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Urban storm water runoff can carry a wide range of contaminants, many of which exceed federal maximum contaminant levels, into surface water resources (e.g., rivers and lakes). The use of filtration systems has received greater attention for its potential to remove particulate matter and other contaminants. Biochar is expected to have excellent potential as an adsorbent or filter given its large surface area and microporous structure. This study evaluated the potential use of biochar as a filter media through a series of column experiments. A column with an inner diameter of 7 cm (2.75 in.) and a length of 61 cm (24 in.) using biochar as filter media was constructed to examine its effectiveness for the removal of mixed contaminants [total suspended solids (TSS), nutrients, heavy metals, polycyclic aromatic hydrocarbons (PAHs), and E. coli] from synthetic storm water. The results demonstrated that this filter reduced the TSS in the storm water effluent by an average of 86% and the concentrations of nitrate and phosphate by 86 and 47%, respectively. After filtration, the concentration of Cd, Cr, Cu, Pb, Ni, and Zn (heavy metals) decreased by 18, 19, 65, 75, 17, and 24%, respectively. The variation can be explained in terms of the chemical behavior of the different heavy metals as well as the properties of the biochar. Among the three PAHs tested, biochar successfully removed phenanthrene (almost 100% removal efficiency) and achieved 76% removal efficiency for naphthalene but resulted in no removal of benzo(a) pyrene; the average removal for the three PAHs was 68%. Biochar was not efficient in removing E. coli from storm water, and the concentration of almost 7,400 MPN=100 mL in the inflow was reduced to approximately 5,000 MPN=100 mL in the outflow, representing a mean removal efficiency of 27%. Overall, the biochar used in this study showed promise to be an effective filter media for the removal of selected contaminants from urban storm water runoff. However, additional research should be conducted using different types of biochars, produced from different feedstock and production conditions, to determine the most effective biochar that can simultaneously remove multiple contaminants from urban storm water. individual papers. This paper is part of the Journal of Environmental Engineering, © ASCE, ISSN 0733-9372/04014043 (10)/$25.00. © ASCE 04014043-1 J. Environ. Eng. © ASCE 04014043-2 J. Environ. Eng. © ASCE 04014043-3 J. Environ. Eng. © ASCE 04014043-4 J. Environ. Eng. © ASCE 04014043-5 J. Environ. Eng. © ASCE 04014043-8 J. Environ. Eng. © ASCE 04014043-9 J. Environ. Eng. © ASCE 04014043-10 J. Environ. Eng.

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No abstract

In recent years, several best management practices have been developed for the removal of different types of pollutants from stormwater runoff that lead to effective stormwater management. Filter materials that remove a wide range of contaminants have great potential for extensive use in filtration systems. In this study, four filter materials (calcite, zeolite, sand, and iron filings) were investigated for their adsorption and efficiency in the removal of nutrients and heavy metals when they exist individually versus when they co-exist. Laboratory batch experiments were conducted separately under individual and mixed contaminants conditions at different initial concentrations. Adsorption capacities varied under the individual and mixed contaminant conditions due to different removal mechanisms. Most filter materials showed lower removal efficiency under mixed contaminant conditions. In general, iron filings were found effective in the removal of nutrients and heavy metals simultaneously to the maximum levels. Freundlich and Langmuir isotherms were used to model the batch adsorption results and the former better fitted the experimental results. Overall, the results indicate that the filter materials used in this study have the potential to be effective media for the treatment of nutrients and heavy metals commonly found in urban stormwater runoff.