EMERGING ORGANIC CONTAMINANTS OF CONCERN FROM LAND APPLICATION OF BIOSOLIDS

Recently, there has been concern as to the occurrence of several organic compounds in biosolids, that when land applied, may impact estuaries, surface waters and ground waters (National Research Council, 2002). The compounds of particular interest are:Brominated Diphenyl Ethers (BDEs) – flame retardantsNatural and synthetic estrogensSurfactantsPharmaceuticals and personal care productsBDEs are of concern because of their being persistent, bioaccumulators and potentially toxic. They are extensively used in polymers and textiles. There is little data on concentration in biosolids and potential fate in soils and the environment. They have been detected in coastal and estuarine environments.Natural and synthetic estrogens are released to the environment from humans, domestic livestock, wildlife and plants. It has been reported that these compounds are associated with abnormal physiological processes and reproductive impairment in animals, fish and birds. It has been suggested that sewage treatment plants may be discharging significant quantities into the environment. Degradation may be an important mechanism for their removal from the environment.Surfactants are present in detergent products, paints, pesticides, textiles, foods and personal care products. They are very abundant in biosolids and concentrations can range from 200 to 20,000 mg/kg dry weight. Certain compounds have been shown to be endocrine disruptors. The type of sewage sludge treatment strongly impacts their presence. When biosolids are land applied, some compounds may be rapidly biodegraded in soil. Others may be persistent and adsorbed on the organic matter with subsequent transport to groundwater.Pharmaceuticals have been detected in wastewater effluents. The concern is regarding antibiotics that could result in microbial resistance. Since most of these are water soluble, their potential to be accumulated in biosolids is low.Nitro and polycyclic musks are extensively used in personal care products such as fragrances, shampoos, detergents and cosmetics. Potential for liver tumors has been indicated. Sewage treatment can greatly reduce the concentration in wastewater. They have been found in sewage sludge and biosolids in very low concentrations. Data on their fate in soils and the environment is very limited.This paper will provide information on the occurrence in wastewater and biosolids and fate in the environment.