Method and reagents for treating materials contaminated with mercury, PFAS, or other contaminants

A method of reducing mercury leachability of mercury-contaminated solid material to below 0.2 mg/L, comprising:

• admixing the mercury-contaminated solid material with a sufficient dose of a reagent set comprising nitric or phosphoric acid, hydrogen peroxide, and activated carbon;
• and
• adding water in an amount of 5-10% by weight of the contaminated material, thereby forming a treated material that leaches mercury in an amount <0.2 mg/L, as measured in EPA Method 1311 (TCLP) extract.

A method of reducing PFAS leachability from biosolids formed at a sewage treatment plant, comprising:

• admixing the biosolids with a sufficient dose of a reagent set comprising nitric acid and activated carbon;
• and
• adding water in an amount up to 10% by weight of the contaminated material, thereby forming a treated material that leaches PFAS in an amount less than untreated biosolids, as measured in EPA Method 1311 (TCLP) extract.

A method of reducing the PFAS leachability of PFAS-contaminated soil, comprising:

• admixing the contaminated soil with a sufficient dose of a reagent set comprising (a) nitric acid and activated carbon, (b) nitric acid, hydrogen peroxide, and activated carbon, or (c) nitric acid, phosphoric acid, hydrogen peroxide, and activated carbon;
• and
• adding water in an amount of 5-10% by weight of the contaminated material, thereby forming a treated material that leaches less than 70 ng/L PFAS, as measured in EPA Method 1311 (TCLP) extract, EPA Method 1312 (SPLP) extract, or EPA modified Method 1312 extract, where the modification is use of deionized laboratory water extraction fluid.

A method of reducing the PFAS leachability of PFAS-contaminated soil, comprising:

• admixing the contaminated soil with a sufficient dose of a reagent set comprising (a) nitric acid and activated carbon, (b) nitric acid, hydrogen peroxide, and activated carbon, or (c) nitric acid, phosphoric acid, hydrogen peroxide, and activated carbon;
• and
• adding water in an amount of 5-10% by weight of the contaminated material and thereby forming a treated material that removes >40% of PFAS in a landfill leachate or contaminated groundwater that contacts treated material, as measured in EPA modified Method 1312 extract, where the modification is use of Subtitle D landfill leachate extraction fluid or contaminated groundwater extraction fluid.