Abstract

Pharmaceuticals and heavy metals derived from point sources and non-point sources find their ways into water bodies. One of the important sources of such pollutants is wastewater or effluents from wastewater treatment plants. The presence of pharmaceuticals and heavy metals in the water bodies causes irreversible damages to flora, fauna and human health. Risk assessment plays a vital role in identifying the pollution intensity. The adsorption process is one of the most appropriate processes in eliminating such pollutants from wastewater. In this study, a fixed-bed column is used to verify the feasibility of using a novel biochar material to remove organic (pharmaceuticals) and inorganic (heavy metals) compounds. This study was conducted in 3 phases. In the first phase, the pollution intensity of pollutants in wastewater effluent was evaluated by risk assessment formulas. In the second phase, the impact of the initial concentration, flow rate and bed depth on the laboratory-scale adsorption column performance were investigated. In the third phase, the Adam-Bohart model was used to design the large-scale fixed-bed column. Moreover, the pollution intensity of pollutants was determined. The results clearly indicated that the presence of venlafaxine and heavy metals in wastewater effluent poses adverse effects on aquatic and marine organisms. The adsorption of venlafaxine, Ni, Pb and Cu on biochar in a laboratory-scale column was observed as well as in the larger-scale column. Increasing the initial concentration and bed depth along with decreasing the flow rate caused the adsorption capacity to be on the rise. The removal over 90% of venlafaxine, Ni, Pb and Cu was found at the breakthrough point where the adsorption capacity was increased from 0.8 to 5.4 mg/g for venlafaxine, from 1.92 to 18.24 µg/g for Ni, from 3.84 to 30.72 µg/g for Pb, and from 2.88 to 24 µg/g for Cu. The large-scale column, tested on real effluent at wastewater treatment plant, confirmed the feasibility of using biochar to eliminate 95% of venlafaxine and 90% of Ni, Pb and Cu at the breakthrough point. The adsorption capacity at the breakthrough point was 3051.406 ng/g for venlafaxine, 24.364 µg/g for Ni, 0.1296 µg/g for Pb, and 7.115 µg/g for Cu. The pollution intensity of venlafaxine, Ni, Pb and Cu to aquatic and marine organisms decreased from a high to low risk due to the utilization of novel biochar in the fixed-bed column.