The effect of various pre-treatment

The effect of various pre-treatment methods, including alkaline hydrolysis (AH), thermal hydrolysis (TH),
thermal alkaline hydrolysis (TAH), thermal oxidation (TO) and thermal alkaline oxidation (TAO), on solubilization
and simultaneous degradation of bisphenol A (BPA), an endocrine disruptor, in wastewater
sludge (WWS) were investigated. The results showed that among AH, TH and TAH pre-treatments, TAH
significantly improved the solubilization of WWS (41.6% suspended solid (SS), 70.7% volatile suspended
solid (VSS) and 48.5% chemical oxygen demand (COD)) with higher degradation of BPA (38.4%). SS, VSS
and COD solubilization were observed to be lower in TO and TAO pre-treatment as compared to TAH
pre-treatment. However, higher degradation of BPA (75.0% and 78.9%) was observed in TO and TAO
pre-treatment due to the presence of oxidation process. The effects of rheology and zeta potential on
degradation of BPA in raw sludge and different pre-treated sludges were also investigated. The results
showed that decrease in viscosity and particle size and increase in zeta potential resulted in higher degradation
of BPA. BPA degradation by laccases produced by Sinorhizobium meliloti in raw and pre-treated
sludge was also determined. Higher activity of laccases (230.9UL−1) was observed in TAH pre-treated
sludge resulting in high degradation of BPA (21.9%) suggesting concomitant biological degradation of
BPA.