We have probably already read (and written) too much about the challenges of dealing with “forever chemicals” in drinking water and wastewater treatment. However, recent developments hold some hope for addressing forever chemicals in our drinking water and wastewater treatment and related sludge disposal.
Forever chemicals, formally known as PFAS (per- and poly-fluorinated substances), have commonly been used in coatings and consumer products to resist stains or heat and are also a component of firefighting foam. While the long-term health effects of PFAS are subject to debate and ongoing studies, the presence of PFAS in drinking water and treated wastewater has caused concern among regulators and in the regulated community, particularly its implications for new treatment requirements. While the EPA focuses on developing new regulations to address PFAS in drinking water, issues remain concerning how to dispose of the PFAS-laden waste left over from water and wastewater treatment without releasing it into the air or water.
Earlier this year, the Colorado School of Mines announced the development of an effective method to destroy PFAS through hydrothermal alkaline treatment (“HALT”). The method relies on very hot boiling sand, high pressure, and the addition of sodium hydroxide, commonly used in consumer products. 2023 has also seen the emergence of several other promising technologies to effectively destroy PFAS using a combination of heat, ultraviolet light, and common chemical additives
Technology to destroy PFAS remains in its infancy. Future applications show promise for reducing PFAS in land disposal, wastewater treatment, and our water supply. Historically, environmental regulation has effectively identified a problem, pushed aggressive regulatory goals, and let the technology market respond. This cycle looks like it is again on the verge of success.
The future development of effective means to destroy PFAS in wastewater and sludge may also help address another difficult issue: how to reclaim phosphorus from wastewater and sludge for agricultural land application. Phosphorous may be as necessary to agriculture as water and sunlight. Its misuse and overuse have depleted the world’s supply of phosphorous produced from limited sources and, according to reports, threatens the future ability to raise food crops to meet an ever-growing worldwide demand.
In recent years, some states, including Maine, have banned the use of sewage sludge left over from wastewater treatment for land application in agriculture due to PFAS content. The sludge also contains high concentrations of phosphorous, which is removed from treated wastewater before it is discharged to receiving waters. Particularly in river systems with restricted flow, added phosphorous enhances the growth of aquatic vegetation, promoting algae growth and dramatically reducing oxygen levels in rivers as it dies off, harming the river biology, fish, and wildlife.
With PFAS destroyed and thereby removed, phosphorous-rich wastewater treatment sludge may again become a critical resource for agricultural land application.
