operasi anaerobic digester

8/10/2019 Operasi Anaerobic Digester

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STUDY GUIDE

ADVANCED

ANAEROBIC DIGESTION

SUBCLASS F

WISCONSIN DEPARTMENT OF NATURAL RESOURCES

BUREAU OF SCIENCE SERVICES

http://dnr.wi.gov/org/es/science/opcert/

JUNE 1992 EDITION *

*Note As of Jan 2010, this study guide contains objectives plus key knowledges.


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ACKNOWLEDGEMENTS

Speci al appr eci at i on i s extended t o t he many i ndi vi dual s whocont r i but ed t o t hi s ef f or t .

Thomas A. Kroehn, Di r ect or of Of f i ce of Oper at i ons andMai ntenance, DNR.

Thomas P. Mickelson, Coor di nat or , Oper at or Cer t i f i cat i on andTrai ni ng, DNR.

Wast ewat er operators were r epr esent ed by:

Mike Bechel - El mwoodVernard Cypher - J anesvi l l eMike Gabrick - Fount i an Ci t yEd Jensen - Menomoni eMike Kelly - J ef f er son

Jerry Kerns - Br oadheadGerald Muehr - LaCr ossePaul Nehm - Madi sonGreg Paul - LaCr osseDon Tinjum - St anl ey

VTAE and educat i onal i nt er est s wer e repr esent ed by:

Glenn Smeaton, Envi r onment al Educat i on

DNR di st r i ct of f i ces wer e repr esent ed by:

Larry Schaefer - West er n Di st r i ct, Eau Cl ai r eTom Tewes - Lake Mi chi gan Di st r i ct , Gr een Bay

DNR cent r al of f i ce was r epr esent ed by:

Mary Anne Lowndes, Madi son.Ron Wilhelm, Madi son


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PREFACE

Thi s oper at or ' s st udy gui de r epresent s t he r esul t s of anambi t i ous pr ogr am. Oper at or s of wast ewat er f aci l i t i es,r egul at or s, educat or s and l ocal of f i ci al s, j oi nt l y pr epar ed t he

obj ect i ves and exam quest i ons f or t hi s subcl ass.

The obj ect i ves i n t hi s st udy gui de have been or gani zed i nt omodul es, and wi t hi n each modul e t hey ar e gr ouped by maj orconcept s.

NOTE: As of J anuar y 2010, t hi s st udy gui de al so i ncl udes keyknowl edges.

HOW TO USE THESE OBJECTIVES WITH REFERENCES

I n pr epar at i on f or t he exams, you shoul d:

1. Read al l of t he key knowl edges f or each obj ect i ve.

2. Use t he r esour ces l i st ed at t he end of t he st udy gui de f oraddi t i onal i nf or mat i on.

3. Revi ew al l key knowl edges unt i l you f ul l y under st and t hemand know t hem by memor y.

IT IS ADVISABLE THAT THE OPERATOR TAKE CLASSROOM OR ONLINETRAINING IN THIS PROCESS BEFORE ATTEMPTING THE CERTIFICATION

EXAM.

Choosing A Test Date

Bef or e you choose a t est dat e, consi der t he t r ai ni ngoppor t uni t i es avai l abl e i n your ar ea. A l i st i ng of t r ai ni ngoppor t uni t i es and exam dat es i s avai l abl e on the DNR Oper at orCer t i f i cat i on home page ht t p: / / dnr . wi . gov/ or g/ es/ sci ence/ opcer t / I t can al so be f ound i n t he annual DNR "Cer t i f i ed Oper at or " or bycont act i ng your DNR r egi onal oper at or cer t i f i cat i on coor di nat or .


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TABLE OF CONTENTS

PAGE NO.

Acknowl edgement s. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

Pr ef ace. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3Tabl e of Cont ent s. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4Resour ces. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34

MODULE A: PRINCIPLES, STRUCTURE AND FUNCTION

Concept : Pr i nci pl es of Anaerobi c Di gestors. . . . . . . . . . . . . . . . . 5Concept : St ructure and Funct i on. . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

MODULE B: OPERATION AND MAINTENANCE

Concept : Oper at i on. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7Concept : Mai nt enance. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

MODULE C: MONITORING AND TROUBLESHOOTING

Concept : Moni t or i ng. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14Concept : Tr oubl eshoot i ng. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

MODULE D: SAFETY AND CALCULATIONS

Concept : Saf et y. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26Concept : Cal cul at i ons. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28


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ADVANCED ANAEROBIC DIGESTION____________________________________________________________________________________________________________________________________

MODULE A: PRINCIPLE, STRUCTURE AND FUNCTION__________________________________________________________________

__________________________________________________________________

CONCEPT: PRINCIPLE OF ANAEROBIC DIGESTION

1. Cont r ast t he envi r onment al sensi t i vi t y of aci d f or mi ngbact er i a t o t hat of met hane f or mi ng bact er i a.

THE ACID FORMING BACTERIA ARE NOT VERY SENSITIVE AS COMPAREDTO THE METHANE FORMING BACTERIA. THE METHANE FORMINGBACTERIA ARE VERY SENSITIVE TO SLIGHT CHANGES IN ORGANICLOADING, pH, AND TEMPERATURE (A TEMPERATURE CHANGE GREATER

THAN 2o

F./DAY WILL AFFECT THE METHANE FORMERS). THE METHANEFORMERS ARE STRICTLY ANAEROBIC BACTERIA AND ARE ALSOEXTREMELY SENSITIVE TO OXYGEN. GOOD DIGESTER OPERATIONSREQUIRES ENSURING THAT CONDITIONS ARE KEPT FAVORABLE FOR THEMETHANE FORMERS. IF THE ACID FORMER POPULATION GROWS TOORAPIDLY (EXCESS VOLATILE ACIDS), A DIGESTER UPSET WILL OCCUR.

2. Descr i be t he meani ng of "di gest er buf f er i ng capaci t y, " as i tr el at es t o di gest er cont r ol .

DIGESTER BUFFERING CAPACITY IS A DIGESTER'S ABILITY TO RESISTA CHANGE IN pH, AND IT IS DIRECTLY MEASURED BY THE AMOUNT OFALKALINITY PRESENT. VOLATILE ACIDS THAT ARE FORMED AS PART

OF THE FIRST STAGE OF DIGESTION CAN REDUCE ALKALINITY. THEVOLATILE ACIDS TO ALKALINITY RATIO IS USED AS A MEASURE OFTHESE TWO IMPORTANT OPERATING FACTORS.

3.

Li st t he t ypi cal val ues f or vol at i l e aci ds and al kal i ni t y i na wel l oper at i ng di gest er .

IN A WELL OPERATING DIGESTER THE VOLATILE ACIDS EXPRESSED ASACETIC ACID WOULD BE IN THE RANGE OF 50 TO 500 mg/L, AND THEALKALINITY EXPRESSED AS CALCIUM CARBONATE WOULD BE IN THERANGE OF 2000 TO 3000 mg/L. IN A HEALTHY DIGESTER, THEVOLATILE ACIDS ARE USED AS FOOD BY THE METHANE FORMERS ATABOUT THE SAME RATE AS THEY ARE PRODUCED. IN GENERAL,KEEPING THE VOLATILE ACIDS TO ALKALINITY RATIO AT 0.25 ORLESS IS DESIRABLE FOR GOOD OPERATIONS.

4. Compare t her mophi l i c bacter i a di gest er oper at i on t o mesophi l ebacter i a di gest er oper at i on.


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TEMPERATURE CONTROL IS IMPORTANT FOR METHANE FORMINGBACTERIA. THEY FUNCTION IN THE RANGE OF 85o-100oF., WHICH ISKNOWN AS THE MESOPHILIC RANGE. ANOTHER TEMPERATURE RANGE IS120o-135oF., AND IS KNOWN AS THE THERMOPHILIC RANGE.

METHANE FORMING BACTERIA'S ACTIVITY OUTSIDE THESE TWO RANGES

IS SEVERELY REDUCED. WHEN OPERATING IN THE THERMOPHILICRANGE, THE DIGESTION TIME IS REDUCED (LESS THAN HALF OFMESOPHILIC), BUT HIGHER OPERATING AND MAINTENANCE COSTS WOULDBE EXPECTED. MOST ANAEROBIC DIGESTION IN WISCONSIN ISOPERATED IN THE MESOPHILIC RANGE, NORMALLY OPERATING BETWEEN90o-98oF.

5. St at e t he expected r educt i on i n vol at i l e sol i ds f r om a wel loper at ed di gest er .

THE EXPECTED REDUCTION OF VOLATILE SOLIDS OF A PROPERLYOPERATING DIGESTER IS 40-60% OF THE TOTAL VOLATILE SOLIDSPRESENT IN RAW SLUDGE FEED. THE VOLATILE SOLIDS IN THE FEED

SLUDGE WOULD BE ABOUT 70% TO 75%, WHILE THE DIGESTED SLUDGEWOULD BE 45% TO 50% VOLATILE SOLIDS.

NOTE: LAND DISPOSAL REGULATIONS ARE BEING PROMULGATED AT THEFEDERAL LEVEL (503). WHEN THESE REGULATIONS AREFINALIZED, STATE CODES WILL HAVE TO BE MODIFIED. ANANAEROBIC OBJECTIVE WILL NEED TO BE ADDED TOINCORPORATE THIS INFORMATION.

CONCEPT: STRUCTURE AND FUNCTION

6.

Li st t hr ee t ypes of di gest er mi xi ng systems.

