Composting for Sustainability

Steven Hall

Biological and Agricultural Engineering

LSU AgCenter

HORT 4012 Feb 2009

Composting

The (aerobic) decomposition of organic material in the presence of

oxgyen.

Composting

GeneralC:N (materials)

Oxygen

Moisture

Temperature

Microbes (good and bad)

Composting: Materials Handling

Composting: Management

Sustainability: $, Env, Social

Composting: Equipment (windrow turner)

Composting: Windrows

Composting: Reduce Waste or Produce Valuable Product?

Composting: Thinking…

Composting

Practical Issues:

Food waste

Vet Waste

Safety (biology)

Aesthetics (odor, appearance, handling, etc.)

Composting

Costs:

Transportation

Equipment

Labor

Value of Product

(Use on Farm, Sell for Profit?)

Composting

From Compost Workshop (see www.agctr.lsu.edu/callegari)

Or Compost Handbook (US Composting Council)

Or Composting Programs Elsewhere

(e.g. Cornell Composting: http://www.css.cornell.edu/compost/

Composting_homepage.html)

Cornell CompostingThe Science and Engineering of Composting

A Note to Casual CompostersBackground InformationGetting the Right MixComposting Experiments

Compost Engineering Fundamentals

Background Information:

Invertebrates

Microbes

Chemistry

Physics

Getting the Right Mix:

Introduction

Moisture Content

C/N Ratio

Bioavailability of Carbon & Nitrogen

Use of fertilizer nitrogen to balance C/N ratio

Lignin effects on bioavailability

Lignin Table

Effect of particle size on bioavailability

Callegari Composting Course:Mixes, Measurements (T, O, Vol,

Density), Materials, Siting…Example: Buffer Zones

Water Sources

Water Runoff/Streams/Wetlands

Residential/Business Areas

Buffer Zones

Recommended Distances from Water Sources

- Private well: 100 feet minimum

(horizontally)

- Water table: 3 feet above max

- Bedrock: 3 feet above max

Buffer Zones

Recommended Distances: Sensitive Wetlands

- Streams, ponds: 100 feet

- Subsurface drainage pipe or ditch: 25 feet

Buffer Zones

Recommended Distances: Residences

- Property lines: 50 feet (500 ideal)

- Residence or business: 200 feet (2000 ideal)

Buffer Zones

Check with local authorities on specifics:

DEQ

Health Dept

Conservation Districts

Army Corps of Engineers

Area Requirements (Practical for this class!!)

Volume of Material

Shape of Pile

Length of Time: Curing/Storage

Equipment Considerations

Area Requirements:Incoming Material

Volume of Material

Volume must be estimated by users

Examples:

- number of animals x volume per animal

- number of trucks x volume per truck (from dining halls…)

Area Requirements:Time Considerations

Volume of Material

Time:

Total volume = residence time x daily volume

- daily volume x number of days

Area Requirements:Volume = CS Area x Length

Shape of pile/container

- High Parabolic

- Low Parabolic

- Trapezoidal

- Triangular

- Rectangular (e.g. between walls)

Cross Sectional Pile Areas

Shape of pile/container

- High Parabolic (front end loader)

h = 6-12 feet, b = 10-20 feet

A = 2/3 x b x h

base

height

Cross Sectional Pile Areas

Shape of pile/container

- Low Parabolic (windrow turners/ wet)

h = 3-4 feet, b = 10-20 feet

A = 2/3 x b x h

baseheight

Cross Sectional Pile Areas

Shape of pile/container

- Trapezoidal (windrow turners/ wet)

h = 4-9 feet, B1 = 10-20 feet

A = (B1 + B2)h/2

B 1

height

B 2

Cross Sectional Pile Areas

Shape of pile/container

- Triangle (static piles/no turning)

h = 5-8 feet, b = 2 x height

A = b x h / 2

base

height

Cross Sectional Pile Areas

Shape of pile/container

- Rectangle (between walls/forced aeration)

h = 6-8 feet, b = 10-12 feet

A = b x h

base

height

Area Requirements:Volume = CS Area x Length

Example:

Trapezoidal pile, 100 feet long, B1 = 12 feet, B2 = 8 feet, h = 6 feet.

