Project No. 21709R
Date: June 22, 2011
Portage la Prairie, Manitoba
MLMMI #2009-09
Final Report
In-vessel Composting of Lagoon Solid
Fractions
For:
Manitoba Livestock Manure Management Initiative (MLMMI),
Winnipeg, Manitoba
Research Report
June 22, 2011
Portage la Prairie, MB
Project #21709R
MLMMI #2009-09
Final Report
Research Report
In-vessel Composting of Lagoon Solid
Fractions
Kelly Egilson
Project Leader
Lorne Grieger, P.Eng.
Project Manager
Agricultural R&D
Acknowledgement
This project was supported by the Manitoba Livestock Manure Management
Initiative (MLMMI) under the Canada-Manitoba Growing Forward Initiative.
PAMI wishes to acknowledge the support provided by the Puratone Corporation
of Niverville, MB. PAMI also wishes to acknowledge the technical support
provided by the Manitoba Agriculture, Food and Rural Initiatives (MAFRI).
PAMI also wishes to acknowledge the technical and equipment support provided
by Pacific Forage Bag Supply Ltd.
1
Table of Contents
Page
1. Executive Summary .......................................................................................................... 2
2. Introduction ....................................................................................................................... 3
3. Project Objective ............................................................................................................... 4
4. Project Description ............................................................................................................ 5
5. Results and Conclusions ................................................................................................. 11
5.1 Component Nutrients ............................................................................................ 11
5.2 In-vessel Compost Results .................................................................................... 13
6. Equipment ....................................................................................................................... 19
7. Project Photos ................................................................................................................. 20
Appendix I Results and Analysis…………………………..……………………………………....23
2
1. Executive Summary
Separating the solid and liquid fractions of manure using a low energy input method has
the potential to reduce liquid application costs. Separation allows more liquid manure to
be applied to a smaller land area while still meeting the phosphorus requirements.
Composting the remaining solid fraction using an in-vessel composting method can
reduce the volume of solids to be handled by 25%, adds value to the manure while
retaining its nutrients and also kills pathogens and weed seeds.
This research project intended to evaluate the effectiveness of the Ag-Bag in-vessel
composting method for use in liquid manure storage applications. The liquid fraction
from the earthen manure storage cells containing hog manure and chicken manure was
pumped out leaving the settled solids at the bottom. The solids were mechanically
removed from the earthen storage for composting. These two types of manure were
combined with both wheat straw and barley straw to obtain four different mixtures for in-
vessel composting.
Wheat straw and barley straw were mixed with each type of manure using a tub grinder
and then placed directly into the compost bags using the Ag-Bagger. Before bagging,
the moisture content was evaluated using the “squeeze test”. Fans were used to aerate
the bags during the composting process. Temperature data was recorded during the
composting process and used to monitor the progress. After approximately two months,
the bags were opened and the individual trials placed in piles for curing. Samples were
taken of the finished compost and sent for analysis.
The finished compost did not meet the CCME Guidelines for Compost Quality for any of
the trials in this project. In specific, the compost did not meet the criteria for pathogens,
having elevated levels of fecal coliforms present. Salmonella was also detected in one
sample.
The in-vessel composting method has advantages in that environmental influences on
the composting process are minimized, especially in years with excess moisture and
less site preparation may be required as compared to open windrow methods of
composting and reduced odour emissions. A disadvantage to an in-vessel composting
method can be the inability to modify the compost mixture whether through moisture
addition or mixing of the compost to break up moisture stratification.
3
2. Introduction
Hauling large volumes of swine manure slurry over long distances to nutrient scarce
fields, and application of the manure in a timely manner, is a costly activity for producers.
Liquid hog manure slurry has a poor nitrogen to phosphorus (N:P) ratio for crop
utilization and therefore increases the number of acres required when applying
according to P requirements. In addition, the majority of the P is resident in the solid
fraction. Separating the solid and liquid fractions of hog manure using a low energy input
method has the potential to reduce liquid application costs because of an improved N:P
ratio. This allows more liquid manure to be applied to a smaller land area while still
meeting the P requirements as compared to a traditional slurry application where the
solids are mixed with the liquid before land application.
