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. 2024 Oct 9;29(19):4773.
doi: 10.3390/molecules29194773.

Effects of Hydraulic Retention Time on Removal of Cr (VI) and p-Chlorophenol and Electricity Generation in L. hexandra-Planted Constructed Wetland-Microbial Fuel Cell

Tangming Li  1 , Peiwen Yang  1 , Jun Yan  1 , Mouyixing Chen  1 , Shengxiong You  1 , Jiahuan Bai  1 , Guo Yu  1 , Habib Ullah  2 , Jihuan Chen  1 , Hua Lin  1   3
Affiliations

Effects of Hydraulic Retention Time on Removal of Cr (VI) and p-Chlorophenol and Electricity Generation in L. hexandra-Planted Constructed Wetland-Microbial Fuel Cell

Tangming Li et al. Molecules. .

Abstract

Hexavalent chromium (Cr (VI)) and para-chlorophenol (4-CP) are prevalent industrial wastewater contaminants that are recalcitrant to natural degradation and prone to migration in aquatic systems, thereby harming biological health and destabilizing ecosystems. Consequently, their removal is imperative. Compared to conventional chemical treatment methods, CW-MFC technology offers broader application potential. Leersia hexandra Swartz can enhance Cr (VI) and 4-CP absorption, thereby improving wastewater purification and electricity generation in CW-MFC systems. In this study, three CW-MFC reactors were designed with L. hexandra Swartz in distinct configurations, namely, stacked, multistage, and modular, to optimize the removal of Cr (VI) and 4-CP. By evaluating wastewater purification, electrochemical performance, and plant growth, the optimal influent hydraulic retention time (HRT) was determined. The results indicated that the modular configuration at an HRT of 5 days achieved superior removal rates and power generation. The modular configuration also supported the best growth of L. hexandra, with optimal photosynthetic parameters, and physiological and biochemical responses. These results underscore the potential of modular CW-MFC technology for effective detoxification of complex wastewater mixtures while concurrently generating electricity. Further research could significantly advance wastewater treatment and sustainable energy production, addressing water pollution, restoring aquatic ecosystems, and mitigating the hazards posed by Cr (VI) and 4-CP to water and human health.

Keywords: Leersia hexandra Swartz; configurations; constructed wetland–microbial fuel cell; electricity generation; hydraulic retention time; wastewater purification.

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Conflict of interest statement

The authors declare no conflict of interest.

Figures

Figure 1
Figure 1
NH4+−N and TN contents in the effluent of different CW-MFC system configurations. Different lowercase letters indicate significant differences between the treatments (p < 0.05).
Figure 2
Figure 2
Removal rates of COD and 4-CP in the effluent of different CW-MFC system configurations. Different lowercase letters indicate significant differences between the treatments (p < 0.05).
Figure 3
Figure 3
Removal rates of Cr (Ⅵ) and TCr in the effluent of different CW−MFC system configurations. Different lowercase letters indicate significant differences between the treatments (p < 0.05).
Figure 4
Figure 4
Voltage of different CW-MFC system configurations.
Figure 5
Figure 5
Power density curve of different CW-MFC system configurations. (a) CW-MFC-A; (b) CW-MFC-B; (c) CW-MFC-C.
Figure 6
Figure 6
Cathode and anode potential of different CW-MFC system configurations. (a) CW-MFC-A; (b) CW-MFC-B; (c) CW-MFC-C.
Figure 7
Figure 7
Plant height and biomass of L. hexandra. Different lowercase letters indicate significant differences between the treatments (p < 0.05).
Figure 8
Figure 8
Soluble protein, chlorophyll, and MDA contents in leaves of L. hexandra. Different lowercase letters indicate significant differences between the treatments (p < 0.05).
Figure 9
Figure 9
Photosynthesis parameters of leaves of L. hexandra. Different lowercase letters indicate significant differences between the treatments (p < 0.05).
Figure 10
Figure 10
The Cr uptake rate of L. hexandra. Different lowercase letters indicate significant differences between the treatments (p < 0.05).
Figure 11
Figure 11
Stereoscopic structure diagram of different CW−MFC system configurations. Note: the units in the figure are cm. (A) Stacked configuration; (B) multistage configuration; (C) modular configuration.
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