Abatement of cadmium (Cd) contamination in sediment using tea waste biochar through meso-microcosm study

The effectiveness of biochar produced from used tea waste was investigated as a potential in-situ amendment for Cd immobilization using a study design based on sediment-water meso-microcosm with 14-days of incubation. The optimum condition for biochar production was evaluated as a function of size, pyrolysis temperature and time. The highest monolayer uptake capacity was found as 42.01 mg/g for selected tea biochar (TB). The TB was mixed with sediment at the ratios of 0%, 2.5%, 5%, and 10%. As compared to the control (0% TB dose), in TB treated sediments, mobile fraction of Cd in sediment was considerably reduced which ultimately decrease the amount of Cd uptake by biota. The efficiency of Cd immobilization increased with the amendment dosage. Overall, sediment treated with 10% TB led to a reduction of Cd by 67.7% in the exchangeable fraction. Additionally, uptake of Cd in mollusc tissue was successfully reduced by 83%, while in case of Eichhornia crassipes root and shoot 75% and 87%, correspondingly. The tea waste biochar had shown its potential to immobilize the Cd from contaminated sediment as an economically and feasible method of abatement. (C) 2018 Elsevier Ltd. All rights reserved.