Composting the remaining solid fraction using an in-vessel composting method can
reduce the volume of solids to be handled by 25%, adds value to the manure while
retaining its nutrients and also kills pathogens and weed seeds. This reduced volume
has the potential to reduce manure handling and spreading costs. In addition, the final
product obtained is nutrient rich compost that has a better N:P ratio for crop utilization
and allows flexibility in application timing due to the stable nature of the finished product.
Composting is a centuries old method of waste management of biological materials.
However, the method of composting is what makes this project unique since the Ag-Bag
composting method is an enclosed process unlike typical exposed composting
processes. This kind of in-vessel composting has the following advantages over other
composting systems:
provides odour, insect and leachate control weather influences are minimized requires less surface preparation where composting process is performed
This research project intended to evaluate the effectiveness of the Ag-Bag in-vessel
composting method for use in liquid manure storage applications.
4
3. Project Objective
The main goal of this project is to determine the effectiveness of the Ag-Bag in-vessel
composting method in handling the solid fraction remaining in liquid manure storages.
The Ag-Bag machine, as shown in Figure 1, was originally developed to ensilage
forages. Trials were performed using solids obtained from two lagoons, one containing
hog manure and the other predominantly poultry manure with a small proportion of hog
manure. These two types of manure were combined with both wheat straw and barley
straw to obtain four different mixtures for in-vessel composting.
Figure 1: Ag-Bagger machine used for in-vessel composting project.
5
4. Project Description
The composting site was located at the Puratone Corporation’s Hog/Poultry operation
approximately 6.4 kilometres north and 1.6 kilometres east of Niverville (SE20-08-04-E).
Two types of manure having different N:P ratios were obtained from separate earthen
manure storages, one containing hog manure and the other, predominantly chicken
manure with a lesser amount of hog manure.
The liquid from the earthen manure storages was pumped out of the storage cells
leaving the settled solids at the bottom. The solids were mechanically removed from the
earthen storage using a combination of tracked hoes, bulldozers and dump trucks. The
solids were placed in separate temporary storage locations for dewatering before land
application. The manure solids used for this research project were taken from the
temporary storage locations.
Before beginning the composting operation, samples of the straw to be used, as well as
the two manure types were collected and sent for analysis. As manure is heterogeneous
in nature, composite manure samples were taken from three separate locations of the
solids manure storage area in order to assess the variability in the manure solids. The
composite samples were comprised of two scoops of manure solids from five separate
spots in each of the three solid manure sample locations. The samples were thoroughly
mixed and subdivided to provide a homogeneous sample for analysis. A target ratio of
straw and manure for each mixture was determined from the averaged manure nutrient
results.
To obtain a moisture content and carbon to nitrogen ration (C:N) ratio suitable for
composting, the mixing portions of straw and manure were chosen based on a nutrient
analyses of samples. Two Ag-Bags designated as A and B were filled, as shown in
Figure 2, on the following page. Bag A was filled with a straw and hog manure mixture
and B made with the hog and chicken manure. Approximately halfway (15 m) along each
bag the straw component was changed from barley to wheat.
6
Figure 2: Ag-Bags filled with compost mixtures.
The bags used for the compost are the same as those used for storing silage. The
difference between the silage and compost bags was in the addition of an aeration pipe
inserted at the bottom portion of the bag while the bag was being filled. Aeration fans
forced air through the bagged mixture via the aeration pipe. The supply air, as well as
gases generated during decomposition, were released through vents placed in
approximately 3 m intervals along the sides of each bag. The fans, each 0.24 kW and
capable of aerating 60 m long bags, were set to cycle on and off using timers. The
configuration of the aeration fans and ducts is provided in Figure 3, on the following
page.
