ENVIRONMENTAL IMPACTS OF WATER TREATMENT CHEMICALS AT INDUSTRIAL SAND MINES
Although no adverse human health effects are associated with the polyacrylamide polymer, adverse human health effects have been linked to an impurity called acrylamide, which is a monomer, or part of the polyacrylamide molecule used in the production of the anionic polyacrylamide flocculant. A very small amount of the monomer molecule is present in the raw chemical feedstock that remains unreacted in the polyacrylamide flocculant when it is mixed in the wash process used in the mine’s wet plant. The acrylamide monomer is highly soluble in water, and has poor adsorption to minerals and organic matter. Thus, the concentration of acrylamide that will exit the clarifier in the underflow slurry will equal the concentration of the process water that overflows the clarifier and is recycled in the process.
Studies dating back to 1979 have shown that the acrylamide monomer is biodegradable. Biodegradation rates vary with the availability of oxygen, temperature, concentration of acrylamide monomer, concentration of capable microorganisms, and whether the capable microbial community had previous exposure to acrylamide monomer. Sampling at several mines has indicated that acrylamide does degrade, as it has not been detected in groundwater to date.