, and Recarbonation    131

            Table B-3;   Removal  of Heavy Metals by  (Secondary)
                        Ferric  Chloride Coagulation  and Settling    132

            Table B-4:  Removal of Heavy Metals by Filtration
                        and Carbon Adsorption                     133
                                 115

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                              Appendix A





                     ANALYTICAL PROCEDURES








 This appendix includes a description of analytical procedures that differ



 from those of Reference 2 and a tabulation of the sampling frequencies



 for the various analytical procedures employed. Sample analysis general-



 ly followed the schedule outlined in this  appendix.   On some occasions,



 the schedule was modified due to process upsets or analytical backlog.








 DETERMINATION OF MERCURY








 The emergence of mercury as a significant environmental contaminant



 stimulated  the need for the  development of methods for its  extraction or



 separation  from a wide variety of  substances, including reclaimed waste-



 water.  In view of the  fact that it is a cumulative-type poison, mercury



 is of particular importance when considering  the use of reclaimed sewage



 as an eventual source  of potable and irrigational waters.








 It was  the purpose of this analytical program  to determine whether mer-



 cury was  present in  sewage and, if so,  to what extent it was  removed by



 conventional sewage treatment processes.   Therefore, it was imperative



 to develop a reasonable method for the determination of mercury in sew-




age.








Summary of Method







Sewage samples were taken periodically, either as 24-hour  composites or



as hourly samples, and placed in a metal-free sulfur ic-nitric acid solution
                                 117

-------
to promote dissolution of metallic compounds and to prevent sorption of
the metals on the walls of the collection vessel.  Glass was the preferred
material for the collection vessel, and great care was taken to avoid  con-
tamination of the sample.  All containers  and utensils making  contact
with the sample were thoroughly washed,  acid cleaned (metal free), and
double rinsed with deionized water.

The acidified sewage sample was blended  for 2 minutes or until com-
pletely homogenized.  An appropriate aliquot (50 ml) of the sample was
digested  in a reflux condenser for at least 30 minutes.  Glass  beads were
used to prevent bumping and excessive foaming during digestion.  The
condenser unit was highly efficient so as to return any mercury that had
been vaporized.  After digestion was completed,  the condenser was
rinsed thoroughly with dilute nitric acid (50 ml) to remove any mercury
adhering to  the walls,  and the digest was filtered through a glass-fiber
filter to remove any organic residue.  Provision was made for any
dilution with the rinse water.

Mercury was determined by a spectrophotometer procedure where the
sample was wet ashed or digested with nitric acid-chromium trioxide.
Potential  interferences were eliminated by adding ethylene glycol mono-
methyl ether and EDTA.  An iodide complex was formed that reacted
with crystal  violet and was extracted with toluene.   The absorbance of
the extracted crystal violet complex  was determined at 605 millimicrons
(m^i), and the mercury concentration was  determined by comparison with
standard mercury solutions.  The detection  limit  was 0.25 micrograms
of mercury.
                                118

-------
Proced
       ure
The following apparatus and reagents were used:


    •   Apparatus

        —   300-ml standard tapered (24/40) Erlenmeyer flasks
        —   250-ml glass stoppered  separatory funnels

        ~   Reflux condensers

        -   Hot plate

        —   Spectrophotometer  (capable of reading absorbance
             in the 600 mpi range)
    •   Reagents

        —   Hydrogen peroxide, 30 percent

        —   Nitric acid, 10 N containing  1-percent chromium
             trioxide
        —   Potassium permanganate,  5 percent
        —   Hydrochloric acid,  5 N
        —   Toluene
        —   Sodium metabisulphite — Na S O ,  20  percent
                                       LJ Lj  O
        ~   Potassium iodide,  2.5 percent
        —   EDTA — disodium salt,  5 percent
        —   Crystal violet,  0. 1- and 1-percent solution
             (Dissolve 1 g of crystal violet in 1 ml  of
             ethylene glycol monomethyl ether.  This
             solution diluted [10-100] with distilled water
             was used in the determination. )

        —   Mercury  stock solution  (Dissolve 135 mg of
             HgCl  in  100 ml of distilled water,  add 2 ml
             of concentrated HC1, and dilute  to 200  ml
             [1 ml = 0. 5 mg].  Working  standard was
             made by diluting [l  ml to 1000] with dis-
             tilled water [1ml = 0.5 g].   The working
             standard  was  made  fresh daily.)
                                119

