Using zeolite filters to reduce activated carbon use in micropollutant removal from wastewater

Micropollutants (MPs) are a wide group of human-made chemicals, such as pharmaceuticals and/or industrial compounds, with a negative impact on ecosystems. As they are discharged through water lines, they are a common presence in wastewater treatment plants (WWTPs). Among the known MPs removal treatments, adsorption-based processes are mostly used given their high MP removal capacity, although their production costs and environmental impact can be high. This is the case of powdered activated carbon (PAC), that remains nevertheless often the best option. Therefore, the optimization of PAC adsorption through the combination with natural zeolites is an interesting perspective. In this study, a combined approach made of zeolite-based filter and PAC to reduce water concentrations of eleven micropollutants is reported. The addition of a zeolite-based removal step increased the overall average removal by 14 % compared to 55 % obtained by the sole PAC adsorption. The combined zeolite-PAC process, by having higher removal efficiency allows a reduction in the use of PAC with interesting potential savings in costs and CO2 emissions. Also, a zeolite step before conventional PAC can ease the organic matter loading on the carbon, allowing for an improved recirculation in the biology tank, and can make the use of renewable sources-based PAC more appealing.