竹炭/陶粒及组合填料BAF处理高氨氮沼液的挂膜启动效应

Start-Up Effect of Bamboo Charcoal/Ceramic Pellets and Combined Filler BAF on Treatment of High Ammonia Nitrogen Digestate

为研究竹炭/陶粒及组合填料曝气生物滤池(BAF)处理高氨氮沼液的启动特性,在水力停留时间为6 h,水温23.2~26.5℃,气水比5:1(DO 3~4 mg/L),进水NH_(4)^(+)-N浓度为33.1~222.3 mg/L,COD 42.5~242.3 mg/L的运行条件下,对比考察了竹炭BAF(Z-BAF)、陶粒BAF(T-BAF)和组合填料BAF(ZT-BAF)的生化特性、沿程变化和挂膜启动效应。结果表明,Z-BAF、T-BAF及ZT-BAF分别在26、18和13 d完成挂膜启动。挂膜期间,平均出水NH_(4)^(+)-N浓度分别为24.4、15.9及8.5 mg/L;平均出水COD分别为78.6、73.02和47.2 mg/L。通过检测不同运行天数BAF的沿程生化特性变化,发现挂膜24 d时,去除COD的异养菌主要集中在反应器下部,负责转化NH_(4)^(+)-N的自养菌主要集中在反应器中下部;在第24~40天,自养菌在与异养菌的竞争中逐步取得优势,逐步向反应器下部生长繁殖。电镜扫描分析确认了各反应器中的填料上附着生长良好的生物膜,且观察到相较于陶粒填料,竹炭填料表面具有更好生物膜生长特性。综上,ZT-BAF挂膜时间最短且对污染物去除效率最高,在高氨氮沼液负荷下,竹炭和陶粒作为组合填料更有利于提升BAF的挂膜启动性能。

The start-up characteristics of bamboo charcoal/ceramsite and combined filler biological aerated filter(BAF)for the treatment of high ammonia nitrogen digestate were investigated.The operating conditions were 6 h hydraulic retention time,23.2~26.5℃water temperature,5:1 gas to water ratio(DO 3~4 mg/L),and influent NH_(4)^(+)-N concentration of 33.1~222.3 mg/L and COD 42.5~242.3 mg/L.The biochemical characteristics,changes along the path and the start-up effect of bamboo charcoal BAF(Z-BAF),ceramsite BAF(T-BAF)and composite filler BAF(ZT-BAF)were compared.The results showed that Z-BAF,T-BAF and ZT-BAF completed biofilm formation at 26,18 and 13 d,respectively.During the biofilm formation period,the average effluent NH_(4)^(+)-N concentrations were 24.4,15.9 and 8.5 mg/L;the average effluent COD concentrations were 78.6,73.02 and 47.2 mg/L.By examining the changes of biochemical characteristics along the BAF at different operating days,it was found that the heterotrophic bacteria for COD removal were mainly concentrated in the lower part of the reactor at 24 d of biofilm formation,and the autotrophic bacteria for NH_(4)^(+)-N conversion were mainly concentrated in the middle and lower part of the reactor;from 24 d to 40 d,the autotrophic bacteria gradually gained advantages in the competition with the heterotrophic bacteria and gradually grew and multiplied in the lower part of the reactor.The scanning electron microscope analysis confirmed the good biofilm growth on the fillers in each reactor,and it was observed that the bamboo charcoal filler had better biofilm growth characteristics compared with the ceramsite filler.In conclusion,the ZT-BAF had the shortest biofilm time and the highest pollutant removal efficiency,and the combination of bamboo charcoal and ceramsite as fillers was more beneficial to enhance the biofilm initiation performance of the BAF under high ammonia-nitrogen digestate load.