A green approach for treatment of wastewater with manganese using wood ash

BACKGROUND In the circular economy context, the present article proposes a green technical solution by manganese ions adsorption on oak wood ash and the reuse of the new waste generated by the adsorption process as soil amendment. RESULTS The influence of the main process variables: pH, adsorbent dose and contact time was investigated for optimal manganese ions adsorption. The highest adsorption efficiency of the wood ash (more than 98%) was recorded at pH 6, adsorbent dose of 10 g L-1 and contact time 15 min. The ion adsorption process is best described by Langmuir isotherm and pseudo second-order kinetic model. Maximum adsorption capacity, 54.94 mg g(-1), is better than other adsorbent materials previously used for manganese adsorption. The exhausted wood ash, resulted after the manganese adsorption was used as soil amendment for barley crop, Hordeum vulgare L. The beneficial effect upon the studied plants was highlighted using the specific parameters: germination percent (up to 10% higher), plant average length (higher by 14-35%), biomass (up to 200%) and relative growth rate (higher by 6-12%) compared to those obtained for the control sample. CONCLUSION These results show that all the wastes involved have been used successfully and support the proposed eco-friendly technical solution for some industrial wastes management. (c) 2020 Society of Chemical Industry