-------
Analysis .  Three ml of 10 N nitric acid containing 1-percent chromium



trioxide were added to  a 100-ml aliquot of the completely mixed waste-



water sample.  The flask was attached to a reflux condenser  (or lightly



stoppered with a glass  stopper using a Teflon shim) and placed  on a hot



plate set at 250 F.  After 30 minutes of refluxing,  the sample was re-



moved, ZO ml of 5-percent potassium permanganate were added, and



the sample was refluxed again for 15 minutes.  The flasks were removed



and 30-percent hydrogen peroxide was added dropwise to react  with



excess permanganate and any manganese dioxide formed.  One  ml of



excess hydrogen peroxide was added, and the digestion was continued



for an additional 30 minutes.  The inside walls of the condenser were



rinsed with a  small amount of distilled water before the flask was re-



moved and cooled to room temperature.  Five ml of 5 N HC 1  and 1 ml



of 2. 5-percent KI were added to the flasks.  A few seconds  were allowed



for the iodide complex  to form, then ZO-percent sodium metabisulphite



was  added dropwise to  reduce the excess iodine,  adding five drops  in



excess (should have odor of SO  ).  Then Z ml of 5-percent disodium



EDTA were added and thoroughly mixed with the  sample. The contents of



the flasks were transferred to a 250-ml separatory funnel,  where 5 ml of



0. 1-percent crystal violet solution was added and mixed in to form an



emerald green color.   If blue or very dark green colors developed,  Z to  5



ml of 5 N HC 1 were added.  Five ml of toluene were added and  the



stoppered flask shaken  gently 10 times, repeating the  shaking after  co-



alescence of  drops. After total coalescence of droplets,  the bottom



(water layer) was drained out.  The stem of the separatory  funnel was



dried, and a  plug was inserted to remove suspended materials.   The



toluene layer was run directly into a 1-cm cell, and the absorbance was



read at 605 m/j within ZO minutes.








A  standard curve was prepared according to the above procedure by



adding 0,  0. 5,  1, 2. 5,  and 5 ^g of mercury  to  100 ml  of the wastewater.
                                 120

-------
Discussion.  It was found that the amount of nitric acid-chromium tri-
oxide digestion mixture was critical.  Too large an excess after digestion
of organic material had a fading effect on the crystal violet-mercury color
complex, with subsequent loss of sensitivity.  The 3-ml addition of nitric
acid outlined in the method in  conjunction with the 20 ml of 5-percent
permanganate and 30-percent  peroxide  should be  ample for complete
digestion of the organic material found  in normal wastewater.  If not,
it is recommended that digestion be continued with 30-percent hydrogen
peroxide.

The above procedure can be used for potable water by using 1 ml of
nitric acid-chromium trioxide mixture  instead of 3 ml and reducing the
digestion time by one-half.

There were no significant differences observed in the partition effects
when the crystal violet-Hg complex was extracted with toluene from
75 ml instead of 150 ml of total solution.

It is important that glassware used for  the mercury determination be
cleaned with either diluted chromic or nitric acid and rinsed with dis-
tilled water before attempting the analysis.

There were no significant mercury losses during  the digestion period.
Wastewater samples spiked with increasing  amounts of mercury gave
the results listed in Table A-l.
                              Table A-l
     RECOVERY OF MERCURY FROM 100 ML OF WASTEWATER
Mercury Added (/ug)
0.0
0.5
1.0
2. 5
5.0
Mercury Found (fjg)
0.00
0.49
0. 94
2.45
5. 05
% Recovered

98.0
94.0
98.0
101.0
                                121

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DETERMINATION OF SELENIUM IN WASTEWATER*





Summary of Method




The method used involved simultaneous evaporation and oxidation of the


sample with hydrogen peroxide in an alkaline medium.   The residue was


further oxidized by taking up with concentrated HNO  and evaporated to


dryness.  The selenate that  was formed was reduced to selenite with


concentrated HC 1.  Reaction with diaminobenzidine produced a yellow


colored compound extractable  with toluene, and the absorbance was


determined at 420 mp. with a spectrophotometer.





An average standard  deviation of - 0. 001 mg/1 was found by spiking five


samples with  10 micrograms of selenium and another five samples with


30 micrograms of selenium.





