Sewage sludge and solid residues from biogas production derived biochar as an effective bio-waste adsorbent of fulvic acids from water or wastewater

Due to environmental concern, direct utilization of sewage sludge or residues from biogas production is restricted. Conversion of problematic bio-wastes into biochars can be a very effective solution. In the presented study, the adsorption of fulvic acids onto series of biochars produced from bio-wastes such as sewage sludge, residues from biogas production, and plant (Miscanthus sp.) were performed to examine the behavior of biochars in the environment and interactions with fulvic acids as the representatives of dissolved organic matter. The results clearly indicate that the highest excess of fulvic acids, 93-96 mg g(-1), was chemisorbed onto biochar obtained specifically from sewage sludge. The mechanism of the adsorption was independent from applied biochar feedstock. Monolayer coverage was dominant onto all biochars. Generally, adsorption was assumed to be controlled by polar interactions between fulvic acids and the biochars or pre-adsorbed and residual fulvic acids molecules (which were dominant) and the strong pi-pi interactions. The obtained high values of the adsorption capacity of sewage sludge derived biochars confirmed that thermal treatment is a very effective tool of bio-waste management. (C) 2021 Elsevier Ltd. All rights reserved.

Automated summary

The study demonstrates that converting bio-wastes into biochars is an effective environmental solution with high adsorption capacity. By converting different types of bio-wastes into biochars, the adsorption behavior of fulvic acids can be effectively controlled. The results show that biochars derived from sewage sludge have the highest adsorption capacity for fulvic acids.