Anaerobic Digestion for Environmental Processes
Pretreatment
Sludge Pretreatment
Anaerobic digestion has proved to be the most beneficial stabilization technique for its
volume reducing capabilities and its ability to create energy in the form of methane gas. This
process becomes most efficient when the sludge is pretreated before it enters the digester. In a
study done by Dynatech Scientific, Inc. for the New York State Energy Research and
Development Authority, they cite exposing the sludge to high temperatures for very short
retention times through the use of a steam injection rapid thermal reactor. The purpose of this
is to solubilize the particulate volatile organics present in the sludge thereby increasing its
biodegradability. They concluded that anaerobic digestion of untreated sludge results in the
destruction of approximately 40 percent of the volatile organics to methane and carbon dioxide
gas. In contrast, pretreated sludge achieves almost 75 percent destruction of volatile organics,
resulting in a greater production of methane gas. Their study also concluded that the
pretreatment process was both technically feasible and economically competitive to other
present pretreatment processes.
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