Grease enters municipal wastewater treatment plants from multiple sources including restaurants, households, and light industrial customers. The fats, oils & grease (FOG) cause problems from the source point all the way down to the outfall of the sewage treatment plant. Each impact is detailed below
Upon allowing grease to enter a drain, the grease begins to accumulate on drain lines. With severe buildup, grease can clog the line causing backups and slow drains. Even with moderate grease accumulation, the restaurants will have problems with odors and drain flies which breed on the grease in the lines. Without proper grease trap maintenance, go the store will have exterior odors and experience excessive grease carryover into municipal sewer lines.
Neighborhoods, shopping centers, and other areas of development are increasingly required to build storm water retention ponds to prevent downstream flooding and pollution from leaving the immediate area before treatment. Being relatively shallow with little mixing, these ponds often have problems related to (1) algae blooms, (2) odors, (3) oil sheen, and (4) solids buildup.
If operators considered the ponds as a small biological treatment unit rather than a "wide spot in the ditch", the problems listed above can be remedied with ease.
Lagoons treating waste water or storm water eventually build up organic solids that reduce hydraulic retention time, periodically washout solids in the effluent, and cause odors from H2S production. The primary quick way to remove solids is to mechanically dredge, dewater and landfill these solids. However, this is a big ticket event that many facilities do not have the budget to undertake. Over the years numerous additives and technologies have been proposed to enable microbes to break down organic sludge into carbon dioxide, water, and methane. None has proven particularly effective and dredging has remained the primary way to deal with sludge.
I have been monitoring new technologies for "biodredging" or biological sludge decomposition for years and evaluated numerous new technologies. To be successful, biological dredging requires the following:
Erik Rumbaugh has been involved in biological waste treatment for over 20 years. He has worked with industrial and municipal wastewater facilities to ensure optimal performance of their treatment systems. He is a founder of Aster Bio (www.asterbio.com) specializing in biological waste treatment.
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