Q1 What are biosolids?
Person Biosolids are the treated residuals removed during the treatment of sanitary wastewater at public wastewater treatment facilities that can be beneficially reused provided a number of requirements and safeguards are met. State and federal agencies have developed these requirements based on extensive risk assessments, developed to assure the practice is both protective of public health and the environment. Biosolids can contain persistent chemicals like PFAS (per-and polyfluoroalkyl substances), a family of man-made chemicals used for their water- and stain-resistant qualities in products like clothing and carpet, nonstick cookware, packaging and firefighting foam. Unfortunately, PFAS was not included in the original risk assessments of biosolids conducted by the Environmental Protection Agency (EPA).
Q2 What are the dangers of PFAS?
Person Research has linked PFAS to health problems including kidney and testicular cancer, liver and thyroid problems, reproductive problems, pregnancy-induced high blood pressure, low birthweight, and increased risk of birth defects, among others (ehn.org). Because of its widespread use over many decades, PFAS is ubiquitous in the environment and in our daily lives. It's present in everyday items like packaging, cosmetics and the dust in our homes. Determining its level of concern must begin with a thorough risk assessment to determine safe concentrations.
Q3 How are wastewater treatment facilities and public utilities now managing their systems and water quality to reduce PFAS?
Person With mounting concerns over PFAS, state and federal agencies and public utilities are working to better understand and quantify these concerns about biosolids. EPA has begun the process of conducting an extensive risk assessment of PFAS in biosolids which is expected to be completed by 2024. Until then, many states are taking approaches to both quantify concentrations in biosolids and utilities are taking source reductions measures to eliminate significant sources entering the collection system. Source reduction has proven to be successful in removing PFAS from ending up in the wastewater effluent or in biosolids.
Q4 How do current treatment technologies compare to biochar’s effectiveness in reducing PFAS levels?
Person Activated carbons and anion-exchange resins are commonly used as adsorbents to reduce PFAS levels in water. Biochars, particularly those with activation processes and surface modifications, could be excellent adsorbents to remove PFAS from water. These are still undergoing research work. The goal is to reach the sorption capability comparable to activated carbons.
Q5 What is the latest research on biochar’s ability to help reduce PFAS-contaminated biosolids?
Person Biochars or modified biochars could be good adsorbents to sequester PFAS from biosolids.They could provide a quick and less-costly solution. Some research recently demonstrated that PFAS was removed from biosolids using pyrolysis and gasification processes. But there is concern over the energy cost and creation of other types of PFAS during the treatment.
Q6 What do you think the future holds for biochar as a PFAS treatment?
Person Biochar could be developed into strong and selective adsorbents targeting the sorption and sequestration of PFAS. This could reduce its harmful impact on humans and other biota. The remaining question is how to treat the PFAS sequestered in the biochars. Fortunately, several research teams are currently working the approaches to destroy PFAS sorbed on charcoal materials.