Benefits of Using Liquid-Solid Separation with Manure

Treatment LagoonsJohn P. Chastain, Ph.D., Professor and Extension Agricultural Engineer, School of Agricultural, Forest, and Environmental

Sciences, Clemson University

Jeffery Porter, Environmental Engineer, USDA-NRCS Manure Management Team

Waste to Worth Conference, Denver, Colorado

Grand Hyatt Hotel • April 1-5, 2013

Purpose Define a manure treatment lagoon and how it

is sized.

Summarize the benefits of using liquid-solid separation prior to lagoon treatment.

Liquid-Solid Separation Options1. Separation based on particle size – screens &

presses.

2. Separation based on density of the manure – gravity & cyclones

3. Can provide solid removal efficiencies in the range of 10% to 60% depending on species and manure solids content.

Some simple screen type separators

Some types of press separators

Combination of an in-channel fighted conveyor screen and a small screw press to treat liquid swine manure

Screw Press

Liquid-solid separator that employs three techniques: fine stationary incline screen (0.020 in), screw press, and an inclined fighted conveyor screen (courtesy of US FARM Systems, Tulare, CA).

Liquid-Solid Separation by Settling

Since the settled solids are slurry they can be used to load a press if dry solids are needed.

Chemicals can be used to remove 70% to 90% of the solids and P for most methods of liquid-solid separation

- Need proper dose- Need proper mixing- Need proper dilution- Need $$$

Benefits of Liquid-Solid Separation for Manure Storages – not for recycle systems

This is not a lagoon.

Benefits of Liquid-Solid Separation for Storages

Remove large particles to reduce energy and time needed for agitation and pumping

Reduce manure storage volume by up to 20% if TS removal is on the order of 40%.

Remove large particles that could cause clogging of pipes and nozzles.

Manure Treatment Lagoons Are Different From Storages– best for recycle systems

Lagoon Sizing Lagoon Volume = (Manure Volume +

Treatment Volume + Sludge Storage Volume) On top of these volumes add DEPTHS for

Net Rain (P+R), 25 year – 24 hr storm + minimum of 12” of freeboard.

These depths are required for any manure storage.

Typical Lagoon System

Well treated recycled lagoon water needed for manure removal.

High loading rates = strong recycle water for flush and pit-recharge buildings.

Need well treated lagoon water to make recycle flush and pit-recharge buildings function properly.

Maximum loading for recycle should be based on ASABE Standard.

Use of a mechanical separator (MS) to reduce loading on lagoon

Enhancing solids and nutrient removal by using chemicals slows the system down in this configuration.

Gravity settling can be used to make high-rate mechanical separation easier – also reduces chemical costs.

Add a settling basin or pond before the lagoon – basins drain dry, ponds do not.

Can use chemicals to enhance removal of solids and plant nutrients for a settling basin or pond.

Manure Storage Volume Will include all manure, wasted water, and

other solids added to manure per day (bedding and wasted feed)

Typically use a storage period ranging from 180 days in warm southern climates to 365 days in cold climates (e.g. Midwest)

Liquid-solid separation can reduce this volume by 10% to 25%. Best to be conservative.

Treatment Volume Depends on VS loading rate , LR = lb

VS/1000ft3/day. TV (ft3) = 1000 (lb VS/day / LR) Design loading rate depends on the climate. Larger loading rates can be used in warm

climates than in cold climates (ANSI/ASAE EP403.4, ASABE, 2011)

Variation of LR With Climate(ANSI/ASAE EP403.4, ASABE, 2011)

LocationLoading Rate, lb VS/1000ft3/day

Southern Minnesota (Cold) 3.0

Iowa 3.5

Kansas 4.0

North Carolina 4.5

South Carolina & Georgia 5.0

Central Texas 5.5

Central Florida (Hot) 6.0

VS Removal Reduces TV, ft3 / 1000 lb of live animal weight, Finishing Swine (5.01 lb VS/1000 lb)

Loading Rate VS Removed by Liquid-Solid Separation

lb VS/1000 ft3-d 0% 20% 40% 60% 80%

3.0, MN 1668 1335 1001 667.3 333.73.5, IA 1430 1144 858.0 572.0 286.04.0, KS 1251 1001 750.8 500.5 250.34.5, NC 1112 889.8 667.3 444.9 222.45.0, SC 1001 800.8 600.6 400.4 200.25.5, TX 910.0 728.0 546.0 364.0 182.06.0, FL 834.2 667.3 500.5 333.7 166.8

VS Removal Reduces TV, ft3 / 1000 lb of live animal weight, Dairy Cows (11.8 lb VS/1000 lb)

Loading Rate VS Removed by Liquid-Solid Separation

lb VS/1000 ft3-d 0% 20% 40% 60% 80%

3.0, MN 3936 3149 2362 1574 787.23.5, IA 3374 2699 2024 1349 674.74.0, KS 2952 2362 1771 1181 590.44.5, NC 2624 2099 1574 1050 524.85.0, SC 2362 1889 1417 944.6 472.35.5, TX 2147 1718 1288 858.8 429.46.0, FL 1968 1574 1181 787.2 393.6

Sludge Storage Volume, ft3/1000lb /year (ANSI/ASAE EP403.4, ASABE, 2011)

Depends on TS loading rate , MTS = lb TS added per year.

Sludge accumulation rates: Swine = 0.0219 ft3/lb TS Added Dairy = 0.0729 ft3/lb TS Added

Liquid-solid separation will reduce sludge build up in a treatment lagoon – Critical for dairy!

TS Removed By Separator

SwineSludge Volume

Per Year

DairySludge Volume

Per Year

0% 52.0 ft3/AU 383.2 ft3/AU

20% 41.6 306.5

40% 31.2 229.9

60% 20.8 153.3

80% 10.4 76.63

Solids Production: Swine = 6.5 lb TS/AU/day, Dairy = 14.4lb/AU/day

Odor Reduction? Research has shown that most of the odor

comes from particles that are smaller than 0.0098” (0.25mm).

Must have high-rate separation to greatly reduce odor production from liquid manure.

However lower VS loading rates have been shown to reduce frequency of odor from a lagoon.

Effect of VS Loading Rate on Odor Frequency (adapted from Humenik, et al. 1981)

Summary Liquid-solid separation can be used to

significantly reduce treatment and sludge storage volumes.

Allows use of smaller structures to save money.

Allows more economical use of lower loading rates to improve recycle water quality.

Can help reduce ammonia and odor production

Summary (2) Can allow use of anaerobic treatment lagoons

in colder climates. Can be used to remove a portion of VS and

Organic-N that would breakdown in the lagoon to yield methane, ammonia, and carbon dioxide.

Reduces cost of sludge management to maintain lagoon function.

Agricultural Mechanization &

Business

School of Agricultural, Forest, and

Environmental Sciences

Contact:

Christi Leard

864.656.3250

ccampb3@clemson.edu

http://www.clemson.edu/cafls/safes/agmec/