technology transfer
     design seminar
         publication
   HANDLING
             AND
               \
   TECHNOLOGY TRANSFER

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           SLUDGE HANDLING AND DISPOSAL
     This publication was prepared for use in the United States
Environmental Protection Agency Technology Transfer Design
Seminar Series. Emphasis is placed on technology which can be
incorporated into design and practice today.
    Prepared by:
         Mr. John R. Harrison
         Black, Crow and Eidsness, Inc.
         Wilmington, Delaware
         Mr. Stanley J. Mogelnicki
         The Dow Chemical Company
         Midland, Michigan
         Dr. Joseph P. Farrell
         National Environmental Research Center
         Environmental Protection Agency
         Cincinnati, Oliio
         November 13-14,1972
         Royal Inn of Anaheim
         Anaheim, California
       United States Environmental Protection Agency
              Technology Transfer Program
                    Washington, D.C.

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                             TABLE OF CONTENTS
SECTION 1        Importance of Sludge Processing and Disposal

SECTION 2        Current and Previous Methodology

SECTION 3        Nature and Handling Characteristics
                 of Sludges

SECTION 4        Sludge Stabilization Processes

SECTION 5        Case Studies - Plant Results - Chemical
                 Conditioning - Conventional Activated Sludge

SECTION 6A      Oxygen Activated Sludge Process

SECTION 6B      Oxygen Activated Sludge
                 Case Study - Fairfax - Westgate

SECTION 6C      Oxygen Activated Sludge
                 Case Study — New Orleans, Louisiana

SECTION 7        Thermal Processing of Sludge

SECTION 8        Final Disposal Processes and Case Studies
 Page Number

1-1        1-7
2-1
3-1
4-1
5-1
6A-1
6B-1
6C-1
7-1
8-1
2-5
3-10
4-7
5-8
6A-4
6B-4
6C-4
7-8
8-3

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        SECTION 1 - IMPORTANCE OF SLUDGE PROCESSING AND DISPOSAL


1.   Amounts and Types of Sludges Produced

         —   Sludges:  Liquid to  semi-solid  residues from  wastewater processing.  Solid
              contents: 1  to 10 percent.

         —   Masses of sludges produced in conventional wastewater processing (see  Table
              1-1, Reference 1).

         —   The use of anaerobic digestion to reduce mass and volume (see Table 1-1 and
              Figure 1-1, Reference 2).

         —   The  quantity  of sludge can be  calculated from wastewater analysis and
              efficiency of the treatment units.

         —   Physical-chemical  treatment  means new  kinds  of sludges,  more mass, and
              sometimes more volume. A calculation of the increase in sludge mass when iron
              and alum are used at various points in the wastewater treatment  sequence is
              presented (see Table 1-2,  from Reference 3).

         —   The sludge produced  when lime is  added to wastewater in  the primary or as a
              tertiary can be  calculated from water and wastewater analysis (see Table 1-3).
              Measured quantities were about 20  percent higher than calculated values.

2.    Costs of Sludge Processing and Disposal

         —   Costs of slutlge processing are a function of:

                  Treatment sequence

                  The raw sewage

                  Location (the surrounding neighborhood)

                  Climate
   i

                  Scale of operation

                  Regulations, etc.
                                        1  - 1

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Costs are  sensitive to all of the above and individual author's assumptions. If
possible, get all  comparisons from the same unbiased source (see Figure 1-2,
calculated from Eilers and Smith, Reference 4).
                           1  -2

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                             TABLE  1-1
          SLUDGES PRODUCED IN CONVENTIONAL TREATMENT*
Overall SS Removal (%)
Total raw sludge (Ib d.s.^ng)
% solids (from clarifier)
% solids (after 2 days thickening)
Digested sludge (Ib d.s./mg)
% solids
% reduction in sludge mass
% reduction in volatile solids
Drying bed loadings (Ib d.s./ft2 - yr)
Primary
Treatment
60
1020
6
8
555
8.8
45.5
65
35
Primary
+ TF
85
1310
5
6.5
710
6.9
45.5
65
30
Primary
+ AS
95
1615
4
5.3
1035
5.5
36
52
25
* From Fischer, A. J., Sewage Works Journal.
                                1 -3

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                                 TABLE 1-2
                    CALCULATED SLUDGE MASS (Ib/mg)
                         Conventional
                    Feto
                   Primary
          Feto
         Aerator
          Alto
         Aerator
         AltoTF
         Clarifier
PRIMARY

  SS Removal
  Sludge Solids
  Fe Solids
  Al Solids
  Total

ACTIVATED SLUDGE

  Secondary Solids
  Fe Solids
  Al Solids

TRICKLING FILTER

  Secondary Solids
  Al Solids

TOTALS
         50%
       1250
          0
          0
       1250
        715
  75%
1875
 605

2480
 536
  50%
1250
1250
 804
 541
  50%
1250
1250


 804

 425
  50%
1250
1250
        656


       1965
3016
2595
2479
 745
 483

2478
                   BASIS FOR SLUDGE MASS CALCULATION
Cation/P Dose
 (mol/mol)
                                 Ib Chemical Sludge/lb Cation
                                 Ib/lb Al          Ib/lb Fe
   1.5

   1.75

Assumptions:
  Cation/P Dose
  Cation/P Dose

  Influent Sewage
       BOD
       SS
       P
                                   3.9

                                   3.8
1.5 mol/mol to aerator
1.75 mol/mol to primary or before trickling filter clarifier


230 mg/1
300 mg/1
10 mg/1
                                2.4

                                2.3
                                    1 -4

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                                 TABLE 1-3

                    CALCULATION OF SLUDGE QUANTITY:
                      LIME ADDED TO THE PRIMARY*
Data Available     On influent and effluent: alkalinity, pH, calcium hardness, phosphorus.
   Change in Ionic Content
    (Influent - Effluent)
AHCO3, as CaCO3
ACO2,asCaCO3
AMg, as CaCO3
mg/1
 223
  14
  66
                                  Sludge Produced
hydroxyapatite
CaCO3
Mg(OH)2
 27
460
 38
Material Balance on Ca

Ca(OH)2 dose = 390 mg/1
Input-Output =-2.9 mg/1
                                               Total Calcd. Sludge
                                                      Meas./Calcd.
                                               525 mg/1
                                               1.25
* Data from Run 6, Eimco's Salt Lake City Pilot Plant.
                                    1 -5

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                            REFERENCES - SECTION 1
1.   Fischer, A.J., Sewage Works Journal, 248 (1936).

2.   Fair, G.M., Geyer, J.C., and Okum, D.A., "Water Purification and Wastewater Treatment
         and Disposal." Water and Wastewater Engineering, 2, 36-6 - 36-8 (1968).

3.   Adrian, D.D., and Smith, I.E., Jr., "Dewatering Physical-Chemical Sludges" Conference
         on  Application  of New Concepts  of Physical-Chemical Wastewater Treatment,
         Vanderbilt University, September 18-22,1972 .

4.   Eilers,  R.G., and Smith, R., "Wastewater Treatment Plant Cost Estimating Program,"
         AWTRL of EPA, April 1971, Internal Report (Computer Deck available).
                                      1  -6

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Table 1-1

Table 1-2


Table 1-3

Figure 1-1

Figure 1-2
 LIST OF FIGURES AND TABLES - SECTION 1


Sludges Produced in Conventional Treatment

Calculated Sludge Mass (Ib/mg)
Basis for Sludge Mass Calculation

Calculation of Sludge Quantity: Lime Added to the Primary

Sludge Quantities

Costs of Sludge Processing and Disposal — Including Amortization
                                         1-7

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                            FIGURE 1-1      SLUDGE QUANTITIES*
                    Basis:  1 million gallons of domestic vastevater
          Quantities Before Digestion
                     Primary Settling
Activated Sludge
Clarifier
 1 mg of
vastevater
                     Primary Sludge  (72.2J& VS)
                     1190 Ib. solids.
                     If 5j> solids, 2830 gal.
                              (70.6J& VS)
                   Waste Activated Sludge
                       660 Ib. solids.
                   If 1.5£ solids, 5260 gal.
          Quantities After Anaerobic Digestion
             If primary only
             is digested,   (l&.ty VS)
                  DIGESTION
                 576 Ib.
            If 1$ solids, 673 gal.
         If primary and W.A.S. are combined,
         1850 Ib. solids.
         If k.5t solids, ^890 gal.
                DIGESTION
                 890 ib.  (^5.5^ vs)
         If 1% solids, 1980 gal.
       * These quantities vere taken from an example in Fair,  G.  M.,  Geyer,  J.  C.
          and Okum,  D. A., "Water and Wastevater Engineering, Vol. 2:  Water Purifica-
          tion and Wastevater Treatment and Disposal," pp.  36-6 to 36-8,  J. Wiley
          and Sons,  N. Y.  (1968).

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    100




£  80
o
CJ



=f  60



S  50
LU
Q_


°  40






""  30
Ik.




Z
UJ


S  20
    10
   A   THICKEN,  DIGEST,  SAND BEDS

   B.  THICKEN,  DIGEST,  FILTER, LANDFILL

   C"  THICKEN.  FILTER,  INCINERATE
                                10           20


                               WASTEWATER  FLOW (MOD)
                             30
                                         60
                                                    100
    30
    20
    10
     2I_L
   FIGURE  1-2

   A:  THICKEN,  DIGEST. SAND BEDS

   B:  THICKEN,  DIGEST, FILTER,  LANDFILL

   C:  THICKEN.  FILTER. INCINERATE
                                10
                                            20
                             30
                                                                  60
                                                    100
        WASTEWATER  FLOW (MOD)



COSTS  OF   SLUDGE  PROCESSING  AND

 DISPOSAL  -  INCLUDING  AMORTIZATION

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              SECTION 2 - CURRENT AND PREVIOUS METHODOLOGY


1.   Project Objectives — Wastewater Treatment Plants

         —   The way it used to be - The old climate surrounding design and startup of
              wastewater treatment plants.

                  Partial funding for and somewhat limited role of the A/E firm.

                  Divided responsibility for design of sub-systems.

                  Emphasis on liquid handling R&D (Quote from agency document - Mea
                  Culpa).

                  Elastic enforcement policies (habit forming).

                  Problems with sludge handling systems.

         —   The way it is now - The new climate (Figure 2-1). (Ostensibly, the objectives
              have always been there but the new climate now makes them obtainable).

              Plants must function properly, both initially and continually.

                  Both liquid and solids fractions must be processed satisfactorily.

                  Effluent standards are going to be enforced.

                  Capital, operating and maintenance costs must be essentially on forecast.

                  The consulting engineer is increasingly responsible for preceding needs.

2.   Essential Ingredients (for a successful project)
         (Figure 2-2)

         —   Optimum Conceptual and Detailed Designs

                  New standards require new processes.

                  New processes mean text books are a questionable source.

                  The importance  of being contemporary in process engineering disciplines.
                                        2- 1

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          —   Construction as Designed

                   Increased A/E involvement, new CM. methods.

          —   Proper Operation and Maintenance

                   Following the Doctor's orders or he is not responsible for the results.

          -   Continuing Plant Service and Development

                   Nobody's perfect; even naval vessels still have a shakedown cruise.

                   A vital source of process improvement and future design information.

3.   Sources — Conceptual Design Information
          (Figure 2-3)

          —   Textbooks and Literature

                   Must be reviewed but rarely give all the answers.

          -   Laboratory and Pilot Studies

                   Practically always necessary.

          -   Supplier's Recommendations

                   Equipment and product firms, their own R&D engineering work.

          —   Previous Experiences

                   All too seldom  available.

         -   Visitation to Other Plants

                   Helpful but sometimes misleading.

         -   Client's Wishes (existing plant results)

                  Depends on the client's  experience and  capability.
                                        2-2

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4.   Special Considerations — Design Rationale
          (Figure 2-4)

          —   Adequacy of Available Literature

                   Self serving publications.

                   Strategic omissions.

                   Post-paper discussions (printed in U.K., not USA)
                   (Note L.A. article).

          -   Supplier's Recommendations

                   Essential but must be sifted carefully.

                   The importance of follow-up.

          -   Plant Data - Fact vs. Folklore

                   Reliability, a function of adequacy of O&M.

                   The "Shrinkage" example.

                   Defending an untenable position - mistakes die hard.

          —   Process Engineering

                   Unit operations technology.

                   Biological process technology.

                   Putting the whole thing together.

                   Experience in other industries and in plant operations.

5.   The Total versus the Fractional Approach
          (Figure 2-5)

          —   A careful choice of words
              (System   vs.  Sub-System,  actually,   but,   such  terminology  somewhat
              disreputable).

          —   The Cardinal  Sin: Optimization of a sub-system must be considered in light of
              total system results.
                                         2-3

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—    Example = Dcwatcring Sludge

         Analysis including only operating cost, production rate, cake moisture
         content.

         Should include complete material  balance  around  process; effect  of
         recycle streams on rest of system;  ratio of volatile solids to moisture
         content (calorific value).
                              2-4

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                   LIST OF FIGURES AND TABLES - SECTION 2







Figure 2-1         Objectives — Wastewater Treatment Plant Project




Figure 2-2         Essential  Ingredients




Figure 2-3         Sources - Conceptual Design Information




Figure 2-4         Special Considerations — Design Rationale




Figure 2-5         The Total versus the Fractional Approach
                                      2-5

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       OBJECTIVES
EFFECTIVE,RELIABLE PROCESSING OF WASTEWATER
    (BOTH LIQUID AND SOLID FRACTIONS)
AT LOWEST PRACTICAL COST
CONCURRENT NON-POLLUTING EFFLUENT STREAMS
      CLIQUID.SOLID AND GASEOUS)
             FIGURE  2-1
    ESSENTIAL INGREDIENTS
  OPTIMUM CONCEPTUAL AND DETAILED DESIGN
  CONSTRUCTION AS DESIGNED
  PROPER OPERATION AND MAINTENANCE
  CONTINUING PLANT PROCESS SERVICE AND
    DEVELOPMENT
             FIGURE  2-2

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SOURCES-
CONCEPTUAL DESIGN INFORMATION
   •  TEXT BOOKS AND LITERATURE
   •  LABORATORY AND PILOT STUDIES
   •  SUPPLIERS RECOMMENDATIONS
   •  PREVIOUS EXPERIENCE
   •  VISITATION TO OTHER PLANTS
   •  CLIENTS WISHES (EXISTING PLANT RESULTS)
                FIGURE 2-3
          SPECIAL  CONSIDERATIONS
            -DESIGN  RATIONALE
           pip* dfectkMteiil - Wffcl-
       ADEQUACY OF AVAILABLE LITERATURE
       SUPPLIERS RECOMMENDATIONS
        PLANT DATA - FACT VS. FOLKLORE
                         __» rn!«Hi6» a la
        PROCESS ENGINEERING
                FIGURE  2-4

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              THE  TOTAL   VERSUS
         THE   FRACTIONAL  APPROACH
INFLUENT
  SOLIDS
SEPARATION
               r
               i
               i
  LIQUID
PROCESSING
LIQUID
                                      EFFLUENT

           SLUDGE
         PROCESSING
                      SOLIDS
                              EFFLUENT
                  FIGURE  2-5

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      SECTION 3 - NATURE AND HANDLING CHARACTERISTICS OF SLUDGES


1.   Fundamental Point

         Need — Knowledge/Insight
              Nature of Sludges/Handling Characteristics

         Potential Pitfall
              (Figure 3-1)

              "All generalities are inherently false, including this one."

