Biotechnology for odor control from sewage treatment plants

The odor generated from sewage treatment plants can cause nuisance to adjacent residents and contribute significantly to atmospheric pollution. Sources of odor from sewage treatment plants include wastewater collection system, wastewater treatment system and sludge handling system. Most of the odor generated are sulfur-based compounds, nitrogen-based compounds and volatile organic compounds including sulfide hydrogen, methyl mercaptan, dimethyl sulfide, ammonia, trimethyl amine, acetic acid and butyric acid. Compared with conventional physical-chemical technologies, biological technologies, such as biofilters, bioscrubbers and biotrickling filters, have been widely applied in sewage treatment plants for odor control owing to their efficiency, cost-effectiveness and environmental acceptability. The operational stability of conventional bioreactors is often hampered by acidification of the packing materials and reduction of removal efficiency. Besides, it is difficulty to remove all odorous compounds with different characteristics effectively at the same time by conventional bioreactors. To overcome these problems, new technologies such as low-pH bioreactor, two-stage bioreactor and combined-bioreactor have been developed.