Optimizing Removal of Estrogenic Compounds in Biosolids: A Comparison of Anaerobic, Post-Aerobic, and Cambi Digestion Processes

Anaerobic digestion is a key treatment step during wastewater treatment because it is often the final significant solids treatment process prior to land application. Land application of biosolids is a vital practice for sustainable waste management; therefore, the presence of estrogenic compounds in biosolids is one concern to this practice. Three digestion processes were studied to determine the optimal method for removing these estrogenic micropollutants: mesophilic anaerobic digestion (MAD), MAD with a post-aerobic digestion phase, and thermal hydrolysis pretreatment followed by MAD. Specific estrogenic compounds were quantified via liquid chromatography/mass spectrometry and total estrogenicity was quantified using the yeast estrogen screen (YES) assay. MAD followed by post-aerobic digestion resulted in a significant reduction in estrogenicity.