Volume = 100 x (12 + 8) x 6 / 2 = 6000 ft cu

12100

Area Requirements:Volume = CS Area x Length

Example:

Trapezoidal pile, Cubic Yards!

Volume = 6000 ft cu / 27 ft cu/yd cu

= 222 cubic yards

Area Requirements:Pad Area per Volume (A/V)

Example:Trapezoidal pile

Volume = 222 cubic yards

Pad Area = 100 feet x 12 feet wide = 1200 sq ft

1200 sq ft/43650 sq ft per acre = .027 acres

(1 acre = 43650 sq ft)

Area Requirements:Pad Area per Volume (A/V)

Example:Trapezoidal pile

Volume = 222 cubic yards

Consider Equipment Needs (12 feet between piles) Pad Area = 1200 sq ft (compost) + 1200

sq ft (equipment room)

= .055 acres (1 acre = 43650 sq ft)

Area Requirements:Pile Shape Comparisons

Example:Trapezoidal pile 100 feet long

Volume = 222 cubic yards

Low parabolic 100 feet long (b = 12, h = 4)

Volume = b x h x 2/3 x length = 118 cu yds

118222

Balance Game:Pile Shape Comparisons

Trapezoidal (222 cu yds) has more volume per area than low parabolic (118 cu yards)

But...

- May require more turning

- May take more energy

- May not accommodate wet materials

118222

Area Requirements Over Time

Longer Residence Time (RT) = Larger Pad Area (PA)

Consider: Daily Volume (Vd)

RT x Vd x V/A = Total Volume

Example: 2 week cycle + 2 week curing

= 4 weeks or 28 days RT

Area Requirements Over Time

Assume Daily Volume (Vd) = 1000 cu yards

Residence Time (RT) = 28 days

A/V = 0.055 acres/222 cu yds = .00025 acre/cy

RT x Vd x V/A = Total Volume

= 28 x 1000 x .00025 = 7 acres

Area Requirements: Time Effects

28 day res time (RT) requires 7 acres

14 day RT requires only 3.5 acres

3 month (90 day) RT requires

= 90 x 1000 x .00025 = 22.5 acres!!

Area Requirements: Time Effects

14 day RT: 3.5 acres

28 day RT: 7 acres

3 month RT: 22.5 acres!

6 month RT: 45 acres!!

Lowering Residence Time Saves $$$

Balance Game:Time Effects

Lowering Residence Time Saves $$$

But…requires

Quick turnaround (marketing)

Consistent conditions (overhead/equipment)

Good biology of compost

Area Requirements:Additional Factors

Buffer zones (50 feet from property lines, 100 feet from water source or streams)

Equipment Space (Room for equipment to move through lanes, make turns, park/stop)

Space for compost (active, curing, storage)

Time; Shape/Volume; Material Production

Area Requirements:Additional Factors

Example (see example p. 3-65):

Buffer (100/25/200)

Equipment (20 ft lanes, 20 ft turns)

Compost (High Parabolic)

100

Ditch

Stream Neighbor

25

200

100 Pad

Overall Site LayoutStorage, Curing, Active Compost

(Equipment)

Active Piles (Plus Lanes)

StoragePiles

55x70

Curing 50 x 54

20 ft lanes

10 ft edges

Other Site Considerations

Nuisance Control: Odors

Runoff Control

Vector Control

Dust and Noise Control

Safety and Accident Prevention

Nuisance Control: Odors

Odorous Raw Materials (e.g. fish, mortalities)

Poor Site Conditions (wet, close to residences)

Ammonia from high N materials (e.g. poultry)

Anaerobic (wet) conditions

Minimizing Odors

- Odorous Raw Materials: Add high C materials

- Plan for good site: space, dry, etc.

- High N material: add Carbon (e.g. wood chips)

- Anaerobic (wet) conditions: drainage, cover

- Turn piles under good conditions/good times

- Biofilters or other technologies to minimize odors

Minimizing Odors

A huge problem in urban/rural conflict areas

Consider your site and materials!

More discussion later...

