Sustainable upgrading of wastewater treatment plant through enhanced adsorption of micropollutants by waste-based biochar activated with in-situ emitted greenhouse gas

The current world's challenges concerning Sustainable Development Goals (SDG) have introduced new principles in environmental engineering. Wastewater treatment plant (WWTPs) is one of the most important parts of modern cities, which is no exception to following these principles. The daily production of a large amount of biosolids, greenhouse emissions, and the effluent quality concerning EMs have made the wastewater treatment plant the center of attention. Consequently, providing solutions for sustainable upgrading of the wastewater treatment plant is of great importance. Emerging micropollutants (EMs), including pharmaceuticals compounds, personal care products, and metals, have been continuously released into aquatic systems due to their lack of removal from the effluents in conventional wastewater treatment plants. Subsequently, these EMs require advanced treatment such as sorption to decrease their harmful effects on human health and the environment. Adsorbing material is expected to adhere to as many sustainable development standards as feasible. This study investigated the preparation of biochar adsorbent from in-situ produced biosolids and industrial waste, which performance was enhanced with CO2 generated at the same WWTP. Designing parameters and optimum operation conditions for scaling up the filtration system are determined by setting pilot adsorption column experiments in three stages. In the first stage, adsorptive material preparation was optimized using three different methods. In the second stage, a series of batch tests was conducted to achieve the highest efficiency of pharmaceutical compound adsorption. In stage three, the fixed-bed column was designed to verify the performance of prepared adsorptive material under continuous flow conditions to determine designing parameters for scaling up the system. Then, the removal of micro & micropollutants was investigated in the pilot system. The designed system successfully removed 96.8% of SMX as a ubiquitous pharmaceutical compound in aquatics systems. Furthermore, metals such as Cr, Mn, Zn, and Pb were removed by 20.2%, 69.9%, 53.2%, and 28.7%, respectively. Additionally, chloride, nitrite, nitrate, ammonia, bromide, phosphate, sulfate, sodium, calcium, and magnesium were eliminated by 22.42%, 23.36%, 30.29%, 34.5%, 99.5%, 27.12%, 22%, 14.96%, 36.94%, and 64.56%, respectively. Moreover, the metals usually present in biosolids were also reduced. Scanning Electron Microscopy and Energy Dispersive X-Ray Spectroscopy (SEM & EDX) showed that waste-based biochar, formulated using an optimal method, demonstrated specific high porosity with the spherical structure that increased its adsorption capacity. The production of waste-base biochar upgraded with GHG might be conducted on-site in WWTP, where it can be used for the effluent filtration before its discharge to a receptor