Slurry phase biological treatment of latosol contaminated with phthalates, adipate, and alcohols

Abstract

This study evaluated the slurry phase biological treatment of a latosol, collected at a contaminated site from a plasticizers industry, containing high concentrations of alcohols, phthalates, and dioctyl adipate. The test was carried out in a bioreactor open to atmosphere with the sludge from the industrial wastewater treatment plant at 18–26°C during 120 days. The dynamics of the microbial populations during biodegradation were evaluated by polymerase chain reaction-denaturing gradient gel electrophoresis. The results suggested that the genera Pseudomonas and Gordonia polyisoprenivorans were the dominant populations until 30 days, Corynebacterium, between 30 and 90 days, and Corynebacterium and Gordonia polyisoprenivorans after 90 days. The addition of sludge and water in the reactor improved the phthalates and adipate bioavailability, initially present in the plasticized soil, and consequently, the pollutant’s removal efficiencies were above 90%. The 2-ethyl hexanoic acid, a toxic metabolite of di-2-ethylhexyl phthalate biodegradation, was completely degraded in 120 days. The most persistent pollutant was di-isodecyl phthalate, which has substituted the di-2-ethylhexyl phthalate nowadays. The pH and the temperature did not need to be corrected, which represents cost savings in soil remediation