Sequential chemical/biological oxidation of chlorendic acid Original Research Article

Chlorendic acid, a fire retardant, was subjected to sequential chemical/biological oxidation. Degradation of chlorendic acid was achieved by ozonation with chlorinated and non-chlorinated by-product production. The destruction of chlorendic acid and by-product distribution was a function of ozone contact time. After 450 min of ozonation, chlorendic acid and TOC removal percentages equaled 98% and 62.5%, respectively. When subject to 210 min of UV oxidation, chlorendic acid and TOC removal equaled 70 and 31%, respectively. With combined ozone/UV, near complete removal of chlorendic acid and TOC was achieved in 90 and 120 min, respectively. In biodegradation testing, chlorendic acid was not degradable. Biodegradation efficiency (DOC removal) of chlorendic acid ozonation by-products was a function of ozone contact time and approached 80%. Chlorendic acid UV oxidation products (210 min contact time) were poorly biodegraded. Ozone/UV oxidation products (40 min contact time) from chlorendic acid achieved 89% biodegradation. Biodegradation rates of chlorendic acid chemical oxidation by-products also were assessed. Based on the computed biokinetic values of biodegradation rates for the chemical oxidation products of chlorendic acid are sufficiently high to enable use of existing biological process infrastructure for treatment of chemical oxidation products.