Biodegradation of household chemicals in river water under untreated discharge conditions

Abstract

A series of batch die-away tests was conducted to evaluate the decay rates of MBAS and COD under conditions simulating untreated discharge. Under aerobic conditions, decay of MBAS was consistently faster than that of COD, and dilution into river water had no effect on either rate. Under strictly anaerobic conditions, neither MBAS nor COD decreased in concentration. Additional testing examined the fate of 14C-LAS and the results showed that LAS disappeared and was mineralized after a lag period. Half-lives were 8–10 hours for loss of parent and 11–12 hours for mineralization. Addition of 14C-LAS in sewage to systems previously exposed to raw sewage resulted in no lag and shorter half-lives. This work indicates that MBAS and LAS degrade more rapidly than COD, suggesting these materials would be at low levels once a stream had recovered from the addition of untreated sewage.