Procedure  (Reference 2)
To  1000 ml of the sample in a 1500-ml beaker were added 5 ml of 0. 1 N


NaOH,  5 ml of calcium chloride solution, and  10 ml of 30 percent HO.
                                                                  <-.  £*

A few boiling chips were added, and the  solution was placed on a hot plate


and evaporated just to dryness.  Ten ml of concentrated HNO  were added


to oxidize any remaining organic material (evaporation to dryness should


take place on a hot plate at low heat or on a steam bath).  The sides of the


beaker  were rinsed with approximately 10 ml of distilled water,  and the


solution was evaporated to dryness. The residue was cooled; 5  ml of


concentrated HC 1 were added,  followed by 10 ml NH Cl solution; and


the mixture was heated on a steam  bath for 10   0.5 minutes.  The warm


solution and precipitate, if any, were transferred  to a graduated 100-ml


beaker  suitable for pH adjustment;  the larger beaker was  rinsed with 5


ml of EDTA-sulfate reagent and 5-ml of 5 N NH OH.  The pH was adjusted



 Modified Diaminobenzidine Method A
                                 122

-------
 to 1.5 - 0 3 with NH OH.  One ml of diaminobenzidine solution was added,
                     4

 and  the mixture was heated on a steam bath for approximately 5 minutes


 and  cooled and  adj


 adjusted to 50 ml.
and cooled and adjusted to pH 8    1 with NH OH.  The volume was then
The contents were poured into a  Z50-ml separatory funnel with 10 ml of


toluene and shaken for approximately 30  seconds.  After the lower aqueous


layer was  drained,  the stem of the separatory funnel was dried and a cotton


plug inserted.   The toluene was allowed to run into a 1-cm cuvette, and


the absorbance was determined at 420 mjj..  If there was any difficulty in


obtaining two distinct layers, as  much of the bottom layer as possible


was drained.   The remaining material was transferred to a centrifuge


tube and centrifuged for approximately 3 minutes, or until a definitely


clear toluene layer  was obtained.  (If no centrifuge is available, the upper


layer could be filtered through paper containing anhydrous sodium sulfate. )




A calibration curve was made by spiking approximately 500 ml of the


sample with 0,  10,  20,  30,  and 40  micrograms of selenium.  The  stock


selenium solution was made by dissolving an accurately  weighed amount


of reagent grade selenium in 5 ml of concentrated HNO .  The solution


was heated to dryness and diluted to  1000 ml with distilled water.  Ap-


propriate dilutions of the  stock solution resulted  in a standard  solution


such that 1 ml was equivalent to  1. 0 microgram of  selenium.




DETERMINATION OF TRACE METALS BY EMISSION SPECTROSCOPY





Summary of Method




Emission spectrography was used as a means of determining total  trace


metal concentration.  Samples were treated with sulfuric acid  and  dried


at 600°C before being weighed'and arced using standard spectographic
                                 123

-------
techniques.   These analyses, coupled with atomic absorption results,



gave values for both soluble and insoluble metal content necessary for



the investigation of treatment removal efficiencies.








Procedure (Reference ll)








Two ml of concentrated H  SO  were added to a 400-ml  water or waste-



water sample of known total solids concentration.  The sample was



partially dried on  a water bath.  A hot plate was used to dry the sample



completely by heating  it under a hood at 600 C.  After 30 minutes, the



residue was scraped with a plastic spatula.  A  10-mg residue sample



was weighed and analyzed using a DC arc  in accordance with ASTM



methods for spectrographic determination of solids.
                                124

-------
                               Table A-2

                 SAMPLING AND ANALYSIS SCHEDULE
                    ACTIVATED SLUDGE PROCESS
Analysis*
Turbidity
PH
Conductivity
Total organic carbon
Soluble organic carbon
Ammonia
Nitrate
Total Kjeldahl nitrogen
Ortho-pho sphate
Total phosphate
Total hardness
Calcium hardness
Total alkalinity
Chloride
Sulfate
Silica
Settleable solids
Suspended solids
Volatile suspended solids
Dissolved solids
Dissolved oxygen
Coliform count
Chemical oxygen demand
Biochemical oxygen
demand
Temperature
Activated Sludge
Influent
D
D
D
D
D
D
D
W
D
D
W
W
W
W
W
W
D
D
D