         But — Methods of process study
              Knowledge of process and equipment performance at various plants.
              Supplement and guide work on a given sludge at a particular plant.

2.   Raw Primary Sludge

         —   Almost universally settles, thickens, dewaters and incinerates relatively easily.

         —   Because (Figure 3-2) is usually coarse and relatively fibrous.

         —   Vacuum filtration and centrifugation work well at low cost (Figure 3-3).

         —   Note heavy thick cake and excellent release.

         —   Costs are low and efficiencies good.
                   (Table 3-1)

         —   Primary sludges give slightly compressible cakes but presence of sufficient gross
              solids - (« 30% < 30 mesh) permits rapid formation of cake with sufficient
              structural matrix = good capture and rapid dewatering.

3.   Effect of Digestion (Primary Sludge)
         (Table 3-2)

         —   Anaerobic digestion,  contrary to  some information in  the literature, makes
              sludges somewhat  more difficult to thicken and dewatcr.

         —   But results arc still good and costs low.

         -   Shear effects on particle size and increased hydration of solids.
                                        3- 1

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4.   Activated Sludges (Conventional)

          -    Inherently more variable

          —    Principal source of variation
                   Configuration and mode of operation of activated sludge system involved.

          —    Also, Domestic/Industrial waste ratio  and type, Nature of Collection System
               can have real effect.

          —    Structure
                   Generally finer in particle size.
                   60-90 percent cellular organic matter.
                   Bioflocculated to some degree, by excretion of natural polymeric material
                   by the microorganisms.
                   Density close to density of water.

          -    Water Content
                   (Figure 3-4)
                   Biomass from conventional air systems has much associated water.

                   Theoretically, if the loosely held  and bound surface water disengaged, up
                   to 29 percent solids obtained.

                   Another way to overcome this problem
                   Endogenous respiration (Figure 3-5, Reference 3).

                   Greater degree of bioflocculation displaces extracellular water*

                   Improves settling and dewatering characteristics.

5.   Summary — Activated Sludges

          -    Conventional  Air Aeration  Systems  Excess Activated Sludge  requires very
               careful operation  to give settleable sludge.

          -    Activated sludge  is sensitive to further processing. Hydration easily and tends
               to float.

6.   Handling Combined Primary and Activated Sludges

          -    Existing plants, many cases designed one of two ways.
                   (Figure 3-6)
                                         3-2

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         - A. Recirculate E.A.S. to head of plant - Primaries

              Results Primary Solids Capture goes to pot.

              Greater BOD load on secondary system.

              More E.A.S. created than necessary.

              Combined Mixed Sludge
                   Settles poorly in digester, another recirculation load.

                   When elutriated (without  flocculants) sludge fractionates - another low
                   efficiency process and recirculation load.

         — B. E.A.S. mixed with Primary Sludge prior to gravity thickening
                   (Figure 3-7)

              Results Better than recirculation to primaries but:

                   Dirty thickener overflow.

                   Activated portion will not settle in digesters or elutriation basins, so still
                   poor.

              Remedy

                   Combine and thicken sludges just before dewatering.

                   Not early in process.

7.   Oxygen Activated Sludges

         -   Biomass from oxygen process has better settling characteristics.
                   (Figure 3-8, Reference 4)

         —   Clarifier  performance, based  on  overflow rate (Figure 3-9) is better with
              oxygen process sludge (Watch bottom loading rates).

         -   Recycle sludge solids (Figure 3-10) are higher with oxygen activated sludge.

         —   Sludge volume indices are improved over air aeration sludge.

         —   Gravity thickening (Figure 3-11).
                                         3-3

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                   Admittedly  different  plants  involved but  best  data available,  higher
                   underflow solids.

                   Chicago results from excellent article by Ettelt (Reference 13) and others.

                   Figure in parentheses for Chicago is for picket fence type thickener.

                   Summation - oxygen activated sludge appears to gravity thicken more
                   readily.

          -    Flotation thickening (Figure 3-12)
                   (From Reference 6 by Stamberg, Bishop, Hais and Bennett of EPA).

                   These results are without floe aid use.

                   Figure 3-13  - additional results  with polymer usage - lower  costs and
                   greater efficiency for the O.A.S.

          —    Vacuum Filtration
                   (Figure 3-14)

                   Batavia results are from a 3 ft2 pilot filter.

                   Louisville results are from filter leaf tests on location. Representative of a
                   workable - logical method. What could be expected in mixing primary and
                   O.A.S. sludges.

          —    Centrifugation
                   (Figure 3-15)

                   Pilot solid bowl scroll type work by Sharpies.

                   Higher throughput, lower chemical cost and better capture for O.A.S.

                   Need results on typical mixed sludge.

8.   Alum Use — Primary Plant — Mixed Chemical Organic Sludge
          (Figure 3-16)

          -   Work by OWRC and plant staffs (Reference 7).

          —   With no chemical addition to primaries,  ferric/lime conditioning, high yield and
              low cost.

          -   With  alum, primary  solids  level drops,  amount of sludge increases,  yield
              decreases and costs go up.


                                         3-4

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         -   Ferric and lime may not be best conditioning system for alum/organic sludge.

9.   Lime Use - Conventional Activated Sludge Plant - Mixed Lime/Organic Sludge (Raw)
         (Figure 3-17)

         -   2.0 mgd, lime added just ahead of primaries.

         -   Sludge volume almost triples, but centrifugation looks easy and inexpensive
              (centrate=10-30MG/LP).

         —   Low polymer dose to clean up centrate.

10.  Alum and Lime Sludges - Windsor Little River Conventional Activated Sludge Plant
         (Figure 3-18)

         -   First  note that  normal, untreated  sludge conditioning costs are abnormally
              high, particularly for a sludge feed to filters of 6.2 percent solids.

          -   Lime usage gave  a mixed  sludge  (with small amount of activated  sludge
              content?) which dewatered well at a lower cost.

          -   Alum lowered  sludge  solids concentration, decreased yield and  increased
              conditioner costs. Cake solids were only 16 percent with alum use.

 11.  Ferric Chloride/Organic Sludge at North Toronto  Conventional Activated Sludge Plant
          (Figure 3-19, Reference 12)

          -   Use of ferric chloride  for phosphorus removal.

          —   Tested for many months.
                                              i
          -    First applied at primary basins.

          —    Current application point = at end of aeration basin.

          -    Chemical conditioning costs about $8/ton.

           —    Reasonable production rate and cake solids content realized.

  12.  Lake Tahoe Solids Handling

           -    Process flow (Figure 3-20, Reference 9)

                    Two sludges handled separately in this tertiary plant.
                                         3-5

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                  Organic sludges (from a system which recirculates activated sludge to head
                  of plant).

                  Lime sludges from tertiary type treatment.

         —   Organic Sludge Processing
                  (Figure 3-21)

                  This section of plant has two design features which, in my opinion, result
                  in abnormal sludge handling costs.

                  First is the recirculation of the  excess activated sludge to  the primaries
                  which has been demonstrated to result in poor primary capture and poor
                  activated sludge quality.

                  Second is the attempt to gravity thicken  a mixture of excess activated
                  sludge and primary sludge - net result is that no thickening occurs.

                  Hence feed  to "Dewatering  Centrifuge" is unthickened and high costs
                  result  in  dewatering.  (Polymer dosage is actually  higher than shown
                  because the basis is  tons of dry solids to furnace which  includes lime
                  wastage).

         —    Lime Sludge Processing
                  (Figure 3-22)

                  The centrifuge serves here as a classification device.

                  First centrifuge operated with high centrate loss to  purge  organics from
                  lime stream to be recalcined.

                  Second centrifuge,  in series on centrate cleans  up the  more  organic
                  portion.

                  Results shown are for 8 percent solids feed to lime - mud centrifuge. Cake
                  solids equal 37 percent. Looks like a good operation.

                  Cake solids from centrate centrifuge average 30 percent.

13.  Aerobically Digested Activated Sludges

         -   Aerobic digestion is an inherently "cleaner" means of reducing  the volume of
              activated sludge to be dewatcred and to stabilize same for land disposal.

         -   Plant scale work current at  several locations.
                                         3-6

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-    Atlanta (Reference 10)

         New 6 mgd Flint River Plant tests.

         Digestion process works well.

         Sludge  compacts  to  2-3 percent and can  be dewatered via vacuum
         filtration using ferric chloride.

         Yield is on the lean side.

         If aerobically  digested sludge were mixed with thickened primary sludge,
         dewatering and incineration would be more efficient.
                                3-7

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                             REFERENCES - SECTION 3
 1.   Reed,  S.E., and  Murph,  R.S., ASCE  Proceedings Paper  6747,  August,  1969; and
         Discussion by Dick, et ah, ASCE Journal, 638-646 (1970).

2.   Goodman, B.L., and Foster,  J.W., "Notes on Activated Sludge," Smith and Loveless.
         (1969).


3.   Tenney, M.W., Echelberger, W.F., Coffey, J.J., and McAloon, T.J., "Chemical Condition-
         ing of Biological Sludges for Vacuum Filtration." Journal  WPCF, 42, No. 2, Part 2
         R1-R20(1971).


4.   Private communications - Union Carbide Corporation.

5.   Unox Design Information, EPA, TT Program, Metcalf and Eddy, Pittsburgh, Pennsylvania,
         August 29, 1972.


6.   Stamberg,  J.B., et ah,  EPA, "System Alternatives in Oxygen Activated Sludge," WPCF
         Meeting, Atlanta, Georgia, 1972.


7.   Van Fleet, B.L., Barr, J.R., and Harris, A.J., "Treatment and Disposal of Chemical Phos-
         phate Sludges in Ontario."


8.   "Report on Phosphorous Removal," Water and Pollution Control, 16(1972).

9.   EPA - W.P.C.R.S. 17010 ELQ08/71 -"Advanced Wastewater Treatment as Practiced at
         Lake Tahoe."


10.  Cameron, J., "Aerobic  Digestion of Activated Sludge to Reduce Sludge Handling Costs,"
         WPCF Conference, Atlanta, Georgia, 1972.

11.  Bolek, M.,  and Helekal, J., "Cake Removal from R.V. Filters by Air Blast, Filtration and
         Separation,"  146 (March, April, 1971).


12.  Private  communication, D.A. Clough, Director, Metro Toronto Water Pollution Control.

13.  Ettelt, G.A., and  Kennedy,  T.J.,  "Research  and  Operational Experience  in Sludge
         Dcwatering at Chicago." JWPCF, 38,  No. 2, 248.
                                       3-8

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                   LIST OF FIGURES AND TABLES - SECTION 3


Figure 3-1          Maxim - "All generalities are inherently false, including this one."

Figure 3-2          Closeup  - Raw Primary Sludge Filter Cake

Figure 3-3          Release Characteristics - Raw Primary Sludge Filters

Table 3-1           Vacuum Filtration — Raw Primary Sludge

Table 3-2           Vacuum Filtration - Digested Primary Sludge

Figure 3-4          Activated Sludge - Aqueous Fluid Distribution

Figure 3-5          Effect of Aeration Time on Biopolymer Production and Dewaterability

Figure 3-6          Secondary Plant with Surplus Activated Sludge to Head of Works

Figure 3-7          Secondary Plant with Surplus Activated Sludge Mixed with Primary Sludge
                   Prior to Thickening and Digestion

Figure 3-8          Settling Characteristics for Air and Oxygen Biomass (ISR vs. Concentration)

Figure 3-9          Typical Clarifier Performance for Air and Oxygen Sludges
                   (at 30 percent Recycle)

Figure 3-10         Typical Clarifier Performance for Air and Oxygen Sludges
                   (at 30 percent Recycle)

Figure 3-11         Gravity Thickening

Figure 3-12         Flotation Thickening

Figure 3-13         Flotation Thickening

Figure 3-14         Vacuum Filtration

Figure 3-15         Centrifugation, Oxygen andConventional Aeration Sludges

Figure 3-16         West Windsor Primary Plant - Alum
                                        3-9

-------
                  LIST OF FIGURES AND TABLES - SECTION 3
                                   (Continued)

Figure 3-17        Newmarket Conventional Activated Sludge Plant - Lime
Figure 3-18        Little River Conventional Activated Sludge Plant - Phosphate Removal
Figure 3-19        North Toronto Conventional Activated Sludge Plant - Ferric Chloride
Figure 3-20        Lake Tahoe Solids Handling System
Figure 3-21        Lake Tahoe, Organic Sludge Handling
Figure 3-22        Lake Tahoe, Lime Sludge Processing
                                        3- 10

-------
MAXIM
   " ALL GENERALITIES
   ARE  INHERENTLY FALSE
   INCLUDING THIS ONE.
11
        FIGURE 3-1

-------
FIGURE 3-2
CLOSE-UP RAW PRIMARY  SLUDGE  FILTER CAKE

-------
FIGURE 3-3
RELEASE  CHARACTERISTICS -  RAW PRIMARY SLUDGE  FILTERS

-------
                                                               SOLIDS
%  SLUDGE    CONDITIONER     COST     YIELD         CAKE      CAPTURE
 SOLIDS	USED       [S/TONI   LB/FT2/HR   SOLID |%]     |%|

    10         CATIONIC       1.67        10           32         90-95
              POLYMER
                   TABLE 3-1    VACUUM FILTRATION - RAW PRIMARY SLUDGE

-------
                                                 CAKE        SOLIDS
%  SLUDGE     CONDITIONER       YIELD         SOLIDS       CAPTURE
  SOLIDS       COST  |$/TON|     #/HR/FT2       1%)	l%l

   12.7             2.64             7.4           28             90+
               TABLE 3-2     VACUUM FILTRATION - DIGESTED PRIMARY SLUDGE

-------
         ACTIWTED SLUDGE
    AQUEOUS FLUID DISTRIBUTION
                             CUMULATIVE
      LOCATION         PARTS      % SOLIDS
SOLIDS              1.0        100
WITHIN CELL          2.5        29
SURFACE BOUND"*"*   5.0         12
LOOSELY HELD *«».    2.5         9  *»w*o
              FIGURE 3-4

