Date of Award
McNamara, Patrick J.
Wastewater treatment processes are not designed to remove estrogenic micropollutants and therefore when wastewater biosolids are land applied estrogenic micropollutants are discharged to the environment. Release of estrogenic compounds has deleterious effects on the terrestrial environment. Public concern stemming from micropollutants may reduce the value of biosolids which are important to water resource reclamation facilities (WRRF) as by-products. The objective of this research was to evaluate pyrolysis, the partial decomposition of organic material in an oxygen-deprived system under high temperatures, as a sustainable solution to remove estrogenic compounds from biosolids while producing a useable soil conditioner called biochar. Batch pyrolysis was conducted at different temperatures (100-500°C) on anaerobically digested biosolids (ADB). Primary sludge (PS) and ADB samples were also collected from a WRRF to compare the estrogenicity of conventionally treated biosolids to pyrolyzed biosolids. These samples were extracted and analyzed via the yeast estrogen screen (YES) assay to quantify total estrogenicity. The YES assay utilizes a yeast strain, but the yeast is susceptible to toxicity from wastewater solids samples, causing estrogen response interference and test inaccuracy. Therefore, a cleanup method employing silica and alumina was developed and implemented prior to the YES assay to remove toxicity while maintaining estrogenicity. In the pyrolysis experiments, more than 95% of the estrogen equivalents were removed from biosolids at 400°C and higher temperatures. The biochar had significantly lower estrogenicity that PS and ADB. The lower estrogenicity in biochar could mean production of a more preferred product coming from WRRFs.