A. DRAFT TUBE AND OTHER MECHANICAL IMPELLERS/MIXERS.B. COMPRESSED DIGESTER GAS MIXING.C. SLUDGE RECIRCULATION.

7. Descr i be t he f unct i on of gas compr essor s, and expl ai n whyt hey ar e used.

A GAS COMPRESSOR TAKES LOW PRESSURE DIGESTER GAS, AFTERCLEANING (SCRUBBING), AND COMPRESSES IT TO A HIGHER PRESSURE.THIS INCREASE IN PRESSURE REDUCES THE VOLUME OF GAS STORAGEREQUIRED. THIS COMPRESSED GAS HAS HISTORICALLY BEEN USED FORSUCH THINGS AS: IT IS BURNED IN BOILERS TO PROVIDE HEAT FORTHE DIGESTER; IT IS BURNED IN NATURAL GAS INTERNAL COMBUSTIONENGINES FOR POWER GENERATION (PUMPING SEWAGE, RUNNINGCOMPRESSORS, GENERATING ELECTRICITY,ETC.); RUNNINGAUTOMOBILES; AND, IT IS USED FOR GAS MIXING IN DIGESTERS.


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8. Descr i be t he t wo met hods of st or i ng di gest er gas.

THE TWO METHODS OF STORING DIGESTER GAS ARE:

A. GAS HOLDING COVER: THIS IS A DIGESTER COVER VERY

SIMILAR TO A FLOATING COVER, EXCEPT IT HAS A MUCHLONGER SKIRT. THE GAS HOLDING COVER MAY BE ABLE TORISE MORE THAN 6 FEET ABOVE THE MINIMUM COVER HEIGHT.THIS TYPE OF COVER PROVIDES MUCH MORE VOLUME FOR GASSTORAGE, BUT HAS SIMILAR OPERATING PROBLEMS AS A NORMALFLOATING COVER, SUCH AS: FREE MOVEMENT UP AND DOWNWITHOUT BINDING, AND PRESSURE/VACUUM RELIEF VALVE.

B. SEPARATE GAS STORAGE TANK: DIGESTER GAS IS OFTENSTORED IN A SEPARATE TANK THAT IS NOT A PART OF THEDIGESTER. NORMALLY, DIGESTER GAS IS CLEANED AND ISCOMPRESSED TO INCREASE PRESSURE AND REDUCE THE VOLUMEOF STORAGE REQUIRED. GAS STORAGE TANKS ARE OFTEN BUILT

AS SPHERES, BUT OTHER TANKAGE CONFIGURATIONS CAN BEUSED.

9. Descri be a f l oat i ng cover posi t i on i ndi cat or , and an al ar m syst em.

A COVER POSITION INDICATOR IS A DIAL, STAFF GAUGE, OR OTHERDEVICE THAT ALLOWS AN OPERATOR TO DETERMINE THE LOCATION OFTHE COVER WITHIN ITS LIMITS OF TRAVEL. THIS WILL PROVIDE AQUICK INDICATION OF COVER LEVEL TO PREVENT SLUDGE OVERFLOW(ATHIGH LEVEL), OR POSSIBLE STRUCTURAL DAMAGE IF THE COVER ISRESTING ON CORBELS(LOW LEVEL). AN ALARM SYSTEM IS NORMALLYPROVIDED TO PREVENT THE PROBLEMS WITH EITHER A HIGH OR LOW

LEVEL COVER POSITION.

____________________________________________________________________________________________________________________________________

MODULE B: OPERATION AND MAINTENANCE____________________________________________________________________________________________________________________________________

CONCEPT: OPERATION

10. Li st t he star t - up pr ocedur es of a di gest er usi ng seed sl udge.

A. ADD WELL BUFFERED SEED SLUDGE. ADD ENOUGH SEED SO THATTHE SEED SLUDGE VOLATILE SOLIDS WILL BE ABOUT 20 TIMESTHE EXPECTED DAILY VOLATILE SOLIDS IN THE RAW SLUDGE.


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B. FILL THE REST OF THE DIGESTER BY CONTINUOUS PUMPING OFPRELIMINARY TREATED SEWAGE TO THE NORMAL OPERATINGLEVEL.

C. BEGIN HEATING AND BRING THE TEMPERATURE UP TO THENORMAL OPERATING LEVEL (95oF.) AS QUICKLY AS POSSIBLE.

D. BEGIN MIXING AND/OR RECIRCULATION AT THE MAXIMUM RATE.

BEGIN ADDING RAW SLUDGE AT A UNIFORM RATE PUMPING SMALLAMOUNTS OFTEN OVER A 24 HOUR PERIOD.E. MONITOR TEMPERATURE, pH, ALKALINITY, AND VOLATILE

ACIDS.F. CONTROL pH, IF NECESSARY WITH CHEMICAL ADDITIONS.G. CONTINUE MONITORING, INCLUDING GAS PRODUCTION AND

CARBON DIOXIDE CONTENT OF THE GAS.H. ADJUST RAW SLUDGE FEED RATE, AS NECESSARY.

11. Li st t he st ar t - up pr ocedur es of a di gest er wi t hout seedsl udge.

A. FILL THE DIGESTER WITH PRELIMINARY TREATED SEWAGE WITH

CONTINUOUS PUMPING TO THE NORMAL OPERATING LEVEL.B. BEGIN HEATING AND BRING THE TEMPERATURE UP TO THE

NORMAL OPERATING LEVEL (95oF.) AS QUICKLY AS POSSIBLE.C. BEGIN MIXING AND/OR RECIRCULATION AT THE MAXIMUM RATE.D. BEGIN ADDING RAW SLUDGE AT A UNIFORM RATE PUMPING SMALL

AMOUNTS OFTEN OVER A 24 HOUR PERIOD.E. MONITOR TEMPERATURE, pH, ALKALINITY, AND VOLATILE

ACIDS.F. CONTROL pH, IF NECESSARY WITH CHEMICAL ADDITIONS.G. CONTINUE MONITORING, INCLUDING, GAS PRODUCTION AND

CARBON DIOXIDE CONTENT OF THE GAS.H. ADJUST RAW SLUDGE FEED RATE, AS NECESSARY.

12.

Def i ne t he or gani c l oadi ng r at es f or a convent i onal and ahi gh r at e di gest er .

CONVENTIONAL DIGESTERS WOULD HAVE A LOADING RATE OF 0.03 TO0.10 POUNDS OF VOLATILE SOLIDS PER CUBIC FOOT PER DAY. THISINCLUDES SINGLE STAGE UNHEATED AND UNMIXED, SINGLE STAGEHEATED AND UNMIXED, AND TWO STAGE DIGESTERS.

A HIGH RATE DIGESTER WOULD HAVE A LOADING RATE OF 0.10 TO0.40 POUNDS OF VOLATILE SOLIDS PER CUBIC FOOT PER DAY. THEHIGH RATE UNITS HAVE HIGHER LOADING RATES BECAUSE THEIRDESIGN INCLUDES UNIFORM TEMPERATURE, GREATER MIXING CAPACITY,OFTEN TIMES ARE DEEPER, AND THEY WILL BE FED ON A NEARLYCONTINUOUS BASIS.

THE ORGANIC LOADING RATE IS DETERMINED BY DIVIDING THE DAILYPOUNDS OF VOLATILE SOLIDS IN THE DIGESTER BY THE VOLUME OFTHE DIGESTER SPACE IN CUBIC FEET.


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13. Expl ai n t he i mpact on t he f ol l owi ng i f a di gest er i s hydr aul -i cal l y over l oaded due to pumpi ng t hi n sl udge:

A. Heat i ng.B. Super nat ant .C. Gas Pr oduct i on.

A. HEATING: THE EXCESS WATER BEING PUMPED WILL INCREASEHEATING COSTS. IT COULD ALSO LOWER THE TEMPERATURE INTHE DIGESTER IF THE HEATING EQUIPMENT CAN NOT KEEP UPWITH THE EXCESS PUMPAGE. ANY SIGNIFICANT TEMPERATURECHANGE COULD AFFECT THE METHANE FORMERS AND A POSSIBLEDIGESTER UPSET.

B. SUPERNATANT: HYDRAULIC OVERLOADING WILL INCREASE THEAMOUNT OF SUPERNATANT VOLUME THAT MUST BE RETURNED TOTHE HEAD OF THE TREATMENT PLANT. THIS COULD CAUSE ANORGANIC OVERLOAD TO THE SECONDARY PROCESS REDUCINGOVERALL TREATMENT EFFICIENCY, BECAUSE IT HAS A HIGH

OXYGEN DEMAND, HIGH AMMONIA, AND IS ANAEROBIC.

C. GAS PRODUCTION: GAS PRODUCTION (METHANE) WOULD BEREDUCED AS THE HYDRAULIC OVERLOAD COULD LOWERTEMPERATURES, REDUCING THE EFFECTIVENESS OF THE METHANEFORMERS.

14. Compare di gest i on t i me when operat i ng at 85oF. , and at 95oF.

THE MESOPHILIC BACTERIA USED IN DIGESTION CAN FUNCTION AT ARANGE OF 85oF. TO 100oF., WITH THE OPTIMUM RANGE FOR NORMALDIGESTION AT 90oF. TO 98oF. THE DIFFERENCE BETWEEN 85oF.AND 95oF. IS THE LENGTH OF TIME REQUIRED TO ACHIEVE A GIVEN

LEVEL OF DIGESTION. IF DIGESTION OCCURS AT 85oF. IT WILLTAKE ABOUT 40% LONGER THAN AT 95oF. THIS MEANS THAT DIGESTERCAPACITY MUST BE LARGER TO PROVIDE THE ADDITIONAL DETENTIONTIME AT THE LOWER TEMPERATURE OR THE RAW SLUDGE LOADING RATEMUST BE REDUCED.

15. Di scuss met hods of i mpr ovi ng a di gest er ' s abi l i t y t o hol d i t st emperatur e dur i ng wi nt er mont hs.

