The Study Of Influence Factors On Short-cut Nitrification Treating High Ammonia Wastewater

Dealing with wastewater under low C/N ratio especially industrial ammonium-rich wastewater, traditional nitrification denitrification process has insufficient carbon source and low efficiency of biological nitrogen removal.Short-cut Nitrification and Denitrification process is considered to be a more economic nitrogen removal method compared with traditional nitrification denitrification for its advantages, such as saving carbon resource and energy,shortening hydraulic residence time, and etc. As a pretreatment process of short-cut nitrification and denitrification, the short-cut nitrification has nitrate accumulation rate more than 50%. Influence factors of short-cut nitrification and nitrification process include temperature, influent ammonia nitrogen loading and sludge retention time(SRT), pH value, dissolved oxygen(DO), free ammonia(FA) and free nitrous acid(FNA)and ways of intermittent aeration. The short-cut nitrification is controlled by gradually increasing influent ammonia concentration and different ways of intermittent aeration that achieves an aerobic and hypoxic environment allernatively in a SBR operation cycle through the automatic control process innovatively,which inhibit the growth of NOB to make the enrichment of AOB, the short-cut nitrification realized. After that, it’s conducted in SBR for the feasibility study of short-cut nitrification denitrification under step-feeding, which will provide a reference for wastewater treatment. The main results were as follows:(1)The experiment is carried in the SBR reactor at room temperature(20~30 ℃) through gradually increasing the influent ammonia concentration for sludge domestication. When the influent ammonia concentration is 100 mg/L and 200 mg/L,ammonia is almost completely removed,but the nitrite accumulation did not appear.But when the influent ammonia concentration increases by 400 mg/L, after a period of acclimatization, ammonia removal is still incomplete, and nitrate accumulation rate more than 50 %, the short-cut nitrification is realized.(2)In the experiment with ammonia increased,trends in changes curve ofvarious forms nitrogen in a typical cycle is corresponding trends in changes curve of pH, DO and ORP. It once again verified that pH, DO and ORP value can indicate ammonia valley point, nitritation end points and control the nitration reaction time to gradually achieve short-cut nitrification. In the experiment with different intermittent aeration ways, the pH, the DO and ORP law clearly, which show the characteristics of alternating anaerobic aerobic.(3)In the experiment with different intermittent aeration ways, at the fourth phase, DO concentration range from 0 to 1.7 mg/L, ammonia removal rate 80%, the nitrite accumulation rate 95%, and good biomass growth and sedimentation performance. At this stage, the growth of AOB is promoted and AOB is guaranteed at a competitive advantage, but activity of NOB suffers from the dual suppression of FA and FNA.