Report No.
CM-00-2
ACKNOWLEDGMENTS
This project was partially funded by CWCs Recycling Technology Assistance Partnership (ReTAP), through a grant from the U.S. Environmental Protection Agency, with supporting funds from the National Institute of Standards and Technology Manufacturing Extension Partnership (NIST MEP).
E & A Environmental Consultants, Inc. was instrumental in completion of this project. The Woodland Park Zoo and Soos Creek Composting also contributed to the research project. FINAL Prepared for:
CWC A division of the Pacific NorthWest Economic Region (PNWER) 2200 Alaskan Way, Suite 460 Seattle, WA 98121
January 2000 Prepared
by: E&A Environmental
Consultants, Inc. 19110 Bothell
Way N.E. Suite 203 Bothell,
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Disclaimer CWC disclaims all warranties to this report, including mechanics,
data contained within and all other aspects, whether expressed or
implied, without limitation on warranties of merchantability, fitness
for a particular purpose, functionality, data integrity, or accuracy
of results. This report was designed for a wide range of
commercial, industrial and institutional facilities and a range of
complexity and levels of data input.
Carefully review the results of this report prior to using
them as the basis for decisions or investments.
Table of Contents
1 Introduction..................................................................................................................................................
1
2 Summary.............................................................................................................................................................
3
3 Compost Facility Runoff Characteristics...............................................................................
8
4 Regulations...................................................................................................................................................
14
5 Process Water Management Capacity Characteristics
of Composting Methods
17
5.1 Factors that Influence the Water Management Capacities of Composting
Processes
17
5.2 Comparison of Composting Methods.........................................................................................
19
6 Best Management Practices..............................................................................................................
23
6.1 Source Reduction of Process Stormwater Runoff..........................................................
23
6.2 Process Water Recycle.......................................................................................................................
24
6.3 Reuse of Process Water......................................................................................................................
24
7 Management Practice Case Study: Compost Tea (Zoo Broo) Production at Woodland
Park Zoo
25
7.1 Potential Fertilizer Value of Process Runoff....................................................................
25
7.2 Bench Scale Pasteurization
Tests..............................................................................................
29
7.3 Pasteurization Process Alternatives for Woodland Park Zoo............................
34
7.4 Zoo Broo Product Nutrient Testing
Characteristics....................................................
41
7.5 Product Bottling and Distribution...........................................................................................
42
7.6 Zoo Broo Customer Survey...............................................................................................................
43
7.7 Zoo Broo Economics..............................................................................................................................
44
7.8 Zoo Broo Marketing.............................................................................................................................
44
8 Management Practice Case Study: Soos Creek Organics Composting Facility Water
Management Evaluation...............................................................................................................................................................
46
8.1 Calibrating the Energy and Water Balance Model.......................................................
46
8.2 Comparison of Rainfall Management Alternatives.....................................................
47
Appendices: Appendix A: Water
Capture and Evaporation Spreadsheet Model Appendix B: Lab
Reports Appendix C: Survey
Form and Information Sheet Appendix
D: Soos Creek Energy Spreadsheets
and Runoff Mgmt. Alternative
Comparison
List of Tables:
Table
1: Composting Process
Water Management Alternatives Table
2: Major Types of
Pollutants in America's Waterways and Aquifers Table 3: Comparison of Yard Debris Composting
Runoff with Regulation and Other Sources Table
4: Pollutants of Concern
in Leachate as Defined by DOE Table
5: Potential Water
Removal Comparison of Compost Technologies Table
6: Growth and Potassium
Treatment Differences Table 7: N:P:K of Commercial Fertilizer Products
and Woodland Runoff as Packaged and as Mixed Table
8: Market Value of
Commercially Available Organic Fertilizer Products Table
9: Runoff Assumptions
Table
10: Container Dimensions Table
11: Heat Profile Every
15 Minutes Table 12: Propane BTU Calculations Table 13: Fecal Coliform Reduction for Pasteurization
Tests Table 14: Nutrient Content of Woodland Park Compost
Facility Runoff Table 15: Nutrient Comparison Table 16: Economics of the Two Methods of Pasteurization Table 17: Composting Process Water Management Alternatives
List of Figures:
Figure
1: Bench Scale Pasteurization
Temperatures Figure
2: Fecal Coliform Reduction
through Pasteurization Figure
3: Temperature Profile
for In-Pile Pasteurization Test Figure
4: Temperature Profile
for Propane Pasteurization Test Figure
5: Fecal Coliform Reduction
Results
1 Introduction
The purpose of this project
is to evaluate and prioritize methods for compost facilities' management
of rainfall runoff. The runoff
contains contaminants that could cause problems if they migrate offsite. Therefore, compost facilities capture and treat
the runoff before release or reuse.
These techniques often require large amounts of space and are
quite costly. This report
explores and evaluates several methods to reduce, reuse, or recycle
the runoff. Another water source that occurs with some
composting systems condensate is not considered in this report.
Two existing compost sites
were used to demonstrate and test these techniques. Soos Creek Organics (Kent, WA) and the Woodland Park Zoo (Seattle,
WA). Soos Creek is a medium-scale
yard debris composter, and the Woodland Park Zoo compost yard produces
Zoo Doo from animal manure and bedding material. Both sites are on the west side of the Cascades,
and therefore are inundated with rain in the fall, winter, and spring.
Neither site is under cover.
