[Performance stability of CANON reactor and temperature impact].

In order to study long-term effect of completely autotrophic nitrogen removal over nitrite (CANON) reactor, performance stability was investigated by using synthetic inorganic ammonia-rich wastewater as raw water with a continuous flow CANON reactor. Both performances of short-cut nitrification and ANAMMOX were stable for more than one year. Under the condition that inner temperature at 35 degrees C +/- 1 degrees C, pH 7.39 and 8.01, and hydraulic retention time 3.7-5.1 h, the average total nitrogen removal load was 1.8 kg x (m3 x d)(-1), and the average and maximum total nitrogen removal efficiency were 65.09% and 81.65% respectively. Under sudden low temperature conditions, both ANAMMOX bacteria and AOB were inhibited, however, the ANAMMOX bacteria were inhibited more, which caused highly accumulated nitrite. When temperature increased to 35 degrees C as normal, the performance of CANON reactor recovered soon, which means low temperature impact will have no significant influence on stability. When the temperature reached more than 50 degrees C, the activity of ANAMMOX bacteria was completely destroyed, so high temperature must be avoided, though AOB can recovered to normal in one week.

[Study of CANON process start-up under aerobic conditions].

The start-up of CANON process was studied to reveal adaptability and how to condense time of start-up with a lab-scale experiment. During start-up stage, temperature was controlled at 35 degrees C +/- 1 degrees C, pH was 7.39-8.01 and free ammonium was 2.89-12.37 mg x L(-1). Partial nitritation was first built up in 60th day and kept steady, nitrite accumulation rate (NO2(-) -N/NO(x) (-) -N) was up to 98%. In the 160th day, the reactor started to show effects of anaerobic ammonium oxidation, and in the 210th day, CANON process was started-up under aerobic conditions successfully, and total nitrogen removal load was 1.22 kg/(m3 x d) and 70% removal rate on average was attained. When using ammonium wastewater without organic carbon sources as influent, there are two signs to indicate the CANON start-up: first, nitrogen gas was produced in carriers; the other one was the ratio of total nitrogen loss and increased nitrate keep steady, and in this study average ratio was 8.61 compared to theoretical value 8.

[Partial nitrification of digested sludge liquor with low C/N and high-concentration ammonia].

The experimental system consisted of anoxic filter and aerobic suspended carrier biofilm reactor. The partial nitrification was achieved and maintained stably in the aerobic reactor under normal temperature (15-29 degrees C) and high DO (6-9 mg/L). The nitritation with 70%-80% nitrite accumulation efficiency was obtained when FA concentration was in the range of 1.0-10.3 mg/L by controlling influent ammonia loading rate (ALR), ratio of alkalinity and ammonia and HRT in the aerobic reactor. The effluent nitrite/ammonia ratio was about 1.25 when the average influent ammonia, influent ALR and influent ratio of alkalinity and ammonia were 315.80 mg/L, 0.43 kg/(m3 x d) and 5.25, respectively. So the effluent of partial nitrification process provided the influent substrate demand for the following ANAMMOX process. The integrative analysis indicated that the proper FA concentration was the main factor achieving the partial nitrification. The study developed a novel partial nitrification technology adapt to water characteristics of digested sludge liquor.

[Effects of Mn2+, Mo6+ and Zn2+ on the components change of extracellular polymeric substances in activated sludge].

By specific oxygen uptake rate, (SOUR) measurements of activated sludge with different metal ion concentration, the optimal stimulation concentrations of Mn2+, Mo6+ and Zn2+ were determined. Then within each metal ion stimulation concentration range, extracellular polymeric substances (EPS) were extracted from activated sludge and its components (protein, polysaccharide and nucleic acid) contents changes were investigated. The results showed that the optimal stimulation concentration of each metal ion is 1mg x L(-1). EPS components of activated sludge vary obviously with Mn2+ and Zn2+ concentration change but not with Mo6+. After storage at low temperature, EPS quantities in activated sludge are reduced with polysaccharide reduction is the most.