Biological Purification Of Odor In Municipal Wastewater Treatment Plant At Low Temperature

With the research of urban wastewater treatment plants in Shenyang, hydrogen sulfide(H2S) was the main one of waste gases. Because of high removal efficiency, low investment and operation cost, simple operation and no secondary pollution, biofiltration has been recognized as a most promising technology for the purification of odor gaseous pollutants. In this work, the performance of the biological purification system which was employed to remove H2 S waste gas with high load and high gas velocity at low temperature was investigated. At the same time, the characterics of packing materials during the operating periods were investigated to affect the removal efficiency of H2 S in biological purification system. Finally, the microorganisms in packing materials were measured.The biofilter was made by plexiglass and divided into upper, middle and lower segments. The height of each segment was 400 mm, and the inner diameter was 80 mm. The packing materials were made up by the mixture of PE and manure. bacteria from a sewage treatment plant was inoculated to the biofilter.At low temperature condition from-1 0C to 14.2 0C, H2 S had been removed for 91 days continuously by the biological purification system. A good performance of the biological purification system was obtained, and the elimination capacity was obtained from 4 g·m-3·h-1 to 776 g·m-3·h-1. In the upper section of the reactor, the high elimination capacity was 1872 g·m-3·h-1. In the experiment periods, packing materials was not compacted and p H of packing was maintained in the neutral range. The removal efficiency of H2 S was not affected by the accumulation of sulfate and the consumption of nitrogen. The performance of the biofilter was maintained in a high level and exhibited a strong long-term potential removal capability.The elimination capacity of H2 S with high load at low temperature conditions didn’t decrease significantly in biological purification system. With high gas velocity, the phenomenon of nitrogen nutrient deficiency appeared and the remove efficiency of the system was reduced. The removal efficiency of H2 S was 98% and 76%, respectively, with the inlet concentration of 3000 mg·m-3 and the empty bed residence time(EBRT) of biofilter of 20 s and 8.8 s when nitrogen nutrients(NH4Cl) was dosed into the biofilter. The compaction and clogging of packing materials were not appeared significantly. SO42-was the main metabolite. Acidification of packing materials appeared with the p H value of 3.78. However, the biological purification system could still maintain the stable performance.In the biofilter, the bacteria were the main species, and were more than fungus and actinomycetes. During this work, microorganisms in packing materials had a good adaptability to high load pollutant and acidic conditions.