一体化全程自养脱氮(CANON)工艺的效能及污泥特性

在氨氮浓度梯度升高的条件下,通过控制DO等方式在一体化CSTR反应器中实现了一体化全程自养脱氮(CANON—completely autotrophic nitrogen removal over nitrite).结果表明随进水氨氮浓度(76.05~583.93mg/L)的升高,系统的氨氮和总氮去除负荷逐渐提高,试验期间无亚硝态氮的积累,反应器后期在高氨氮进水下最高氨氮去除率84.4%,最高去除负荷0.42kg/(m3·d);最高总氮去除率72.0%,最高去除负荷0.35kg/(m3·d).污泥氧消耗速率实验得出好氧氨氧化菌的耗氧速率为169.46 mgO2/(gVSS·h)、硝酸化细菌的好氧速率为39.63 mgO2/(gVSS·h).采用总氮去除量和硝态氮产生量的比值(△TN /△NO3-)表征硝酸化反应对出水氨氮浓度的影响.试验进一步研究了反应器内污泥形态的变化,得出第102d的污泥粒径(86.36μm)比第30d(54.09μm)增加60%,污泥的SEM分析得出实验后期相对于前期污泥表面丝状菌减少,胞外聚合物增多.以上结果表明该反应器具备良好的造粒功能,有利于自养脱氮工艺的启动与稳定.

Performance and sludge characteristics of the CANON process

Completely autotrophic nitrogen removal over nitrite (CANON) has been regarded as an efficient and economical process for nitrogen removal from wastewater. The CANON process was successfully developed in an CSTR (Continuous Stirred-Tank Reactor) which was fed with synthetic wastewater and operated at 30°C and mean DO 0.27mg/L. The experiment lasted for 120 days. Under high ammonium influent, the highest ammonium removal efficiency was 84.4% and the maximum ammonia removal rate was 0.42kg/(m3·d), the highest total nitrogen removal efficiency was 72.0% and the maximum removal rate was 0.35kg/(m3·d). Rising ammonium concentration (76.05~583.93mg/L) in the influent caused the increase of ammonium (2.66~167.52mg/L), and no accumulation of nitrite was found in the reactor. In order to indicate the contribution of nitrifiers to the nitrate production, the ratio of total nitrogen removal and the amount of nitrate generated (△TN/△NO3-) was used. According to the OUR test experiment,the rate of oxygen consumption of the ammonia-oxidizing bacteria was 169.46 mgO2/(gVSS·h) while the rate of nitrite-oxidizing bacteria was 39.63 mgO2/(gVSS·h). Sludge particle size on day 102 (86.36μm) increased by 60% than the size on day 30 (54.09μm). Sludge SEM analysis showed filamentous bacteria decreased while extracellular polymeric substances increased on surface of sludge sample. The experimental results proved that the system had a certain granulation capability, which was beneficial to the start-up and improvement of autotrophic nitrogen removal.