Effects of organic matter in drinking water and wastewater on micropollutant adsorption to activated carbon

Summary

Improving the removal of micropollutants from wastewater effluent is crucial to protect surface water quality. This can be achieved by applying adsorption to granular activated carbon. However, activated carbon filters used for wastewater treatment have a shorter lifetime than filters used for drinking water production. It was assessed whether this is related exclusively to the higher organic matter concentration in wastewater effluent, compared to drinking water, or also to organic matter characteristics. Influent of activated carbon filters from a drinking water plant and wastewater effluent were used as organic matter sources, and their effect on micropollutant affinity for activated carbon and adsorption rate was compared at the same dissolved organic carbon concentrations. Organic matter characterization (excitation–emission matrices and parallel factor—PARAFAC—analysis) and fractionation methods, based on size and hydrophobicity, were combined to assess the relevance of specific components that affect micropollutant removal. The results show that both organic matter concentration and composition determine their effect on micropollutant affinity for activated carbon and adsorption rate. The affinity of micropollutants for activated carbon is more reduced in the presence of organic matter from wastewater effluent. Adsorption rate is lower in the presence of organic matter originating from drinking water plants at levels around 10 mg/L, compared to wastewater effluent. One PARAFAC component is more abundant in drinking water organic matter and is likely responsible for this effect. This knowledge supports the development of strategies to overcome bottlenecks on the application of activated carbon filters in water treatment.