Bag A (west bag) Bag B (east bag)
7
Figure 3: Fans used to aerate compost.
Wheat straw and barley straw were mixed with each type of manure and then placed
directly into the bags. The wet conditions made accessing the stockpiled manure solids
challenging and necessitated the use of a tracked loader to remove the solids from the
stockpile. The straw and manure solids were mixed on site using a Supreme Feed
Processor model 900T. Straw was added to the mixing tub and broken up followed by
the manure and allowed to mix. Before bagging, the moisture content was evaluated
using the “squeeze test”, which suggests that if water may be squeezed out of a sample,
the mixture is too wet while one too dry will not keep a formed shape. The straw and
manure mixture before bagging is shown in Figure 4, below.
Figure 4: Mixture of straw and manure before being placed in the bags.
Bag Vent
Aeration pipe
Aeration fans
8
The manure and straw mixture was placed in the hopper of the Ag-bag machine.. A
large plunger forced the mixture into the bag, the density of which was controlled by a
braking system on the machine. Additional braking increases the density of the compost
mixture placed in the bags. The filling of the bags is shown in Figure 5, below.
Figure 5: Mixing and bagging operation.
Once the mixture was placed in the bags, the composting progress was monitored by
measuring the temperature at the perimeter (approximately 150 mm into) and core of the
bagged mixture by inserting one set of thermocouples into one vent for each mixture as
shown in Figure 6 & 7. In-vessel composting was expected to take 8 to 12 weeks after
which the bags were to be opened and the mixture allowed to mature for 3 to 4 weeks.
The composting progress of the piles was also monitored by temperature measurement.
9
Figure 6 & 7: Thermocouples to measure central and perimeter temperatures inside bags.
Initially, four bags were to be filled each with a separate straw/manure combination,
however due to the extreme amount of rain seen in the months of May, June and July,
the land south of the electrical source became too soft for access. Instead, each of the
two north bags were filled part way with a wheat straw/manure mixture and then finished
with the corresponding manure mixed with barley straw. A final analysis of the compost
was performed by A & L Canada Laboratories Inc. The filled bags are shown in Figure
58.
10
Figure 8: Filled compost bags.
11
5. Results and Conclusions
5.1 Component Nutrients Before initiating the composting process, samples were collected of the liquid manure,
solid manure and straw for both manure and straw types. A single composite sample of
the liquid manure and straw was collected. The results of the nutrient analysis of the
straw samples are presented in Table 1, below.
Table 1. Straw sample analysis results.
Sample Moisture
(%)
Total
Nitrogen
(%)
Total
Phosphorus
(mg/kg)
Total
Carbon
(%) C:N Ratio
Barley Straw 11.4 1.08 1700 42.3 39.2
Wheat Straw 14.2 0.72 1060 39.7 55.4
Liquid manure samples were also collected from the surface of the earthen manure
storages before draining. The liquid samples were collected for comparison to the solid
samples collected from the settled solids removed from the storage. The analysis results
for the liquid samples are presented in Table 2, below.
Table 2. Liquid manure fraction analysis results.
Sample Solids
(%)
Total
Nitrogen
(mg/kg)
Total
Phosphorus
(mg/kg)
Total
Potassium
(mg/kg) N:P Ratio
Hog Manure 0.5 640 <1.0 870 >6.4
Chicken manure 1.1 2140 <1.0 1085 >21.4
Additional composite samples of the manure solids were collected in order to determine
the variability of the solids collected at various locations from the earthen manure
storage. The analysis results for the manure solids are presented in Table 3, on the
following page.
12
Table 3. Solid manure sample analysis results.
