Page 264 - Materials Chemistry, Second Edition

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Composting MSW 235
Workers should also be informed that disease-producing microorganisms are present in the work
environment. Precautions should be followed for personal protection and include (U.S. EPA, 1994):

● Wear dust masks or respirators under dry and dusty conditions, especially when the com-
post is being turned.
● Cuts should receive prompt attention to prevent contact with incoming loads or feedstock.
● Individuals with asthma, diabetes, or suppressed immune systems should be advised not
to work at a composting facility because of their greater risk of infection.

8.9.2 POTENTIALLY TOXIC CHEMICALS
Compounds such as benzene, chloroform, and trichloroethylene can present potential risks to work-
ers at MSW composting facilities (Gillett, 1992). Certain solvents, paints, and cleaners contain
volatile organic carbon compounds (VOCs). The combination of forced aeration (or periodic turn-
ing in the case of window systems) and elevated temperatures serve to release VOCs from the com-
post pile into the local atmosphere.
To avoid worker exposure to VOCs, adequate ventilation is needed. Control technologies
developed for odor control also apply to VOC control. The best method of controlling VOC emis-
sions, however, is to limit their presence in the feedstock in the first place. Limiting MSW com-
posting to residential and high-quality commercial feedstocks, instituting source separation, and
implementing effective household hazardous waste collection programs will minimize the amount
of VOCs in MSW.

8.10 FACILITY SITING
As discussed, compost feedstock is originally derived from MSW and is therefore odoriferous. It is
thus logical and practical to locate a composting site in proximity to a solid waste transfer station,
landfill, wastewater treatment plant, or similar disposal facility in an area zoned for industry or com-
mercial use. Some of the major factors in facility siting include (U.S. EPA, 1994):

● Location to minimize hauling distances
● Adequate buffer between the facility and nearby residents
● Suitable site topography and soil characteristics
● Sufficient land area for the volume of material to be processed

Current federal guidelines prohibit siting any solid waste facility, including composting facili-
ties, within 10,000 ft of an airport. This is to prevent birds, which could be attracted to the site by
potential food sources, from interfering with airplanes (see Chapter 10).
Local residents may be concerned about potential odors and other nuisance conditions. Locating
a site with an extensive natural buffer zone, planted with trees and shrubs, is an effective way to
reduce such concerns. Artificial buffers might also need to be constructed. Visual screens such as
berms or landscaping can be installed to protect the aesthetics of the surroundings. Figure 8.12 shows
a suggested field plan for a large-scale composting facility.

8.10.1 TOPOGRAPHY
The composting site should be graded to avoid standing water, runoff and erosion. The land at a
composting site should be sloped at least 1% and ideally 2 to 4% (Rynk, 1992).
The type and structure of the soil present at the site should be assessed to control runon and
runoff. A firm base is preferred in order to capture and control liquids and prevent groundwater con-
tamination. If the site is unpaved, the soil should be permeable enough to ensure that excess water