METHODS TO IMPROVE A DIGESTERS ABILITY TO HOLD TEMPERATUREWOULD INCLUDE: MAINTENANCE OF THE HEATING SYSTEM; ADDINGADDITIONAL INSULATION; FURTHER CONCENTRATE SLUDGE; FEED

SMALLER QUANTITIES OF SLUDGE MORE FREQUENTLY; AND, INCREASESLUDGE MIXING TIME.

16. Di scuss oper at i onal al t er nat i ves when i t i s di f f i cul t t o hol dconst ant di gest er t emper at ur e i n ver y col d weat her .

THE METHANE FORMING BACTERIA ARE AFFECTED BY CHANGES IN TEMP-ERATURES OF AS LITTLE AS 1oF. PER DAY, AND METHANE FORMERS


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ACTIVITY WILL BE REDUCED WITH CHANGES GREATER THAN 2oF. IFALL OPERATIONAL CONTROLS AND THE ADDING OF INSULATION STILLCAUSE TEMPERATURE FLUCTUATIONS DURING VERY COLD WEATHER, ITIS BETTER TO SLOWLY REDUCE THE TEMPERATURE (AT A RATE NOT TOEXCEED 1oF. PER DAY) AND HOLD IT AT THIS LOWER CONSTANTLEVEL, THAN TO ALLOW FLUCTUATIONS THAT WILL AFFECT THE

METHANE FORMERS.IT WOULD BE BETTER TO OPERATE AT A CONSTANT90oF. THAN TO BOUNCE BETWEEN 92oF. AND 95oF. AS WEATHERCONDITIONS VARY.

17. Expl ai n t he i mpact on t he f ol l owi ng i f a di gest er i s bei ngor gani cal l y over l oaded:

A. Gas Composi t i on.B. Vol at i l e Aci ds Concent r at i on.C. Tot al Al kal i ni t y.D. pHE. Gas Pr oduct i on.

A. GAS COMPOSITION: A DIGESTER THAT IS BEING OVERLOADEDWILL HAVE AN INCREASE IN CARBON DIOXIDE PRODUCTION ANDA DECREASE IN METHANE PRODUCTION.

B. VOLATILE ACIDS CONCENTRATION: VOLATILE ACIDSCONCENTRATION WILL INCREASE. THIS WILL BE THE FIRSTINDICATION OF AN ORGANIC OVERLOAD.

C. TOTAL ALKALINITY: TOTAL ALKALINITY WILL DROP.

D. pH: pH WILL REMAIN CONSTANT UNTIL THE VOLATILE ACIDSEXCEED THE ALKALINITY, AT WHICH TIME THE pH WILL DROPSHARPLY.

E. GAS PRODUCTION: GAS PRODUCTION WILL DECREASE.

18. Expl ai n why t he r at i o of vol at i l e aci d t o t ot al al kal i ni t y i smor e sensi t i ve t o di gest er changes t han i s t he pH t est .

THE VOLATILE ACIDS TO ALKALINITY RATIO WILL SHOW CHANGESOCCURING WHILE THE pH LEVEL WILL REMAIN CONSTANT, BECAUSE THEBUFFERING AFFECT OF THE ALKALINITY MUST BE USED-UP BEFORE THEpH WILL CHANGE.

19. I dent i f y t he vol at i l e aci d t o al kal i ni t y r at i os f or t he

f ol l owi ng:A. A cont i nuousl y under f ed di gest er .B. A cont i nuousl y over f ed di gest er .C. The poi nt at whi ch oper at or shoul d t ake act i on.D. The poi nt at whi ch pH wi l l st ar t dr oppi ng.


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A. AN UNDERFED DIGESTER: A RATE OF LESS THAN 0.1.

B. AN OVERFED DIGESTER: A RATIO OF GREATER THAN 0.5.

C. THE POINT AT WHICH OPERATOR SHOULD TAKE ACTION: ANYCHANGE IN THE NORMAL RATIO FOR GOOD OPERATIONS SHOULD

BE WATCHED. ANY TIME THE RATIO REACHES 0.5, CORRECTIVEACTIONS MUST BE INITIATED.

D. THE POINT AT WHICH pH WILL START DROPPING: A RATIO OF0.8. TO 1.0.

20. St ate the gas pr essure manomet er r eadi ng i n i nches of waterf or a t ypi cal di gest er .

A TYPICAL DIGESTER HAS A GAS PRESSURE MANOMETER READING OF8-9 INCHES OF WATER.

21. St ate the met hane concent r at i on l evel i n di gest er gas when

combust i on can occur .

METHANE CONCENTRATIONS IN DIGESTER GAS WILL BURN WHEN THELEVEL REACHES 56%, BUT IS NOT USABLE AS A FUEL UNTIL THEMETHANE LEVEL REACHES 62%. WHEN GAS IS MIXED WITH AIR, ANDMETHANE IS IN THE 5% TO 20% RANGE, IT IS EXPLOSIVE.

22. Expl ai n why di gest er gas has an appr oxi mate f uel val ue of600 BTU' s compared t o 1000 BTU' s of pur e met hane.

DIGESTER GAS IS NOT PURE METHANE AS IT HAS APPROXIMATELY 30%CARBON DIOXIDE AND OTHER GASES LEFT FROM THE DIGESTIONPROCESS.

23. Di scuss why hydr ogen sul f i de and moi st ur e i s r emoved f r om di gest er gas.

DIGESTER GAS IS NORMALLY CLEANED BEFORE BEING COMPRESSED ANDSTORED. THE CLEANING(SCRUBBING) OF GAS INVOLVES REMOVAL OFMOISTURE AND HYDROGEN SULFIDE. THIS IS DONE TO REDUCEDOWNSTREAM CORROSION OF OTHER GAS HANDLING EQUIPMENT, PIPING,AND PARTS.

24. Descr i be how t o sel ect t he l evel f or super nat ant wi t hdr awal .

DRAW-OFF SUPERNATANT FROM SEVERAL DIFFERENT LEVELS TOVISUALLY FIND THE BEST SUPERNATANT QUALITY.

25. Di scuss t he super nat ant r emoval st r at egi es f or t he f ol l owi ngmi xed and heat ed di gest ers:A. Si ngl e Fi xed Cover .B. Si ngl e Fl oat i ng Cover .C. Two- St age wi t h at l east one f l oat i ng cover .


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A. SINGLE FIXED COVER: SHUT-OFF MIXING AND ALLOW

SETTLING(8-12 HOURS). WITHDRAW AT THE LEVEL WITH THEBEST SUPERNATANT. DO NOT WITHDRAW SUPERNATANT IN AVOLUME THAT WILL CAUSE A VACUUM IN THE DIGESTER.

B. SINGLE FLOATING COVER: SHUT-OFF MIXING AND ALLOWSETTLING (8-12 HOURS). WITHDRAW AT THE LEVEL OF BESTSUPERNATANT. DO NOT LOWER THE LIQUID OPERATING LEVELBELOW THE CORBELS.

C. TWO-STAGE DIGESTER WITH AT LEAST ONE FLOATING COVER:WITHDRAW FROM THE LEVEL WITH THE BEST SUPERNATANT INTHE SECONDARY DIGESTER. DO NOT LOWER THE LIQUIDOPERATING LEVEL BELOW THE CORBELS.

CONCEPT: MAINTENANCE

26. Devel op a mai nt enance schedul e f or weekl y, mont hl y,quar t er l y, and semi - annual acti vi t i es.

IN GENERAL, CONSULT THE O&M MANUAL AND MANUFACTURERSRECOMMENDATIONS FOR PREVENTIVE MAINTENANCE SCHEDULES.

WEEKLY:

INSPECT ALL PUMPS(RAW FEED SLUDGE AND RECIRCULATION).OPERATE AND INSPECT VARIABLE SPEED DRIVES.CHECK FLOATING COVER FOR EVENNESS.CHECK FOR GAS LEAKS.

INSPECT ALL SAFETY EQUIPMENT.CHECK MECHANICAL MIXER EQUIPMENT.

MONTHLY:

INSPECT AND CLEAN ALL DRIVE MOTORS (RAW SLUDGE, RECIRCULATIONAND COMPRESSORS).INSPECT AND LUBRICATE RAW SLUDGE PUMPS (PISTON TYPE,BELTDRIVEN).INSPECT PIPING AND EXERCISE VALVES.INSPECT AND CHECK SLUDGE FLOW METERING DEVICES.LUBRICATION AS NEEDED.

QUARTERLY:

LUBRICATE ALL EQUIPMENT AS NEEDED(INCLUDING MECHANICAL MIXERGEAR REDUCERS).CHECK SPARE PARTS INVENTORY.


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SEMI-ANNUALLY:

CLEAN AND FILL GAS MANOMETERS.DISASSEMBLE AND CLEAN DRIP (CONDENSATE) TRAPS.DISASSEMBLE AND CLEAN FLAME ARRESTORS.INSPECT AND CLEAN GAS COMPRESSOR.

CLEAN HEAT EXCHANGER.DISASSEMBLE AND CLEAN PRESSURE/VACUUM RELIEF VALVES.

27. Di scuss procedur es f or compl et e di gest er cl eani ng.

THE FIRST CONSIDERATION FOR COMPLETE DIGESTER CLEANING ISWHETHER THE WORK IS TO BE DONE WITH PLANT PERSONNEL OR TOUSE AN OUTSIDE CONTRACTOR SPECIALIZING IN THIS SERVICE, ORA COMBINATION OF BOTH. DEPENDING ON THE TYPE OF SYSTEM(SINGLE VERSUS MULTIPLE TANKS), IT WILL BE NECESSARY TODETERMINE HOW TO HANDLE RAW SLUDGE WHILE THE UNIT IS DOWN,THE EQUIPMENT NECESSARY TO ACCOMPLISH THE JOB, AND HOW ANDWHERE TO DISPOSE OF DIGESTED SLUDGE. OTHER ADVANCE PLANNING

WOULD INCLUDE ACCURATE INFORMATION AND A SUPPLIER FOR ALLINTERNAL PARTS THAT MAY HAVE TO BE REPLACED DURING THECLEANING PROCESS.

