https://gaftp.epa.gov/ap42/ch02/s02/reference/ref_02c02s02.pdf
Sludge is not rendered totally inert by composting. The composting process is
considered complete when the product can be stored without giving
rise to nuisances such as odors, and when pathogenic organisms
have been reduced to a level such that the material can be
handled with minimum risk.
The aerobic reaction
provides heat for warming the windrows. This causes the air
to rise, producing a natural chimney effect. The rate of air
exchange can be regulated by controlling the porosity and
size of the windrow (2). The turning of the windrow also
introduces oxygen to the microorganisms.
BACKHUS self-propelled windrow turners are widely utilized in large-scale biosolids and sewage sludge composting. Florida biosolids composting in windrows
Each
windrow must be turned two or three times a day for the first
five days to mix the material completely, minimize odors, and
ens ure suf f ic ient oxygen trans fer. The sl udge is then turned
once a day for abou t 30 days, depending on weather condi tions.
Figure 12-5 shows a windrow being turned at Los Angeles
The forced air method provides for more flexible operation and
more precise control of oxygen and temperature conditions in
the pile than would be obtained with a windrow system. Since
composting times tend to be slightly shorter and anaerobic
condi tions can be more readily prevented, the risk of odors is
reduced.
Two distinct aerated static pile methods have been developed,
the individual aerated pile and the extended aerated pile.
The composting and
all other outdoor operations will take place on a concrete pad
which is easier to clean than a gravel base, prevents rocks from
mixing with the compost, and is a better year-round working
surface. The pad is sloped to allow runoff collection from the
compost piles. The runoff is recycled to the treatment plant to
provide protection for the surrounding land and streams.
The construction of composting plants has almost ceased in
European countries other than Sweden. Apparently most
operating plants have difficulties in marketing the compost
at a satisfactory price.
https://cwmi.css.cornell.edu/chapter2.pdf
https://www.biocompost.se/en/solutions/
“Hauling dewatered biosolids three times a day more than 80 miles was not financially viable, so we explored the possibility of in-vessel composting. Utilizing MSW to supply the carbon side of the composting equation is what led us to start our original plant.” An article in the August 2004 issue of BioCycle (“Expanding The Potential of In-Vessel Composting”) documents the evolution of the Pinetop-Lakeside plant, which started out with a used Eweson digester
https://www.biocycle.net/mixed-msw-composting-facilities-in-the-u-s/
frozen solid biosolids composting vid
https://popedouglasrecycle.com/glacial-ridge-compost-facility/
As a result, the addition of a biolayer cover was written into the EPA regulations governing the static composting of biosolids, and subsequently adopted into many state composting regulations concerning pathogen control. As biolayer covers became widespread, air quality regulators began to characterize them as pollution control devices; they appear in many air quality permits. During this evolution, equipment manufacturers such as ECS introduced a series of fabric covers to the market with claims of improving both the composting process and thermal and environmental control (especially control of odor and VOC’s).
https://compostsystems.com/compost-covers/
This acts as an insulation layer for pathogen destruction as well as a modest surface biofilter. Biolayer covers need to be at least 6 inches deep to function but are often required to be 12 inches in very cold climates and by some regulators.
Rynk, Robert et. al. The Composting Handbook: A how-to and why manual for farm, municipal, institutional, and commercial composters. 2022. Compost Research & Education Foundation.
https://www.youtube.com/watch?v=HZIsnzBnTKQ
https://www.biocompost.se/en/sustainability/
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