-------
 ACCUMULATED
POLYSACCHARIDE
     mg/l
600
500
400
300
800
600
400
200
POLYSACCHARIDE RELATIONSHIPS
   POLYSACCHARIDE/BACTERIA
          RATIO
                                                    ACCUMULATED
                                               POLYSACCHARIDE
                                           FILTRATION RATE
                                                                  1.5
                                                                  1.0
                                              mg POLYSACCHARIDE
                                           0.5   mg BACTERIA
                             50
                                      200
                                    250
            FIGURE 3-5
              100       150
              TIME - HOURS
EFFECT OF AERATION TIME ON BIOPOLYMER PRODUCTION AND DEWATERABILITY

-------
   GRIT
 REMOVAL
        PRIMARY
       CLARIFIERS
              AERATION
               BASINS
   FINAL
CLARIFIERS
                 ........ i ..... in ........ i ...... mi ...... iniir^ .............. IIIIHIIIIII ........ iiiiiiiin
            •^IIIIIIH	innim
        ANEROBIC
        DIGESTION
       .........
ELUTRIATION
                iiiiiiiiiniiiii
            WASTE WATER

            SLUDGE
                ~—   PROCESS LIQUIDS
                                   FILTERS
FIGURE 3-6
SECONDARY PLANT WITH SURPLUS ACTIVATED SLUDGE TO HEAD OF WORKS

-------
»-
=1111111111
PUMPING


GRIT
REMOVAL rfY
PRIMARY
CLARIFICATION


HIGH RATE
ACTIVATED
SLUDGE
j j = i
iiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiimiiiiiiiiiiiiiiiiiiiiiiiiiiiiniiiiiiiiiir
r___
SLUDGE
THICKENING
	 *
DIGESTION 	 •>

ELUTRIATION
	 *
j
DEWATERING

!
	 >•
— WASTE WATER
	 SLUDGE
-— PROCESSING LIQUIDS
FIGURE 3-7      SECONDARY PLANT  WITH SURPLUS ACTIVATED  SLUDGE MIXED WITH  PRIMARY SLUDGE  PRIOR
               TO  THICKENING  AND  DIGESTION

-------
                       10.0
       SETTLING
   CHARACTERISTICS
     FOR AIR AND
   OXYGEN BIOMASS
(ISR VS. CONCENTRATION
                        i.o
            INITIAL SETTLING
             RATE, FI/Hr.
                       0.1
                         1000
 AIR
BIOMASS
                                                      OXYGEN
                                                      BIOMASS
     j   iii
               10,000
         CONCENTRATION  mg/l
                            FIGURE   3-8
100,000
       TYPICAL CLARIFIER PERFORMANCE FOR  AIR AND OXYGEN SLUDGES
                            (AT 30 % RECYCLE]
             10,000r
              8000
  MLSS  |mg/l ]   6000
              4000
              2000
                              OXYGEN SLUDGE
                                                         AIR SLUDGE
                       200    400    600   800   1000   1200
                                 OVERFLOW RATE, GPD/FT2
                              1400   1600
                            FIGURE   3-9

-------
    TYPICAL CLARIFIER PERFORMANCE FOR AIR AND OXYGEN SLUDGES

                       (AT 30 % RECYCLE)

            5r
   % RSS
                                                 OXYGEN SLUDGE
                                                  AIR SLUDGE
                   200   400   600    800    1000   1200   1400   1600

                        OVERFLOW  RATE, GPD/FT2
                       FIGURE   3-10
              GRAVITY  THICKENING
         FEED SLUDGE
    TYPE
OXYGEN W.A.S.
AIR W.A.S.
OXYGEN MIXED
AIR MIXED
% SOLIDS
   1.7
   0.9
   2.3
   1.1
  SOLIDS
 LOADING
#/Ft.2/DAY

    10

    20
    20
UNDERFLOW
  CONC.
% SOLIDS   LOCATION
   4.8
                 5.6
LOUISVILLE
 1.4-2.8    CHICAGO
           MIDDLESEX
 3.3(4.4)    CHICAGO
                      FIGURE   3-11

-------
        FLOTATION THICKENING

                     LOADING        THICKENED
     FEED SLUDGE       #/Ft.2 /DAY       SOLIDS |%)
   OXYGEN ACTIVATED        95              4


   BLENDED OXYGEN         —             11

      ACTIVATED (0.3)  +

      PRIMARY  (1.0]

                 FIGURE  3-12
           FLOTATION THICKENING

   FEED SLUDGE	    POLYMER    LOADING     THICKENED
 TYPE       % SOLIDS     #/TON    #/Ft.2/HR.    SOLIDS |%|
OXYGEN
ACTIVATED      (1.7)         2.9      6.4-10.2        6.6

AIR
ACTIVATED      (0.9)         9.0      2.0-4.0        4.5


                 FIGURE   3-13

-------
          VACUUM FILTRATIpN
LOCATION
                CONDITIONER
 	#/TON D.S.
  TYPE  % SOLIDS   FeCI3  LIME
        FEED SLUDGE
BATAVIA    OXY.W.A.S.    4.4
                200   —
LOUISVILLE
OXY.W.A.S.= 3
RAW PRIM
DIG. = 6
   TYPE
  SLUDGE
5.3
50
142
 YIELD
#/Ft.2/HR.

   5.1

   7.2
                   FIGURE  3-14
 CAKE
SOLIDS %

  14.5

  26.4
      CENTRIFUGATION
  OXYGEN a CONVENTIONAL
     AERATION SLUDGES
        FEED        POLYMER   SOLIDS    CAKE
   % SOLIDS  RATE (GPM) (#/TON)   CAP. (%) SOLIDS (%)
  OXYGEN
  W.A.S.
     2.5
   95
           92
  AIR
  W.A.S.
     1.0
   60
   12.5
      82
          8.5
                   FIGURE  3-15

-------
              WEST WINDSOR

        PRIMARY PLANT-ALUM
    CHEMICAL ADDITION     PRIMARY  SOLIDS             $
   METAL  DOSE  POLYMER  SLUDGE  TONS/         9  COND.
   SALT  MG/L   MG/L    %  SOLIDS   >"lM.G. #/HR./Ft.  COST

   NONE    —     —      11.5     0.5      11.3     3.10
   ALUM    90     0.4      7.6     1.1      5.8     9.50
                   FIGURE  3-16
                NEWMARKET
    CONV ACT. SLUDGE  PLANT-LIME
CHEMICAL ADDITION MIXED    SOLIDS      CENTRIFUGATION	
  METAL  DOSE   SLUDGE   TONS/   POLYMER  % CAKE   SOLIDS
                       /M.G.
SALT   MG/L  % SOUPS    /M.G.   |#/TON|  SOLIDS   CAPTURE

NONE   —      3.5      0.85     —     —       —

LIME   200      10      2.45    <1       31       97


                FIGURE  3-17

-------
tf LITTLE RIVER w ~
(CONV ACT. SLUDGE -PHOSP. REM.
CHEMICAL ADDITION MIXED SOLIDS FILTER S
METAL DOSE
SALT MG/L
NONE —
- LIME 125
T*
ALUM 150
SLUDGE
% SOLIDS
6.2
11.6
5.7
TON^ YIELD
/M.G. #/HR/Ft.2
0.8 5.2
1.2 7.2
1.2 4.6
COND
COST
^•BI^^BKBi
11
18
                                              s,
                  FIGURE  3-18
             NORTH TORONTO

CONV ACT. SLUDGE -FERRIC  CHLORIDE
CHEMICAL ADDITION   MIXED
                       COND.|lb/TON
  METAL    DOSE  SLUDGE  FERRIC                % CAKE
   SALT    M6/L  % SOLIDS  CHLORIDE   LIME   Ib/HR/Ft.2 SOLIDS
FERRIC
CHLORIDE 25-35   8
                     104    200   3.3
                                            21
                 FIGURE  3-19

-------
            LAKE TAHOE SOLIDS HANDLING
                          POLYMER

RAV
INFLU














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ENT
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"* CENTM

ASH


P
c








kTE




RIMARY
-ARIFIER



1 '
SLU
THICK
1
CENT

,
FUR







1
DGE
tM
r
HFl

i
MAC






1
r

R

ICE


E

















AERATION
BASINS

AC
S














riv
LU














ATED
5GE


LU

1


,
RE-C/








HE
ENER
i


i
ILCINE

















SECON
CLARI

>

I
1


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DARY
FIERS

r





fE 1


LIME
CHEM. C

1
t ^. CHEMICAL
w CLARIFIERS




FURTHER
REACTION PROCESSING ^





TO
LARIFIERS

             FIGURE  3-20
           LAKE TAHOE
  -ORGANIC  SLUDGE HANDLING
% FEED
SOLIDS
COND.
#/TON
FEED
RATE
% SOLIDS
CAPTURE
% CAKE
SOLIDS
2.0
5.1     —
90
17
             FIGURE  3-21

-------
        LAKE TAHOE
-LIME SLUDGE PROCESSING
                FRACTION LOST TO CENTRATE
FEED RATE
(GPM)
10
20
% SOLIDS
CAPTURE
93
79
TOTAL
SOLIDS
0.10
0.20
ACTIVE
LIME
0.04
0.08
PHOSPHATE
0.19
0.39
MGO
0.17
0.35
         FIGURE  3-22

-------
                 SECTION 4 -SLUDGE STABILIZATION PROCESSES*'
1.   Anaerobic Digestion

         -   Anaerobic  digestion is the  most  frequently employed  process  for  sludge
          4r  stabilization. When digestion  operates properly,  it converts raw sludge  to a
        \^r   stable  material which  is inoffensive to the  senses,  and which has a greatly
       v(r     reduced pathogen content. A recent exposition of sludge digestion is available
       *      (Reference 1).

         —   Anaerobic digestion produces changes in sludge which, on the average, reduce
              the filter yield.  If  ferric  chloride and  lime are used,  chemical  demand is
              increased (Table 4-1 from Reference 2). If sludge density is increased (e.g., by
              two-stage high rate digestion), yield can be increased.

         —   Schepman and Cornell (Reference 3) conclude that raw sludges may vary from
              very good to very poor yields, whereas digested sludges from different sources
              are more uniform (Table 4-2).

         —   Anaerobic  digestion  solubilizes  much  sludge,  releases  nutrients  back to
              treatment plant. High dissolved solids can interfere with chemical conditioning.
              Table 4-3 shows some supernatant compositions reported recently (Reference
              4).

2.   Aerobic Stabilization

         —   Aerobic stabilization is often used  to  stabilize waste activated sludges or the
              waste  sludges  from  smaller  plants  which  do  not have  separate primary
              clarification. See Reference 1  for a recent presentation.

         —   Aerobically  stabilized  sludge  has Bflfli_dewatering characteristics on vacuum
              filters although a recent publication claims otherwise (Reference 6). Ordinarily,
              this sludge is dewatered on sand beds or applied in liquid form to cropland.

3.   Chlorine Oxidation

         —   The Purifax process oxidizes sludge with heavy doses of chlorine (circa 2,000
              mg/1). Sludge dewaters well on sand beds. Stability is excellent.

         —   Purifaxed sludges present some  difficulties when they must  be dewatered on
              vacuum filters. Chemical (or polymer) conditioning is needed, but  the low pH
              (circa 2) interferes with the  action of conditioning agents.  Pilot plant  tests
              indicate that pH must  be increased  to greater than 4 to get good conditioning
              (Reference 7).
                                        4- 1

-------
          —   Supernatant  and filtrate  contain high  concentrations of chloramines. They
              should not be carelessly discharged.
4.   Lime Treatment
          —   Lime treatment of sludge stabilizes the sludge as long as the pH stays high. Kill
              of pathogenic bacteria is excellent  (Reference 8). Sludge  dewaters  well on
              sandbeds without odor.

          —   Sludge filtrability is improved. Caution is advised on disposal of sludge cake to
              landfills to avoid thick layers. The pH could fall to near 7 before the sludge
              dries out, permitting regrowth and noxious conditions.
                                        4-2

-------
                                                    TABLE 4-1
                             TYPICAL AVERAGE SEWAGE SLUDGE FILTRATION RATES
                                                                                                   Average Chemicals

                                                                                                        (percent)
Type of Sludge
Primary Sludge
Raw
Digested
Digested — Elutriated
Primary - Trickling Filter
Raw
Digested
Digested - Elutriated
Primary - Activated Sludge
Raw
Digested
Digested — Elutriated
Activated Sludge - Concentrated
Feed Solids2
(percent)

8
8
8

7
8
8

5
6
6
3
Filtration Rate
Drylb/hr-ft2

10.0
8.0
6.5

9.0
7.0
6.5

4.5
4.5
4.5
2.0
Average Cake
Moisture (percent)

66
70
71

68
71
72

79
76
78
84
FeClj

1.5
3.0
2.5

1.5
3.0
2.5

4.0
4.0
5.0
5.5
CaO

7.0
8.5
(4.0)1

8.0
8.5
(4.0)1

4.0
9.0
(5.0)1
0
1 Lime is frequently added to elutriated sludges to give higher filtration rates and lower cake moistures.


2 If feed sludge concentration differs from value listed, the expected filtration rate will differ directly in proportion to the change in

  feed solids concentration. Example:  If 9% solids raw primary sludge is filtered an average filtration rate of 9 x 10 =  11.25 lb/hr/ft2
                                                                                               O
  may be expected.                                                                              °

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                                   TABLE 4-2

                   FILTRATION RATES AND CAKE MOISTURE

                      FOR DIFFERENT TYPES OF SLUDGES
Plant
Sludge
Cone. (%)
Chemicals (%)
CaO FeCl3
Filter
Rate1
Cake
Moisture (%)
Saginaw, Mich.
Providence, R.I.
Wyandotte, Mich.2
Rockford, 111.
Schenectady, N.Y.
Long Beach, N.Y.3
Greenwich, Conn.
Dallas, Texas
      PRIMARY SLUDGES
    16       9.9         0
   5.5       6           2.2
   8.0       15          5

DIGESTED - PRIMARY SLUDGES
   9.5
   8.5
   3.8
   5.6
   7.5
 7.1
 6.0
17.0
 6.0
 5.5
5.4
4.0
3.5
3.0
2.5
                        8.5
                       13.0
                        8.0
11.5
11.5
14.0
11.0
14.5
                  ELUTRIATED - DIGESTED - PRIMARY SLUDGES
Cincinnati, Ohio
Toronto, Ont.
East Providence, R.I.
Dallas, Texas
   8.5
   7.7
   9.0
   8.0
 0
 0
 0
 0
4.5
4.0
1.5
0.8
 3.1
 8.0
20.0
15.5
                        54.0
                        73.0
                        70.0
71.5
77.0
73.0
74.0
72.5
64.0
70.0
72.5
70.5
                   DIGESTED - PRIMARY - ACTIVATED SLUDGE

Nassau County, N.Y.          4.5      12.0         8.0        3.0
                                                  79.0
           ELUTRIATED - DIGESTED - PRIMARY - ACTIVATED SLUDGES
Cranston, R.I.
Houston, Texas
Ann Arbor, Mich.
Cleveland, Ohio
Hyperion, (L.A.) Calif.4
2.4
2.7
5.0
5.5
5.1
0
0
15.0
9.0
0
7.0
5.5
3.0
2.5
1.9
3.4
5.5
5.0
6.3
5.8
85.0
84.2
72.5
71.5
76.5
 1 Filter rate or yield, lb/(hr)(ft2)
 2 Sludge hauled to plant from other collecting points in county; therefore, it is somewhat
  septic, depending on temperature and elapsed time.
 3 Testing conditions prevented optimum operation.
 4 Separan also added at approximately 0.02 percent.
                                       4-4

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                           TABLE 4-3




                 AVERAGED RESULTS OF ANALYSES



                OF DIGESTER SUPERNATANTS (MG/L)

PH
Suspended Solids
Total Solids
Total Volatile Solids
Total PO4 (as P)
Soluble-Ortho-PO4 (as P)
NH3-N
Organic-N
Alkalinity
COD
Hardness
Irvington
7.3
2,200
4,540
2,930
143
66
850
290
3,780
4,560
264
Milpitas
7.0
383
1,470
814
63
45
253
53
1,350
1,380
322
Massolli*
7.3

3,260
1,540
56

402

1,675

890
* Reference 5
                              4-5

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                             REFERENCES - SECTION 4
 1.   Weston,  Roy F., Inc.,  "Process Design Manual for Upgrading Existing Wastewater
         Treatment Plants," EPA Report 17090 GNQ, October, 1971.

