Biodegradable organic matter and rapid-rate biofilter performance: A review.

Biodegradable organic matter (BOM), found in all surface waters, is a challenge for drinking water utilities because it can lead to distribution system bio-regrowth, react to form disinfection by-products, or be a specific compound of concern. A critical review of BOM (occurrence and oxidant effects) and rapid-rate biofiltration performance (preozonation, backwashing with an oxidant, empty bed contact time (EBCT) and temperature) was carried out. An extensive literature data analysis (n = 100) found total organic carbon (TOC) in nonozonated water is comprised of 20% (median) biodegradable organic carbon (BDOC) and 3% (median) assimilable organic carbon (AOC). For ozonated waters (n = 103), these values increased to 30% (median) BDOC and 9% (median) AOC. For all operation conditions (n = 117), biofilters (12 min average EBCT) removed 12% (median) of the influent TOC with higher removals for ozonated waters, 15% (median), compared to nonozonated waters, 10% (median). As temperature increased from ≤10 °C to ≥20 °C, TOC removal increased from 10% to 17% (median). This review demonstrates biofiltration can be an efficient treatment technology to remove a portion of the BOM from the filter influent and should be optimized to achieve maximum removal.