Performance and Its Influencing Factors of a Zeolite Biofilter for Dilute Domestic Wastewater Treatment
沸石生物滤池处理低浓度生活污水的工艺性能及影响因素

To reuse dilute domestic wastewater in power plant region as the makeup of recirculating cooling water, a renovate reactor--zeolite media biological aerated filter (ZBAF) was developed. A pilot scale ZBAF of 0.2 m in diameter and 3 m in media height was tested to treat dilute domestic wastewater. The results showed that turbidity, BOD5, CODcr and NH4(+)-N in effluent was 3.2 NTU, 3.2 mg/L, 14.5 mg/L and 0.5 mg/L when the corresponding influent concentration was 59 NTU, 30 mg/L, 81 mg/L and 16 mg/L, respectively, under the conditions of t = 12 degrees C-17 degrees C, HRT = 1.4 h and gas/liquid = 4:1. The effluent quality met the water quality standards of the treated water reused for cooling water makeup. The removal rate of BOD5, COD and turbidity did not change much with the change of HRT and the ratio of gas to liquid, but NH4(+)-N removal rate changed greatly. The parameters along the depth of ZBAF showed that the biofilm phase was abundant in carbon-oxidation/nitrification(C/N) zone and simplex in nitrification (N) zone. Ciliate was plentiful in C/N zone. Biofilm in N zone was mainly consists of nitrifiers. The point that the number of ciliate decreased apparently was the boundary of the two zones.