| Microbial fuel cell(MFC)can realize biological power generation and resource recovery while treating wastewater.However,there are relatively few researches on the use of MFC in the treatment of coking wastewater and other practically difficult-to-degrade industrial wastewater.This is because when industrial wastewater is used as a substrate for MFC,the refractory organics usually have strong toxicity and hydrophobicity,which affects the operation of the system and restricts the application of MFC in industrial wastewater treatment.Low-molecular-weight carbon sources such as sodium acetate can alleviate the toxicity of difficult-to-degrade organics in wastewater.At the same time,surfactants are amphiphilic,which can improve the bio-accessibility of hydrophobic organics and enhance the removal effect of organics and power generation performance of MFC system.In this paper,sodium acetate and surfactants were added to the MFC system to enhance the removal of pollutants in coking wastewater,and the mechanism of action of sodium acetate and surfactants in the treatment of coking wastewater was discussed.The specific research content includes:(1)In order to alleviate the toxicity of organic matter in coking wastewater,sodium acetate was selected as the co-metabolism carbon source,and the effect of sodium acetate on the performance of MFC treatment of coking wastewater and its mechanism of action were studied.The results showed that the addition of sodium acetate improved the degradation efficiency of organic matter in coking wastewater and the electricity generation performance of MFC.MFC effluent TOC removal rate increased from 55.1% to 66.2%,TN removal rate increased from 38.8% to 42.7%,output voltage increased from 109.08 m V to 251.82 m V,and power density increased by 2.1 times.GC-MS analysis showed that sodium acetate promoted the degradation of nitrogen-containing heterocyclic substances,aniline and halogenated hydrocarbons in coking wastewater,and produced some intermediate metabolites such as lipids and alcohols.Electrode polarization curve analysis showed that sodium acetate reduced the anode potential,which may be related to the fact that sodium acetate promoted the enrichment of electroactive microorganisms on the electrode surface.(2)In order to improve the bio-accessibility of refractory organics in coking wastewater and improve the treatment effect of MFC coking wastewater,the effect of APG and Tween 80 on the performance of MFC and the mechanism of action was studied from three aspects: the migration and transformation of organics and nitrogen,electrochemical behavior and microbial morphology.It was found that the addition of surfactants enhanced the metabolism of organic matter in coking wastewater,promoted the enrichment of electroactive microorganisms,and improved the removal of refractory organic matter and the electricity production of the system.In addition,APG’s removal of organic matter in coking wastewater and electricity generation were better than Tween 80.After adding Tween 80 and APG,the TOC removal rate of the MFC effluent was increased by 14.16%and 20.4%,the TN removal rate of the effluent was increased by 14.89% and24.79%,and the output voltage was increased by 1.45 times and 1.71 times,respectively.GC-MS analysis showed that the addition of surfactants further enhanced the removal of aromatic organics,especially polycyclic aromatic hydrocarbons and heterocyclic organics,and the addition of APG reduced the types of organics in the MFC effluent.Polarization curve analysis showed that after APG was added to MFC,the anode potential was lower.This is related to the strong biodegradability of APG,which can provide more energy for the growth of microorganisms and promote the enrichment of electroactive microorganisms on the anode.The results of SEM analysis of the microbial morphology of the electrode surface showed that more nanowire ancillary structures were observed on the surface of the MFC anode after APG was added. |
PDF Full Text Request