BASIC REQUIREMENTS FOR CLEANING:

A. ADVANCE PLANNING FOR ALL PHASES OF CLEANING.

B. ALL SLUDGE PIPING AND VALVES MUST BE OPERABLE.

C. TEMPORARY SLUDGE LINES FOR EMPTYING DIGESTER.

D. ADEQUATE ACCESS TO THE INSIDE OF DIGESTER (FOR WASHDOWN

WATER & ENTRY FOR FINAL CLEANING AND REPAIR OF INTERNALPARTS).

E. ALL SPARK PROOF/EXPLOSION PROOF EQUIPMENT(VENTILATIONFANS, TOOLS, LADDERS, LIGHTS, ETC.).

F. ALL OTHER SAFETY ITEMS (EXPLOSION METER, TRI-GAS METER,SELF-CONTAINED BREATHING APPARATUS, SAFETY HARNESS ANDTRIPOD, HARDHATS, PROTECTIVE CLOTHING, PERSONALHYGIENE, ETC.)

G. ADEQUATE SOURCE OF CLEAN-UP WATER (THIS COULD INCLUDETHE USE OF FINAL EFFLUENT IF LOCAL POTABLE SOURCE ISINADEQUATE). THIS WOULD BE AN INEXPENSIVE SOURCE JUSTREQUIRING PUMPING.

H. WASHDOWN WATER HOSE WITH NOZZLES FOR HIGH PRESSUREAPPLICATION.

I. SLUDGE PUMPS (FIXED AND PORTABLE).


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J. HOIST FOR INSTALLING AND REMOVING EQUIPMENT.

K. TANK TRUCK TO HAUL DIGESTED SLUDGE TO POINT OF ULTIMATEDISPOSAL. THIS MAY REQUIRE RENTING UNITS TO ENSURE AQUICK TAKE-DOWN AND START-UP.

L. CRANE - THIS UNIT SHOULD BE AVAILABLE IF THE DIGESTERCOVER IS EXPECTED TO BE REMOVED AND ON-CALL IN CASE THEDIGESTER COVER MIGHT HAVE TO BE REMOVED.

THE ACTUAL SEQUENCE OF EMPTYING AND WASHING DOWN THE INSIDEOF THE DIGESTER IS DEPENDENT ON THE TYPE OF DIGESTER AND THETYPES OF MIXING/RECIRCULATION/HEATING THAT THE UNIT HAS.REFER TO THE PLANT O&M MANUAL AND THE MANUFACTURER FORSPECIFICS ON A GIVEN TYPE OF DIGESTER.

IN SMALLER COMMUNITIES IT IS ADVANTAGEOUS TO GIVECONSIDERATION TO USING A CONTRACTOR FOR DIGESTER CLEANING,AS DIGESTER CLEANING IS NOT A ROUTINE OPERATIONAL ACTIVITY.

DEPENDING ON THE TYPE OF WASTEWATER TREATED, AMOUNT OF GREASEAND THE EFFICIENCY OF GRIT REMOVAL, COMPLETE DIGESTERCLEANING WOULD BE DONE ON A 3-5 YEAR INTERVAL.

____________________________________________________________________________________________________________________________________

MODULE C: MONITORING AND TROUBLESHOOTING____________________________________________________________________________________________________________________________________

CONCEPT: MONITORING

28. Expl ai n how t o use t he quant i t y of gas pr oduct i on as ani ndi cat or of di gest er per f or mance.

GAS PRODUCED SHOULD RANGE BETWEEN 7 AND 12 CUBIC FEET PERPOUND OF VOLATILE MATTER DESTROYED.

LOW GAS PRODUCTION INDICATES PROBLEMS - TOXICITY,TEMPERATURE, VOLATILE ACID TO ALKALINITY RATIO, MIXING, ORFEED RATES.

29. Descr i be a met hod of anal ysi s of di gest er gas composi t i on.

THE USE OF A CARBON DIOXIDE GAS ANALYZER WILL PROVIDE AN IN-DICATION OF GAS QUALITY. GOOD DIGESTER GAS WILL HAVE ACARBON DIOXIDE CONTENT OF 30% TO 35%. IF THE CARBON DIOXIDEREACHES 42%, THE DIGESTER IS IN POOR CONDITION AND THE GAS ISCLOSE TO THE BURNABLE LIMIT OF 44% TO 45%.


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30. Out l i ne pr ocedur e f or f i ndi ng per cent sol i ds concent r at i on of

sl udge and per cent vol at i l e sol i ds.

A. COLLECT A REPRESENTATIVE SLUDGE SAMPLE.B. WEIGH EMPTY DRY CRUCIBLE.

C. ADD SAMPLE TO CRUCIBLE AND WEIGH.D. DRY SAMPLE BY HEATING IN AN OVEN AT 103oC. TO 105oC.E. COOL IN DESICCATOR.F. REPEAT DRYING UNTIL A CONSTANT WEIGHT IS ACHIEVED.G. WEIGH SAMPLE -

DRY WEIGHTWET WEIGHT X 100% = % SOLIDS(BY WEIGHT)

H. HEAT SAMPLE IN MUFFLE FURNACE AT 550oC.I. COOL SAMPLE IN DESICCATOR AND WEIGH (ASH WEIGHT).

J.DRY WEIGHT - ASH WEIGHT

DRY WEIGHT X 100% = % VOLATILE

SOLIDS(BY WEIGHT)

EXAMPLE:

EMPTY CRUCIBLE = 110.3642 GMSCRUCIBLE WITH WET SLUDGE = 466.6742 GMSCRUCIBLE WITH DRY SLUDGE = 136.8726 GMSCRUCIBLE WITH ASH = 122.4672 GMS

% SOLIDS = DRY WEIGHT - CRUCIBLE WEIGHTWET WEIGHT - CRUCIBLE WEIGHT X 100

136.8726 - 110.3642

466.4642 - 110.3642 X 100

= 7.4%

% VOLATILE SOLIDS = DRY WEIGHT - ASH WEIGHTDRY WEIGHT X 100

= (136.8726 - 110.3642) - (122.4672 - 110.3642)136.8726 - 110.3642 X 100

= 26.5084 - 12.103026.5084 X 100

= 14.405426.5084 X 100

= 54.6%


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31. Descr i be t he l ocat i ons f or obt ai ni ng sampl es f or t hef ol l owi ng:

A. Feed Sl udge Vol at i l e Sol i ds.B. Di gest er Ef f i ci ency.C. Vol at i l e Aci d To Al kal i ni t y Rat i o.

D. Di gest er Gas Composi t i on.A. FEED SLUDGE VOLATILE SOLIDS: COLLECT A COMPOSITE

SAMPLE MADE OF GRABS AT THE BEGINNING, MIDDLE, AND ENDOF THE SLUDGE PUMPING PERIOD.

B. DIGESTER EFFICIENCY: COLLECT REPRESENTATIVE SAMPLES OFTHE FEED SLUDGE AND DRAW-OFF DIGESTED SLUDGE FORVOLATILITY TESTING, AND CALCULATE THE PERCENT REDUCTIONIN VOLATILE SOLIDS.

C. VOLATILE ACID TO ALKALINITY RATIO: A REPRESENTATIVESAMPLE OF DIGESTING SLUDGE IS OBTAINED FROM THE

RECIRCULATION SLUDGE PUMP, OR A WELL MIXED LOCATIONWITHIN THE DIGESTER IF MECHANICAL OR GAS MIXING IS

EMPLOYED. FOR BOTH VOLATILE ACIDS AND ALKALINITY, THESAMPLES MUST BE SETTLED OR FILTERED AS THE TEST ISPERFORMED ON THE LIQUID PORTION. THE SAMPLE SHOULD BEFREE OF SOLIDS. AFTER TESTING, THE VOLATILE ACID TOALKALINITY RATIO CAN BE CALCULATED. ANOTHER SAMPLESOURCE FOR THIS WOULD BE TO USE DIGESTER SUPERNATANT.

D. DIGESTER GAS COMPOSITION: A REPRESENTATIVE SAMPLE OFDIGESTER GAS SHOULD BE COLLECTED FROM THE GAS DOME ONTHE DIGESTER, OR FROM DIGESTER GAS LINES WHERE THE GASIS ACTIVELY BEING USED ( HEAT EXCHANGER, OR WASTE GAS

BURNER). A BUNSEN BURNER SHOULD BE CONNECTED TO THEGAS OUTLET, IGNITED, AND ALLOWED TO BURN FOR ASUFFICIENT LENGTH OF TIME TO ENSURE THAT AREPRESENTATIVE SAMPLE OF GAS WILL BE COLLECTED. THEACTUAL ANALYSIS OF THE GAS WILL BE FOR CARBON DIOXIDE,WHICH WILL AVERAGE ABOUT 30% CARBON DIOXIDE WITH THEREMAINDER BEING MOSTLY METHANE.

32. Descr i be how heat t r ansf er ef f i ci ency i s det er mi ned f ori nt er nal heat i ng coi l s.

HEAT TRANSFER EFFICIENCY CAN BE DETERMINED BY MONITORING THEHEATING COIL WATER TEMPERATURE IN AND OUT OF THE DIGESTER ANDMONITORING THE TEMPERATURE OF THE DIGESTER SLUDGE. CARE MUSTBE TAKEN TO KEEP THE WATER TEMPERATURE BELOW 130oF. OR SLUDGEWILL BAKE ON THE TUBES AND CUT DOWN ON HEAT TRANSFEREFFICIENCY.

