Influence And Mechanism Of Plant Radial Oxygen Loss In Constructed Wetland Combined With Microbial Fuel Cell On Nitrobenzene Removal From Aqueous Solution

Nitrobenzene(NB)wastewater has bioaccumulation,and carcinogenic,teratogenic and mutagenic effects,which causes serious harm to humans and the environment.Based on the concept of sustainable wastewater treatment,it becomes a new goal to recycle wastewater.Constructed wetland coupled microbial fuel cell(CW-MFC)is a environment-friendly and energy-efficient technology,which can effectively combine the advantages of energy recovery by MFC and high efficient degradation of organic wastewater by CWs.Wetland plants play an important role in CW-MFC system.The radial oxygen loss(ROL)of plants can provide oxygen to the cathode region of MFC and improve the activity of aerobic microorganism,which is conducive to the degradation of NB.In this study,four reactors were constructed: M1(control),M2(Scirpus validus),M3(Typha orientalis)and M4(Iris pseudacorus),and the effects and mechanisms of ROL of three different plants simultaneously on NB wastewater and bioelectricity generation performance in CW-MFC were investigated.The main research contents and results are as follows:(1)The ROL and root biomass from wetland plants in M2,M3 and M4 had positive effect on NB wastewater compared with M1(p < 0.05).Scirpus validus exhibited higher tolerance to NB,had higher ROL and root biomass than Typha orientalis and Iris pseudacorus at 200 mg/L NB,which resulted in higher NB removal efficiency in M2 than the other three reactors.(2)When NB concentration was 200 mg/L,the M2 planted with Scirpus validus had high DO(2.57 ± 0.17 mg/L)and root biomass(16.42 ± 0.18 g/m2),which resulted in the highest NB removal efficiency(93.9%)and power density(19.5 mW/m2)as well as voltage(590 mV).(3)Wetland plant ROL could significantly improve the richness and evenness of the microbial community of the anode and cathode samples.High-throughput sequencing results suggested that EAB(e.g.,Ferruginibacter,Geobacter)and dominant NB-degrading bacteria(e.g.,Pseudomonas,Comamonas)could be enhanced in M2,M3 and M4,especially in M2 planted with Scirpus validus.Scirpus validus has a high tolerance to high concentrations of NB,which contributes to improve the NB wastewater treatment performance and power generation efficiency in CW-MFC system.