The Cambi Thermal Hydrolysis Process™ (THP) can be utilized as a pretreatment to anaerobic digestion (AD) of wastewater sludge, improving the efficiency of AD treatment and leading to an increased production of beneficially reusable biogas, among other benefits. While the sustainability of THP-AD has been demonstrated, limited studies have focused on the fate of endocrine disrupting compounds (EDCs) throughout the process. This research centers on the fate of antimicrobials and phthalic acid esters (PAEs) as well as their transformation products (TPs) during AD of sludge with and without THP pretreatment. Experiments were carried out for 22 days using sealed, constantly shaken 250 mL bottles maintained at 35°C. Preliminary results demonstrate that concentrations of triclosan (TCS) and triclocarban (TCC) steadily increased during both AD treatments. The TCS TP 2,4-dichlorophenol increased during AD at a rate of 0.060 d-1 without TH pretreatment and 0.078 d-1 with TH pretreatment. Three TCC dechlorination compounds and the TCS TP triclosan-o-sulfate were not detected above the limit of quantification. Samples are still being analyzed for methyltriclosan. Preliminary results indicate that the PAE di(2-ethylhexyl) phthalate (DEHP) fluctuated during the experiments, appear related to concentrations of its metabolite mono(2-ethylhexyl) phthalate, and was more steadily degraded without TH pretreatment. Diisononyl phthalate (DiNP) did not significantly change over 22 days. Its metabolite, monononyl phthalate, increased more rapidly after TH pretreatment (0.083 d-1) than without (0.063 d-1) but concentrations were an order of magnitude lower than DiNP. Benzyl butyl phthalate (BBP) levels decreased rapidly within the first 3 days (0.32 d-1) without TH pretreatment and remained steady afterwards while concentrations oscillated in samples pretreated via TH. Its metabolite, monobutyl phthalate, increased to levels &gt;10x BBP concentrations - likely due to degradation of other PAEs. This study indicates that TH pretreatment can have a varied effect on concentrations of these EDCs in sludge.

Influence of anaerobic digestion with and without thermal hydrolysis pretreatment on concentrations of endocrine disrupting compounds and their transformation products in wastewater sludge

255th National Meeting (2018)

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