2.   Teletzke, G.H., "Sludge Dewatering by Vacuum Filtration," presented at Annual Meeting
         of Rocky Mountain Sewage and Industrial Wastes Association, Colorado Springs,
         Colorado, October 24-26, 1960.

3.   Schepman, B.A., and Cornell, C.F., "Fundamental Operating Variables in Sewage Sludge
         Filtration." Sew. and Industrial Wastes, 28, No.  12, 1443-1460 (1956).

4.   Bennett, G.E., "Development of a Pilot Plant to Demonstrate Removal of Carbonaceous,
         Nitrogenous, and Phosphorus Materials from Anaerobic Digester  Supernatant and
         Related Process Streams," U.S. EPA, Report ORD-17010 FKA 05/70, May, 1970.

5.   Masselli, Joseph W., et al., "The Effect of Industrial Wastes on Sewage Treatment," New
         England Water Pollution Control  Commission, Boston, Massachusetts, 1965 .

6.   Cameron, J.W.,  "Aerobic Digestion  of Activated Sludge to Reduce  Sludge Handling
         Costs,"  45th Annual  Conference,  Water Pollution Control Federation, Atlanta,
         Georgia, October, 1972.

7.   Personal communication with Mr. Pearson of BIF Purifax, Providence, Rhode Island.

8.   Farrell, J.B.,  Smith, J.E., Jr., Hathaway, S.W., and Dean, R.B., "Lime Stabilization of
         Chemical-Primary Sludges at 1.15 mgd," 45th Annual Conference, Water Pollution
         Control Federation, Atlanta, Georgia, October, 1972.
                                      4-6

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                   LIST OF FIGURES AND TABLES - SECTION 4







Table 4-1          Typical Average Sewage Sludge Filtration Rates




Table 4-2          Filtration Rates and Cake Moisture for Different Types of Sludges




Table 4-3          Averaged Results of Analyses of Digester Supernatant (mg/1)
                                        4-7

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   SECTION 5 - CASE STUDIES - PLANT RESULTS - CHEMICAL CONDITIONING -
                      CONVENTIONAL ACTIVATED SLUDGE
CASE STUDY - WASHINGTON, D.C.

1.   Extensive History, Plant Process Engineering Studies

         -   Reference 2, Dahl, Zelinski and Taylor (WPCF award 1972).

         —   Important regarding efficiency of various methods of handling organic sludges.

2.   Plant Process
         (Figure 5-1)

         -   Currently modified high rate activated sludge.

         -   Expanded to activated sludge in 1959 - Original rationale - same solids handling
             system as for primary sludge.

                  Gravity thickening of excess activated with raw primary.

                  Anaerobic high rate digestion, elutriation, vacuum filtration.

         —   Problems

                  Dirty thickener overflow and very polluted elutriate.

                  Results -  Fines build up in system, upset and high cost solid - liquid
                  separation steps.

          —   Temporary solution

                  Vent elutriate (15-30 tons/day).

                  Accept poor primary capture.

          —   Current solution
                  (Figure 5-2)

                  Flocculation in elutriation basins.

                  Careful operation of basins to promote sludge compaction and thickening
                  and good solids capture.

                                        5- 1

-------
3.   Sludge Removal Practices and Costs
              (Table 5-1)

          -   Initial  results, even with venting of elutriate, costs were high and 3  lb/hr/ft2
              filter yields experienced.

          -   During initial months of treating  elutriation basins and providing good solids
              removal  rate, higher than normal rates were  maintained to  clean out plant
              system.  (Prior to this  work, another long term attempt had been made to
              recycle the elutriate - this loaded up the plant).
                   (Figure 5-3 showing vacuum filters)

          -   After prolonged  efficient thickening,  solids capture and removal rates being
              attained, costs and required steady  state rates became lower as a new plant
              equilibrium established (4 lb/hr/ft2 yield).

4.   Current Operations

          —   New belt type filters installed.
                   (Figure 5-4)

          —   Interim  use of alum/ferric  in final clarifiers  for increased BOD and solids
              removals.

          -   Some  problems with release of cake from belt filters. Requires  $3.80/ton more
              ferric chloride than older drum filters.

          —   Cloth use data comparison shows favorable results for drum type filters.

          -   Drum cloth life = 2,000 hours:  preliminary indications are belts go same time
              before maintenance or changes required.
                                          5-2

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CASE STUDY - METRO TORONTO MAIN PLANT

1.   Definitive, Thorough Plant Process Studies By Plant Personnel

          -   Plant expanded over 1967-71 period to provide full scale secondary treatment.

          —   Sludge processing problems encountered.

          -   No separate activated sludge thickening, once again  recirculation of same to
              head of plant. Digestion of mixed sludges.

          —   Plant personnel responded to the challenge.

2.   Process Description
          (Figure 5-5)

          -   Step aeration,  two-stage anaerobic digestion, elutriation, vacuum filtration,
              incineration.

          —   Slide does not completely reflect all available options on  recycle stream
              directions.

          -   Loadings and degree of treatment gradually increased 1967-71.

3.   Effects of Increased Proportion of Activated Sludge
          (Figure 5-6)

          -   Gradual decrease in solids content of elutriated sludge  to filters.

          —   By 1970, below 4  percent, that  critical level as far as efficient dewatering is
              concerned. By August, "to hell in a handbasket," below 3 percent regularly.

          -   Concurrently (Figure 5-7), the solids content of the raw sludge from the
              primaries was decreasing. The effect of recirculation of activated sludge to the
              head of the plant.

4.   Sludge Removal Needs
          (Table 5-2)

          —   Due to loadings increase and full  secondary treatment, solids removal rates as
              shown were essential.

          -   But processing problems cited made attainment with normal mode of operation
              questionable.
                                         5-3

-------
          —   As recirculating solids occurred in plant, odor problems arose.

          —   Work commenced to improve the elutriation/filtration process.

5.   Elutriation/Filtration Studies
          (Table 5-3)

          -   Over  two  month  period, small polymer add  in  feed  to elutriation; ferric
              chloride in decreasing amounts, plus polymer at vacuum filters.

          -   Elutriated  sludge solids up to 4 percent with corresponding increase in filter
              production rate.

          -   After 2-3 months of operation (Table 5-4), results improved even further as
              some of the fines were cleaned out of the plant.

          -   The elutriation/filtration (Figure 5-8) process improved in uniformity and ease
              of operation. Note excellent cake discharge and thickness of filter cake.
                                         5-4

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CASE STUDY - RICHMOND, CALIFORNIA
1.   On-Going, Plant Process Studies on Solids Handling

         —   During  1967-69  (Figure  5-9) expanded  plant  to secondary treatment  via
              activated sludge process (surface aeration).

         —   Design included provision for separate thickening of activated sludge via D. A.F.

         —   Combined  sludges then  to two stage anaerobic digestion, elutriation and
              vacuum  filters.  Filter cake  to  incinerator or  landfill  (40 mgd  hydraulic
              capacity, average flow = 9 mgd).

2.   Process Considerations

         -   While D.A.F.  thickening  of E.A.S., was  a  positive step, there was  some
              speculation about mixing the sludges early in the process.

         —   Shortly after the advent of activated sludge operation, the same problems arose
              as in Toronto and Washington.  Recirculation of loaded digester supernatant
              elutriate caused solids build-up within plant.

3.   Remedial Action

         —   Plant personnel  carried out process studies  on elutriation/filtration process
              (Table 5-5).

         —   Note that with primary sludge, before  secondary treatment, things were rosy.

         —   During  the period when solids recirculation was occurring, note in column 2
              the nigh costs - low yields and low cake solids obtained.

         —   After realizing good  compaction and solids capture in elutriation via flocculant
              use, note dramatic improvement in filtration performance.

4.   Current Results

     —   After protracted operation with effective  elutriation (Table 5-6) the results were as
         shown.

     —   Total  conditioning costs  in elutriation and on filters (ferric  chloride/lime) were
         about $11.00/ton.
                                         5-5

-------
Richmond  has belt filters which do not have particularly good cake release
capabilities. This necessitates  a higher  than normal ferric/lime dosage. How
many times have you seen a filter cake with all those drying cracks?

More important, if the thickened activated sludge could be mixed with primary
sludge just before filtration, results would improve and costs would decrease.
                             5-6

-------
                   LIST OF FIGURES AND TABLES - SECTION 5
Figure 5-1

Figure 5-2

Table 5-1

Figure 5-3

Figure 5-4


Figure 5-5

Figure 5-6

Figure 5-7

Table 5-2

Table 5-3

Table 5^

Figure 5-8

Figure 5-9

Table 5-5

Table 5-6
Plant Flow Diagram - District of Columbia

Elutriation/Filtration System - District of Columbia

Sludge Removal Practices and Costs - District of Columbia

Vacuum Filter Operation — District of Columbia

New Filter Installation with Individual Conditioning Boxes - District of
Columbia

Plant Flow Diagram - Metro Toronto

Percent Solids in Elutriated Sludge - Metro Toronto

Percent Solids in Raw Sludge - Metro Toronto

Sludge Removal Needs — Metro Toronto

Elutriation/Filtration Results October-November - Metro Toronto

Elutriation/Filtration Results 1971  - Metro Toronto

A View of Filters - Metro Toronto

Plant Flow Diagram — Richmond, California

Filtration Results — Richmond, California

Elutriation/Filtration Operations - Richmond, California
                                         5-7

-------
                             REFERENCES - SECTION 5
1.   Goodman, B.L, and Whitcher, C.P., "Polymer Aided Sludge Elutriation and Filtration."
         Journal WPCF.37, 12, 1643 (1965).

2.   Dahl, B.W., Zelinski, J.W., and Taylor, O.W., "Polymer Aids Dewatering and Eliminates
         Solids Loss  in  Elutriation," presented at the 43rd Annual WPCF  Conference,
         Boston, Massachusetts, October 6, 1970.

3.   Ashman,  P.S.,  "Operating Experiences  of Vacuum  Filtration at St.  Helens." Water
         Pollution Control, 20-39 (1969)-
                   /
4.   Ashman, P.S.,and Roberts, P.P., "Operating Experiences with Vacuum Filtration at St.
         Helens: A  Solution to the Problem." Water Pollution Control, 638-648 (1970).

5.   Stanbridge, H.H., "Operation and Performance of the Hogsmill Valley Sewage Treatment
         Works of the Greater London Council, 1958-1966." Water Pollution Control, 67,21
         (1968).

6.   Private  communications with:  David A.  Clough, Director  of Metro Water Pollution
         Control; Earl Baldock,  Assistant Director of Water  Pollution Control; Wadid Salib,
         Plant Engineer — Main Plant.

7.   Private   communications  with:  E.L. MacDonald, Jr.,  Superintendent,  and  William
         Kennedy, Plant Supervisor, City of Richmond, California.
                                        5-8

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   INFLUENT
                GRIT
              REMOVAL
 N  PRIMARY
     BASINS
AERATION
 BASINS
                           THICKENER
                             0-FLOW
                               4
                             ELUTRIATE
                     HIGH
                     RATE
                  DIGESTION
         WASH
         WATER
B.O.D. REMOVAL 70-90%
  SS REMOVAL 70-90%
                                       ELUTRIATION
  FINAL
CLARIFIERS
                                                    EFFLUENT
                                                    15-25%
                                                    FILTER
                                                     CAKE
            FIGURE 5-1
PLANT FLOW  DIAGRAM - DISTRICT OF  COLUMBIA

-------
          WASH
          WATER
DIGESTED
 SLUDGE
         ELUTRIATE
         RECYCLED OR TO RIVER
    2 STAGE
   ELUTRIATION
                                            VACUUM
                                             FILTERS
                                       FILTER
                                        CAKE
          X =  CATIONIC POLYELECTROLYTE APPLICATION  POINT
        FIGURE 5-2
ELUTRIATION/FILTRATION SYSTEM - DISTRICT OF COLUMBIA

-------
                         TONS/DAY      CHEMICAL COST (S/TON)
                          REMOVED    ELUTRIATION    FILTRATION
 ELUTRIATE TO  RIVER
 POST ELUTRIATE
 RECYCLE PERIOD
(POLYMER IN ELUTRIATION]

 AFTER PROLONGED
 POLYMER USE  IN
 ELUTRIATION
               45
               80
               70
              13.50
4.68
7.42
  TOTAL = 9.75
  TABLE 5-1
SLUDGE REMOVAL PRACTICES AND COSTS - DISTRICT OF COLUMBIA

-------
FIGURE 5-3
VACUUM  FILTER  OPERATION  -  DISTRICT  OF COLUMBIA

-------
FIGURE5-4
NEW FILTER  INSTALLATION WITH INDIVIDUAL CONDITIONING  BOXES  - DISTRICT  OF  COLUMBIA

-------
PLANT
INFLUENT ^
f
GRIT
REMOVAL

T
PRIMARY
CLARIFICATION
=
                        ACTIVATED

                          SLUDGE
                              FINAL

                            CLARIFIERS
PLANT EFFLUENT
              »
   11111111111111111


PRIMARY
DIGESTION
^
w~~~\ S.N.
SECONDARY
DIGESTION
{ELUTRIATE
	 *
2 STAGE
ELUTRIATION


* FILTRATE
VACUUM
FILTRATION
TO INCINERATORS

     WASTE WATER
.„ PROCESS LIQUIDS
  FIGURE 5-5
PLANT FLOW DIAGRAM - METRO TORONTO

-------
9.0
8.0
7.0
6.0
5.0
4.0
3.0
2.0
1.0
                              MONTHLY AVERAGES
       FIGURE 5-6
M      A      M      J     J      A      S      0
PERCENT SOLIDS IN  ELUTRIATED  SLUDGE - METRO TORONTO
                                                                           N

