Enhancing sensitivity of microbial fuel cell sensors for low concentration biodegradable organic matter detection:Regulation of substrate concentration,anode area and external resistance

The relatively low sensitivity is an important reason for restricting the microbial fuel cell(MFC)sensors'application in low concentration biodegradable organic matter(BOM)detection.The startup parameters,including substrate concentration,anode area and external resistance,were regulated to enhance the sensitivity of MFC sensors.The results demonstrated that both the substrate concentration and anode area were positively correlated with the sensitivity of MFC sensors,and an external resistance of 210Ωwas found to be optimal in terms of sensitivity of MFC sensors.Optimized MFC sensors had lower detection limit(1 mg/L)and higher sensitivity(Slope value of the linear regression curve was 1.02),which effectively overcome the limitation of low concentration BOM detection.The essential reason is that optimized MFC sensors had higher coulombic efficiency,which was beneficial to improve the sensitivity of MFC sensors.The main impact of the substrate concentration and anode area was to regulate the proportion between electrogens and nonelectrogens,biomass and living cells of the anode biofilm.The external resistance mainly affected the morphology structure and the proportion of living cells of the anode.This study demonstrated an effective way to improve the sensitivity of MFC sensors for low concentration BOM detection.

Modeling of Biofiltration Process in Drinking Water Treatment

The aim of this research is to develop a representative model which simulates the performance of a biofilter used to treat drinking water. A steady-sate model is applied. The Monod-type substrate utilization is used, and the external and the internal mass transfer are neglected in this model. The model describes the process of substrate biodegradation, bacterial attachment onto filter media, and detachment of suspended bacteria. It simulates the natural organic matter （NOM） and biomass profiles in a biofilter as a function of filter depth and filtration velocity. The key biokinefie parameters k and Ks are estimated through a special experiment. The results of the model testing show that the model prediction agrees well with the experimental data.

Effects of Cu^(2+)and humic acids on degradation and fate of TBBPA in pure culture of Pseudomonas sp.strain CDT

Soil contamination with tetrabromobisphenol A（TBBPA） has caused great concerns;however, the presence of heavy metals and soil organic matter on the biodegradation of TBBPA is still unclear. We isolated Pseudomonas sp. strain CDT, a TBBPA-degrading bacterium, from activated sludge and incubated it with ^（14）C-labeled TBBPA for 87 days in the absence and presence of Cu^（2＋）and humic acids（HA）. TBBPA was degraded to organic-solvent extractable（59.4% ± 2.2%） and non-extractable（25.1% ± 1.3%） metabolites,mineralized to CO_2（4.8% ± 0.8%）, and assimilated into cells（10.6% ± 0.9%） at the end of incubation. When Cu^（2＋）was present, the transformation of extractable metabolites into non-extractable metabolites and mineralization were inhibited, possibly due to the toxicity of Cu^（2＋）to cells. HA significantly inhibited both dissipation and mineralization of TBBPA and altered the fate of TBBPA in the culture by formation of HA-bound residues that amounted to 22.1% ± 3.7% of the transformed TBBPA. The inhibition from HA was attributed to adsorption of TBBPA and formation of bound residues with HA via reaction of reactive metabolites with HA molecules, which decreased bioavailability of TBBPA and metabolites in the culture. When Cu^（2＋）and HA were both present, Cu^（2＋）significantly promoted the HA inhibition on TBBPA dissipation but not on metabolite degradation. The results provide insights into individual and interactive effects of Cu^（2＋）and soil organic matter on the biotransformation of TBBPA and indicate that soil organic matter plays an essential role in determining the fate of organic pollutants in soil and mitigating heavy metal toxicity.