Rodgers M, Healy M G, Mulqueen J
Department of Civil Engineering, National University of Ireland, Galway, Ireland.
Water Res. 2005 Sep;39(14):3279-86. doi: 10.1016/j.watres.2005.05.035.
The current practice of spray irrigation of dairy parlour wastewaters is laborious and time consuming. Intermittent sand filtration systems may offer an alternative to spray irrigation when designed to remove organic carbon, nitrogen, phosphorus, coliforms and viruses from such wastewaters to allow discharge of the final effluent directly into receiving waters without damage to the environment. In this study two instrumented stratified sand filter columns (0.425 and 0.9 m deep, and both 0.3 m in diameter) were intermittently loaded for 439 days with synthetic dairy parlour washings at a number of hydraulic and organic loading rates. At a biochemical oxygen demand (BOD) loading of 22 g m(-2) d(-1), over 92% of the BOD and suspended solids in the wastewater was removed in the two filters and nitrification was complete. The 0.9 m column had a sustained ability to adsorb the influent phosphorus during the study period; however, the phosphorus adsorption capacity of the 0.425 m column began to decrease after approximately 30 days. Biomass, comprising hydrated extracellular polymers (exopolymers) and living and dead cells, accumulated in the 0.9 m column; it was assessed by sodium bromide tracer studies and by variations in the sand volumetric water contents using time domain reflectometry (TDR). The biomass growth increased the retention time of the wastewater in the filter media, and occurred mainly at the top of the first sand layer. Intermittent stratified sand filters appear to offer an effective and sustainable treatment process for the removal of BOD from high-strength wastewaters, and for the complete nitrification of ammonium.
目前对挤奶厅废水进行喷灌的做法既费力又耗时。当设计间歇式砂滤系统用于去除此类废水中的有机碳、氮、磷、大肠菌群和病毒，以便将最终出水直接排放到受纳水体而不损害环境时，它可能是喷灌的一种替代方法。在本研究中，两个装有仪器的分层砂滤柱（深度分别为0.425米和0.9米，直径均为0.3米）以多种水力和有机负荷率，间歇加载合成挤奶厅冲洗废水达439天。在生化需氧量（BOD）负荷为22克/平方米·天的情况下，两个滤柱去除了废水中92%以上的BOD和悬浮固体，并且硝化作用完全。在研究期间，0.9米深的滤柱具有持续吸附进水磷的能力；然而，0.425米深的滤柱的磷吸附能力在大约30天后开始下降。通过溴化钠示踪研究以及使用时域反射仪（TDR）测量砂层体积含水量的变化，评估了由水合细胞外聚合物（胞外聚合物）以及活细胞和死细胞组成的生物量在0.9米深的滤柱中的积累情况。生物量的增长增加了废水在过滤介质中的停留时间，且主要发生在第一层砂的顶部。间歇式分层砂滤似乎为去除高强度废水中的BOD以及使铵完全硝化提供了一种有效且可持续的处理工艺。