-------
7.0
6.0
5.0
4.0
3.0
2.0
1.0
                                                                     7.0
                                                                     6.0
                                                                     5.0
                                                                     4.0
                                                                     3.0
                                                                     2.0
                                                                      1.0
    JAN.
JUNE
                1968
DEC.
JUNE
DEC.
                             1969
                         FIGURE5-7      PERCENT  SOLIDS  IN RAW SLUDGE
                                             METRO TORONTO
JUNE
                                        1970

-------
                     OPERABLE       PREFERRED       REQUIRED
                       1970            1970            1971
DRY TONS/MO.        2000            2500            3000
#/HR./FT.2             3.0             3.7             4.4
               TABLE 5-2     SLUDGE REMOVAL NEEDS - METRO TORONTO

-------
                 POLYMER USED        SLUDGE                    CAKE
  1970              I#/TO.N|            SOLIDS               2      SOLIDS
 PERIOD       ELUT.         FILT.        |%]       #/HR./FT.
OCTOBER      1.26          7.77        3.6         4.7             16
NOVEMBER      1.75          8.20         4.1          4.3             16
           TABLE 5-3     ELUTRIATION/FILTRATION RESULTS OCTOBER-NOVEMBER - METRO TORONTO

-------
  ELUT. FLOW       POLYMER       ELUTRIATE
    IMGPDI	I#/TONI       s.s. IPPMI    SLUDGE           CAKE
 WASH   DIGEST                                 SOLIDS  %&/    SOLIDS
WATER  SLUDGE   ELUT.   FILT.     1ST     2ND     l%l       /TT.2   1%)
  1.0     0.6      1.94    10.96     120     18      6.1       4.7      16.0
  3.5      1.4     0.62    9.34    6250    208     3.5      5.8      15.4
              TABLE 5-4     ELUTRIATION/FILTRATION RESULTS 1971 - METRO TORONTO

-------
FIGURE 5-8
A  VIEW OF FILTERS  -  METRO  TORONTO

-------
PLANT
INFLUENT '
GRIT
REMOVAL

r
PRIMARY
CLARIFIERS


AERATION
BASINS


FINAL
CLARIFIERS
PLANT
EFFLUENT
                                            SIIIIIIIIIIIIIIIIIJIIIIIIIIIIIII Hill Illll Mil Hill""""!
                                                    IIUI
             Illllllllllllllll Illlllllllllllllllll
        (lllllllllllllllllllllllllllllllllllllllllll


                           L
                                                               D.A.F.
                                                             THICKENER
                         4,,;

      PRIMARY
      DIGESTION
       r
SECONDARY
 DIGESTION
              iimi
                                                          1
ELUTRIATION
VACUUM
 FILTERS
WASTE WATER
                FIGURE 5-9
            i mi






	SLUDGE                   —-— PROCESS LIQUIDS

  PLANT  FLOW DIAGRAM  - RICHMOND,  CALIFORNIA

-------
                                                   MIXED SLUDGES
                             PRIMARY           NO        POLYMER IN
                              SLUDGE       POLYMER     ELUTRIATION
YIELD (LB./HR./FT.2)             7-9             1-2           5-7
CONDITIONER COST |$/TON)   $3.80/$4.00      S25/S30       $11/$14
CAKE  SOLIDS (%)               29-31            16-18         20-22
                 TABLE 5-5    FILTRATION RESULTS - RICHMOND, CALIFORNIA

-------
ELUTRIATION
 DIGEST
 SLUDGE
%  SOLIDS

   3.85
ELUTRIATE
 SLUDGE
%  SOLIDS

   7.8
POLYMER
 #/TON

  2.12
ELUTRIATE
 SOLIDS
  PPM

   450
FILTRATION
                  FeCI3
                 S/TON
   3.00
                 LIME
                $/TON
   4.85
 FILTER
  CAKE
% SOLIDS

   20.8
           TABLE 5-6
      ELUTRIATION/FILTRATION OPERATIONS - RICHMOND, CALIFORNIA

-------
               SECTION 6A - OXYGEN ACTIVATED SLUDGE PROCESS
1.   Significant Process Development

         —   Engineering innovations
                  Production and cost of oxygen.
                  Application of oxygen within system.

         —   Two major suppliers

                  Union Carbide - Unox system.
                  Air Products and Chemicals - Oases system.

         —   Many pilot plants and several full scale plants

         —   Overriding Importance

                  Improvement in sludge handling and disposal processes and costs.

         —   Through  documentation, both suppliers and  TTP. Note reference list - only
              broad generalities here.

2.   Basic Process Nature
         (Figure 6A-1)

         —   Utilization of pure oxygen in place of air in activated sludge basins

         —   Higher oxygen transfer driving force (more totally aerobic conditions)

         —   Higher mixed liquor solids inventory

         —   Lower production of excess activated sludge

3.   Oxygen Activated Sludge Aeration Basins

         —   (Figure 6A-2) - Sparger  type oxygen injection system (low pressure). Note gas
              recirculation compressors 90 percent oxygen efficiency.

         —   (Figure 6A-3) - Surface  aerator type  oxygen  system - Power requirements for
              dissolution = 1/5 — 1/6 of that for air systems.
                                       6A- 1

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4.   Oxygen Availability

         -   Generation = 2 systems
                  Cryogenic
                  Pressure Swing Adsorption

         —   Liquid (for small plants)

5.   Oxygen Process Characteristics
         (Figure 6A-4)

         —   Concurrent gas flow

         —   High D.O. levels - all stages

         -   System pressure 2/4 inches

         —   Resistance to shock loads

6.   Reasons for Process Effectiveness
         (Figure 6A-5)

         -   Oxygen utilization efficiency - 90+%

         —   Power requirements - low

         —   Improved sludge characteristics

7.   Comparison of Design Conditions
         (Figure 6A-6)

         —   Most important for purposes of this seminar.

                 Recycle sludge  concentration - 2/4 percent vs. 0.5/1.5  percent Sludge
                  Volume Index.

8.   Summary Design Data — Oxygenation Tanks
         (Figure 6A-7)

         -   Comparison of design figures for Carbide and results of Metcalf and Eddy study
              and design - Middlesex City.
                  (References 5  and 7)

         -   Seem to be comparable - tank sizing a little low in Middlesex County.
                                        6A-2

-------
9.   Middlesex County Costs Forecast
         (Figure 6A-8)

         —   Large municipal/industrial plant.

         -   Most speculative portion = sludge processing and disposal costs. Wonder what
              detailed design shows.

         —   In any event, impressive.

10.  Detroit Costs Forecast
         (Figure 6A-9)

         —   Billion gallon/day plant with several modules.

         —   Side by  side oxygen and air aeration modules.

         —   Impressive forecast.

11.  Plants Constructed, Under Construction or Publicly Announced Design Phase
         (Figure 6A-10)

         —   An impressive total (35).

         -   Many more in consideration or bidding phase.

12.  Estimated New Plant Total Treatment Costs, Air Aeration and Oxygen Activated Sludge
         (Figure 6A-11)

         —   From Reference 17, an excellent summation by Stamberg of EPA.

         —   Once again, how much is due to solids handling savings?

13.  Typical Plant Installation
         (Figure 6A-12)

         —   Compact, relatively simple plant.

         —   Full scale operations with regular plant personnel have been demonstrated.
                                         6A -3

-------
                  LIST OF FIGURES AND TABLES - SECTION 6A






Figure 6A-1       Oxygen Process Flow Sheet




Figure 6A-2        Schematic Diagram of Oxygen System with Rotating Sparger




Figure 6A-3        Schematic Diagram of Oxygen System with Surface Aerator




Figure 6A-4        Oxygen Process Characteristics




Figure 6A-5        Reasons for "Cost Effectiveness" of the Oxygen System




Figure 6A-6        Comparison of Process Design and Performance Parameters




Figure 6A-7        Design Data — Oxygenation Tanks




Figure 6A-8        Middlesex County Costs




Figure 6A-9        Detroit Costs




Figure 6A-10       Oxygen Activated Sludge




Figure 6A-11       Estimated Costs Comparison — Air Aeration and Oxygen Aeration




Figure 6A-12       Typical Plant Photograph
                                       6A -4

-------
  OXYGEN   PROCESS   FLOW   SHEET
     RETURN
     SLUDGE
 PUMP
WASTE
SLUDGE
               RAW OR SETTLED WASTE WATER
                      MIXED LIQUOR
                          IN
                        COVERED
                       OXYGENATION
                         TANKS
                       WITH MIXERS,
                        OXYGEN
                       COMPRESSORS
                       AND SPARGERS
            OXYGEN GAS
                                  WASTE GAS
 FINAL
SETTLING
 TANKS
EFFLUENT
OXYGEN
SOURCE &

STORAGE
                FIGURE   6A-1

-------
            AERATION
            TANK COVER
                        GAS RECIRCULATION
                        COMPRESSORS
       CONTROL
        VALVE
OXYGEN
FEED GAS
   WASTE
   LIQUOR
   FEED
   RECYCLE_
   SLUDGE
                                                       EXHAUST
                                                       GAS
                                                        MIXED LIQUOR
                                                        EFFLUENT TO
                                                        CLARIFIER
              FIGURE 6A-2
SCHEMATIC DIAGRAM OF OXYGEN SYSTEM WITH
ROTATING SPARGER

-------
        AERATION
        TANK COVER
     CONTROL
     VALVE
OXYGEN
FEED GAS
  WASTE
  LIQUOR
  FEED
  RECYCLE
  SLUDGE"
AGITATOR.
                         Q
                                  Q
^
r^
                                              *~
                                                     5


-------
OXYGEN  PROCESS  CHARACTERISTICS
 COCURRENT GAS-LIQUID FLOW
 HIGH  D.O. LEVELS IN ALL STAGES
 LOW SYSTEM PRESSURE (2-4 INCH W.G.)
 LOW WASTE GAS VOLUME
 HIGHLY AEROBIC WASTE GAS
 OXYGEN DISSOLUTION DRIVING FORCE AND
 STAGE UPTAKE DEMAND ARE MATCHED
 HIGH  MLVSS- SHORT DETENTION
 AUTOMATIC  OXYGEN FEED CONTROL
 RESISTANCE TO SHOCK LOADS
           FIGURE  6A-4

-------
REASONS  FOR  "COST  EFFECTIVENESS"  OF
           THE  OXYGEN  SYSTEM
 HIGH PURITY OXYGEN IS GENERATED ON-SITE ECONOMICALLY
 IN ALL  PLANT SIZES
 OXYGEN UTILIZATION GREATER THAN 90 %  IS TYPICAL
 POWER REQUIREMENTS FOR OXYGEN DISSOLUTION ARE
 EXTREMELY LOW
 MIXING POWER INPUT CAN BE OPTIMIZED
 REDUCED WASTE ACTIVATED SLUDGE PRODUCTION IS
 EXPERIENCED
 DEWATERING AND HANDLING CHARACTERISTICS OF WASTE
 SLUDGE ARE UNIQUE
 HIGH RATE TREATMENT IS EASILY ACHIEVED

                 FIGURE  6A-5

-------
          COMPARISON OF PROCESS DESIGN
          AND PERFORMANCE PARAMETERS

                              "UNOX" CONVENTIONAL
                              SYSTEM AIR SYSTEMS

I. D.O. LEVEL (mg/l)               6-10       1-2

2. DETENTION TIME (hrs)             1-2       3-6

3. MLSS CONC. (mg/l)          6,000-10,000 1,500-4000

4. VOLUMETRIC ORGANIC LOADING   150-250    30-60
      (lbsBOD/DAY/l,OOOft3)

5 F/m RATIO                    0.4-0.8   0.3-0.6
    (IbsBOD/DAY/lbMLVSS)

6. RECYCLE SLUDGE RATIO        0.2-0.5    0.3-1.0

7 RECYCLE SLUDGE CONC.(m8/l) 20,000-40,000 5,000-15,000

8. SLUDGE PRODUCTION           0.3-0.45   0.5-0.75
     (Ibs VSS/lb BOD REMOVED)

9. SVI                          30-50    100-150
                    FIGURE  6A-6

-------
 DESIGN DATA-OXYGENATION TANKS
                       MIDDLESEX CTY.     SUMMARY
MIXED LIQUOR D.O.             3-9 MG/L        8-10 MG/L

MIXED LIQUOR SUSP. SOLIDS       5500 MG/L      6-10,000 MG/L

MIXED LIQUOR V.S.S.            5000 MG/L       4-6500 MG/L

FOOD BIOMASS RATIO            0.51           0.4-0.8

TANK SIZING-|# BOD/K Cu. Ft.)      160            215 +


               FIGURE  6A-7
     MIDDLESEX COUNTY COSTS

                       OXYGEN         AIR
                       PROCESS      AERATION
CAPITAL             83,580,000   104,020,000
OPERATING/YEAR      7,390,000     8,290,000
               FIGURE  6A-8

-------
     DETROIT  COSTS
                OXYGEN PROCESS    AIR AERATION
CAPITAL          39,500,000   51,700,000




OPERATING  YEAR    1,599,000     1,911,000
            FIGURE  6A-9
    OXYGEN  ACTIVATED SLUDGE




    STATES      NO. OF PLANTS   FLOW TOTAL - MGD
FLORIDA
PENNSYLVANIA
N. YORK/N. JERSEY
MICHIGAN/OHIO
OTHERS
TOTAL
4
3
3
3
22
35
171
370
144
422
779
1886
            FIGURE 6A-10

-------
    ESTIMATED  COSTS  COMPARISON-
AIR  AERATION  AND  OXYGEN  AERATION
                    TYPICAL RANGES
                  TOTAL TREATMENT COSTS
              NEW PLANTS WITH PRIMARY SEDIMENTATION
                  40    60
                  PLANT SIZE-M6D
           FIGURE   6A-11

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FIGURE 6A-12      TYPICAL PLANT PHOTOGRAPH

-------
                   SECTION 6B - OXYGEN ACTIVATED SLUDGE


CASE STUDY - FAIRFAX - WESTGATE

1.   Detailed Study - (Reference 13)

         -   Robson, Block, Nickerson, Klinger

         —   A landmark paper

         —   Conversion of an overloaded intermediate treatment level plant into a 90
             percent BOD removal plant

         —   Dispatch and efficiency (180 day conversion)

2.   Most Important Facet

         -   Sludge handling data generated

3.   Original Plant

         -   (Figure 6B-1) = Process Flow

                  Comminution - Sedimentation/Aeration/Clarification

                      Chlorination (digesters not used)
                      Vacuum filtration (landfill)

         —   (Figure 6B-2) = Longitudinal Section - Sedimentation Tank

                  Original use building moratorium problems

         —   Westgate Plant Functions - (Figure 6B-3)

                  Original plant design
                  Overload by 1970
                  Interim chemical treatment 1971
                  Oxygen activated sludge October 1971
                                       6B- 1

-------
4.   Current Westgate Process Flow
         (Figure 6B-4)

         -   Converted 3 phase tank to do two jobs
                   (Oxygen activated sludge use)

         -   Installed 2 -120' diameter x 1P S.W. depth clarifiers

         -   Installed 2 - 250 ft2 D.A.F. units

         -   Installed 2 - 5 hp mixers on sludge decant tanks

         -   LOX because of temporary nature

5.   Results Liquid Treatment
         (Figure 6B-5)

          —   Liquid treatment has been highly successful.

