Effect of microwave pretreatment on removal of triclosan during anaerobic digestion of wastewater treatment sludge

The effect of different microwave (MW) pretreatment on the removal of triclosan (TCS) was assessed in ten semi-continuous flow anaerobic digesters operated under thermophilic (TH) and mesophilic (MH) conditions at sludge retention times (SRTs) of 20, 12 and 6 days. The antimicrobial TCS was quantified in total and supernatant (liquid) phases of the digester influents and effluents. TCS occurred predominantly in the solid (sorbed) fraction of total phase. MW pretreatment was found to improve TCS removals at TH temperatures at the highest and lowest SRTs. Digesters pretreated with shorter holding time (1 min) achieved better TCS elimination under TH and MH conditions at the SRT of 6 d. Higher chemical oxygen demand and biopolymer solubilization was achieved at higher temperature/holding time combinations. Regarding methane production, MW final temperature was an important parameter under MH whereas holding time played a significant role under TH conditions.