Insight into the application of biochars produced from wood residues for removing different fractions of dissolved organic material (DOM) from bio-treated wastewater

Abstract

The primary aim of this study was to conduct a comparative analysis of four distinct biochar types, which were derived from wood residues through varied production methods. To assess their efficacy in removing dissolved organic matter (DOM) from bio-treated wastewater, this study examines the capacity of these biochars to extract DOM fractions from wastewater sourced from landfill leachate. Three types of the biochar were raw gasification biochar , and gasification biochars activated with H2O and CO2 respectively. The other one was a pyrolytic biochar produced from wood residues. To evaluate the biochars’ performance in DOM removal, various wastewater DOM components were analyzed. The study found that the production method significantly impacted the biochars’ ability to remove DOM while the activation technique showed slight impact on the biochars’ performance in DOM removal. Activated gasification biochars exhibited superior DOM removal compared to pyrolytic biochar. 78% of the wastewater COD was removed by activated gasification biochars while the raw biochar only removed 48% of the COD, at 7 gL−1 of the biochars. Pyrolytic biochar could remove 64% of the wastewater COD at 7 gL−1 of the biochar and showed better fluorescent compounds adsorption. Further analysis revealed that pyrolytic biochar was more selective in removing higher molecular weight compounds. In contrast, activated gasification biochars removed compounds with a broad range of molecular weights. The biochars’ adsorption efficiency were attributed to changes in specific biochar characteristics, such as pore size distribution and changes in functional groups. This study suggests that the gasification biochars have great capability in DOM removal.