Runoff control

Runoff can contain:

Sediment

Nutrients

Pathogens

Organic Matter

Runoff control

Runoff can cause

Disease

Sedimentation

Eutrophication

Runoff control

Use Best Management Practices:

Minimize eutrophication, sediment, nutrients, pathogens, etc:

- C: N ratio

- Material management

- Grassed Filter area

- Grass Buffer Strips near water bodies

Runoff control

Grassed Filter Area:

Grassed Filter Area

From compostpad area

Level lip spreader: line/channel

2-5% slope

Well estab-lishedvegeta-tion

Vector control

Insects: Flies, mosquitoes

Raccoons, bats, birds, etc.

Dust and water

Vector control

Keep site clean

Proper drainage

Appropriate mixing esp. high-N materials

Turning as necessary

C: N ration

Housing for insectivores: bats, martins, etc.

Rodent control: owls and hawks, etc.

Dust control

Dampen heavy traffic areas

Keep site clean

Especially loading and processing areas

Water control

Keep site clean

Maintain good drainage

Noise control

Traffic on site

Equipment (hammermills, grinders, etc.)

Motors and generators

Noise control

Time of day (early AM, late PM)

Seasons: open windows in comfortable weather

Vegetation and berms can cut noise

Safety concerns for sites

Site should be laid out to maximize safety:

- Operator health

- Safety Training

- Clean, dry site

- Fires

- Dry compost, large piles can burn

- Wood, etc. can burn

Facility Siting Review

Buffer zones

Area requirements: Vol, Time, Equipment

Nuisance Control:

Runoff Control

Vector Control

Dust and Noise Control

Safety and Accident Prevention

Wheel Spacing (Front End Loader)

PhD: Pile it higher and deeper…Forced Aeration, Static Bed Rectangular (Concrete Walls)

8’ deep

22’(with aeration)

30’(total length)

12’ wide

12” concretewallbetweenbays

Piled 8’ deep;sloped from 22’to toe of pile

Typical Compost Control Bay Configuration

Temperature Probe

To Controller

8’ deep

22’(with aeration)

30’(total length)

12’ wide

12” concretewallbetweenbays

Piled 8’ deep;sloped from 22’to toe of pile

Typical Compost Control Bay Configuration

Temperature Probe

To Controller

Lower Condensate Collector: 1liter, 1”-12 tapped for PVC pipe

Removable Top:Two Piece ThreadedRubber “T”-cone, 8” Sewer Drain Stopper(6” thread, 3 tpi ref.)etco, patent 4506705.

Hi viscosity sealing greaseto seal threads

5/8” Nalgene VI Grade clear tubing for exit

1/4” Nalgene PremiumAutoclavable USP VI Grade clear tubing for incoming air.

PVC Barb fitting to9/16-8 NPT in T(3/16” ID ref).

Schedule 80 PVC T: 1”-12-F.

Schedule 80 PVC pipe 1”-12male thread.

Tap NPT 1”-12 through cap center;seal with teflon tape.

Schedule 80 PVC cap, 8”(0.32” ref thickness).

Schedule 80 PVC: 8” ID Sewer Pipe x 18” (46cm) long.

Nominal wallthickness 0.25”.

Thermocouple ports:Parflex Fast&Tite Fittings.See detailed figure.

Prime and glue with PVC adhesive.

Moisture access ports:1”-12 NPT PVC plugssealed with teflon tape

Plenum plate 0 datum.

10 cm.

20 cm.

30 cm.

40 cm.

Compost in Enclosed Vessel: from Dr. Hall’s PhD

Control Algorithm

Compost Process Mapping

Outputs

ProcessOutputToutMoutO2outto DataAcquisition

T1 M1 Ox1T2 M2 Ox2T3 M3 Ox3T4…

ControlledVariable:Air FlowRate, Q

NominalAir FlowRate, Qo;Substrate;Moisture;EnvironmentalConditions

Net Input

Compost Process Data Acquisition and Control,Closed Loop Process With Temperature Feedback

Feedback Variable:Temperature

Control in Biological Composting Systems

Numerical simulations with considerations for temperature feedback control via aeration

regulation

Steven Hall

Objectives of Controlled Composting Process

• Control Temperature in Composting to: Degrade Substrate Reduce Pathogens Minimize Odors Manage Moisture

Control of Composting

Some practical control research (Stentiford, 1996; Jeris and Regan, 1973; DeBertoldi et al, 1988, 1996)

Very little available on controllability of composting

This project looks at controllability Input/Output analysis Input: Aeration; Output: Temperature

