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Treatment of Slaughterhouse Wastewater Mike Lawrence NDSU Fall 2006.

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Presentation on theme: "Treatment of Slaughterhouse Wastewater Mike Lawrence NDSU Fall 2006."— Presentation transcript:

1 Treatment of Slaughterhouse Wastewater Mike Lawrence NDSU Fall 2006

2 Overview  Challenges  Wastewater Parameters  Treatment Options  Process Modifications  Typical On-site Treatment Options  Design Problem

3 Challenges of Slaughterhouse Wastewater  Wastewater contains large amounts of blood, fat, and hair  Wastewater is above municipal standards which leaves two options; on site treatment or pay to be treated elsewhere  On site treatment with low capital and maintenance costs is desirable

4 Wastewater Parameters  BOD approx. 1,000 to 4,000 mg/L  COD approx. 2,000 to 10,000 mg/L  SS approx. 200 to 1,500 mg/L  High Oil and Grease content  Possible high chloride content from salting skins

5 Treatment Options  Discharge to sewer to be treated by municipal treatment plant  Land application of wastewater for irrigation  Reduce amount of wastewater and/or concentrations with the wastewater by changing the processes  On site Treatment –Flow Equalization, Screening, Dissolved Air Flotation, Primary Sedimentation –Aerobic Treatment –Anaerobic Treatment

6 In-Plant Modifications to Reduce Pollution  Main goal should be to prevent product from entering the waste stream and using the least amount of water possible  Reduce the amount of water used, saves money in two ways  Use high pressure and just enough  Proper detergents  Lower volume of water helps equipment  Reuse as much water as possible

7 Line Separation  Separating the various waste streams as much as possible  Sanitary lines should be discharged directly to the city sewer  Grease waste streams and non grease waste streams can help reduce treatment costs  Separate Blood line

8 Blood Recovery  Blood has ultimate BOD of 405,000 mg/L  One head of cattle contains 49 lbs. of blood which equals 10 lbs. BOD, compared to 0.2 lbs. discharged per person per day  All blood should be recovered in a separate line draining to a tank  Blood is then dried, commonly a continuous drier is used  Profitable end product

9 Stockpen Area  Stockpen waste and other manure should be hauled away as a solid  Cleaned periodically with as little water as possible  Ideally this water would go to a separate tank  From the tank it would be emptied into a truck and land applied

10 On-Site Treatment  Costs of treating on site or letting the municipality treat the waste should calculated  Maintenance and operation should be also put into cost analysis  Flow equalization is usually a very good first step in on-site treatment

11 Hydrasieve  BOD Removal 5-20%  TSS Removal 5-30%

12 Hydrasieve Width (ft) Height (ft) Capacity (gpm) Estimated Price 2575$5, $6, $8, $10, $12, $20, $40, $60, $80, $100,000

13 SS and Grease Removal  Grease removal could be very profitable  Skimming operations –20 to 30 % BOD removal –40 to 50 % SS removal –50 to 60 % grease removal  Dissolved Air Flotation, DAF –30 to 35 % BOD removal –60 % SS removal –80 % grease removal

14 Skimming Operation (Primary Sedimentation)  Detention time 1.5 to 2.5 hr  Overflow Rate 800 to 1200 gal/ft 2 *d

15 Dissolved Air Flotation (DAF)  Hydraulic Loading Rate –1.5 to 5.0 gpm/ sq. ft.  Solids Removal Rate –1.0 to 2.0 lbs/hr/sq. ft.

16 Anaerobic Lagoons  Ideally the lagoon would be covered, odor & gas production contained, heat retention  Not well suited for colder climates  Detention time 20 to 50 days  BOD5 loading= 200 to 500 lb/ac.-d

17 Anaerobic Contact Reactor (ACR)  Hydraulic Retention time days  Organic Loading rate of kg COD/m 3 -d Flocculator or

18 Anaerobic Sequencing Batch Reactor (ASBR)  HRT 6 to 24 hours  SRT 50 to 200 days  98% removal with 1.2kgCOD/m 3 -d  92% removal with 2.4kgCOD/m 3 -d  Possibly rates to 5 kgCOD/m 3 -d  Effluent SS range between 50 – 100mg/L depending on HRT

19 Upflow Anaerobic Sludge Blanket (UASB)  Proteins and fats may cause problems in formation of granules.  Loading rates of 4-12 kg sCOD/m 3 -d  Retention times of 7-14 hours

20 Design Problem  Flowrate:120,000 gpd, 83 gpm, Max 300 gpm  TSS=1500 mg/L  COD=5000 mg/L  sCOD=3000 mg/L  BOD 5 =2,000 mg/L  Reduce levels to municipal levels and discharge into sewer

21 Screening  Hydrasieve  Use prior to flow equalization to save on pumps and buildup in the tanks  Design for max flow of 300 gpm  4.5 by 7 foot model will handle flow  Approximate cost of $8,000

22 Primary  Loading Rate of 600 gal/ft 2 -d  Final Design –8 ft. wide, 25 ft. long, 10 ft. deep –8 ft. of weir w/ loading rate of 15,000 gpd/ft –HRT = 3 hours 25 ft 10 ft 8 ft

23 Anaerobic Lagoon  Covered for heat retention  Side depth = 8 feet  Final Design 540 lb BOD 5 /ac-d  HRT=80 days Plan View 400 ft

24 Anaerobic Contact Reactor  Final Design HRT=5 days  Loading Rate 1.0 kg COD/m 3 -d  Clarifier design based on 24m/d settling velocity 30 ft 56 ft 10 ft 16ft Clarifier Anaerobic Contact Reactor, Completely Mixed Flocculator, Deglassifier

25 Aerated Sequencing Batch Reactor  Two reactors of same size  Feed 8 hr, react 37.5 hr, settle 2 hr, drain.5 hr  Feed 8 hr, react 13.5 hr, settle 2 hr, drain.5 hr 46 ft 24 ft Sludge waste at bottom Supernatant Drain 11.5 ft above bottom

26 Upflow Aerated Sludge Blanket Reactor  Loading Rate of 10 kg sCOD/m 3 -d  Two tanks, operated in parallel  Diameter = 4.5 m, Height= 7 m, 2.5 m for gas storage 7 m 4.5 m

27 Final Design  Include Hydrasieve: effectiveness and low capital, O & M costs  Upflow Anaerobic Sludge Blanket Reactor  Tank is smaller than most of the others due to high organic loading rate  Provides constant source of methane gas


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