Elimination of micropollutants from municipal wastewater by adsorption on powdered activated carbon and separation by innovative precoat filtration

Abstract

• PAC with smallest particle size ( x 50.3 = 10 µm) shows fastest adsorption kinetics. • The correlation of the UV 254 and trace substance removal is not given for powdered activated carbon made from coconut shells. • Background organic matter present in wastewater decreases trace substance removal. • Precoat filtration is a possible alternative for PAC separation. • A precoat of ≈ 0.5 kg∙m −2 cellulose to achieve a clear filtrate. Anthropogenic trace substances are residues from pharmaceuticals, detergents, care products and other areas of everyday use. Municipal wastewater treatment plants (WWTPs) are unable to remove these substances adequately and are therefore among the main emitters. The treatment of municipal wastewater with powdered activated carbon in combination with precoat filtration is a suitable downstream stage. Within the scope of this work, four powdered activated carbons (PACs) with different particle sizes in the range of 10–200 µm are compared (#1-#4). The sum parameters UV absorption at 254 nm (UVA 254 ), dissolved organic carbon (DOC), chemical oxygen demand (COD), as well as the analysis of seven trace substances, characterize the removal performance of the activated carbons. As result, only the PAC #4 with the smallest particle size ( x 50.3 ≈ 10 µm) shows a target-oriented reduction of the parameters from a concentration of 30 mg∙l −1 and a contact time of 30 min. The other carbons with higher particle size do not achieve sufficient removal rates. Due to the selectivity of the activated carbons towards trace substances, a correlation of trace substance removal is not given for every PAC. Besides, investigations on a continuously operated pressurized filter cell (PFC) for filtration of an activated carbon show the separation performance. A precoat of cellulose supplies the filtration process and can improve the backwashing application.