Department of Civil and Environmental Engineering, National University of Kaohsiung, Nanzih District, Kaohsiung, Taiwan, ROC.
Water Environ Res. 2010 Jan;82(1):27-33. doi: 10.2175/106143009x447957.
This study investigated organic matter and nitrogen reduction and transformation mechanisms within a field-scale hybrid natural purification system. The system included an oxidation pond, two serial surface-flow wetlands with a cascade in between, and a subsurface-flow wetland receiving secondary treated dormitory sewage. The average biochemical oxygen demand (BOD) and chemical oxygen demand (COD) removal was 81 and 48%, respectively. Microbial degradation was the primary process contributing to organic reduction. Total Kjeldahl nitrogen (TKN) and ammonium decreased from 7.1 to 3.9 and 5.58 to 3.25 mg/L, respectively, within the surface-flow wetlands. The results indicated that nitrification occurred within the aerobic compartments. The nitrate levels continued to decrease from 1.26 to 1.07 mg/L, indicating nitrate reduction occurred in the surface-flow wetland. Total nitrogen decreased from 8.61 to 5.12 mg/L, equivalent to a 41% reduction, within the surface-flow wetlands. Results revealed that denitrification might concurrently occur in the compartment of surface-flow wetland. Total nitrogen continued to decrease from 5.12 to 3.99 mg/L within the anoxic subsurface-flow wetlands through denitrification transformation. The significant total nitrogen reduction observed was 65%. The predominant reduction of total nitrogen might take place within the sediment of surface flow and the subsurface-flow wetland where denitrification occurred. The microbial identification results also indicated that nitrification/denitrification might occur concurrently within the sediments of surface-flow wetlands. The results of this study show that hybrid wetland systems are a viable option for organic matter and nitrogen transformation and removal in tropical regions where tertiary wastewater systems are too costly or unable to operate. Treated water from these systems can comply with local surface water criteria rendering water for reuse and groundwater recharge.
本研究调查了田间规模混合自然净化系统中有机物和氮的还原和转化机制。该系统包括氧化塘、两个串联的表面流湿地，其间有一个级联，以及一个接收二级处理宿舍污水的地下流湿地。平均生化需氧量（BOD）和化学需氧量（COD）去除率分别为 81%和 48%。微生物降解是有机还原的主要过程。总凯氏氮（TKN）和铵分别从表面流湿地中的 7.1 降至 3.9 和 5.58 降至 3.25mg/L。结果表明，硝化作用发生在好氧隔室中。硝酸盐水平继续从 1.26 降至 1.07mg/L，表明硝酸盐还原发生在表面流湿地中。总氮从 8.61 降至 5.12mg/L，表面流湿地中总氮减少了 41%。结果表明，反硝化作用可能同时发生在表面流湿地隔室中。总氮通过反硝化转化继续从 5.12 降至 3.99mg/L，在缺氧地下流湿地中。总氮的显著减少量为 65%。总氮的主要还原可能发生在表面流和地下流湿地的沉积物中，反硝化作用发生在那里。微生物鉴定结果还表明，硝化/反硝化作用可能同时发生在表面流湿地的沉积物中。本研究结果表明，混合湿地系统是热带地区有机物和氮转化和去除的可行选择，在热带地区，三级废水系统成本过高或无法运行。这些系统处理的水可以符合当地地表水标准，用于再利用和地下水补给。
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