Mineralization of organic contaminants in sludge-soil mixtures

The mineralization of C-14-labeled linear alkylbenzene sulfonate (LAS), non ylphenol (NP), nonylphenol-di-ethoxylate (NP2EO), di-(2-ethylhexyl)phthalat e (DEHP), pyrene, and 1,4-dichlorobenzene (DCB) was investigated in differe nt sludge-soil mixtures and soils. Under aerobic conditions, the mineraliza tion of LAS, NP, and NP2EO was between 50 and 81% of the added amounts afte r two months, while DEHP and pyrene were mineralized more slowly. The miner alization of the model chemicals was indirectly affected by the amount of s ludge in the test mixtures. A higher content of sludge in the mixtures redu ced the overall concentration of oxygen, which resulted in a decrease of th e mineralization of several of the model chemicals. In sludge-soil mixtures with predominantly anaerobic conditions, the mineralization was slower for all of the chemicals with the exception of DEHP and DCB. The mineralizatio n of DCB was enhanced in mixtures with a high sludge content. No pronounced difference in the mineralization of the model chemicals (except DEHP) was observed when the sludge was mixed with three, different agricultural soils .