TREATING ORGANIC POLLUTANTS IN URBAN RUNOFF USING CONTROLLED-RELEASE SYSTEM AND ADVANCED OXIDATION PROCESSES

Storm runoff may contain pollutants of all kinds, and is considered as a leading contributor to non-point source (NPS) pollution in urban watersheds. Despite development of best management practices (BMPs), treating urban NPS pollution remains a challenge due to prevalent sources and first flush phenomenon. Development of a novel technology that can effectively reduce NPS pollutants in urban runoff is warranted.

Oxidation of MTBE and BTEX, common organic pollutants in urban runoff, by five advanced oxidation processes (AOPs) coupled with controlled-release system (CRS) was investigated: sodium persulfate alone (SP), sodium persulfate activated by ferrous ion (SP/Fe) or hydrogen peroxide (SP/HP), persulfate activated by hydrogen peroxide and ferrous ion (SP/HP/Fe), and hydrogen peroxide activated by ferrous ion (HP/Fe). The CRS forms (CRS-HP, CRS-SP, and CRS-Fe) were manufactured by mixing paraffin wax and oxidant salts in specially designed cylindrical molds. Release kinetics and durations of the CRS forms with variable compositions were characterized using column tests and numerical modeling.

Of the five AOPs, SP/Fe, SP/HP/Fe, and HP/Fe showed higher degradation efficiencies for BTEX and MTBE, with 80% and 20% degradation within 10 min, respectively. Column test and modeling data indicated that the CRS-HP and CRS-SP forms continuously released oxidants at 10 mg/hr and 20 mg/hr for the testing period of 15 days and the durations of these CRS forms can be tailored to be months to years. Further facilitating the removal efficiencies of the CRS forms would provide a novel efficient option for efficiently treating organic pollutants in urban storm runoff.