Sample Moisture
(%)
Total
Nitrogen
(mg/kg)
Total
Phosphorus
(mg/kg)
Total
Potassium
(mg/kg) N:P Ratio
Hog manure
Sample 1 54.6 7200 5800 3895 1.24
Sample 2 75.8 5550 2545 1005 2.18
Sample 3 70.2 6800 3975 1670 1.71
Average 66.9 6517 4107 2190 1.71
Chicken manure
Sample 1 38.7 4985 10350 3935 0.48
Sample 2 57.4 6000 3755 3520 1.60
Sample 3 50.3 6750 7800 2710 0.87
Average 48.8 5912 7302 3388 0.98
The manure solids were removed from the bottom of the manure storage cells after the
liquid fraction had been pumped out. Samples were taken over three different regions of
the manure stock piles of both the hog and chicken solids. The resulting analysis of the
samples revealed high variability in the nutrient content of the solids, with some samples
having two to three times the concentration of a specific nutrient. The variability is
attributed to the region of the stock pile that the sample was collected. The moisture
content also varied significantly between samples with differences up to 1.5 times higher
for the chicken solids. This variability has a potential to influence the compost quality and
performance of an in-vessel composting system since additional moisture cannot be
added once the mixture is placed in the bags.
In addition to the variability inherent with the heterogeneous manure composition, the
weather also has the potential to influence the manure moisture content. The delay
between sampling and obtaining the analysis results increases the risk of weather
influences on the manure solids.
The combination of high N:P ratio of the liquid fractions for both manure types and the
low N:P ratio of the solid fraction, may provide opportunities for producers to apply liquid
manure at a higher rate per acre and transport the relatively dense solids a greater
distance where additional phosphorus is required.
The carbon to nitrogen ratio is an important factor in successful composting. An
acceptable range is from 20 to 40 percent with 30 percent being ideal. Of even greater
importance is the percent moisture content of the mixture. Moisture content between 40
and 65 percent is needed with 55 percent being ideal. The analysis information was
used to develop a recipe for the four combinations of manure and straw types for this
project. The recipe was derived based on a relative proportion of straw to solid manure
to obtain a target moisture content of 55% and a C:N ratio of 30. The recipe targeted
13
moisture content as the major variable to have in the desired range of 40-65% with the
secondary variable being the C:N ratio in the range of 20 - 40. Table 4 summarizes the
composition of the composting components.
Table 4: Carbon/Nitrogen Ratio and Moisture Content of Composting Components
Sample
Total
Phosphorus
(mg/kg)
Total
Carbon
(g/kg)
Total
Nitrogen
(mg/kg)
C:N Ratio Moisture
(%)
Barley Straw 1700 423 10800 39.2 11.4
Wheat Straw 1060 397 7150 55.4 14.2
Hog Solid 4107 98.8 6517 15.2 67
Chicken Solid 7302 77.2 5912 13.1 49
5.2 In-vessel Compost Results
The first bag containing a mixture of hog solids combined with wheat straw and barley
straw was filled on July 15, 2010. A total of 12 bales of wheat straw combined in a ratio
of approximately 3:1 hog manure to straw was used for the hog solid/wheat straw trial.
An additional 11 bales of barley straw combined in a ratio of 3:1 hog manure to straw
was used for the hog solid/wheat straw trial. The total length of the filled bag was
approximately 30 m.
A second bag containing a mixture of chicken solids combined with wheat straw and
barley straw was filled on July 16, 2010. A total of 9 bales of wheat straw combined in a
ratio of approximately 4.5:1 chicken manure to straw was used for the hog solid/wheat
straw trial. An additional 12 bales of barley straw combined in a ratio of 4.5:1 chicken
manure to straw was used for the hog solid/wheat straw trial. Similarly to the hog solids
mixture bag, the total length of the filled bag was approximately 30 m.
5.2.1 Temperature Data
The in-vessel composting process requires aeration of the mixture to ensure adequate
microbial activity. The fans used to aerate the mixture were controlled by mechanical
timers that cycled the fans on and off. The timers were set as recommended by Pacific
Forage Bag, the representative of the Ag-Bagger equipment, during the course of the
composting process.
Thermocouples were installed at the centre and perimeter of the bag at one location in
each of the four combinations of manure and straw types. The temperature data was
recorded over the length of the composting period. Charts of the temperature data are
provided in Appendix I.