33. Descr i be how t o det ermi ne t he amount of al kal i ni t y needed t ocor r ect an upset di gest er , i ncl udi ng chemi cal f eedi ng r at e.


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TO DETERMINE THE AMOUNT OF CHEMICAL NEEDED TO ACHIEVE A GIVENALKALINITY TO CORRECT A SOUR DIGESTER WOULD REQUIRE THEDETERMINATION OF THE AMOUNT OF VOLATILE ACIDS PRESENT, THEAMOUNT OF ALKALINITY PRESENT, THE EXCESS ALKALINITY DESIRED,AND THE CHEMICAL TO BE USED. KNOWLEDGE OF THE CONTROL

CHEMICAL WOULD INCLUDE THE AMOUNT NEEDED(BASED ON EQUIVALENTWEIGHT [ATOMIC WEIGHT]), AND THE PERCENT AVAILABILITY OF THECHEMICAL, ALL RELATIVE TO CALCIUM CARBONATE. THE EQUIVALENTWEIGHT OF THE COMMON CHEMCALS WOULD BE:

A. CALCIUM OXIDE = 56B. CALCIUM HYDROXIDE = 74C. ANHYDROUS AMMONIA = 17D. AMMONIUM HYDROXIDE = 35E. SODIUM CARBONATE = 106F. SODIUM BICARBONATE = 84G. SODIUM HYDROXIDE = 40

AS AN EXAMPLE, GIVEN THE FOLLOWING INFORMATION, CALCULATE THEAMOUNT OF CHEMICAL NEEDED.GIVEN:

DIGESTER VOLUME = 250,000 GALLONSVOLATILE ACIDS = 3,000 mg/LSODIUM BICARBONATE EQUIVALENT WEIGHT = 84PERCENT AVAILABILITY CALCIUM CARBONATE = 68%EQUIVALENT WEIGHT = 100ALKALINITY(AS CALCIUM CARBONATE) = .833 VOLATILE ACIDS

(AS ACETIC ACID)

1. FIND THE POUNDS OF VOLATILE ACIDS IN THE DIGESTER.

FORMULA:

POUNDS = CONCENTRATION(mg/L) X VOLUME(MG) X 8.34

= 3000 X .25 X 8.34

= 6255 POUNDS(VOLATILE ACIDS)

2. FIND POUNDS OF CALCIUM CARBONATE NEEDED.

FORMULA:

POUNDS = ALKALINITY X POUNDS VOLATILE ACIDS

= .833 X 6255

= 5210 POUNDS(CALCIUM CARBONATE)


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3. FIND POUNDS OF 100% SODIUM BICARBONATE NEEDED.

FORMULA:

100% BICARB = EQUIVALENT WEIGHT OF SODIUM BICARBEQUIVALENT WEIGHT OF CALCIUM CARB XPOUNDS

= 84100 X 5210

= 4376 POUNDS(AS 100% SODIUM BICARBONATE)

4. FIND POUNDS OF CHEMICAL NEEDED AT 68% ALKALINITY.

FORMULA:

CHEMICAL POUNDS = 100%

68% X POUNDS

= 100%68% X 4376

= 6435 POUNDS OF CHEMICAL

THE AMOUNT OF CHEMICAL CALCULATED SHOULD NOT ALL BE ADDED ATONCE, BUT FED IN INCREMENTS SPREAD OVER A WEEK OR LONGER.MONITORING OF VOLATILE ACIDS, ALKALINITY, AND pH, IN THEACTIVE ZONE OF THE DIGESTER WILL INDICATE PROGRESS TOWARDSRECOVERY AND WOULD DETERMINE WHEN TO STOP FEEDING CHEMICALS.

ANOTHER METHOD FOR DETERMINING CHEMICAL AMOUNTS WOULD BE TOOBTAIN A REPRESENTATIVE SAMPLE OF DIGESTER SLUDGE (ABOUT 5GALLONS), AND ADD A CHEMICAL UNTIL A DESIRED pH IS REACHED.CALCULATE THE AMOUNT OF CHEMICAL NEEDED FOR THE ENTIREDIGESTER PROPORTIONAL TO THE AMOUNT USED IN THE 5 GALLONSAMPLE.

A FINAL METHOD WOULD BE TO USE A CHART BASED ON THE ACTUALPOUNDS OF VOLATILE ACID PER 100 GALLONS IN THE DIGESTER, ANDTHE AMOUNT OF CHEMICAL NEEDED TO NEUTRALIZE THE VOLATILEACIDS.


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QUANTITIES OF VARIOUS ALKALIES REQUIREDTO NEUTRALIZE VOLATILE ACIDS

Actual* NH3 NH4OH Na2CO3 NaOH NaOHlbs.of Anydrous Aqua Anhydrous Liquid FlakeAcid per Ammonia Ammonia Soda Ash Caustic Caustic

100 gals. lbs. gals. lbs. Soda,lbs.Soda,lbs.

.834 .236 .197 .736 1.11 .5551.67 .472 .216 1.47 2 22 1.112.50 .708 .322 2.21 3.32 1.663.34 .944 .429 2.94 4.44 2.224.17 1.18 .536 3.68 5.54 2.775.00 1.42 .645 4.43 6.68 3.345.84 1.65 .750 5.14 7.76 3.886.67 1.89 .859 5.89 8.88 4.44

7.51 2.12 .963 6.61 9.96 4.988.34 2.36 1.07 7.36 11.10 5.5516.71 4.73 2.15 14.74 22.24 11.1225.10 7.11 3.23 22.16 33.42 16.7133.51 9.49 4.31 29.58 44.60 22.3041.96 11.88 5.40 36.84 55.84 27.9250.42 14.27 6.49 44.48 67.06 33.5384.50 23.92 10.87 74.56 112.42 56.21171.30 48.50 22.05 151.17 227.96 113.98

1kg = 2.205 lb. & 1L = 0.264 gallons)

POUNDS OF VOLATILE ACIDS

DIGESTER VOLUME/100 GAL.

CHEMICAL DOSAGE = POUNDS OR GALLONS NEEDED100 GALLONS X DIGESTER VOLUME

(CHART FROM "OPERATIONS MANUAL ANAEROBIC SLUDGEDIGESTION" EPA 430/9-76-001, FEBRUARY, 1976)

CONCEPT: TROUBLESHOOTING

34. I dent i f y the causes and cor r ect i ve act i ons f or t he f ol l owi nggas syst em pr obl ems:

A. Gas Pressur e Lower Than Normal .B. Gas Pressur e Hi gher Than Normal .C. Wast e Gas Burner Probl ems.D. Gas Met er Fai l ur e.


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A. GAS PRESSURE LOWER THAN NORMAL:

CAUSE: GAS LEAKING OUT THROUGH PRESSURE/VACUUMRELIEF VALVE.

CORRECTION: SERVICE VALVE TO ENSURE PROPER SEATING,

ADDING MORE WEIGHTS IF NECESSARY.INSTALLNEW PARTS IF WORN.

CAUSE: HIGH GAS USAGE IN THE PLANT.

CORRECTION: CHECK GAS USAGE IN THE PLANT AGAINST GASPRODUCTION AND ADJUST USAGE.

CAUSE: GAS LEAKING OUT OF THE COVER OR GAS PIPING.

CORRECTION: CHECK FOR LEAKS AROUND THE COVER AND

REPAIR. CHECK ALL PIPING FOR LEAKS ANDREPAIR.

CAUSE: POOR DIGESTER OPERATIONS.

CORRECTION: MONITOR ALKALINITY, VOLATILE ACIDS, pH,AND GAS QUALITY(CARBON DIOXIDECONCENTRATION). ADJUST RAW SLUDGE FEEDRATE(TO PREVENT ORGANIC OR HYDRALICOVERLOADING), AND ADD CHEMICALS TORESTORE GOOD DIGESTER OPERATIONS.

CAUSE: EXCESSIVE SLUDGE OR SUPERNATANT REMOVAL.

CORRECTION: STOP SLUDGE OR SUPERNATANT REMOVAL UNTILTHE DIGESTER GAS PRESSURE RETURNS TONORMAL.

CAUSE: EXCESSIVE USE OF LIME.

CORRECTION: STOP ADDITION OF LIME AND INCREASEMIXING TO RESTORE NORMAL GAS PRESSURE.

B. GAS PRESSURE HIGHER THAN NORMAL:

CAUSE: STUCK PRESSURE/VACUUM RELIEF VALVE.

CORRECTION: SERVICE THE VALVE TO ENSURE PROPEROPERATIONS AND INSTALL NEW PARTS ASNECESSARY. IN WINTER, CONDENSATION ANDFREEZING CONDITIONS CAN CAUSE THE VALVETO FREEZE. THE VALVE SHOULD BEINSPECTED REQULARLLY IN VERY COLDWEATHER AND VENTED BARREL COULD BEPLACED OVER THE VALVE WITH AN EXPLOSION


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PROOF LIGHT BULB INSIDE TO REDUCEFREEZING TEMPERATURES.

CAUSE: LOW GAS USAGE IN THE PLANT.

CORRECTION: CHECK THE WASTE GAS BURNER AND ALL

PIPING FOR PROPER OPERATION SO EXCESSIVEGAS WILL BE BURNED.

CAUSE: GAS PIPING BLOCKED OR PRESSURE REGULATINGVALVE NOT FUNCTIONING.

