Tyrrel S F, Leeds-Harrison P B
Institute of Water and Environment, Cranfield University, Silsoe, Bedfordshire, MK45 4DT, UK.
Water Sci Technol. 2005;51(9):73-9.
"Dirty water", a wastewater produced on dairy farms, is typically disposed of by application to land with no prior treatment. Pollution can occur if the dirty water reaches a watercourse following an inadequate period of retention in the soil. This paper describes experiments using a novel, soil-based batch recirculation system for pre-treating dirty water prior to land application. Three polythene-lined, vegetated soil-based treatment planes (23 m long, 1 m wide, 0.25 m deep) were constructed. Each treatment plane was supplied with approximately 1 m3 of dirty water which was recirculated until a clear treatment pattern had emerged. Five batches were treated over a six-month period. The soil-based treatment system could typically be expected to achieve a 90% removal of key pollutants in approximately two weeks for BODs and NH4-N, and three weeks for MRP and total solids. An exponential trendline gave a good fit to the treatment curves for BOD5, NH4-N and MRP after the first day or two of batch treatment. The data for total solids removal were more variable. Treatment rates were sustained throughout the five runs for BOD5 and NH4-N, indicating no apparent effect of seasonal weather on the treatment process. The apparent progressive slowing of the MRP removal rate throughout the treatment of the five batches may have implications for the sustainable use of this technology for phosphorus control.
“脏水”是奶牛场产生的一种废水，通常未经预处理就直接用于农田灌溉。如果脏水在土壤中停留时间不足就流入水道，就可能造成污染。本文介绍了一项实验，该实验使用一种新型的基于土壤的间歇循环系统，在将脏水用于农田之前对其进行预处理。构建了三个内衬聚乙烯、植被覆盖的土壤处理平面（长23米、宽1米、深0.25米）。每个处理平面供应约1立方米的脏水，脏水进行循环，直到出现清晰的处理模式。在六个月的时间里处理了五批脏水。基于土壤的处理系统通常预计在大约两周内可去除90%的主要污染物，其中生化需氧量（BOD₅）和氨氮（NH₄-N）的去除时间为两周，溶解性活性磷（MRP）和总固体的去除时间为三周。在间歇处理的头一两天后，指数趋势线与BOD₅、NH₄-N和MRP的处理曲线拟合良好。总固体去除的数据变化更大。在五次运行中，BOD₅和NH₄-N的处理率保持稳定，表明季节性天气对处理过程没有明显影响。在处理五批脏水的过程中，MRP去除率明显逐渐放缓，这可能对该技术在控制磷方面的可持续利用产生影响。
