Humic Substances—Common Carriers of Micropollutants in Municipal Engineering

Abstract

Research over several years has shown that municipal engineering is an important source of humic substance formation (HS). Effluents from municipal landfills and digested sludge, due to high concentrations of organic pollutants, including HS and inorganic pollutants, are discharged to a biological treatment plant, where their largely non-biodegradable pollutants constitute a burden on the activated sludge and generate problems related to wastewater treatment. To demonstrate that humic substances, primarily soluble acids, are the carriers of micro-pollutants, their isolation was carried out from samples taken at different municipal management sites. The following analyses were performed: elemental composition, and the content of inorganic micropollutants, including heavy metals. In addition, the sorption affinity of pure HS to selected pharmaceuticals was investigated. The sorbed pharmaceuticals were Diclofenac and Estrone. HS commonly found in municipal engineering have been shown to be carriers of inorganic and organic micropollutants, including pharmaceuticals. Based on the study data, surface water’s primary source of micropollutants is treated municipal wastewater and fulvic acids are the transfer agent. To demonstrate the locations of HS occurrence within municipal engineering and the micropollutants they carry, their isolation was carried out from samples taken at different municipal management sites. Fulvic acids were studied due to their high mobility. Extraction was carried out according to the method recommended by the International Humic Substances Society (IHSS) with the author’s modification. The following analyses were performed: elemental composition (N, C, O, and H); the content of inorganic micropollutants, including heavy metals; and the IR spectrum. In addition, the sorption affinity of pure HS to selected pharmaceuticals was investigated. The sorbed pharmaceuticals were Diclofenac and Estrone. The study confirmed the occurrence of HS in municipal landfill effluents, activated sludge, excess and digested sludge effluents, and treated wastewater. At the same time, HS commonly found in municipal engineering have been shown to be carriers of inorganic and organic micropollutants, including pharmaceuticals.