CORRECTION: CHECK ALL DRIP(CONDENSATE) TRAPS, CHECKALL LOW SPOTS IN THE PIPING FOR WATER OROTHER BLOCKAGE, AND CLEAN/REPAIR ASNECESSARY. ISOLATE PRESSURE REGULATINGVALVE,AND SERVICE/REPAIR AS NECESSARY.

CAUSE: SUPERNATANT LINES ARE FROZEN OR BLOCKED.

CORRECTION: CHECK LINES FREQUENTLY IN VERY COLDWEATHER AND PROTECT WITH INSULATION TOREDUCE FREEZING PROBLEMS.

C. WASTE GAS BURNER PROBLEMS:

1. YELLOW GAS FLAME AT THE WASTE GAS BURNER:

CAUSE: POOR QUALITY DIGESTER GAS WITH A HIGH CARBONDIOXIDE CONTENT FROM POOR DIGESTEROPERATIONS.

CORRECTION: CORRECT DIGESTER OPERATIONS. CHECK RAWFEED SLUDGE OPERATIONS TO PREVENTHYDRAULIC OR ORGANIC OVERLOADING, CHECKVOLATILE ACIDS, ALKALINITY, AND pH.ADJUST WITH CHEMICALS TO IMPROVE GASCOMPOSITION.

2. GAS FLAME LOWER THAN USUAL:

CAUSE: HIGH GAS USAGE IN THE PLANT.CORRECTION: CHECK GAS PRODUCTION AGAINST USAGE.

CAUSE: GAS LEAKAGE IN THE COLLECTION ANDDISTRIBUTION SYSTEM.

CORRECTION: CHECK FOR GAS LEAKS AND REPAIR PIPINGAND OTHER APPURTENANCES AS NEEDED.

CAUSE: LOW GAS PRODUCTION DUE TO PROCESS PROBLEMS.

CORRECTION: CORRECT DIGESTER OPERATIONS(SEE ABOVE).


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3. WASTE GAS BURNER NOT LIT:

CAUSE: PILOT FLAME NOT BURNING.

CORRECTION: CHECK FOR ADEQUATE PRESSURE, SERVICE,

AND RELIGHT.

CAUSE: OBSTRUCTION OR WATER IN THE PILOT GAS LINE.

CORRECTION: CLEAN WITH AIR AND CHECK LOW SPOTS FORIN-LINE WATER.

CAUSE: OBSTRUCTION OR WATER IN MAIN GAS LINE.

CORRECTION: DRAIN ALL DRIP(CONDENSATE) TRAPS. CHECKFOR LOW SPOTS IN PIPING FOR WATER OROTHER BLOCKAGES. CLEAN AND REPAIR ASNECESSARY.

4. PRESSURE CONTROL VALVE:

CAUSE: MALFUNCTION OF THE VALVE.

CORRECTION: CLEAN, SERVICE, AND REPAIR VALVE ASNECESSARY.

D. GAS METER FAILURE:

CAUSE: DEBRIS IN GAS LINE.

CORRECTION: CLEAN BY FLUSHING WITH WATER.

CAUSE: MECHANICAL FAILURE OR DIAPHRAGM PROBLEMS.

CORRECTION: ISOLATE THE METER, DISASSEMBLE, SERVICE,AND REPLACE WORN OR DAMAGED PARTS.

35. Li st t he met hods f or t est i ng f or di gest er gas l eaks.

A. ON-LINE : 1. GAS DETECTOR.2. SOAPY WATER.

B. OFF-LINE : 1. PRESSURE TEST WITH AIR.2. VACUUM TEST.

NOTE: ALWAYS USE SPARKPROOF TOOLS AND KEEP ANY OPEN FLAMESAWAY FROM ALL DIGESTER EQUIPMENT AND STRUCTURES TOPREVENT FIRE OR EXPLOSION.


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36. I dent i f y the causes and cor r ect i ve act i ons f or t he f ol l owi ngpump probl ems:

A. Pl uggi ng.B. Motor Runs, But I s Not Pumpi ng.C. Dr i ve Mot or St ops.

PROBLEMS CORRECTIVE ACTIONS

A. PLUGGING CLEAN IMPELLERS ON CENTRIFUGALPUMPS. CLEAN BALL CHECK VALVES ONPISTON PUMPS. CLEAN ALL PIPING.

B. MOTOR RUNS BUT NOT EXAMINE SHEAR PIN ON PISTONPUMPING. PUMPS. EXAMINE CHECK VALVE

BALLS FOR SEATING ON PISTON PUMPS.MAKE SURE DRIVE BELTS ARE NOTBROKEN ON PISTON PUMPS(REPLACE IFNEEDED).EXAMINE COUPLING ON THE

SHAFT TO MAKE SURE IMPELLER ISTURNING ON CENTRIFUGAL PUMPS.MAKESURE THAT ALL PROPER VALVES AREOPEN.

C. DRIVE MOTOR STOPS CHECK CIRCUIT BREAKERS OR THERMALOVERLOAD SWITCH. CHECK FOR OVER-HEATING (CLEAN VENTS AND COOLINGFINS AND DETERMINE THE CAUSE OFOVERHEATING).CHECK FOR LOOSECONNECTIONS OR AN OPEN CIRCUIT.CHECK BRUSH OR SLIP RINGS FORPROPER OPERATION AND REPLACE IF

NECESSARY.

37. I dent i f y the causes and cor r ect i ve act i ons f or t he f ol l owi ngmechani cal mi xi ng equi pment pr obl ems:

A. Shaf t Seal Leaks.B. Gear Reducer Wear .C. I nt er nal Mi xi ng Par t s.

A. SHAFT SEAL LEAKS:

CAUSE: PACKING DRIED-OUT OR WORN CAUSING GASLEAKAGE(CONFIRMED BY GAS ODOR OR BUBBLES WITHA SOAP SOLUTION).

CORRECTION: REPACK SHAFT SEAL AS NEEDED AND ANYTIMETHE TANK IS DOWN FOR CLEANING.


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B. GEAR REDUCER WEAR:

CAUSE: LACK OF PROPER LUBRICATION WHICH WOULD CAUSENOISE, VIBRATION, AND SHAFT WEAR.

CORRECTION: USE CORRECT TYPE AND AMOUNT OF

LUBRICATION AS RECOMMENDED BY THEMANUFACTURER.

CAUSE: POOR ALINEMENT OF EQUIPMENT.

CORRECTION: PROPERLY ALINE EQUIPMENT AND CORRECT FORANY IMBALANCE OF INTERNAL PARTS WHICHCAUSE ALINEMENT PROBLEMS.

C. INTERNAL MIXING PARTS:

CAUSE: IMBALANCE FROM DEBRIS ON MOVING PARTS CAUSINGVIBRATION, MOTOR OVERHEATING, AND NOISY

OPERATIONS.

CORRECTION: MAKE SURE PRELIMINARY TREATMENT(COMMINUTION AND SCREENING) IS OPERATINGPROPERLY TO PREVENT DEBRIS FROM GETTINGTO THE DIGESTER. IF POSSIBLE, REVERSEDIRECTION OF THE MIXER OR ALTERNATELYSTART AND STOP THE MIXER TO DISLODGE THEDEBRIS. IF THIS DOES NOT CORRECT THEPROBLEM, THE DIGESTER WILL NEED TO BETOTALLY DRAWN-DOWN AND CLEANED TO REMOVETHE ACCUMULATION OF DEBRIS.

CAUSE: WEAR ON INTERNAL PARTS FROM GRIT ORMISALIGNMENT.

CORRECTION: MAKE SURE PRELIMINARY TREATMENT(GRITREMOVAL) IS OPERATING PROPERLY TOMINIMIZE GRIT GETTING TO THE DIGESTER.EXCESSIVE WEAR WILL REQUIRE REPLACEMENTOF THE WORN INTERNAL PARTS.

38. Di scuss probl ems associ at ed wi t h cont r ol of scum bl anket s.

THICK SCUM BLANKETS IN DIGESTERS CAN HAVE AN ADVERSE AFFECTON DIGESTION AS THEY CAUSE A LOSS OF DIGESTER CAPACITY, CANPLUG THE SUPERNATANT LINE, CAN LEAK OUT AT THE WATER SEAL ONFLOATING COVERS, AND COULD AFFECT THE HEAT EXCHANGER. THICKSCUM BLANKETS ARE NORMALLY ASSOCIATED WITH INADEQUATE MIXINGAND HIGH GREASE CONTENT. TO KEEP SCUM BLANKETS AT A MINIMUMWILL REQUIRE ADEQUATE MIXING AND THE MINIMIZING OF GREASESOURCES WITHIN THE SEWER COLLECTION SYSTEM BY PRETREATMENT,USING GREASE TRAPS. IF SLUDGE MIXING OR RECIRCULATION IS


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DONE INTERMITTENTLY, THE MIXING TIME SHOULD BE INCREASED ORRUN CONTINUOUSLY TO REDUCE SCUM BLANKET THICKNESS. IFADEQUATE SLUDGE MIXING HAS NOT BEEN PROVIDED AS PART OF THEDIGESTER CONSTRUCTION, IT MAY BE NECESSARY TO RECONSTRUCT THEDIGESTER OR PROVIDE SOME FORM OF PORTABLE MIXER TO REDUCESCUM BLANKET THICKNESS. OTHER ALTERNATIVES WOULD BE TO

PHYSICALLY BREAK-UP THE SCUM BLANKET WITH POLES OR PADDLES,AND USE CHEMICALS TO SOFTEN THE SCUM BLANKET, OR CONTRACTCOMMERCIAL HAULERS TO REMOVE IT.

