St. Anthony Falls Laboratory, Department of Civil Engineering, University of Minnesota, 2 Third Ave SE, Minneapolis, MN 55414, USA.
Water Res. 2012 Jun 1;46(9):3032-42. doi: 10.1016/j.watres.2012.03.009. Epub 2012 Mar 14.
Most treatment practices for urban runoff capture pollutants such as phosphorus by either settling or filtration while dissolved phosphorus, typically as phosphates, is untreated. Dissolved phosphorus, however, represents an average 45% of total phosphorus in stormwater runoff and can be more than 95%. In this study, a new stormwater treatment technology to capture phosphate, called the Minnesota Filter, is introduced. The filter comprises iron filings mixed with sand and is tested for phosphate removal from synthetic stormwater. Results indicate that sand mixed with 5% iron filings captures an average of 88% phosphate for at least 200 m of treated depth, which is significantly greater than a sand filter without iron filings. Neither incorporation of iron filings into a sand filter nor capture of phosphates onto iron filings in column experiments had a significant effect on the hydraulic conductivity of the filter at mixtures of 5% or less iron by weight. Field applications with up to 10.7% iron were operated over 1 year without detrimental effects upon hydraulic conductivity. A model is applied and fit to column studies to predict the field performance of iron-enhanced sand filters. The model predictions are verified through the predicted performance of the filters in removing phosphates in field applications. Practical applications of the technology, both existing and proposed, are presented so stormwater managers can begin implementation.
大多数城市径流污染物处理方法，如磷，通过沉降或过滤来处理，而溶解态磷，通常以磷酸盐的形式，未得到处理。然而，溶解态磷占雨水径流水体总磷的平均 45%，有时甚至超过 95%。在本研究中，引入了一种新的雨水处理技术，即明尼苏达过滤器，用于捕获磷酸盐。该过滤器由铁粉与砂混合而成，并用于去除合成雨水中的磷酸盐。结果表明，混合 5%铁粉的砂至少可以处理 200 米的深度，平均去除 88%的磷酸盐，效果明显优于不含铁粉的砂滤器。在重量比为 5%或以下的混合物中，向砂滤器中添加铁粉或在柱实验中捕获磷酸盐对滤器的水力传导率均没有显著影响。在长达 1 年的时间内，对高达 10.7%铁含量的现场应用进行了操作，对水力传导率没有不利影响。该模型应用于柱研究，以预测铁增强砂滤器的现场性能。通过该模型对过滤器在现场应用中去除磷酸盐的性能进行预测，验证了模型的预测。本研究提出了该技术的实际应用，包括现有的和拟议中的应用，以便雨水管理者可以开始实施。
