Biosolids Management

Portland Water District takes proactive steps to tackle PFAS-contaminated wastewater biosolids.

A regional solution is being developed to reduce or eliminate PFAS, so called “forever chemicals” from wastewater biosolids.

PWD is exploring options for an advanced regional facility to treat PFAS-contaminated biosolids. Solutions being explored include advanced thermal destruction technologies, such as pyrolysis and gasification, to safely and economically reduce or eliminate PFAS from biosolids.

At its four wastewater treatment facilities (WWTFs), PWD treats wastewater to produce clean water and biosolids. The clean water is released into receiving waters, and the biosolids are treated, then transported to landfills.

PWD is working with the environmental consulting firm Brown and Caldwell, which is developing a conceptual plan and vetting prospective technologies. One such solution under consideration is pyrolysis and gasification, the chemical decomposition of organic materials via heat application to produce fuel-rich off-gas and valuable, environmentally-safe biochar. By using thermal oxidation, the off-gas can be reused as the heat source or to generate power. In tandem, these processes can potentially destroy PFAS to alleviate concerns with biochar reuse or air emissions.