Study Of A/O-Biofilm Process Treat Coal Chemical High Strength Ammonia Wastewater

For protecting the East Route of South-to-North Water Transfer Project of China’s was carried out smoothly, protecting water quality safety and improving the discharge standard of industrial wastewater along the river. It is particularly necessary that we need to strictly control NanSi Lake basin water quality and the emissions of industrial enterprises.Pollutants of NanSi Lake basin mainly were the coal chemical industry, papermaking, food industry. Ammonia nitrogen and COD pollutants within the basin from coal chemical industry wastewater that contain the high ammonia nitrogen, low COD/N includes mainly low-quality carbon sources (difficult to use by biochemical). It is the key to solve this problem how to upgrade the poor quality coal chemical wastewater and meet the effluent emission national standard.This experiment was using A/O-biofilm system to complete lab test and a pilot. The A/O-biofilm system was constructed by adding polyurethane carriers as biological carrier into the aerobic section of conventional A/O process, which to immobilized microorganisms and enhance the A/O nitrogen removal performance.Laboratory test provide reference data for the pilot actual operation running. To determine the specific running the system programs meet the needs of the actual wastewater treatment. This test explored the temperature, reflux ratio, DO and HRT basic parameters of the entire system.Laboratory experimental data shows that temperature enormous influence on microbial activity, as well as the entire system. When the temperature is above20℃, the activity of suspended sludge and biofilm sludge is very good, ammonia nitrogen and COD removal rate remains more than95%and90%, respectively. But the temperature is below20℃, the suspended sludge activity is inhibited and biofilm activity has a stronger low-temperature resistance performance. Reflux ratio is an important influencing factor on ammonia and total nitrogen removal efficiency, when reflux ratio is200%, NH4+-N and TN removal efficient can reach95%and75%, respectively.DO permeate from the outside into inside of carrier, the formation of the oxygen concentration gradient directly affect the species distribution, such as nitrifying bacteria and denitrifying bacteria in the biofilm, thus affect the nitrification and denitrification and determine the processing performance of the entire system. When DO is4mg/l in laboratory test, ammonia nitrogen and COD treatment efficiency to achieve a good result, but the DO value is slightly higher in the pilot, which is about5-6mg/1. According to treatment efficient of the whole system, HRT needs to be adjusted with the COD and NH4+-N load. The system usually can complete the degradation in the24-48h, besides longer HRT can not get treatment efficient improvement.Experiments show that the process is able to overcome the traditional A/O process demand the constant pH, appropriate temperature, the great return flow and low efficient. This system could adjust and control sludge structure and the microbial healthy situation of activated sludge, then enhanced resistance performance on the low temperature and impacted Shock loading resistance, also reduced the sludge bulking and shortened the recovery time of microbial activity, improved the microbial utilization of low-quality carbon source in the wastewater and reduced the effluent nitrate concentration. This system achieves a great nitrogen removal efficient and be good at the industrial wastewater treatment real situation.The pilot system is stable and good running indicate that A/O-biofilm system has obvious advantages for treating coal chemical wastewater. The effluent COD and ammonia nitrogen can reach respectively60mg/1and10mg/1under the properly operating conditions, which meet South-to-North Water Transfer Project emission standards about the NanSi Lake basin. The project was expected to provide strong scientific support regulation and protect lake water quality safe through demonstration and promotion projects, which is able to promote the environment, economic, Sustainable social development and achieve economic restructuring and change the growth pattern of the NanSi lake basin to ensure the economic, social and environmental win-win situation.