Methods for Exploring Composting Control

• Modeling/Simulation• Laboratory Experimentation• Field Scale Studies

Modeling: Equations Used

• Four Major EquationsBiological Volatile Solids (Substrate)OxygenMoistureTemperature/Energy

Kb value

Temperature, C

0

Modeling Equations: BVS

Biological Volatile Solids (BVS) d(BVS)/dt = -Kb*BVS

Kb = KTKO KM [hr-1]

KT = F(T) (Andrews et al) Graph:(0.0126)*[1.066)T-20-(1.21)T-60]

Modeling Equations: O2

Oxygen/Aeration Controlled Variable Related to Aeration Rate, Breakdown Rate

( O 2 ) t

Q * ( O 2 inO 2 out ) C * d ( BVS )

dtV r *

Modeling Equations: Water

Water is Produced by Respiration Water Vapor is Removed Air Holds More Water Vapor as

Temperature Rises

where rH2O = Qa*[Wa(Tr)-Wa(Ta)]/Vr*e.

( M ) t

1 m dry

r 1000

Base Case: Constant Aeration = 0.04kg/kg/h; kBVS = 0.008/h; Initial Moisture = 68%wb; Tin = 25C; Convection/Phase Change Only

0

10

20

30

40

50

60

70

80

90

100

-20 0 20 40 60 80 100 120

Time, Hours

Ou

tpu

t V

ari

ab

le V

alu

e

BVS, %

Oxygen, %

Moisture, %

Temperature, C

Moisture, %

Temperature, C

BVS, % of original

Oxygen, %

Compost Temperature Profiles Varying with Aeration Rate

0

10

20

30

40

50

60

70

80

0 10 20 30 40 50 60 70 80 90 100

Time, Hours

Tem

pe

ratu

re, C Temp, C, Q = 0.001

Temp, C, Q = 0.005

Temp, C, Q = 0.04

Temp, C, Q = 0.16

Temp, C, Q = 0.40

Compost Variable Profiles, Aeration = 0.16kg/kg/h

0

10

20

30

40

50

60

70

80

90

100

0 10 20 30 40 50 60 70 80 90 100

Time, Hours

Va

ria

ble

Va

lue

BVS, %

Oxygen, %

Moisture, %

Temperature, C

Compost Substrate Profiles Varying with Aeration Rate, Moderate to High Flow

50

55

60

65

70

75

80

85

90

95

100

0 10 20 30 40 50 60 70 80 90 100

Time, Hours

BV

S, %

of

Ori

gin

al

Q = 0.02

Q = 0.04

Q = 0.08

Q = 0.16

Q - 0.40

Compost Oxygen Profiles Varying with Aeration Rate

0

5

10

15

20

25

0 10 20 30 40 50 60 70 80 90 100

Time, Hours

Ox

yg

en

, % Oxygen, %, Q = 0.001

Q = .01

Q = 0.04

Q = 0.16

Impulse Response, 0.10kg/kg/h aeration pulse for 1 hour at 50 hours.

0

10

20

30

40

50

60

70

80

90

100

0 10 20 30 40 50 60 70 80 90 100

Time, Hours

Va

ria

ble

Va

lue

BVS, %

Oxygen, %

Moisture, %

Temperature, C

Flow Rate, kg/100kg/h

Closed Loop Simulations

• Control Algorithms Using Temperature Feedback

• Both Time and Temperature Used • Aeration Rate Regulated

Compost Simulations, Three Stage Aeration Strategy: Q=0.02, 0<t,10; Q = 0.04, 10<t<15; Q = 0.16, t>15

0

10

20

30

40

50

60

70

80

90

100

0 10 20 30 40 50 60 70 80 90 100

Time, Hours

Va

ria

ble

Va

lue

BVS, %

Oxygen, %

Moisture, %

Temp, C

Flow, kg/100kg/h

BVS, %

Oxygen, %

Moisture, %

Temp, C

Flow, kg/100kg/h

Moisture, low flow

Moisture, high flow

Temperature, low flow

Temperature, high flow

Oxygen, low flow

Aeration, low flow

Oxygen, high flow

BVS, high flow

BVS, low flow

Compost simulations compared with bench scale temperature results; SMSW substrate, 15 liter reactors, 1 lpm constant flow

(~0.02kg/kg/h)

