Advanced micropollutant and phosphorus removal with superfine powdered activated carbon and pile cloth media filtration

Organic micropollutants (OMP) are ubiquitous in aquatic ecosystems and have a proven negative impact on the environment and drinking water resources. To remove OMP from municipal wastewater, the use of superfine Powdered Activated Carbon (sPAC) (d₅₀ = 1.0 µm) compared to Powdered Activated Carbon (PAC) (d₅₀ = 30.1 µm) was tested in combination with Pile Cloth Media Filtration (PCMF). sPAC was produced by ball milling PAC to a d₅₀ of 1.0 µm. No difference was found between the grinding time or energy demand when grinding different raw materials. Different Pile Cloth Media (PCM) were investigated for sPAC retention. The Ultrafiber UF-10 demonstrated superior efficiency in removing sPAC and achieved a turbidity reduction of over 90 % and a total phosphorus concentration (TP) of 40 µg/L, outperforming Microfiber PES-14, which only achieved turbidity reductions of 50 - 80 % and TP concentrations of 80 µg/L. The contact time of sPAC and wastewater before the PCMF was between 0.5 and 8 min depending on the filter velocities (v_F) (1.0 - 9.0 m/h). A contact time < 2 min in front of the PCMF and 6 - 8 mg sPAC/L was necessary for over 80 % removal of OMP across the entire WWTP. Flocculation and coagulation of sPAC with iron(III)chloride was essential for sufficient sPAC removal with PCMF. With dosage of 150 - 500 mg Fe³⁺/g AC and the use of UF-10, a residual concentration of sPAC in the PCMF effluent of < 0.2 mg/L was achieved. The energy requirement of the process, including the grinding process of the sPAC production, was around 27 Wh/m³ (v_F = 5 m/h, sPAC = 10 mg/L).