                   Exceeded removal goals
                   93 percent instead of 80 which was goal
                   Equivalent to conventional aeration with 3 times tank volume
                   T.S.S. removal efficiencies of 90 percent
                   Stable operation with routinely qualified personnel
                   Oxygen cost = lower than predicted

6.   Solids Settling Results

          -   Excellent Settling Characteristics

                   Note good SVI
                   Reasonable zone settling velocity

          —   Significantly less excess activated sludge produced - due to
               endogenous respiration.

 7.   Thickening and Dewatering Results
          (Figure 6B-6)

          -   D.A.F. units worked but  ingenuity and benefits of oxygen activated sludge
               prevailed.

           -   Mixture of O.A.S. and  primary sludge  proved  very amenable to  gravity
               thickening.
                                          6B -2

-------
Small dose of  flocculant  = clear supernatant and  rapid thickening to 6—8
percent solids.

Key point = mixers provided on sludge decant or blend tanks
     So many plants not provided.

Efficient thickening  and good drainability characteristics of Primary/O.A.S.
blend = efficient, economical dewatering
(Figure 6B-7 - Sludge Filters).

Production rate = 5 lb/hr/ft2
     (Good for 90+% removal plant.

Cake solids = 22-28 percent also good.

Filtrate = 0.05 percent T.S. (very low recycle rate).

Sludge conditioning =  can and have used  both polymers and FeCl3/lime
combinations.

     Routinely use FeCl3 lime because of odor control problem in haulage.

     Normal  optimized  conditioning cost based  on proper conditioning for
     vacuum  filtration = 5 to 6 dollars/ton.

     For purposes of odor control  and adding excess lime for landfill and
     haulage purposes, use about S8.00/ton of ferric and lime.

     If plant were not going - phase out other odor control and lower costs.

     (Figure 6B-8) — Photograph of plant.

     Note proximity to residential areas.
                            6B -3

-------
                  LIST OF FIGURES AND TABLES - SECTION 6B







Figure 6B-1        Westgate - Original Process Flow




Figure 6B-2        Westgate Sedimentation Tank Longitudinal Section




Figure 6B-3        Westgate Plant Functions




Figure 6B-4        Current Westgate Process Flow




Figure 6B-5        Results - Westgate Oxygen Process




Figure 6B-6        Thickening and Vacuum Filtration - Westgate Oxygen Process Sludge




Figure 6B-7        Photograph of Sludge Off Filters




Figure 6B-8        Photograph of Plant
                                        6B-4

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                  WESTGATE- ORIGINAL PROCESS FLOW
 PLANT
INFLUENT
COMMINUTION
PRIMARY SEDIMENTATION
      AERATION
                              CLARIFICATION
CHLORINATION
           LAND FILL
                                      DIGESTION
                                                      PLANT
                                                             EFFLUENT
                         FIGURE   6B-1
                   WESTGATE SEDIMENTATION TANK
                        LONGITUDINAL SECTION
        •COMMINUTION

            PRIMARY
          CLARIFICATION    AERATION
                                 SECONDARY
                                CLARIFICATION
   SUMP
                                               SCRAPERS
                              •AIR DIFFUSERS
                         FIGURE   6B-2

-------
        WESTGATE PLANT FUNCTIONS
       PERIOD
             DESIGN     % REMOVAL

            FLOW IMGDI    BOD 5     PLANT PROCESS
1954
1970
1971
1971-72
8
12
12
12
50 +
35-40
75 +
80-90
ORIGINAL
ORIGINAL
CHEMICAL Ppt.
OXYGEN
                                         ACTIVATED SLUDGE
                      FIGURE  6B-3
                CURRENT WESTGATE PROCESS FLOW
 PLANT

INFLUENT
COMMINUTION
                  PRIMARY SEDIMENTATION
 DUAL OXYGEN

ACTIVATED SLUDGE
    BASINS
SECONDARY
CLARIFIERS
   12)
CHLORINATION
PLANT
	>
EFFLUENT
                            1
FILTER
CAKE
VACUUM
FILTERS


SLUDGE
DECANT
                                        D.A.F.

                                       UNITS
                      FIGURE  6B-4

-------
                 RESULTS

      WESTGATE  OXYGEN  PROCESS

                           W.A.S.         ZONE
     % REMOVAL               Ib V.S.S.       SETT. VEL.
   BODS    T.S.S.      S.V.I.    Ib BOD REMOVED   |Ft./HR|
    93 +  90 +   35-56     0.33       6.0
                 FIGURE  6B-5
   THICKENING AND VACUUM FILTRATION

   WESTGATE OXYGEN PROCESS SLUDGE

  	THICKENING               VACUUM FILTRATION
        POLYMER     % SOLIDS              % CAKE
  METHOD  Ib./TON    THICK. SLUDGE   Ib/HR/Ft2    SOLIDS
GRAVITY   3         6-8      4.0-5.0   22-28
                FIGURE  6B-6

-------
FIGURE 6B-7
PHOTOGRAPH OF SLUDGE OFF FILTERS

-------
FIGURE 6B-8
PHOTOGRAPH OF PLANT

-------
                   SECTION 6C - OXYGEN ACTIVATED SLUDGE


CASE STUDY - NEW ORLEANS, LOUISIANA

1.   Reference 8
                                                          r
         —   Grader and Dedke of Union Carbide
             Powell and Wiebelt of New Orleans
                  Sewerage and Water Board

         —   "Pilot plant results using pure oxygen for treating New Orleans Wastewater'
             A.E.CH.E. Meeting.

         -   Consultant - Waldemar S. Nelson and Co., Inc.

         —   Design Criteria - 141 mgd East Bank Plant

2.   Characteristics of New Orleans Sewage
         (Figure 6C-1)

         -   Primarily domestic
                  Brewery, food processing (chicken/shrimp)

         -   BOD = 200 mg/1
                  COD/BOD = 1.5 (high fraction organic biodegradables)

         —   Flow Variation -» Sunday -160 mg/1 BOD
                             Wednesday - 266 mg/1 BOD

3.   Proposed Plant Process Flow
         (Figure 6C-2)

         —   Screening - grit removal - oxygenation  tanks - clarifiers - chlorination

         —   Solids handling - to be determined

4.   Unox Pilot Plant Used

         —    Biological Reactor

                  Liquid Depth = 5' x 2"
                  Stage Volume = 400 gallons
                  Total Liquid Volume = 1,600 gallons
                                       6C- 1

-------
         -   Clarificr
                  Two different ones used
                  Details later

5.   Process Results
         (Figure 6C-3)

         -   Phased Study

                  Steady state design flows
                  Diurnal flow feed pattern
                  Steady state with centrate recycle (all gave 93-95 percent BOD removal
                       and 88-90 percent S.S. removal)

6.   Excess Sludge Production

         (Figure 6C-4) (Biomass Loading vs. Excess Sludge Production)

         —   Staged process = high degree of endogenous respiration

         —   High D.O. levels = lower excess sludge production

         -   Slide shows higher loading = more net excess activated sludge

         —   Claimed * 30—50 percent less excess sludge than air system

7.   Settling and Compacting of Excess Sludge in Clarifier

         —   2.5 to 3.2 percent solids in clarifier
              Underflow (at least double what could be expected in air systems)

         -   Mass loadings = 50 lb/SS/ft2 /day at 699-900 gpd/ft2

8.   Centrifugation Tests
         (Figure 6C-5)

         -   Evaluation carried out —  solid  bowl scroll type centrifuge

         -   Purpose

                   Dewatering performance of oxygen E.A.S.
                                         6C- 2

-------
         —   Provision

                   Recycle solids laden centrate

         —   Evaluate

                   Effect on oxygenation system and centrifuge performance

         —   Results
              (Figure 6C-6)

                   As expected - without polymers - centrifuge fractionates sludge.

                   Heavy solids captured
                   Light solids in centrate

         -   Postulation made

                   Operation  of  centrifuges   on  excess  oxygen  A.S.  without sludge
                   conditioning (solids capture of 35-60 percent) is feasible in that polluted
                   recycle stream can be handled in oxygen system (Figure 6C-7).

         —   Observations

                   No data presented  on  feed  rates. Centrate solids  data skimpy. An
                   incomplete picture.

9.   Intrenchment Creek Work
         (Figure 6C-8)

         —   Two stage trickling filter plant

                   90 percent removal - 20 mgd design
                   90 percent removal -  14 mgd design

         —   Interesting Centrifugation  Works
                   (Figure 6C-9)

                   Relatively economical and efficient dewatering
                   Question = production rate data
                   Optimized centrate recycle load
                   (Plant at 14 = 70 percent design  capacity
                            ?0
                                         6C-3

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                  LIST OF FIGURES AND TABLES - SECTION 6C


Figure 6C-1        New Orleans, Louisiana Feed Wastewater Characteristics

Figure 6C-2        New Orleans, Louisiana Process Flow

Figure 6C-3        Oxygen System - New Orleans, Louisiana

Figure 6C-4        "Unox" System New Orleans, Louisiana, Effect of Biomass Loading on
                  Solids Wasting Rate

Figure 6C-5        "Unox" System New Orleans, Louisiana, Flow Diagram with Centrate Recycle

Figure 6C-6        "Unox" System New Orleans, Louisiana, Centrifuge Performance

Figure 6C-7        Centrifugation - New Orleans, Louisiana Oxygen Activated Sludge

Figure 6C-8        Intrenchment Creek Flow

Figure 6C-9        Centrifugation - Atlanta
                  Mixed Sludge - Primary and T.F.
                                      6C-4

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                   NEW ORLEANS, LA.
            FEED WASTE WATER CHARACTERISTICS
       PARAMETER


     CHEMICAL OXYGEN DEMAND, mg/l
             TOTAL
             SOLUBLE

     BIOCHEMICAL OXYGEN DEMAND.mg/l
             TOTAL
             SOLUBLE

     SUSPENDED SOLIDS,mg/l
             TOTAL
             VOLATILE

     PH
     TEMPERATURE, °F
DEGRITTED RAW WASTE
     AVERAGE
                   FIGURE   6C-1
      316
      183
      210
       98


      183
      133

   7.4(6.6-8.8]
   71(65-831
NEW  ORLEANS  PROCESS  FLOW


SCREENING


GRIT
REMOVAL
k.

OXYGENATION
TANKS
PLANT
EFFLUENT
CHLORINATE
^

CLARIFIERS
                  FIGURE  6C-2

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      OXYGEN SYSTEM-NEW ORLEANS
  RETENTION [HRS.j

  MLSS (mg/l)

  Ib. BOD/KFt3-DAY

  OVERFLOW(GAL/Ft2/DAY|

  SLUDGE VOL. INDEX
STEADY
STATE
DESIGN
1.8
5560
181
655
79
DIURNAL
FLOW
PATTERN
1.4
5770
246
855
64
                                       CENTRATE
                                       RECYCLE

                                         1.8

                                         7350

                                          193

                                          655

                                           48
                      FIGURE   6C-3
EXCESS SLUDGE
 PRODUCTION
  LB. TSS
  LB. BODA
0.8


0.7


0.6


0.5


0.4
            0.3
             0.5
                          "UNOX" SYSTEM
                         NEW ORLEANS, LA.
                   EFFECT OF  BIOMASS LOADING ON
                        SOLIDS WASTING RATE
PHASE II
                        PHASE III

                    PHASE V ICENTRATEj
          0.6      0.7

             BIOMASS LOADING
                                               PHASE IV
 0.8       0.9
  LB. BODA
 LB. MLVSS-DAY
1.0
                      FIGURE   6C-4

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                          "UNOX"  SYSTEM
                          NEW ORLEANS, LA.
                FLOW DIAGRAM WITH CENTRATE RECYCLE
RAW
DEGRITTED
WASTEWATER
•    *
 UNOX
REACTOR
                     RECYCLE SLUDGE
                        CENTRATE
SECONDARY
 CLARIFIER
                                                        CLARIFIER
                                                        EFFLUENT
                                               CENTRIFUGE
                                       SOLID CAKE
                                      FOR DISPOSAL
 % DRY SLUDGE
 SOLIDS IN CAKE
               20
                15
                10
                         FIGURE   6C-5
    AVG.
  3 RUNS V
         ^•>
                                  "UNOX"  SYSTEM
                                 NEW ORLEANS, LA.
                             CENTRIFUGE PERFORMANCE
                                AVG. 6 RUNS
                                             AVG. 4 RUNS
                          SOLID BOWL SCROLL TYPE
                              CENTRIFUGE
                         NO CHEMICAL CONDITIONING
                                          AVG. 5 RUNS
5
2

0 30 40 50 60 70 80 90
% RECOVERY »..."
                                                                AND SHARPLES
                         FIGURE    6C-6

-------
   CENTRIFUGATION-NEW ORLEANS
     OXYGEN ACTIWTED  SLUDGE
   FEED COND.
 % SOLIDS    GPM
% SOLIDS
CAPTURE
% CAKE
 SOLIDS
CENTRATE
SOLIDS [%|
                   60
                   35
            15
            20
                                   -  2.1
                 FIGURE  6C-7
         INTRENCHMENT  CREEK  FLOW
PLANT
           CENTRATE
                 TWO STAGE
               TRICKLING FILTERS
                                    FINAL
                                   CLARIFIERS
                          PLANT
                         EFFLUENT
      CAKE TO
      TRUCK
FIGURE  6C-8

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   CENTRIFUGATION-ATLANTA

 MIXED SLUDGE -PRIMARY a T. E

  FEED COND.     % SOLIDS    % CAKE    POLYMER
% SOLIDS   GPM    CAPTURE    SOLIDS     $/TON
             FIGURE  6C-9
  4-6    -      90      21      5.74
 4-6    -      80      24      4.05

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                     REFERENCES - SECTIONS 6A, 6B, AND 6C
1.   Union Carbide Corporation Unox System  - Status of Unox Sludge Pretreatment and
         Dewatering.