The Soos Creek site was used
to examine techniques to minimize the quantity of runoff generated,
and therefore reduce the burden of treatment and disposal. Different feedstocks and composting techniques
generate varying levels of microbial activity, and therefore use different
amounts of water during the process.
The more water that is used by the process, the less runoff
is generated. Different compost
techniques require varying amounts of impervious surface, and therefore
generate vastly different quantities of runoff.
The Soos Creek site was used to develop energy and runoff models,
which show the quantity of runoff generated for a given storm from
different compost technologies. In
addition, management techniques were examined to determine how to
reduce runoff from the site.
The Woodland Park Zoo compost
facility is quite a bit smaller than Soos Creek, but some of the same
concerns exist regarding the runoff.
The Zoo produces a compost product (Zoo Doo) which has a strong
market and public acceptance in Seattle.
At this site, after analysis of nutrient content and testing
following pathogen reduction, the project manager determined that
it might be feasible to produce a compost tea (liquid plant food)
from the runoff. This product (Zoo Broo) could be sold as a companion product to
the Zoo Doo, and in fact might generate a substantial revenue stream. The Zoo made some product and gave it away
at its quarterly compost sale. The
response was quite positive, based on the surveys returned.
2
Summary
This project has revealed that
there are several methods of reducing, reusing, and recycling process
and non-process runoff as well as leachate from compost operations. Modification of operation technique and operating
procedures can eliminate up to 90% of the runoff generated from a
facility. These estimates
are based on the energy and water needs of a system before and after
optimizing the conditions for microbial growth.
This optimization is achieved by:
ˇ
Managing
composting process so that moisture and heat release occur at the
same place in the pile.
ˇ
Manage the
composting process such that evaporated moisture is released to the
atmosphere.
ˇ
Inducing
air in quantities sufficient to evenly distribute oxygen throughout
the pile and remove heat (by evaporating water) when above the temperature
set point.
ˇ
Reducing
pad space by changing pile configuration to extended pile instead
of windrows (with space between).
ˇ
Covering
the compost process areas, and/or:
ˇ
Diverting
rainfall pad water away from the active composting areas, thus preventing
contamination.
In addition to these techniques, this report
also shows that it is feasible to produce a product from the process
runoff and leachate generated at a compost facility.
The runoff, a disposal problem and a costly management burden,
can be treated with heat in order to achieve complete pathogen destruction.
The two trial tests of pasteurization generated results indicating
that the pathogens can be controlled by heat generated within the
pile, and by heat generated from burning propane.
The results also show that re-growth does not occur within
the first three weeks. The product, from the standpoint of pathogens,
is safe for use by consumers.
Summary of Best
Management Practice (BMP) Case Studies
The first case study considers
methods of managing stormwater at the Soos Creek Organics Facility.
Most composting facilities generate runoff, and are faced with high treatment and disposal costs. Applying the principles of waste reduction, reuse and recycling to compost facility runoff management is an elegant solution to a problem currently experienced by many compost facility operators.
The following BMP methods were
evaluated for Soos Creek:
§
Separation of Process Water
and Storm Water on the Composting Pad Since winter time yard debris quantities are generally reduced significantly,
the option of reducing the operating size of the pad becomes available.
§
Larger volume compost piles Larger composting piles will do a better job of capturing water because
of increased level surface area.
Larger piles will also do a better job of retaining generated
heat. The expected result would be increased rainfall
capture and evaporation.
§
Larger volume piles with low
rate aeration Optimum heat utilization
can be achieved by adding a minimal aeration system to the larger
composting piles. The aeration
will provide a continuous supply of air to capture and carry away
the evaporated moisture.
§
Extended Aerated Static Pile
This established composting
process generates far more energy than needed to evaporate all rain
falling on the surface. It
is considered as a comparison baseline. § Structural Cover A structural method of reducing process water is to cover the composting area. This prevents the rainfall from contacting the composting material except as desired by the operator.
During this project, a spreadsheet
model was developed to determine the quantity of runoff generated
from different composting technologies and management practices. Application of this model to Soos Creeks situation
indicates that a significant reduction in process water runoff can
be accomplished by seasonally modifying the composting process. The results of the alternative comparison for
that facility are provided on Table 1.
All alternatives have assumed volumes of 15,000 cubic yards
of material on site, and a pile depth of 12 feet.
Table 1 - Composting Process Water Management Alternatives
1large static pile (no aeration) 2extended aerated static pile composting
The second case study involved producing a compost tea product at Seattle's Woodland Park Zoo.
The organic and nutrient content of the runoff was used to develop a valued product. Pathogens in the runoff were treated prior to reuse. This project tested two methods of pasteurization. Lab testing determined that both methods provided complete pathogen destruction.
Pasteurization
Method 1 Buried Containers - This method uses the residual
heat of the pile to heat and pasteurize the liquid. Containers, if placed in the core of the pile,
were heated to the temperature of the pile core. See the photos below.
The temperatures must exceed
55o C for three consecutive days or 70o C for
30 minutes.
Pasteurization Method 2 Propane
Burner - The second method of pasteurization
uses a propane burner to heat a 55-gallon drum of process runoff.
The process was heated to 70o C (approximately 158o
F in approximately 100 minutes. The propane required to pasteurize 100 gallons
of process runoff using this method would be approximately 1.1 gallons
of propane. Therefore, fuel
costs for pasteurizing 100 gallons of runoff would be approximately
$1.10.
The compost tea produced in
these tests was bottled and labeled as Zoo Broo. The product was distributed with a survey form at the Fecal Fest
sponsored by the Zoo.
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