39. Di scuss t he t oxi ci t y concer ns of t he f ol l owi ng:

A. Heavy Met al s.B. Sul f i des.C. Ammoni a.D. Al kal i ne Sal t s.

A. HEAVY METALS: HEAVY METALS IN SOLUTION CAN ACT ASBIOCIDES (WILL KILL THE BACTERIA IN THE

DIGESTER). HEAVY METAL SOURCES AREOFTEN FROM INDUSTRIAL SOURCES,ESPECIALLY, METAL FINISHING AND METALPLATING OPERATIONS. COMMON TOXIC HEAVYMETALS WOULD INCLUDE: ALUMINUM, COPPER,CHROMIUM, MERCURY, ARSENIC, NICKEL, ANDZINC.

B. SULFIDES: SULFIDES CAN COME FROM INDUSTRIAL SOURCES ASSULFATE SALTS THAT ARE REDUCED TO SULFIDES INTHE DIGESTER. THE BACTERIA CAN TOLERATEBETWEEN 50-100 mg/L OF SOLUBLE SULFIDE,BUT CONCENTRATIONS ABOVE 200 mg/L ARE TOXIC

AND WOULD REQUIRE TREATMENT WITH IRON SALTSTO PRECIPITATE THE SULFIDES. THE SOURCE OFTHIS WASTE STREAM SHOULD BE ELIMINATED ORPRETREATED.

C. AMMONIA: AMMONIA FROM INDUSTRIAL SOURCES, ORGANICOVERLOADING, OR FROM USING ANHYDROUS AMMONIATO CORRECT A DIGESTER pH PROBLEM, CAN CAUSE ADIE-OFF OF BACTERIA. AMMONIA TOXICITY BEGINSAROUND 1500 mg/L, AND IS TOTALLY TOXIC AT3000 mg/L.

D. ALKALINE SALTS: THE ALKALINE SALTS CAN CAUSE TOXICITYAND WOULD ORIGINATE FROM INDUSTRIALSOURCES OR CHEMICALS USED TO CORRECTDIGESTER pH PROBLEMS.


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SALT MODERATELY INHIBITORY TOXIC

CALCIUM(mg/L) 2500 4500 8000MAGNESIUM(mg/L) 1000 1500 3000POTASSIUM(mg/L) 2500 4500 12000

SODIUM(mg/L) 3500 5500 8000

____________________________________________________________________________________________________________________________________

MODULE D: SAFETY AND CALCULATION____________________________________________________________________________________________________________________________________

CONCEPT: SAFETY

40. Descr i be the stor age and handl i ng concer ns f or t he f ol l owi ngchemi cal s:

A. Cal ci um Oxi de.B. Cal ci um Hydr oxi de.C. Anhydr ous Ammoni a.D. Ammoni umHydr oxi de.E. Sodi um Car bonat e.F. Sodi um Bi car bonat e.G. Sodi um Hydr oxi de.

THESE CHEMICALS ARE ALL USED TO CONTROL pH IN DIGESTORS. INHANDLING, AT A MINIMUM, AN OPERATOR SHOULD PREVENT THECHEMICAL FROM TOUCHING THE SKIN (WEAR RUBBER GLOVES AND FULLFACE MASK OR GOGGLES). IN ADDITION TO THE ITEMS LISTEDBELOW, THE OPERATOR SHOULD BE SURE TO READ ALL LABELINSTRUCTIONS PROVIDED BY THE MANUFACTURER AND STORE ASDIRECTED IN THE ORIGINAL CONTAINERS.

CHEMICAL STORAGE AND HANDLING

CALCIUM OXIDE THIS CHEMICAL COMES IN 50 POUNDBAGS (QUICKLIME) IN POWDER FORM.NORMALLY, WATER MUST BE USED(SLAKED) TO FORM A SLURRY BEFOREUSING. ALWAYS ADD QUICKLIME TOWATER TO PREVENT A VIOLENT REACTIONWHICH CAN CAUSE SPLATTERING. IT ISVERY CAUSTIC, AND CAN CAUSE SEVEREBURNS. IT IS DIFFICULT TO WASH OFFAS IT IS A VERY SLIMY MATERIAL WHEN


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SLAKED. THE POWDER IS DUSTY ANDCAN CAUSE NASAL IRRITATIONS. THISPOWDER IS HYGROSCOPIC, ABSORBINGMOISTURE FROM THE AIR, SO NEEDS TOBE STORED IN A DRY AREA.

CALCIUM HYDROXIDE THIS CHEMICAL COMES AS A POWDER,AND (SLAKED OR HYDRATED LIME)KEEPS BETTER IN STORAGE THANCALCIUM OXIDE. IT IS SIMILAR TOCALCIUM OXIDE AND ALL THE SAMEPRECAUTIONS (AS NOTED ABOVE) SHOULDBE TAKEN. STORAGE BIN AGITATIONMUST BE PROVIDED.

ANHYDROUS AMMONIA THIS CHEMICAL IS COMMONLY USED ASAN (AGRICULTURAL FERTILIZER)AGRICULTURAL FERTILIZER AND COMESIN CYLINDERS OR TANKS AS A GAS. IT

SHOULD BE STORED AT TEMPERATURESBELOW 70oF. IN A WELL VENTILATEDROOM. THE GAS SHOULD NOT COME INCONTACT WITH CHLORIDE SOLUTIONS ASFREE CHLORINE GAS CAN BE LIBERATED.

AMMONIA IS AN IRRITATING ALKALI THAT CANCAUSE SEVERE SKIN BURNS AND ISCORROSIVE TO COPPER AND BRASS.WHENUSING IT TO RAISE DIGESTOR pH, CAREMUST BE EXERCISED TO PREVENTAMMONIA TOXICITY WHICH OCCURS ATCONCENTRATIONS OF 1500-1600 mg/L AS

NITROGEN.

AMMONIUM HYDROXIDE THIS CHEMICAL IS AVAILABLE INLIQUID (LIQUID AMMONIA) FORM FROMFARM SUPPLY DEALERS. AS WITH THEOTHER CAUSTICS, IT CAN CAUSESKIN BURNS AND IS AN EYE IRRITANT.

SODIUM CARBONATE THIS CHEMICAL IS USUALLY SUPPLIEDIN (SODA ASH) 50 POUND BAGS INPOWDER FORM. IT IS HIGHLY SOLUBLEIN WATER, IS CAUSTIC, CAN CAUSESKIN BURNS, AND IS AN EYE IRRITANT.

SODIUM BICARBONATE THIS CHEMICAL IS SUPPLIED AS APOWDER (BAKING SODA OR IN 50 POUNDBAGS, AND SHOULD BE TREATEDBICARBONATE OF SODA) THE SAME ASSODIUM CARBONATE.


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SODIUM HYDROXIDE THIS CHEMICAL IS SUPPLIED IN STEEL(CAUSTIC SODA) DRUMS OR IN BAGS.IT IS AVAILABLE AS A FLAKE,CRYSTALS, OR A LIQUID. NORMALLY,IT IS PURCHASED AS A FLAKE OR ACRYSTAL FORM. THE COMMON NAME IS

"LYE", AND HAS ALL THE PROBLEMS OFTHE OTHER CAUSTICS PREVIOUSLY MEN-TIONED.

41. Di scuss t he r el at i ve saf et y of t he chemi cal s used t o adj ustdi gest er pH.

ALL CHEMICALS USED TO ADJUST DIGESTER pH HAVE HANDLING ANDSAFETY PROBLEMS. AT LARGER TREATMENT PLANTS CHEMICALHANDLING EQUIPMENT IS USUALLY AVAILABLE WHICH REDUCESHANDLING AND FEEDING PROBLEMS. AT SMALLER PLANTS, LACK OFCHEMICAL HANDLING EQUIPMENT AND EXPERIENCE WOULD FAVORCERTAIN CHEMICALS. THE USE OF SODIUM BICARBONATE(BAKING

SODA) IS PROBABLY THE LEAST HAZARDOUS OF THE CHEMICALS,FOLLOWED BY SODIUM CARBONATE. SODIUM BICARBONATE CAN BEAPPLIED AS A POWDER OR AS A PREMIXED SOLUTION WITHWATER.

THE USE OF CALCIUM OXIDE(QUICKLIME) OR CALCIUM HYDROXIDE(SLAKED OR HYDRATED LIME) IS PROBABLY THE MOST DANGEROUS WHENTHESE CHEMICALS ARE MIXED WITH WATER PRIOR TO FEEDING. THEYMUST ALWAYS BE ADDED TO WATER AND NOT THE WATER ADDED TO THECHEMICAL. THIS CAN CAUSE A VIOLENT REACTION AND SPLATTERINGOF THIS STRONG CAUSTIC. SODIUM HYDROXIDE WOULD BE THE NEXTMOST DANGEROUS, FOLLOWED BY AMMONIUM HYDROXIDE(WHICH ISSUPPLIED AS A LIQUID ELIMINATING THE MIXING PROBLEM). THE

USE OF ANHYDROUS AMMONIA SHOULD BE LIMITED TO FACILITIES THATHAVE THE EQUIPMENT TO HANDLE GAS CYLINDERS AND THAT HAVE FEEDCONNECTIONS OR THE ABILITY TO MAKE THE NECESSARY FEEDCONNECTIONS. DO NOT USE COPPER OR BRASS FITTINGS, AS THEYWILL BE AFFECTED BY AMMONIA. THE FEEDING OF LIME CAN ONLYRAISE THE DIGESTER pH TO ABOUT 6.8. WHEN LIME IS ADDED, ITREACTS WITH CARBON DIOXIDE TO FORM CALCIUM BICARBONATE.EXCESSIVE FEEDING OF LIME CAUSES INSOLUBLE CALCIUM CARBONATETO FORM. IN ADDITION, EXCESSIVE LIME MAY REMOVE TOO MUCHCARBON DIOXIDE WHICH COULD LOWER GAS PRESSURES, OR EVEN THEFORMATION OF A VACUUM. THIS COULD CAUSE AIR TO BE DRAWN INTOTHE DIGESTER AND CAUSE AN EXPLOSIVE GAS MIXTURE.

