3BER-S耦合脱氮系统运行特性研究

为了强化三维电极生物膜脱氮工艺(3BER)的脱氮效果,将3BER与硫自养反硝化技术耦合成3BER-S工艺,用于低碳氮比城市污水厂尾水的深度脱氮处理.与3BER对比研究结果表明,3BER-S工艺在TN去除率、系统pH平衡能力和NO2--N积累方面均优于3BER工艺;当进水C(NO3--N)= 35±2mg/L,TOC:N:P=10.7:10:1,pH=7.0~7.5时,3BER-S耦合工艺对TN和NO3--N的去除效率分别为85%和94%,分别比3BER高15%和10%;出水中NO2--N的浓度为3.04mg/L,比3BER低2mg/L.3BER-S中硫自养反硝化作用定量分析表明,硫自养脱氮作用在整个脱氮过程中所占比例为14.07%,单质硫的有效利用率达到79.5%,硫自养反硝化过程对稳定3BER-S系统出水pH值起重要作用.根据3BER-S中微生物基于反硝化细菌特异性基因nirS的克隆文库结果,系统中反硝化细菌都与β变形菌纲中的细菌有较高的同源性,其中61.41%的反硝化细菌属于陶厄氏菌属(Thauera);脱氮硫杆菌和嗜酸菌属(Acidovorax)分别占3.50%和19.30%.表明当碳源比较充足时,3BER-S工艺的脱氮作用主要以异养反硝化过程为主,以单质硫和氢为电子供体的自养反硝化脱氮作用也占有一定比例.

Study on the performance for a coupleddenitrifying systemof 3BER-S

To improve the denitrogenation effect of three-dimensional biofilm-electrode reactor (3BER), 3BER-S coupled system of 3BER and sulfur autotrophic denitrification technology has been applied for nitrate removal of simulated municipal wastewater treatment plant (WWTP) effluentwithlowcarbon-nitrogen ratio (C/N). Results of the comparative test between 3BER and 3BER-S indicated that 3BER-S was superior in TN removal efficiency, pH buffering and nitrite nitrogen accumulation. When TOC:TN:P = 10.7:10:1, C(NO3--N) = 35±2mg/L and pH=7.0~7.5 in the influent of the systems, the average total nitrogen and nitrate removal efficiency was about 85% and 94% for 3BER-S, which was 15% and 10% higher than 3BER respectively. And the average accumulation of nitrite nitrogen was 3.04mg/L for 3BER-S, which was 2mg/L lower than 3BER. The quantitative analysis of sulfur autotrophic denitrification process in 3BER-S showed that the effective availability of elemental sulfur was about 79.5%, and sulfur autotrophic denitrification process accounted 14.07 percent of whole denitrification process which played an important role in buffering pH of the coupled system. Based on the clone library of nitrite reductase genes (nirS) fragments, all the denitrifying bacteria in 3BER-S system showed a high similarity with Betaproteobacteria, in which Thauera, Thiobacillusdenitrificans and Acidovoraxhavea accounted for 61.41%, 3.50% and 19.30% respectively. Therefore when the organic carbon source was sufficient relatively in influent of 3BER-S, the heterotrophic denitrification process played the dominant role, as well ashydrogenotrophicand sulfur autotrophic denitrification processes owe a certainproportionin the system.