Simultaneous removal of heavy metals and bioelectricity generation in microbial fuel cell coupled with constructed wetland: an optimization study on substrate and plant types

Abstract

A microbial fuel cell coupled with constructed wetland (CW-MFC) was built to remove heavy metals (Zn and Ni) from sludge. The performance for the effects of substrates (granular activated carbon (GAC), ceramsite) and plants (Iris pseudacorus, Water hyacinth) towards the heavy metal treatment as well as electricity generation were systematically investigated. The CW-MFC systems possessed higher Zn and Ni removal e ciencies as compared to CW. The maximal removal rates of Zn (76.88%) and Ni (66.02%) were obtained in system CW-MFC based on GAC and Water hyacinth (GAC-and WH-CW-MFC). Correspondingly, the system produced the maximum voltage of 534.30 mV and power density of 70.86 mW•m -3 , respectively. Plant roots and electrodes contributed supremely to the removal of heavy metals, especially for GAC-and WH-CW-MFC systems. The coincident enrichment rates of Zn and Ni reached 21.10% and 26.04% for plant roots, 14.48% and 16.50% for electrodes, respectively. A majority of the heavy metals on the sludge surface were con rmed as Zn and Ni. Furthermore, the high-valence Zn and Ni were effectively reduced to low-valence or elemental metals. This study provides a theoretical guidance for the optimal construction of CW-MFC and the resource utilization of sludge containing heavy metals. Highlights a. Six lab-scaled CW-MFCs were constructed to remove Zn and Ni from sludge. b. GAC and Water hyacinth boosted the heavy metal removal and bioelectricity generation. c. High-valence Zn and Ni were effectively reduced to low-valence or elemental metals.d. The ndings may be extended to the treatment of refractory heavy metals from excess sludge.

RETRACTED: Treatment mechanism of hexavalent chromium wastewater in constructed wetland-microbial fuel cell coupling system

“…C is generated by exposure to small molecules in carbon dioxide, air, and water. The peak position of O is attributed to the high oxygen content of the system's cathode, and it is classified as the peak of surface chemisorption oxygen (Wang et al, 2022), and the other elements may exist in the form of oxides or hydroxides (Liu et al,…”

“…Because both CW and MFC can remove Cr in water, the redox gradient of the natural layering of the CW system is highly consistent with the operating conditions of MFC, thus providing the feasibility for the coupling of CW and MFC systems (Yadav et al, 2012). In recent years, the ability of constructed wetlandmicrobial fuel cell (CW-MFC) systems to provide low electricity while improving the treatment capacity of heavy metal wastewater has attracted considerable attention (Wang et al, 2022). A removal study of Pb(II) by CW-MFC displayed that the removal efficiency was up to 85% with a maximum power density of 7.432 mW m −3 (Zhao et al, 2020).…”

Reduction of hexavalent chromium using sulphonated polyether ether ketone as proton exchange membrane in microbial fuel cells

“…Researchers have started using MFCs to remove heavy metal contamination from water and soil through the cathodic reduction reaction 8–14 . One such heavy metal generating effluents are from tanneries.…”

“…7 Researchers have started using MFCs to remove heavy metal contamination from water and soil through the cathodic reduction reaction. [8][9][10][11][12][13][14] One such heavy metal generating effluents are from tanneries. Chrome tanning is indispensable in the leather making process because, the chromium salts speed up the tanning process, and the tanning can be done in less than a day.…”

Removal of Cr(vi) and p-chlorophenol and generation of electricity using constructed wetland-microbial fuel cells based on Leersia hexandra Swartz: p-chlorophenol concentration and hydraulic retention time effects

“…[9][10][11] Therefore, the combination of CW and MFC (CW-MFC) has been used to treat single pollutants. 12,13 Fang et al utilized CW-MFC to treat azo dyes at a power density of 11.8 mW m À2 , and the azo dye decolorization efficiency was 91.05%. 14 Studies also used other technologies such as biolm electrode reactor-MFC and photocatalytic-MFC to treat refractory organics and synchronize electricity generation.…”