Application of co-immobilized microbial biochar beads in hybrid biofilter towards effective treatment of chrome tanning wastewater

Deepa, Arukula; Sonal, Sonalika; Mishra, Brijesh Kumar

doi:10.1016/j.jwpe.2022.102821

Cited by 7 publications

(1 citation statement)

References 71 publications

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“…Several separation techniques for the removal of Cr (VI) substances from contaminated groundwater and wastewater were reported in the literature [15][16][17][18], for instance, activated carbon filtration (ACF), reduction/coagulation/filtration (RCF) with iron (II) salts, membrane filtration, ion exchange and electrochemical treatment. Recent studies on the removal of Cr (VI) from industrial wastewater using new adsorbents based on biomass wastes, microalgae and co-immobilized microbial biochar beads were reported in the literature [19][20][21]. Moreover, recent review articles on advances in separation technologies for Cr (VI) removal were reported [22][23][24].…”

Section: Introductionmentioning

confidence: 99%

Removal of Chromium Species from Low-Contaminated Raw Water by Different Drinking Water Treatment Processes

Konradt¹,

Dillmann²,

Becker³

et al. 2023

Water

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The occurrence of Cr (VI) in drinking water resources in low but toxicologically relevant concentrations requires the development of reliable and industrially applicable separation processes in drinking water treatment. There is little information in the literature on the removal of chromium species at concentrations below 10 µg/L. Therefore, in this study, the removal of chromium in the concentration range ≤ 10 µg/L was investigated using three separation processes, activated carbon filtration (ACF), reduction/coagulation/filtration (RCF) and low-pressure reverse osmosis (LPRO), in both laboratory- and pilot-scale tests. In ACF treatment, Cr (III) was removed by deep bed filtration over 1.5 m of anthracite at a pH of 7.5 (which was used as a prefilter prior to ACF), while Cr (VI) was removed up to 75% via ACF at a filter bed depth of 2.5 m. Fresh activated carbon (AC) exhibited the highest adsorption capacity for Cr (VI), while reactivated AC had a significantly lower capacity for Cr (VI), which was attributed to calcium and iron deposits. In technical filters, where multiple reactivated activated carbon is used, this led to a low removal rate for Cr (VI). Using the RCF process with Fe (II) dosing in a continuous flow reactor at a specific coagulant dosing ratio, high Cr (VI) removal, down to a concentration of 0.1 µg/L, was achieved within minutes. The subsequent anthracite filtration ensured the complete removal of Fe (III) and Cr (III) precipitates. The RCF process was limited by the oxygen side reaction with Fe (II), which dominated at Cr (VI) concentrations below 1 µg/L. In addition, a four-step LPRO process with concentrate recycling showed effective removal (>99%) of both Cr (III) and Cr (VI) species in raw water as well as a negligible effect of pH in the testing pH range of 5.6 to 8.3 on the Cr (VI) removal. Nevertheless, the water hardness and pH of the LPRO permeate must be increased to make it available as drinking water. The three separation processes were found to be able to meet the expected more stringent future regulations for Cr (VI) level in drinking water. The most suitable technology, however, can be selected with respect to the raw water quality/characteristics, site-specific conditions and the already existing equipment.

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