Pyrolysis: An Emerging Biosolids Treatment Process to Remove Trace Organic Contaminants

Increased public concern over the land application of biosolids due to the presence of TOrCs has sparked interest in alternative biosolids management strategies. One promising technology is pyrolysis, the thermal decomposition of organics under high temperatures in an anoxic environment. Pyrolysis has been demonstrated to remove organic contaminants such as PCB’s in lab-scale pyrolysis experiments of biosolids and contaminated sediment, yet the effect of pyrolysis on TOrCs has not been evaluated. In this experiment, tests were conducted to determine the effect of pyrolysis temperature and reaction time on TOrC removal from biosolids and to elucidate the behavior of the TOrCs within the pyrolysis system. Maximum pyrolysis temperature was observed to be an important parameter as individual TOrCs required different temperatures for removal to below quantification, yet the reaction time required for removal was similar between compounds. A fraction of the TOrCs partitioned to pyrolysis oil and their fate was linked to individual vapor pressure values. In summary, this work demonstrates that pyrolysis can be utilized as a biosolids management strategy that controls the discharge of TOrCs into the environment while producing the valuable, clean product, biochar, and renewable energy.