木质框架土壤渗滤系统处理养猪废水厌氧消化液的效能

Efficiency of wood-chip-framework soil infiltration system in treating anaerobically digested swine wastewater

为处理高氨氮、低C/N比的养猪废水厌氧消化液,构建了具有缓释碳源特性的木质框架土壤渗滤系统(WFSI),并通过运行测试了进水浓度和表面水力负荷(SHL)对系统处理效能的影响。在SHL为0.2 m3·m-2·d-1条件下,当进水COD和NH+4-N平均浓度分别从152和175.5 mg·L-1提高到421和788.7 mg·L-1时,系统对COD的去除率从52.3%提高到61.2%,NH+4-N去除率从84.2%下降到61.5%,TN去除率从28.6%提高到了33.5%,NH+4-N和TN去除负荷分别达到了75.5和41.7 g·m-3·d-1。当SHL提高为0.32 m3·m-2·d-1时,系统仍能维持运行,但处理效能受到显著影响。在进水COD和NH+4-N分别为265和465 mg·L-1左右时,COD、NH+4-N及TN的去除率分别平均为56.5%、53.3%和20.9%。木质填料及其附着层形成的NH+4-N浓度梯度,可使系统承受较高的SHL的同时获得缓释碳源,并保护氨氧化细菌免受自由氨毒性。

A wood-chip-framework soil infiltrator（WFSI） with slow-release of carbon source was constructed and used to treat an anaerobically digested swine wastewater characterized with high NH＋4-N and low C/N ratio. Pollutant removal efficiency of the WFSI was investigated under various influent concentration and varying surface hydraulic load（SHL）. Under SHL of 0.2 m3·m-2·d-1, influent averaged COD and NH＋4-N increased from 152 and 175.5 mg·L-1 to 421 and 788.7 mg·L-1, respectively. The resultant COD, NH＋4-N and TN removal by the system was 52.3% to 61.2%, 84.2% to 61.5% and 28.6% to 33.5%, respectively. Meanwhile, NH＋4-N and TN removal loading reached 75.5 and 41.7 g·m-3·d-1, respectively. Though SHL was as high as 0.32 m3·m-2·d-1, the system still performed but its efficiency was remarkably influenced. When influent COD and NH＋4-N was around 265 and 465 mg·L-1, COD, NH＋4-N and TN removal was about 56.5%, 53.3% and 20.9%, respectively. The wood carrier observably worked as a slow-release carbon source, and protected the ammonia oxidizing bacteria from free ammonia toxicity due to the concentration gradient of NH＋4-N in the adhesive layers.