Fate of Nonylphenol Compounds during Aerobic and Anaerobic Digestion of Sludge

This study investigated the aerobic and anaerobic digester performances when a toxic and endocrine disrupting substance nonylphenoldiethoxylate (NP2EO) was spiked into the digesters. The performances of digesters were measured by gas production and COD reduction in anaerobic and VS and COD reduction in aerobic systems. The results showed that the NP2EO spike did not influence the digester performance negatively. The only parameter affected was the methane formation, which showed an initial delay, but later towards the reactor termination, almost caught-up with the performance of control reactor. The analysis of the nonylphenol compounds indicated that the transformation of the parent compound in digesters was possible, with different reactions prevailing and end products dominating under aerobic and anaerobic conditions.