2.   Robson, C.M., Nickerson, G.L., Clinger,  R.C., and  Burke,  Donald, "Pure Oxygen
         Activated Sludge Operation in Fairfax County, Virginia," WPCF Meeting, Roanoke,
         Virginia, 1972.

3.   EPA  Technology Transfer Program,  New  York City, February, 29, 1972; "Operating
         Experience and Design Criteria for Unox Wastewater Treatment Systems," by Union
         Carbide Corporation, Linde Division, Tonawanda, New York.

4.   EPA  17050  DNW 02/72, "Activated Sludge  Processing,"  February,  1972, by  Union
         Carbide Corporation, Linde Division, Tonawanda, New York.

5.   McWhirter,  J.R.,  Union Carbide,  "Oxygenation Challenges  Air Aeration." Water and
         Wastes Engineering, 53 (September, 1971).

6.   McWhirter, J.R., Union Carbide, "New Era for an Old Idea." C. & E. News,3l (April 26,
         1971).

7.   EPA  Technology Transfer Program,  Pittsburgh, Pennsylvania, August 29,  1972, Unox
         Design Information for Contract Documents, by Metcalf and Eddy, Inc., Engineers.

8.   Grader, R.J., Dedeke, W.C.,  Union Carbide, and Powell, C.J.,  Wiebelt, A.H., of New
         Orleans, Louisiana,  "Pilot Plant Results  Using  Pure  Oxygen for Treating New
         Orleans Wastewater," 71st National Meeting of A.I.Ch.E., Dallas, Texas, February
         21, 1972.

9.   Stamberg, John B., Bishop, D.F.,Hais, A.B., and Bennett, S.M., "System Alternatives in
         Oxygen Activated  Sludge," EPA, paper  presented at WPCF Atlanta  Meeting,
         October, 1972.

10.  Speece, R.E., and Humenick, M.J., University of Texas,  "Solids Thickening Limitation
         and Remedy in Commercial Oxygen Activated Sludge," presented at WPCF Atlanta
         Meeting, October 9, 1972.

11.  Dick,  R.I.,  and  Young, K.W., "Analysis of Thickening  Performance  of Final Settling
         Tanks," Purdue Industrial Waste Conference, May 2-4, 1972.

-------
                            REFERENCES (Continued)
12.  Eckenfclder, W.W., Jr., "Boost Plant Efficiency." W. & W. Engineering, E-l (September,
         1972).

13.  Robson, C.M., Block, C.S., Nickerson, G.L., and Klinger, R.C., "Operational Experience
         of a  Commercial Oxygen Activated  Sludge Plant," presented at WPCF  Atlanta
         Meeting, October,  1972.

14.  Wastewater Treatment,  Unox System, Union Carbide, 82-0258.

15.  Newtown  Creek project, personal communication, William Pressman, Project Engineer,
         New  York City Department of Water Resources.

16.  Vandiver,  E.G., and Noble, James A.,  "Centrifuge Improves  Intrenchment Creek Water
         Pollution Control Plant." Water and Sewage Works, (September, 1972).

17.  EPA Research and Development Activities with Oxygen Aeration, Technology Transfer
         Design Seminar, Pittsburgh, Pennsylvania, August,  29, 1972.

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                  SECTION 7 - THERMAL PROCESSING OF SLUDGE
 1.   High Temperature and High Pressure Sludge Treatment

          -   Two  basic  types  -  European  origin  (wet  air  oxidation and  thermal
              conditioning).

          -   Old processes - few installations - 1930's (not widely adopted in Europe).

          -   Thermal  conditioning - August  -  1970, "Wastewater Treatment in  Great
              Britain" - "A few  years ago much interest and promise were shown with heat
              treatment and sludge pressing, but lately there is less enthusiasm for this type
              of plant."

          -   Wet air oxidation  - relatively few U.S. plants in operation; some have closed
              down. Still, a few more are being built.
WET AIR OXIDATION

2.  Process Description
         (Figure 7-1)

         -    Flameless combustion, burning of sludge at 450°- 550° F. and high pressures
              (1,200 psig) with air injection.

         -    Equipment  -  sludge grinder,  heating tank,  heat exchangers, high  pressure
              reactors, separators, expansion engine and auxiliaries.

         -    End products - ash and sludge liquor.

         —    Insoluble organics converted to soluble organics CO2, H2 O, ammonia, sulfatcs,
              acetates.

         -    At  250° C. and 83.4 percent COD reduction of sludge the oxidized liquor
              shows a COD of 10,000 mg/1 + BOD is only 54 percent of COD.

         -    The pH of the oxidized liquor is 4.8.

         -    Summation, W.A.O.  docs reduce sludge volumes and  produce a stable solid
              residue, but the nature of the oxidized  acidic liquor and  the costs of the
              process arc of some concern.
                                      7-1

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3.    Installations and Operating Experiences

         -   Chicago - South West, Wheeling - West Virginia, Rye -  New York, South
              Milwaukee - Wisconsin, Wausau - Wisconsin (have been in operation  for  a
              number of years).

         -   Few additional installations underway.

4.    Wheeling, West Virginia Installation
         (Figure 7-2)

         -   Plant = thickened raw primary sludge 25 mgd design/8 mgd flow 5.6 tons/day
              dry solids.

         -   W.A.O. process - 500° and 1,200 psig.

         -   Maintenance = alternate caustic and muriatic acid washing of exchangers.

         -   Capital cost = $284,000 in 1963-65.

         —   Design and Operating Conditions (Table 7-1)
              90 percent removal of insoluble organic matter.

         —   But?? Quantity and quality of oxidized liquor?

         -   Sludge Disposal Costs (Table 7-2).

                   $20/ton for raw primary sludge operating and maintenance
                   (No amortization)
                   (Not  particularly  low  contrasted  to  plants  employing  conventional
                   methods)

 5.   Chicago, South West, Wet Air Oxidation

          -   Commenced operation 1962 (500° F. -1,500 psi)
              $17,900,000 for 300 tons/day design capacity.

          -   Modifications = $4,000,000
              Total = $20/annual ton (design)
              Capacity achieved =125-188 tons/day
              Actual = $32/annual ton performance - maximum

          -    Safety improvmcnts - $ 1,000,000.

           -   Two serious accidents - 4 fatalities.
                                        7-2

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         —   Over years much intensive R&D to improve performance.

         -   W.A.O. costs = S50/ton (including high rate digestion).

         —   Ceased operation about September 1, 1972.

6.   Summation

         —   Very few new installations.

         —   Cost Analysis (Kansas City - Reference 21) (Primary Sludge).

                                                                 Annual
                                                Plant Cost     Operation Cost
              Dewatering and Incineration           1.0             1.0
              Wet Air Oxidation                    1.97            1.54
THERMAL SLUDGE CONDITIONING

7.   Two Similar Processes

         —   Porteous (Figure 7-3) steam injection, batch process.

         —   Sludge storage - grinding - pre/heater - liigh pressure and temperature (365° F.
              and 250 psi) - decanter/thickener - dewatering - auxiliary liquor treatment - off
              gas deodorizer - steam boiler.

         -   Zimpro LPO (Figure 7-4) same as Porteous except adds air via compressors.

         -   Fairer (Figure 7-5) same as Zimpro but claims continuous operation mode.

8.   Installations

         -   Porteous - U.S. 1 operating and 2/3 planned (10 in U.K.).

         —   Ziinpro - 14 built and 12 under construction.

         —   Farrer - No U.S. installations, to my knowledge.
                                       7-3

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9.   Porteous Type Process

     Coors/Golden  (5.0 mgd plant)

         —   Activated sludge plant - 5.0 mgd.

         —   Domestic and brewery wastes.

         -   1970 - Porteous type plant installed.

         —   Vacuum filters - still required 3.8 percent ferric chloride (Table 7-3).

         —   Cooking liquor - sometimes as high as 20,000 ppm solids content.

         —   Discontinued after about one year's operation.

10.  Colorado Springs

         —   Only domestic Porteous installation.

         —   Currently 66 percent BOD removal trickling filter plant - 25 mgd.

         -   Porteous unit - built 1968/69 - 2,000 Ib/hr 370° F. and 250 psi.

         —   Results reported (to some extent).

         —   Reference 4 - Good vacuum filtration results (12 lb/hr/ft2 - 37 percent).
              (Cake Solids)

         —   No chemical conditioning required (used to be SI8—20/ton).

         —   Stated filtrate and decant streams easily handled with no additional aeration
              requirement.

         —   Does not provide even cursory material balance data on process.

         —   Periodic visits to plant reveal many problems encountered with the recycle load
              from heat treatment and with odor.

         -   Recycle load is much greater than expected even though this is a primary and
              trickling filter sludge (not activated sludge).

         —   Lengthy plant process work trying to reduce recycle load.  Including massive
              lime chemical precipitation of liquors.
                                        7-4

-------
         -    Stated cost of operation for J'ortcous process and dcwatering = $2/ton.

         -    Reference  9 -  State's chemical conditioning costs used to run $20-S40/ton.
              States operating costs for Portcous run $15/lon (fuel, power, labor and water).

         -    Current  plans - convert  to activated sludge. Porteous = 400°  F. and 300 psi
              (this will surely increase recycle load).

11.  United Kingdom Experiences

         -    Very little published definitive data.

         -    Most informative = Reference 13, 14 and 16.
              (Brooks - Fisher/Swanwick)

         -    Lab and subsequent plant scale analyses/cooking liquors (Table 7-4).

         —    Brooks - Based on solids percent solids in sludge - this data assumes 4 percent
              sludge (typical).

         —    Fisher/Swanwick    -  Both  W.A.O.   and  thermal  conditioning  at various
              temperatures and pressures (Figure 7-6).

                   Up to  66  percent suspended solids dissolved  and recycled - thermal
                   conditioning.

                   Up to 79  percent during W.A.O.

                   Effect most marked for activated sludge.

                   About  33 percent of cooking liquor not amenable to biological treatment.

 12.  Borough of Pudsey - United Kingdom - Farrer
         (Reference 23)

         -   The only  paper seen which attempts  to present thorough  definitive data on
              plant performance.

         -   Farrer process -  1969/70 - sludges about 82 percent content trickling filter and
              18 percent activated sludge.

         -   One and one half years operation.

         -   Many qualifying statements reflect severe operation and maintenance problems
              encountered.
                                        7-5

-------
              "Teething  troubles  were  perhaps to  be expected - unfortunately  these
              expectations have been realized and substantial periods of nonopcration of the
              plant have been due to the necessity of carrying out modifications."

              "The operator requires to be of a higher skill than the grade of labor normally
              associated with natural sludge dewatcring."

              Cost Data - "Here again the authors found themselves in some difficulty since
              the operation  so far makes running costs appear disproportionate due to the
              modifications, maintenance and  supervision required during the first year.
              Sufficient experience has, however, been gained to make it possible to estimate
              costs, these excluding cake disposal and liquor treatment" (Figure 7-7).

              Total heat treating  and dewatering costs are estimated  to be $51.40/ton dry
              solids, assuming problems mentioned are easily overcome.

              Cost of treating recycle  liquors from heat  treatment (50  percent BOD
              reduction via plastic trickling filter) are estimated to be $5/ton.

              Thus exclusive of press cake disposal, total costs, on an  optimistic basis are
              $56.40/ton of dry solids.
13. Kalamazoo
         —   Reference papers 17 and 24 describe installation and operation of Zimpro LPO
              unit at Kalamazoo.

         —   Activated sludge, 1965, 34 mgd.
              Influent = domestic + paper mills + pharmaceutical wastes.

         -   Sludge volatile/inert =1:1 originally (supposed to settle in lagoons).

         —   Sludge 1.5:1 volatile/inert because  of change in influent characteristics (77
              percent waste activated/23 percent raw primary now).

         —   Quote - "Our sludge is unusual, what with large proportion of paper mill wastes
              and pharmaceutical wastes loads,  and requires very  high chemical  dosages in
              order to dewatcr either by vacuum filtering or centrifuging."

         -   Installation Costs (Figure 7-8)

                   Zimpro - $1,908,557 (97.5 tons/day)

                   Incinerator - $658,511
                                        7-6

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         Electrical-SI 54,950

         General Contract - $1,212,534

—    Treating lagooncd sludge initially

-    Operating temperatures = 358° F.
     (Figure 7-9) Pressure = 400 psi

-    Performance (Figure 7-10) thickening and dewatering

         Good gravity thickening - no data on decantate
         Cake solids good, but only 4.9 lb/hr/ft2 rate

-    Cost Data -  Not clear =  $20/ton processing  costs, but does not  include
     operating and maintenance labor, must be amortization (SlO/ton) plus fuel,
     power, etc.

—    No significant data on:

         Recycle liquor loads
         Effect of same on plant
         Total cost of systems
                              7-7

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                             REFERENCES - SECTION 7
1.   Lumb,  C., "Heat  Treatment as an Aid to Sludge Dewatering - Ten Years Full-scale
         Operation." Water and Sanitary Engineer, (March, 1951).

2.   Mulhall, K.G., and  Nicks,  B.D., "The Heat Treatment of Sewage Sludge,"  a  paper
         presented for discussion  by the East  Anglian  Branch of the Institute of  Water
         Pollution Control.

3.   Personal  communication  with  R.J. Sherwood,  Director of  Marketing,  Municipal
         Equipment Division, Envirotech Corporation.

4.   Sherwood, R., and Phillips, James,  "Heat  Treatment Process Improves Economics of
         Sludge Handling  and Disposal."  Water and  Wastes  Engineering,  42 (November,
         1970).

5.   McKinley, J.B., "Wet Air Oxidation Process, Wheeling, West Virginia." Water Works and
         Wastes Engineering, (September,  1965).

6.   Bjorkman, A., "Heat Processing of Sewage  Sludge," 4th International Congress  of the
         I.R.G.R., Basle,  June 2-5,  1969.

7.   Koenig, L., for U.S.P.H., AWTR - 3,  "Ultimate Disposal of Advanced Treatment Waste,"
         (October, 1963).

8.   Martin, Louis V.,  "Wet Air Oxidation  for Sludge  Treatment." WPCF Deeds and Data,
         (March, 1972).

9.   Kochera,  B., "Operation of a  Thermal Treatment System  for Sludge," WPCF Meeting,
         Atlanta, Georgia, 1972.

10.  Harrison,  J. and Bungay, H.R., "Heat Syneresis of Sewage  Sludges." Water and Sewage
         Works,"  (May,  1968).

11.  Sebastian,  P.P., and Cardinal,  P.J., "Solid Waste  Disposal." Chemical  Engineering,
         (October, 1968).

12.  Bennett, E.R., and Rein, D.A., "Vacuum Filtration - Media and Conditioning Effects."

13.  Brooks, R.B., "Heat  Treatment of Sewage Sludge." Water Pollution  Control, 92 (1970).
                                       7-8

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                            REFERENCES  (Continued)
 14.  Everett, J.G., and Brooks, R.B., "Dewatering of Sewage Sludges by Heat Treatment."
          Water Pollution Control, 458 (1970).

