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 2 575
$5,200
3.5
150
$6,400
4.5 7
300
$8,000
5.5
400
$10,000
6.5
500
$12,000
7.3
1000
$20,000 14
2000
$40,000 21
3000
$60,000 28
4000
$80,000 35
5000
$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/ft2*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/m3-d
Flocculator or

18. Anaerobic Sequencing Batch Reactor (ASBR)
HRT 6 to 24 hours
SRT 50 to 200 days
98% removal with 1.2kgCOD/m3-d
92% removal with 2.4kgCOD/m3-d
Possibly rates to kgCOD/m3-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 kg sCOD/m3-d
Retention times of 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
BOD5=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/ft2-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
10 ft
8 ft
25 ft

23. Anaerobic Lagoon Covered for heat retention Side depth = 8 feet
Final Design 540 lb BOD5/ac-d
HRT=80 days
Plan View
400 ft
400 ft

24. Anaerobic Contact Reactor
Final Design HRT=5 days
Loading Rate 1.0 kg COD/m3-d
Clarifier design based on 24m/d settling velocity
56 ft
16ft
10 ft
Anaerobic Contact Reactor, Completely Mixed
Clarifier
30 ft
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
24 ft
46 ft
Supernatant Drain 11.5 ft above bottom
Sludge waste at bottom

26. Upflow Aerated Sludge Blanket Reactor
Loading Rate of 10 kg sCOD/m3-d
Two tanks, operated in parallel
Diameter = 4.5 m, Height= 7 m, m for gas storage
4.5 m
7 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