Abstract

Landfill leachates (LLs) is a complex, refectory and difficult to depurate liquid generated from sanitary landfills. It contains excessive levels of biodegradable and in particular non-biodegradable products (e.g. heavy metals, phenols, sulphide, plasticisers). LLs are among the effluents that may pose major environmental concerns, they can be a dangerous source of pollution e.g. due to infiltration into soil and underlying water. The biological refractory nature of LLs makes it necessary to search effective, alternative (other than biodegradation) methods to reduce the contaminant loading of these effluents.In this study, the role of the BDD anodes, with different content of boron and substrates such as silicone and niobium was evaluated in the removal of macropollutants and selected MPs from LLs. By-products formed during electrolysis have been identified, too. The investigations have shown that macropollutants removal efficiency increases with higher applied current density (but also the energetic costs do). The best anode substrate was Nb, yielding very positive pollutants reduction results (better than Si substrate). Moreover, this substrate was durable and resistant to damage. The highest efficiency of macropollutants removal was achieved at 100mA/cm2 current density by BDD 0.5k, Nb (COD= 97.1%, BOD20=93.8%, N-NH4+=62%, TN=29.3%) followed by BDD 10k, Nb (COD= 86.3%, BOD20=63.5%, N-NH4+=40%, TN=34.5%). BDD electrodes were also tested in terms of MPs removal. The obtained results indicate that the BDD10k/Nb anodic oxidation in 0.1 M phosphate buffer solution (pH 7.8) is able to degrade BPA with approximately 80% efficiency, diclofenac sodium with 60%, trimethoprim 96%, sulfamethoxazole 94%, PFOA 90% and PFOS 90%. It was preliminarily found that BDD 0.5k electrode is the most efficient at investigated MPs removal (e.g. BPA removal with 90% efficiency, diclofenac sodium with 85%). Formation of by-products during this process was also observed, e.g. m/z=243 and m/z=241 for BPA, m/z=264 for diclofenac sodium, m/z=284 and m/z =299 for sulfamethoxazole. It can be concluded that BDD/Nb is a promising material in wastewater treatment. The results confirmed high performance of BDD electrodes in pollutants removal from the studied matrixes, nevertheless this method still requires further optimization.

Authors (6)