W

W

Mixed
Liquor
















D
D
D

D




D
Effluent
D
D
D
D
D
D
D
W
D
D
W
W
W
W
W
W
D
D
D


W
W



Filter
Effluent
D

D
D
D
D
D
W
D
D











D


W

Activated Car-
bon Effluent
1st
D
D
D
D
D



















W

2nd
D
D
D
D
D
D
D
W
D
D











D
W

W

D   =  Daily
                                 Three times/week
W
Weekly
   All samples were hourly samples composited on a daily basis except for
   the mixed liquor sample,  which was a daily "grab" sample.
                                  125

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                                 Table A-3

                SAMPLING AND ANALYSIS SCHEDULE
          NITRIFICATION/DENITRIFICATION PROCESSES
Analysis •
Turbidity
pH
Conductivity
Total organic
carbon
Soluble organic
carbon
Ammonia
Nitrate
Ortho-phosphate
Total phosphate
Total hardness
Calcium hardness
Total alkalinity
Chloride
Sulfate
Silica
Scttleable solids
Suspended solids
Volatile suspen-
ded solids
Dissolved solids
CCCSD
Primary
Influent

T
T
T
T


T
W






T
W

W
Primary
Effluent

T
T
T
T










r
\\


Nitrification
Influent
D
T
T
T
T
D
D
T
W







T


Mixed
Liquor
"














D
D
W

Effluent
D
D

T
T
D
D
Denitrification
Mixed
Liquor







T
w ;







r






D
U
W

Effluent
D
D
T
T
T
D
D
T
W
W
W
W




T


Filter
Effluent
D


T
' T
W
W

W







W


Activated Car -
bon Effluent
1st
D


T
T














2nd
D
T
T
T
T
W
W
T
W
W
W
W
w
\v
w

w

w
    Daily
                           Three times/week
                                                             Weekly
All samples were hourly samples composited on a daily bnsis except for the mixed liquor samples,
which were daily "grab" samples.
                                     126

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                              Table A-4

               SAMPLING AND ANALYSIS SCHEDULE
                PHYSICAL/CHEMICAL PROCESSES
Analysis-'-
Turbidity
pH
Conductivity
Total organic carbon
Soluble organic carbon
Ammonia
Nitrate
Ortho-phosphate
Total phosphate
Total hardness
Calcium hardness
Total alkalinity
Chloride
Sulfate
Silica
Settleable solids
Suspended solids
Volatile suspended solids
Dissolved solids
Flocculation
Influent
1st

T
T
T
T
W
W
T
W
W
W
W
W
W
W

T
W
W
2nd
D
D
D
T
T


T
W
W
W
W




T
W
W
Effluent
2nd
D
D
D
T
T
W
W
T
W
W
W
W




T

W
Filter
Effluent
D
T
T
T
T



W







W


Activated Car-
bon Effluent
1st
D


T
T














2nd
D
T
T
T
T
W
W
T
W
W
W
W
W
W
W

W


D      Daily            T   =    Three time's/week      W   = Weekly
* All samples were hourly samples composited on a daily basis.
                                127

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                              Table A-5

               SAMPLING AND ANALYSIS SCHEDULE
                     INDUSTRIAL TEST LOOPS
Analysis*
Turbidity
pH
Conductivity
Total organic
carbon
Ammonia
Nitrate
Ortho-phosphate
Total phosphate
Total hardness
Calcium hardness
Total alkalinity
Chloride
Sulfate
Silica
Sulfite
Suspended solids
Corrator
Temperature
Circulating Water
Tower
No. 1
T
D
D
W
W
W
W
W
W
W
W
W
W
W

W
D
D
Tower
No. 2
T .
D
D
W
W
W
W
W
W
W
W
W
W
W

W
D
D
Tower
No. 3
T
D
D
W
W
W
W
W
W
W
W
W
W
W

W
D
D
Boiler
Blow-
down :

W
W




W


W



W



Softener
. Effluent

W
W





W
W
W







Con-
densate
W
W
W
W
W













Canal
Water
.. W

W
W
W

W

W
W
W
W
W
W

W


D  = Daily          T  = Three times/week        W  = Weekly

* All samples were hourly samples composited on a daily basis.
                                 128

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                              Appendix B
                           TRACE METALS