14
It is interesting to note that the perimeter temperature within the Ag-Bag was greater
than that of the centre. This is likely caused by a combination of air flow being from the
center outward, bringing the hot gasses evolved to the thermocouples at the vent
outlets.
5.2.2 Bag Opening
The bags were placed across the slope of the earthen manure storage embankment due
to the excess moisture conditions experienced at the compost site. The original planned
location of the bags was on a flat section of the field; however, the soil was too wet to
operate the equipment for composting in this area. The bags settled into a lop-sided
shape during the course of the composting process due to the slope as shown in Figure
9, below.
Figure 9: Compost bags prior to opening.
The bags were opened after approximately two months on September 15, 2010. Several
observations were noted at the time of the bag opening. The bottom and perimeter
through the cross section of the bags were saturated while the center was quite dry.
The flow of air through the compost, tended to dry the mixture from the center outward.
Since water vapour is a by-product of the composting process, or due to the
condensation of vapours on the interior of the bag, the mixture at the perimeter of the
bag tended to be quite wet. This separation of moisture or stratification was clearly
visible when the bags were opened. It was also observed that liquid was found to have
15
separated from the mixture and settled to the bottom of the bag. In addition, material at
the perimeter was saturated while the interior was quite dry. Mushroom growth in
chicken/hog mixture was observed, indicating high moisture content and insufficient
temperatures to kill weed seeds and pathogens at this location. Photos of the interior of
the bags are provided in Figures 10 through 13.
Figure 10: Interior of compost pile after bags opened.
Figure 11: High moisture layer at perimeter of compost pile.
16
Figure 12: Pooled liquid evident during bag opening.
Figure 13: Fungal growth at perimeter of compost pile evident during bag opening.
17
5.2.3 Cured Compost Results
The compost material from each combination of manure solids and straw types were
mixed and placed into curing piles after the bags were opened. The compost mixture
cured in the piles for 40 days before final sampling on October 25, 2010. A composite
sample was collected from each compost type and submitted for analysis. Results of the
compost analysis are provided in Table 5, below.
Table 5: Cured Compost Analysis Results.
Measure CCME, 2005
Limits
Mixture Types
Chicken/
Barley
Chicken/
Wheat
Hog/
Barley
Hog/
Wheat
Trace Elements (mg/kg)
Arsenic (As) 13 1.7 1.4 1.5 1.6
Cadmium (Cd) 3 <1* <1* <1* <1*
Cobalt (Co) 34 4.3 5.0 4.4 4.3
Chromium (Cr) 210 20 20 20 21
Copper (Cu) 100 44.3 43.3 68.7 86.8
Mercury (Hg) 0.8 <0.1* <0.1* <0.1* <0.1*
Molybdenum (Mo) 5 <2* <2* <2* <2*
Nickel (Ni) 62 17.05 18.50 15.7 16.3
Lead (Pb) 150 3.8 5.6 4.3 3.5
Selenium (Se) 2 <1* <1* <1* <1*
Zinc (Zn) 500 170.7 161.6 162.0 174.4
Maturity
CO2 Respiration
< 4 mg CO2-
C/g Organic
Matter per day
1.40 1.20 2.70
2.80 mg
CO2-C/g
O.M./day
Maturity Index
8 – Inactive, highly matured
compost, very well aged,
possibly over-aged, like soil;
no limitations for usage.
7 – Well matured, aged
compost, cured; few
limitations for usage.