0

10

20

30

40

50

60

0 20 40 60 80 100

Time, Hours

Va

ria

ble

Va

lue

T1 (C)

T4

T8 (C)

T12 (C)

Simulated Temp, cond=250,kBVS = 0.02, Q = 0.04

Simulated Temp, cond=290,kBVS = 0.02, Q = 0.04kg/kg/h

6/17-7/1/97, West Pile (Finish) Agway Compost Control, 1,15 and 30 min/30 simple control (note overshoot)

Control Temp is Average of 3 and 4 (4 and 5 feet up)Upper Control Band is 63-67, Lower is 53-57

0

10

20

30

40

50

60

70

80

0 10 20 30 40 50 60 70 80 90 100

110

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220

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250

260

270

280

290

300

310

320

330

340

350

360

370

Time, Hours

Tem

p, C

T1b (C)

T2b (C)

T3b (C)

T4b(C)

T5b (C)

7/7-22/97; West Pile, Agway Compost Control Temperatures; 3 speed Control in Phase II: 9%, 56%, Full

0

10

20

30

40

50

60

70

80

0 10 20 30 40 50 60 70 80 90 100

110

120

130

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160

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200

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220

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250

260

270

280

290

300

310

320

330

340

350

360

370

Time, Hours

Tem

p, C

Control Temp = (T3+T4)/2

Lower Control = 55C

Upper Control = 65C

T7 (Ambient)

Conclusions

• Modeling provides support for designing experiments and field studies

• Information from experiments is used for improving the model

• Practical, effective system control was achieved using guidance rule algorithms

Objectives Met

• Pathogen Destruction >3 orders of magnitude (below measurable levels)

• Moisture reduced• BVS, volume reduced significantly• Low Odors

Closed Loop Simulations

• Control Algorithms Using Temperature Feedback

• Both Time and Temperature Used • Aeration Rate Regulated

Compost Simulations, Three Stage Aeration Strategy: Q=0.02, 0<t,10; Q = 0.04, 10<t<15; Q = 0.16, t>15

0

10

20

30

40

50

60

70

80

90

100

0 10 20 30 40 50 60 70 80 90 100

Time, Hours

Va

ria

ble

Va

lue

BVS, %

Oxygen, %

Moisture, %

Temp, C

Flow, kg/100kg/h

BVS, %

Oxygen, %

Moisture, %

Temp, C

Flow, kg/100kg/h

Moisture, low flow

Moisture, high flow

Temperature, low flow

Temperature, high flow

Oxygen, low flow

Aeration, low flow

Oxygen, high flow

BVS, high flow

BVS, low flow

Compost simulations compared with bench scale temperature results; SMSW substrate, 15 liter reactors, 1 lpm constant flow

(~0.02kg/kg/h)

0

10

20

30

40

50

60

0 20 40 60 80 100

Time, Hours

Va

ria

ble

Va

lue

T1 (C)

T4

T8 (C)

T12 (C)

Simulated Temp, cond=250,kBVS = 0.02, Q = 0.04

Simulated Temp, cond=290,kBVS = 0.02, Q = 0.04kg/kg/h

6/17-7/1/97, West Pile (Finish) Agway Compost Control, 1,15 and 30 min/30 simple control (note overshoot)

Control Temp is Average of 3 and 4 (4 and 5 feet up)Upper Control Band is 63-67, Lower is 53-57

0

10

20

30

40

50

60

70

80

0 10 20 30 40 50 60 70 80 90 100

110

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220

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250

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270

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290

300

310

320

330

340

350

360

370

Time, Hours

Tem

p, C

T1b (C)

T2b (C)

T3b (C)

T4b(C)

T5b (C)

Compost and the Kingdom of God

• Sermon at Oasis Christian Fellowship www.firstoasis.org

• “Pruning” metaphor• Death and new life• Submitting to change can be good• Environment is about beliefs

Conclusions

• Modeling provides support for designing experiments and field studies

• Information from experiments is used for improving the model

• Practical, effective system control was achieved using guidance rule algorithms

Back to HORT 4012

• Pathogen Destruction: safety• Moisture reduced: Good product• BVS, volume reduced significantly• Low Odors: Aesthetics• Cost/Transport!• Practical • Use on farm, gardens, sell?• How much, when?