CONCEPT: CALCULATIONS

42. Gi ven dat a, f i nd how much seed sl udge i s needed f or apar t i cul ar di gester .


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THE AMOUNT OF SEED REQUIRED IS ABOUT 20 TIMES THE ANTICIPATEDVOLATILE SOLIDS IN THE DAILY RAW FEED SLUDGE.

GIVEN: IF RAW SLUDGE IS 1000 GPD AT 4% SOLID AND 80%VOLATILE. SEED SLUDGE IS 5% SOLIDS AND 50%VOLATILE.

FORMULA:

POUNDS = % SOLIDS X VOLUME(GALLONS) X % VOLATILE X 8.34

GALLONS = POUNDS% SOLIDS X % VOLATILE X 8.34

NOTE: PERCENT EXPRESSED AS A DECIMAL

POUNDS = .04 X 1000 X .8 X 8.34

= 270 POUNDS

270 X 20 = 5400# OF VOLATILE SOLIDS NEEDED AS SEED SLUDGE

5400GALLONS = .05 X 8.34 X 0.5

= 25,900 GALLONS OF SEED SLUDGE

43. Gi ven vol umes and concent r at i ons, cal cul ate i mpact ofdi gest er super nat ant on pl ant l oadi ng.

THREE FACTORS AFFECTING PLANT LOADING ARE VOLUME AND STRENGTHOF:

A. BOD.B. AMMONIA.C. SUSPENDED SOLIDS.

GIVEN:

VOLUME OF SUPERNATANT = 2000 GALLONS/DAYBOD OF SUPERNATANT = 1500 mg/LCONCENTRATION OF AMMONIA = 300 mg/LCONCENTRATION OF SS = 2000 mg/L

FORMULA:

POUNDS = VOLUME(MGD) X CONCENTRATION(mg/L) X 8.34

BOD LOADINGS #/DAY = .002 X 1500 X 8.34

= 25.0 #/DAY

AMMONIA LOADINGS #/DAY = .002 X 300 X 8.34


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= 5.0 #/DAY

SUSPENDED SOLIDS #/DAY = .002 X 2000 X 8.34

= 33.4 #/DAY

44. Gi ven vol umes of f eed sl udge, sl udge concent r at i ons, vol at i l esol i ds and vol ume of a di gest er , cal cul at e t he or gani cl oadi ng r at e.

GIVEN: DIGESTER VOLUME = 40,000 CUBIC FEETRAW SLUDGE VOLUME = 5000 GALLONS PER DAYSLUDGE CONCENTRATION = 5%VOLATILE SOLIDS = 80%

FORMULA:

POUNDS PER DAY = VOLUME(GPD) X % SOLIDS X 8.34 X % VOLATILE

NOTE: % EXPRESSED AS DECIMAL

LOADING #'S VOLATILE SOLIDS/DAY/FT3= POUNDS PER DAYDIGESTER VOL. CUBIC FEET

LOADING = 5000 X .05 X 8.34 X 0.840,000

= 166840,000

= 0.042 # VOLATILE SOLIDS/DAY/F3

45. Gi ven dat a, cal cul at e t he amount of t i me t o r eci r cul at e t hevol ume of sl udge i n a di gest er .

GIVEN: DIGESTER VOLUME = 320,000 GALLONSRECIRCULATION PUMP = 300 GPM

FORMULA:TIME = DIGESTER VOLUME (GALS.)

PUMP CAPACITY (GPM)

RECIRCULATION TIME = 320,000

300

= 1067 MINUTES

= 1067 MINUTES60 MIN/HOUR

= 17.8 HOURS


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46. Gi ven dat a, cal cul at e per cent ef f i ci ency of an anaer obi c

di gest er .

GIVEN: % VOLATILE SOLIDS VS. IN = 70%% VOLATILE SOLIDS VS. OUT = 50%

FORMULA:

% EFFICIENCY = % VS IN - % VS OUT% VS IN - (% VS IN X % VS OUT) X 100

NOTE:VS = VOLATILE SOLIDS% VOLATILE SOLIDS EXPRESSED AS DECIMAL NUMBER

% EFFICIENCY = .70 - .50.70 - (.70 X .50 ) X 100

= .20.70 - .35 X 100

= .20.35 X 100

= 57%

47. Gi ven gal l ons of sl udge pumped, sl udge concent r at i on, andvol at i l e sol i ds i n and out of t he di gest er , est i mat e di gest ergas pr oduct i on.

GIVEN: RAW SLUDGE PUMPED = 12,000 GALLONS/DAYRAW SLUDGE CONCENTRATION = 5%RAW SLUDGE VOLATILE SOLIDS = 70%DIGESTED SLUDGE VOLATILE SOLIDS = 45%GAS PRODUCTION RATE/POUND OF VOLATILE SOLIDSDESTROYED = 9 FT3/DAY

FORMULA:

POUNDS PER DAY = VOLUME(GAL) X % CONCENTRATION X 8.34 X % VOLATILE% EXPRESSED AS A DECIMAL

GAS PRODUCTION = VOLATILE SOLIDS DESTROYED X EST. GAS PRODUCTION

RAW VOLATILE SOLIDS #/DAY = 12,000 X 0.05 X 8.34 X 0.70

= 3503 POUNDS OF VOL. RAW SOLIDS/DAY

RAW FIXED SOLIDS/DAY = 12,000 X 0.05 X 8.34 X (1-0.70)


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= 12,000 X 0.05 X 8.34 X .30

= 1501 POUNDS OF FIXED RAW SOLIDS/DAY

FIXED SOLIDS REMAIN CONSTANT IN THE SLUDGE SO THE DIGESTEDFIXED MATTER IS (1-0.45) = 0.55 FIXED. THE VOLATILE MATTER

DESTROYED IS EQUAL TO THE VOLATILE SOLIDS IN THE RAW SLUDGEMINUS THE VOLATILE SOLIDS IN THE DIGESTED SLUDGE.

VOLATILE #'S OF DIGESTED SLUDGE = 1501 X .45 = 1228 #/VOLATILE.55

POUNDS VOLATILE SOLIDS DESTROYED = 3503 - 1228 = 2275 #'S/DAY

ESTIMATED GAS PRODUCTION = 2275 X 9

= 20,500 CUBIC FEET/DAY

(OR ANOTHER METHOD)

% REDUCTION = % V.S.IN - % V.S.OUT% V.S.IN - (% V.S.IN X % V.S.OUT) X 100

= .70 - .45.70 - (.70 X .45) X 100

= .25.385 X 100

= 64.94%

POUNDS OF DESTROYED V.S. = % REDUCTION X POUNDS OF RAW V.S.

= .6494 X 3503

= 2275 POUNDS/DAY

48. Gi ven dat a, cal cul at e t he vol ume i n cubi c f eet and gal l ons ofa di gest er .

GIVEN: DIGESTER DIAMETER = 40 FEETDIGESTER HEIGHT = 20 FEET (NOT COUNTING THE CONE)DEPTH OF BOTTOM CONE = 6 FEET

1 CUBIC FOOT = 7.5 GALLONS

FORMULA:VOLUME = VOLUME OF CYLINDER + VOLUME OF CONE

= 3.14 X R2X H + 3.14 X R2X H3


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RESOURCES

1. ADVANCED WASTE TREATMENT. 1st Edi t i on ( 1987) , Kennet h D.

Ker r i . Cal i f or ni a St at e Uni ver si t y, 6000 J St r eet ,Sacr ament o, CA 95819- 6025. Phone ( 916) 278- 6142.

ht t p: / / www. owp. csus. edu/ t r ai ni ng/

2. ANAEROBIC SLUDGE DIGESTION. Zi ckenf oose, Char l es and Hayes,R. B. J oe. Oper at i ons Manual EPA 430/ 9- 76- 001 ( 1976) . U. S.Envi r onment al Pr ot ect i on Agency, Of f i ce of Wat er Pr ogr amOper at i on, Washi ngt on, DC 20090.

3. CONTROLLING WASTEWATER TREATMENT PROCESSES. ( 1984) .

Cor t i novi s, Dan. Ri dgel i ne Pr ess, 1136 Or char d Road,Laf ayet t e, CA 94549.

4. OPERATION OF MUNICIPAL WASTEWATER TREATMENT PLANTS. Manual ofPract i ce No. 11 ( MOP 11) , 2nd Addi t i on ( 1990) , Vol umes

I , I I , andI I I . Wat er Envi r onment Feder at i on ( Ol d WPCF) , 601Wyt he St r eet , Al exandr i a, VA 22314- 1994. Phone ( 800) 666- 0206.ht t p: / / www. wef . or g/

5. OPERATION OF WASTEWATER TREATMENT PLANTS. 3r d Edi t i on ( 1990) ,Vol umes 1 and 2, Kennet h D. Ker r i , Cal i f or ni a St at eUni ver si t y, 6000 J St r eet , Sacr ament o, CA 95819- 6025.Phone ( 916) 278- 6142.ht t p: / / www. owp. csus. edu/ t r ai ni ng/

6. OPERATION OF WASTEWATER TREATMENT PLANTS. Manual of Pr act i ceNo. 11 ( MOP 11) ( 1976) . Wat er Pol l ut i on Cont r ol Feder at i on,601 Wyt he St r eet , Al exandr i a, VA 22314- 1994. Phone ( 800) 666-0206. ( Probabl y Out - Of - Pri nt , See Ref er ence Number 4) .

operasi anaerobic digester

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