Biological Properties (Pathogens)
Fecal Coliform <1000MPN/g Exceeded Exceeded Exceeded Exceeded
Salmonella
None
D.L.<3MPN /
4g dry basis
<3 <3 Positive <3
18
Measure CCME, 2005
Limits
Mixture Types
Chicken/
Barley
Chicken/
Wheat
Hog/
Barley
Hog/
Wheat
Foreign Matter
Total Inert Material
<2 foreign
pieces/500ml
>25mm
Below detectable levels Total Sharp Inert
Material
None
>3.0mm/500ml
Total Plastic Inert
Material 0.01%
CQA Product Quality Test Requirements
Recommended
Product Use
No Limit
Specified
Landscaping/Soil amendment, Mulching
pH 7.2 7.5 6.9 6.9
C/N 13:1 12:1 17:1 17:1
Moisture 27.7 % 34.3 % 33.8 % 31.8 %
Particle size 1-2 in. 1-2 in. 1-2 in. 1-2 in.
Soluble Salts 1.3 ms/cm 1.4 ms/cm 1.3 ms/cm .7 ms/cm
*Below detection limit
The CCME Guidelines for Compost Quality consider four criteria for assessing compost
safety and quality: foreign material, maturity, pathogens, and trace elements. Compost is
further classified as Class A – unrestricted, or B – restricted, in which allowable trace
element of Class A are exceeded but may still be used safely in some situations.
The finished compost did not meet the CCME Guidelines for Compost Quality for any of
the trials in this project. In specific, the compost did not meet the criteria for pathogens,
having elevated levels of fecal coliforms present. Salmonella was also detected in one
sample.
The in-vessel composting method has advantages in that environmental influences on
the composting process are minimized, especially in years with excess moisture and
less site preparation may be required as compared to open windrow methods of
composting and reduced odour emissions. A disadvantage to an in-vessel composting
method can be the inability to modify the compost mixture whether through moisture
addition or mixing of the compost to break up moisture stratification.
19
6. Equipment
The following equipment was used for the project
CT-5 Ag-Bagger
Loader tractor with bucket and grapple
Mixer machine (Supreme Mixer Model 900T)
Tractor w/PTO
5 ft diameter, 200 ft long bags (x2)
Aeration tubes
Aeration fans
Extension cords
Temperature probe (thermocouples on a 1/4” rod)
Instrumentation and data collection/communication equipment
Sampling equipment/tools
20
7. Project Photos
21
22
23
Appendix I
Results and Analysis – Temperature Data
24
0
10
20
30
40
50
60
70
80
Temperature (⁰C)
Time
Hog Manure/Barley Straw
Center
Perimeter
0
10
20
30
40
50
60
70
80
Temperature (⁰C)
Time
Hog Manure/Wheat Straw
Center
Perimeter
25
0
10
20
30
40
50
60
70
80
Temperature (⁰C)
Time
Chicken Manure/Barley Straw
Center
Perimeter
0
10
20
30
40
50
60
70
80
Temperature (⁰C)
Time
Chicken Manure/Wheat Straw
Center
Perimeter
26
0
10
20
30
40
50
60
70
0 20 40 60 80 100 120
Temperature (Degrees C)
Feet (from South end of Bag)
Manual Temperature Readings along East Side of West (Hog Solids) Bag
Jul‐27
30‐Jul
5‐Aug
11‐Aug
20‐Aug
25‐Aug
7‐Sep
0
10
20
30
40
50
60
70
0 20 40 60 80 100
Temperature (Degrees C)
Feet (from South end of Bag)
Manual Temperature Readings along West Side of West (Hog Solids) Bag
Jul‐27
30‐Jul
5‐Aug
11‐Aug
20‐Aug
25‐Aug
7‐Sep
27
0
10
20
30
40
50
60
0 20 40 60 80 100 120
Temperature (Degrees C)
Feet (from South end of Bag)
Manual Temperature Readings along East Side of East (Chicken Solids) Bag
Jul‐27
30‐Jul
5‐Aug
11‐Aug
20‐Aug
25‐Aug
7‐Sep
0
10
20
30
40
50
60
0 20 40 60 80 100 120
Temperature (Degrees C)
Feet (from South end of Bag)
Manual Temperature Readings along West Side of East (Chicken Solids) Bag
Jul‐27
30‐Jul
5‐Aug
11‐Aug
20‐Aug
25‐Aug
7‐Sep