This appendix contains a summary of a separate study concerned with the
removal of heavy metals in the various treatment stages of a physical-
chemical pilot treatment facility.  The treatment plant influent was dosed
with a mixture of heavy metals, and their removal was monitored through
the treatment process.  Although this study was not within the scope of
work of the project, the results are included here for informational pur-
poses.  A complete discussion of the data may be found in a paper by
Yerachmiel Argaman  and Clark L.  Weddle (Reference 12).
                                 129

-------
                              Table B-l

         SUMMARY OF HEAVY METALS TESTING PROGRAM
Run
No.
     Heavy Metals Added
    Point of Addition
 NTA
Added
 1
Zn  10 xng/1,  Mn  2. 0 mg/1,
   others*   0. 5 mg/1

Zn  10 mg/1,  Mn  2. 0 mg/1,
  others  -2.0  mg/1

Zn  10 mg/1,  Mn  2. 0 mg/1,
  others   2. 0  mg/1

As,  Cd,  Cu, Hg    10. 0 mg/1,
  Mn  2. 0 mg/1
As,  Cd,  Cu    10 mg/1,  Hg
  5 mg/1, Mn   20. 0 mg/1

Zn  10 mg/1,  Mn  2. 0 mg/1,
  others   2. 0  mg/1
Zn - 10 mg/1,  Mn  2. 0 mg/1,
  others   2. 0  mg/1
Ahead of lime coagulation


Ahead of lime coagulation


Ahead of lime coagulation


Ahead of lime coagulation


Ahead of lime coagulation


Ahead of ferric coagulation
(2nd stage)
Ahead of filtration
0
                                                                    10.0mg/l
' Other metals added were:  Ag, As,  Ba,  Cd, Co,  Cr, Cu,  Hg, Ni, Pb
                                 130

-------
                      Table B-2

REMOVAL OF HEAVY METALS BY LIME COAGULATION,
           SETTLING, AND RECARBONATION
            (In and Out Concentrations in mg/1)
Metal
Ag
As
Ba
Cd
Co
Cr
Cu
Hg
Mn
Ni
Pb
Zn
Run #1
In
0.04

0. 36
0. 54
0.42
0. 45
0.60

2.2k
0. 75
0. 41
9.61
Out
0.01

0.04
0.01
0. 04
0. 30
0.04

0.02
0. 11
0.04
0. 12
%
rem
96

89
98
90
33
93

99
85
90
99
Run t>2
In
1. 51

-1.08
1. 42
1.29
1.40
1.47

1. 37
1.36
1.21
7. 34
Out
0.02

0. 14
0.02
0.05
1.25
0.23

0.01
0. 20
0.05
0. 18
%
rem
99

87
99
96
11
84

99
85
96
97
Run #3 (NTA)
In
1.20

1.48
1.48
2.07
2.95
0.71

2. 37
1.48
1.48
10.00
Out
0.06

0.06
0. 19
1.58
2. 53
0.32

1.27
1.27
0.25
1. 58
%
rem
95

96
87
24
14
55

46
14
83
84
Run #4
In

8.40

4.00


4.60
4.45




Out

0. 30

0. 19


0. 31
0.61




%
rem

96

95


93
86




Run #5
In

7.00

5.78


4.60
3.26




Out

0.20

0. 13


0.20
0.29




%
rem

97

98


96
91




                           131

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                    Table B-3

 REMOVAL OF HEAVY METALS BY (SECONDARY)
FERRIC CHLORIDE COAGULATION AND SETTLING
        (In and Out Concentrations in mg/1)

Metal
Ag
As
Ba
Cd
Co
Cr
Cu
HS
Mn
Ni
Pb
7.n
R
In
0. 01

0.04
0.01
0. 04
0. 30
0.04

0.02
0, 11
0.04 '
0. 12
un 11
Out
0.01

0.03
0.01
0.017
0.07
0.03

0.02
0.09
0.04
0. 13

r em


25

58
72
25


18


-R
In
0.02

0. 14
0.02
0.05
1.25
0.23

0.01
0,20
0.05
0. 18
u'n "2
I
Out
0.01

0.07
0.01
0.02
0.63
0,02

0.01
0. 15
0.023
0. 04

rem
50

50
50
60
50
56


25
54
78
R
In
0.06

0.06
0. 19
1. 58
2, 53
0. 32

1.27
1. 27
0. 25
1. 58
un' "3
Out
0,02

0.09
0.01
0. 49.
0.65
0. 29

0. 19
0. 66
0. 12
0. 53

rem
Ij7


95
69
78
9

85
48
52
66
•' -R
In

0. 30

0.-19

0. 31
0.61




un M
Out

0.01

0.-04

0. 32
0. 28





„. -
rem

97

79


54




• ' R
'In-

tl. 20

0: 13-
-
'0, 2T)
0,29;