 15.  Bouthilet, R.J., and  Dean,  R.B., "Hydrolysis of Activated Sludge,"  5th International
          W.P.R. Conference, July - August, 1970.

 16.  Fisher, W.J., and  Swanwick, J.D., "High Temperature Treatment of Sewage Sludges."
          Water Pollution Control,  London,  70,  355-373 (1971).

 17.  Swels, D.H., Pratt, L, and Mctcalf, C., "Combined Industrial - Municipal Thermal Sludge
          Conditioning and Multiple Hearth Incineration," WPCF Annual Meeting, Atlanta,
          Georgia, 1972.

 18.  Bacon, V.W., and  Dalton, F.E., "Professionalism and Water Pollution Control in Greater
          Chicago." Journal WPCF, 40, No. 9, 1586.

 19.  "Stickney Sludge Site Closed Temporarily," Chicago Tribune, October 1, 1972.

20.  Hurwitz,  E., Teletzke, G.H., and Gitchel, W.B., "Wet  Air Oxidation of Sewage Sludge."
          Water and Sewage Works, 298 (1965).

21.  Weller, L., and Condon,  W.,  "Problems in Designing Systems  for Sludge  Incineration,"
          16th University of Kansas Sanitary Engineering Conference, 1966.

22.  Grant,  R.J., "Wastewater Treatment in Great Britain." Water  and Sewage Works,"
          266-270  (August,  1970).

23.  Hirst, G., Mulhall, K.G.,  and Hemming, M.L., "The Sludge  Heat Treatment Plant at
          Pudsey," Northeastern Branch  of  the Institute of Water  Pollution Control, March
          25, 1971.

24.  Swets, D.H., "Trials, Tribulations, and Now Triumph." Public Works, (August, 1971).
                                       7-9

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                  LIST OF FIGURES AND TABLES - SECTION 7


Figure 7-1         Wheeling, West Virginia Flow Diagram

Figure 7-2         Wet Air Oxidation System - Wheeling, West Virginia

Table 7-1          Design and Operating Conditions - Wheeling, West Virginia

Table 7-2          Sludge Disposal - Operating Costs Wheeling, West Virginia

Figure 7-3         Flow Diagram of the Porteous Process

Figure 7-4         Thermal Sludge Conditioning and Dewatering

Figure 7-5         Flow Sheet for the Dorr-Oliver Fairer System

Table 7-3         Total Solids PPM - Heat Treatment Liquors

Table 7-4         Percent Solids Solubilized - Heat Treatment and Wet Air Oxidation at
                  Various Temperatures

Figure 7-6         Cost Data - Pudsey Plant

Figure 7-7         Sludge Disposal  Facilities

Figure 7-8         Operating Temperature Balance

Figure 7-9          Kalamazoo - Thickening and Dewatering

Figure 7-10        Cooking Liquor Treatment
                                        7-10

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  RAW SEWAGE
          GRIT TANKS
         y
          GRIT
       PRIMARY
      XSETTLING
                              CHLORINE
                              CONTACT
                 DILUTE RAW
                 SLUDGE AND SCUM
             SLUDGE
             THICKNER
                 THICKNED RAW
                i SLUDGE
                 AND SCUM
             SLUDGE
             STORAGE
                       OHIO
                       RIVER
                             OXIDIZED
                              SLUDGE
             ZIMPRO
     SLUDGE OXIDATION UNIT
FIGURE 7-1
WHEELING, WEST VIRGINIA FLOW DIAGRAM

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                                                                                   REACTOR
              HEATING
             VWVW-I—i
               COILS
                          HELIFLOW
                        HEAT EXCHANGER
      HIGH PRESSURE PUMP
                                    AIR
                                                                 WATER AND
                                                                CONDENSATE
FIGURE 7-2
WET AIR OXIDATION SYSTEM - WHEELING, WEST VIRGINIA

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TABLE 7-1 DESIGN AND OPERATING CONDITIONS -
WHEELING, WEST VIRGINIA
Conditions —
Max. & Min.
Processing
Rates

Processing Rate tons
per day dry solids
Flow— gpm
Total Solids— %
Chemical Oxygen De-
mand— g/l
Insoluble Organic
matter removed — %
Design

5.6
15.5
6

90

90
Ave. Max.

7.35 12.2
17.35 21.0
7.14 9.7

70 95

90 82.6
Maximum Insoluble Organic Removal = 93.
Min.

4.1
16.7
4.0

43.0

90.2
2%

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 TABLE 7-2       SLUDGE DISPOSAL - OPERATING COSTS
               WHEELING, WEST VIRGINIA


                                   Cost/Ton Solids
                                     Processed
                                    To January 1,
                                        1965

Electricity                              $ 6.11
Chemicals                               4.13
Start-up Fuel                             1.65
Maintenance                             1.17
                                       $13.06
Labor—1 man during Zimpro
  Unit Operation                         6.91
Total Operating Cost—$/ton            $19.97

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                              BOILER FDR PROCESS STEAM
                                                STEAM
RAW SLUDGE
 STORAGE   DISINTEGRATOR
       PUMP
I  HEAT EXCHANGER    REACTION VESSEL
                   AUTOMATIC DISCHARGE VALVE
                            THICKENED
                              SLUDGE
                                                                   RESIDUAL LIQUORS
                                                                                              I ED SLUDGE
                                                           VACUUM FILTER
FIGURE 7-3
                                   FLOW DIAGRAM OF THE PORTEOUS PROCESS

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SLUDGE
             GRINDER
                  AIR
          AIR COMPRESSOR
     TO INCINERATOR
                                              GROUND
                                              SLUDGE
                                              HOLDING
                                              TANK
                                                        i	ir
                                    PUMP
   POSITIVE
DISPLACEMENT
 SLUDGE PUMP
                                             OXIDIZED
                                              SLUDGE
                                               TANK
                                                                                      HEAT
                                                                                   EXCHANGER
                                                                                                       REACTOR
                                                                                                    EXHAUST GAS
               PRESSURE
               CONTROL
                VALVE
   VAPOR
COMBUSTION
    UNIT
                                                                                      TREATED
                                                                                      BOILER
                                                                                      WATER
                                   FILTER
                                                         PUMP
                                              BOILER
                             FIGURE  7-4      THERMAL  SLUDGE  CONDITIONING  AND  DEWATERING

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   REACTOR
 SECOND HSAT
 EXCHANGER
   PRE- HEATER
       THICKENER
                                          CONTROL
                                          PANEL
                                    BOILER
                                   CIRCULATING
                                   PUMP
                         1H       P
                         •4%5V COMPRESSOR  / '
              ₯
      \

 "AUTOMATIC
   VALVES
(ONE BACK-UP)
                                   LEVELING
                                   VESSEL
                                         DECANTING
                                         AND STORAGE
                                         TANK
                                                   CENTRIFUGE
                             i—h-»
                                      TO FS     SOIL   LAND FILL
                                           CONDITIONING
                GRINDER   PUMP
FIGURE 7-5
FLOWSHEET FOR THE DORR-OLIVER FARRER SYSTEM

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                      LABORATORY        PLANT SCALE
WOKINGHAM              35,880             35,940
FARNSBOROUGH           29,800             29,800
        TABLE 7-3     TOTAL SOLIDS PPM - HEAT TREATMENT LIQUORS

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                          TEMPERATURES         % SUSPENDED SOLIDS
                                (°C.|                   SOLUBILIZED
 (HEAT TREATMENT)        "0:200:230                     66
        W 0
|WET  AIR OXIDATION)       170:200:230                     79
  TABLE 7-4     PERCENT SOLIDS SOLUBILIZED - HEAT TREATMENT AND WET AIR OXIDATION AT VARIOUS TEMPERATURES

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     COST  DATA-PUDSEY
      |$/TON OF SLUDGE-EX CAKE DISPOSAL]
 0/M
19.20
CAPITAL
32.20
TOTAL
51.40
LIQUOR TREAT.
  5.00
            FIGURE  7-6
       SLUDGE DISPOSAL FACILITIES
                                    SCRUBBER
         VACUUM
         FILTER
                 MULTIPLE
                 HEARTH
                INCINERATOR
            FIGURE  7-7

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               OPERATING TEMPERATURE BALANCE
                HIGH
              PRESSURE PUMP
      Sludge-
                              HEAT
                              EXHANGERS
                           REACTOR
                                Feed Water—,
                                          35«fF
                       I08°F
                       uu
                       PCV
     AIR COMPRESSOR
           DECANT
            TANK



             JlOd0
        Thickened Oxidized Sludge
        to Vacuum Filters
                                     Feed Water-
                                        Gai-»
                                INCINERATOR
                                WASTE HEAT
                                RECOVERY
                                STEAM BOILER
                                          PROCESS STEAM
                      FIGURE   7-8
                   KALAMAZOO

   -THICKENING AND  DEWATERING
      % SOLIDS
THICKENER    THICKENED
   FEED       SLUDGE
           Ib/HR/Ft.'
            % CAKE
            SOLIDS
           COST
           S/TON
   5.0
9.7
4.9
45
20
                      FIGURE   7-9

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         COOKING   LIQUOR  TREATMENT
                      t
                      GAS
                     BURNER
PORTEOUS
EFFLUENT
ANAEROBIC
 FILTERS
              FEED/RECYCLE
                PUMPS
                               CM

                               O
CHLORINE
REACTION
 VESSEL
                          EFFLUENT TO SECONDARY
                                                TREATMENT SYSTEM
            (75 TO 90 PERCENT
            BOD REDUCTION]
               RECYCLE
                PUMPS
                (OXIDATION OF
                SULFUR COMPOUNDS)
                     FIGURE  7-10

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           SECTION 8 - FINAL DISPOSAL PROCESSES AND CASE STUDIES


1.   Incineration

         -   Introduction

         —   Incinerator types

         —   Heat recovery by countercurrent action by heat recovery boilers

         -   Air pollution requirements, devices for controlling air pollution

         —   Multiple hearth incinerator

                   Continuous operation, Minneapolis, St. Paul

                   Intermittent operation, town X

         —   Fluidized bed incinerator

                   Air pollution measurements, Waldwich, New Jersey

                   Intermittent operation, East Cliff- Capitola, California

         —   Flash drying/incineration

2.   Landfill

         —   Bad practice

         —   Good practice

3.   Land Spreading

         a.   Background

         -   Landsprcading is popular with wastewater plants treating less than 10 mgd, and
              in a few largo cities.  Its  use is widespread in  Europe. U.S. practice  is being
              critically assessed in an EPA study.
                                      8-1

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-    Potential  problems   are   contamination  of  the  soil  with  metals,   and
     contamination of the groundwatcr with  nutrients.  Both can be handled by
     proper design. Chance of bacterial contamination can be reduced to a negligible
     degree by proper procedures or, if indicated, by pasteurization.

-    Sludge has been transported by truck, barge, or pipeline. The choice depends
     on scale of operation and the circumstances.

—    Deep, well drained, permeable, level soils arc usually preferred. A careful survey
     of the soils, geology, and hydrology  is important for proper design of a land
     disposal system. Lands that  are  used for tilled  crops, pastures, forests, and
     recreation have been used for sludge spreading.

b.    Procedures

—    Methods for discharging sludge to  the land

-    Rates of application

—    Means for controlling pathogens

-    Assessment of the hazard of metal contamination

c.    Land  Spreading at Chicago

—    Chicago is transporting sludge 200 miles  by  barge, and disposing it to the land
     for a  total cost,  including digestion, of 572/dry  ton. Barging costs are inflated
     because dock and 20-mile pipeline had to be amortized over 3 years. When a
     pipeline is built,  costs will fall to $3S/dry ton.
                               8-2

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                            REFERENCES - SECTION 8
1.   Dalton, F.E.,  and Murphy, R.R., "Land Reclamation," presented at the 45th Annual
         Conference of the Water Pollution Control Federation, Atlanta, Georgia, 1972.

2.   Lynam, B.T.,  Sosewitz,  B., and Hinesly, T.D., "Liquid  Fertilizer to Reclaim Land and
         Produce Crops." Water Research, 6, 545-549 (1972).

3.   Dotson, G.K., Dean, R.B., and Stern, G., "The Cost of Dewatering Digested  Sludge on
         Land," to be presented at the 65th Annual  Meeting A.I.CH.E., New York, New
         York, November, 1972.

4.   White, R.K., and  Hamdy, M.Y., "Sludge Disposal on Agricultural Soils," presented at the
         27th Annual Purdue Industrial V/aste Conference, 1972.

5.   Graham, R.E., and Dodson,  R.E., "Digestion Sludge Disposal at San Diego's Aquatic
         Park," presented at the 41st Annual Conference of the Water Pollution Control
         Federation, Chicago, Illinois, September 22-27, 1968.
                                       8-3

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                  LIST OF FIGURES AND TABLES - SECTION 8







Figure 8-1         Flash-Drying System with Mixed-Refuse Incinerator




Figure 8-2         Flow Diagram of Waste-Disposal System




Figure 8-3         Typical Section of Multiple Hearth Incinerator




Figure 8-4         Typical Section of a Fluid Bed Reactor (Dorr-Oliver, Inc.)
                                        8-4

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                     _   _
                '.  r'f/.r.r.'f; i
                                                                Cyc I one
                                                         Coo Iing-Conveying
                                    Ash
FIGURE 8-1        FLASH-DRYING SYSTEM WITH MIXED-REFUSE INCINERATOR
           Refuse
    Asn Quench
        FIGURE 8-2        FLOW DIAGRAM OF WASTE-DISPOSAL SYSTEM

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              WASTE COOLING AIR
              TO ATMDSPHERB
          CLEAN GASES TO
           ATMS SPHERE
          ^INDUCED DRAFT  FAN
           BYPASS ON POWER OR
                 STOPPAGE
                 NERCO-ARCO
                 CYCLONIC JET
                 SCRUBBER
                          TING DAMPER
                  GREASE
                   / SKIMMINGS
MAKEUP WATER
TO DISPOSAL
                                        FILTER CAKE
                                             SCREEN-
                                             INGS &
                                             GRIT
                                                         COMBUSTION AIR
                                                       /"RETURN
                                                    RABBLE ARM DRIVE
  ASH PUMP
'ASH HOPPER
                                   COOLING AIR
   FIGURE 8-3
  TYPICAL SECTION OF MULTIPLE HEARTH INCINERATOR

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                                SIGHT GLASS
         EXHAUST
       SAND FEED
     FLUIDIZBD
        SAND
PRESSURE TAP.
ACCESS DOOR
                                                           PREHEAT BURNER
                                                         THERMDCOUPLE
                                                   JLSLUDGB INLET
                                                         FLUIDIZING AIR
                                                           ' INLET
 FIGURE 8-4
TYPICAL SECTION OF A FLUID BED REACTOR (DORR-OLIVER,  INC.)

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