| Biological nitrogen removal (BNR) technology was always being regarded as the research development and application focus in the domestic and foreign wastewater treatment domain, and more and more new technics were devised in these years. The current research is focused on extra carbon sources and high-performance nitrogen removal technical due to the extra carbon sources significantly increased operating costs, and nitrification/denitrification unit required sedimentation tank respectively. However, lack understandings of the characteristics of the micro-organisms and the reaction mechanism of the efficient nitrogen removal technology, brought a certain amount of resistance to its practical applications. Therefore, how to solve the BNR problems of municipal sewage with the low temperature and low C/N was the key points of this research.The overall water quality of urban sewage of upper waters of the Yangtze Three Gorges Reservoir Region (TGRR) were in good condition, the effluent TN was out of standard occasionally, that was involved with deterioration of water quality, non-perfect drainage system, excessive discharge of industrial wastewater, rare low temperature weather and low C/N mainly. In view of this, the improvement measures of adding raw sewage, enhancing activated sludge performance in low temperature were proposed, both to overcome shortcomings of the high cost of adding methanol to run, large toxicity and to overcome practical of adding tofu wastewater and solid carbon source.A sewage treatment system of the region was one of systems that various factors were more comprehensive and advanced in the upper waters of the Yangtze TGRR, and was core content of drainage works of the zone. Research on that how to improve their biological nitrogen removal system for the protection of the upper waters of the Yangtze River TGRR water environment and maintain sustainable economic development of Chongqing had great significance.When the influent C/N was too low, the denitrification reaction would be inhibited because of lacking of carbon sources, and system-wide nitrogen and phosphorus removal would be affected. For this reason, the paper took the improvement measure of giving original sewage that use bio-degradable organic matter as carbon sources for denitrification. Temperature decrease had significant impacts on the adsorption properties of activated sludge, sedimentation properties, microbial growth and development, population composition and total aeration tank of oxygen transfer efficiency. The nitrification basically stopped under low temperature (≤10℃). To this end, this paper took the improvement measures that put up underwater mixing devices, increased the volume of anoxic zone where denitrification is and extended HRT in anoxic areas.After above-mentioned improvements for the sewage treatment system, expect that the TN concentration of effluent quality is in a significant reduction and the main effluent indicators of sewage treatment plant reach "Discharge standard of pollutants for municipal wastewater treatment plant"(GB18918-2002) Class A level standard. Removal rates of COD, BOD5, SS and TP are more than 90%. In the upper waters of the Yangtze River TRGG improvement measures of urban sewage TN removal have achieved the expected goals, effectively improved the sewage effluent quality. The improvement has played an important role for the water environment of the upper waters of the Yangtze River TRGG. |
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