un »5
Out

0.01


-------
                    Table B-4

    REMOVAL OF  HEAVY METALS BY
FILTRATION AND CARBON ADSORPTION
      (In  and Out Concentration in mg/1)
Metal
Ag
Ba
Cd
Co
Cr
Cu
Mn
Ni
Pb
Zn
Dual Media Filtration
Run #6
In
0. 09
0. 23
0.29
1.40
3.40
0. 17
2. 30
1. 10
0,23
00 04
Out
0.02
0. 16
0.01
0. 16
0. 83
0. 24
0. 27
0.41
0.03
0. 03
%
rem
78
30
96
89
76

88
63
87
25
Run #7
In
1.90
1.90
2. 10
1. 90
2. 70
0. 54
2. 70
1.60
1.40
4, 30
Out
0.02
0.05
0.02
0.48
1. 04
0. 28
0.29
0. 51
0. 02
Oo 05
%
rem
99
97
99
75
61
48
89
68
99
99
Activated Carbon Adsorption
Run #6
In
0.02
0. 16
0. 01
0. 16
0. 83
0. 24
0. 27
0.41
0.03
0. 03
Out
0.01
0.02
ND
0.014
Oo 01
0. 01
0. 01
0. 0014
0.04
0, 03
%
rem
50
88

91
99
96
96
97


Run #7
In
0.02
0.05
0. 02
0.48
1. 04
0. 28
0,29
0. 51
0.02
0.05
Out
0.01
0,01
0.01
0. 004
0. 01
0.01
0. 28
0. 12
0.0002
0. 02
%
rem
50
80
50
99
99
96
34
76
90
60
                        133
                                    fiU.S. GOVERNMENT PRINTING OFFICE:1973 546-310/72  1-3

-------
SELECTED WATER
RESOURCES ABSTRACTS
INPUT TRANSACTION FOI?M
                     t. Report Ho.
                                                                      ccf.iaiou ffo.
                                         w
4  Tit! a
          Pilot-Demonstration Project  for Industrial
          Reuse of Renovated Municipal Wastewater
  Asithor(s)
          Mr.  G.  A. Horstkotte, Jr.
           Contra Costa County Water District
           Central Contra Cpsta  Sanitary District
                                         5.  Report Date
                                         6.
                                         9.  Perfarmia&Ofgaaizatioa
                                            Report No,
                                         10.  Project No.

                                             17080 FSF
                                                                 11, Contract/Great Nu
                                                                 13. Type of Report and
                                                                    Period Covered
12. Sponsoring Organization
           Environmental Protection Agency report number,
           EgA-670/2-73-064. August 1973. _
IS. Abstract
Three  pilot plant treatment  sequences were operated during this study"to produce
various  grades of effluent for subsequent testing  as  industrial water sources.  The
testing  was conducted in pilots-sized test loops consisting of small cooling towers  and
heat exchangers.  At the same time the renovated waters  were tested, Contra Costa
Canal  water, which is presently used by industry in the  study area, was also  investi-
gated  in a test-loop identical to those used for the  renovated water.

The study results illustrated that the wastewater  investigated can be treated satis-
factorily for reuse in  industrial applications.  Corrosion rates and fouling  factors
observed with renovated water were equal to or less than found with the canal water.
Precipitation of phosphorous was the major source  of  scale formation while using
renovated water for copling  purposes, thus indicating the need for phosphorous
removal.
I7a. Descriptors Water reuse  ,  Reclaimed water  , Sewage  treatment, tertiary treatment,
             Waste water
17b. Identifiers
17c. CO WKR Field & Group   05D
IS. Availability
19. Security Class.
   (Report)

20. Security Class.
   (Page)
                                          27.
1ft. ot
Pages
                                          22. Price
                                                      Send To:
        WATER RESOURCES SCIENTIFIC INFORMATION CENTER
        U.S. DEPARTMENT OF THE INTERIOR
        WASHINGTON, D. C. ZO24O
Abstractor
                                      [tift'tutton
                      Central Contra Costa Sanitary  District

-------