Application of circular economy in wastewater treatment using biochar based adsorbent derived from sewage sludge

Abstract

The Circular Economy intends to reuse wastewater and recover resources and energy from the sludge in the wastewater sector. The conversion of sewage sludge into biochar by pyrolysis technique is a sustainable, environmentally friendly option for sewage sludge management. In the current work, biochar was produced by co-pyrolyzing sewage sludge and coconut shell, and it was then utilized as an adsorbent to eliminate methylene blue (the model pollutant) from wastewater. The sewage sludge is abundant in functional groups and metal ions, and the addition of coconut shells increased the porosity of the adsorbent. The biochar produced by mixing coconut shell and sewage sludge in the ratio1:1 showed higher adsorption capacity compared to biochar obtained from pure sewage sludge; hence the co-pyrolyzed biochar was used for further studies. The morphology and functional groups present on biochar were examined using SEM and FTIR analysis. The kinetics and mechanism of methylene blue adsorption was adequately explained by the pseudo-second-order kinetic model. Using the Langmuir isotherm model, the maximal adsorption capacity of the methylene blue dye on biochar was observed to be 31.64 mg/g. © Published under licence by IOP Publishing Ltd.