Optimization of free chlorine, electric and current efficiency in an electrochemical reactor for water disinfection purposes by RSM.
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ABSTRACT:
SUBMITTER: Naderi M
PROVIDER: S-EPMC7721780 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:The degradation efficiency of chloroquine phosphate (CQ), an anti-COVID-19 drug, was investigated in a flow-by electrochemical reactor (FBER) provided with two boron-doped diamond (BDD) electrodes (as cathode and anode) under batch recirculation mode. A central composite rotatable design (CCRD) was run down to model and assess the influence of initial pH in an interval of 3.71 to 11.28, the current density in an interval of 34.32 to 185.68 mA cm−2, and liquid volumetric flow rate in an interval of 0.58 to 1.42 L min−1, and conduct the convex optimization to obtain the maximum degradation efficiency. Experimental results were modeled through a second-order polynomial equation having a determination coefficient (R2) of 0.9705 with a variance coefficient of 1.1%. Optimal operating conditions found (initial pH of 5.38, current density (j) of 34.4 mA cm−2, and liquid flow rate (Q) of 1.42 L min−1) led to a global maximum degradation efficiency, COD removal efficiency, and mineralization efficiency of 89.3, 51.6 and 53.1%, respectively, with an energy consumption of 0.041 kWh L−1 within 9 h of treatment. Additionally, a pseudo-zero-order kinetic model was demonstrated to fit the experimental data and the calculated pseudo-zero-order kinetic constant (kapp) was 13.14 mg L−1 h−1 (2.54 × 10−5 mol dm−3 h−1). Furthermore, the total operating cost was of 0.47 US$ L−1. Finally, this research could be helpful for the treatment of wastewater containing an anti-COVID-19 drug such as CQ. Supplementary Information The online version contains supplementary material available at 10.1007/s10008-023-05452-7.
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Project description:The control of cellular processes by direct electronic interface will facilitate the development of biosensors, synthetic biology, and nanobiotechnology by providing the means to pass information from synthetic to living elements of hybrid systems. To investigate the potential of manipulating cellular gene expression by means of electric current, Escherichia coli cultures were screened for electric current inducible genes using global gene expression profiling. Cells in stationary phase were subjected to a DC current density of 2.5 mA/cm2 for 2 min after which the cells were lysed and the total RNA extracted. Of the 4290 expressed genes in E. coli , 432 genes were found to be significantly differentially expressed at an effective alpha value of 5.8 X 10-6. Of these, 333 genes were induced and 99 repressed. Several genes were verified as differentially expressed by quantitative real-time RT-PCR. The set of differentially expressed genes were examined for the presence of regulatory factors, subsidiary regulon genes, and biological function, particularly redox functions. Transcripts for the regulatory proteins fnr, sspB, soxS, oxyR, creB and yeiL were found to be up-regulated, and crp was down regulated. While soxS and oxyR were up-regulated, the downstream genes controlled by these regulatory proteins were not differentially expressed, suggesting that the oxidative stress level of low-current electric exposure is small. Genes controlled by FNR and CRP, many of which have redox function, were found to be differentially expressed suggesting modulation by direct reduction that can only be partially explained as a response to the reducing environment created by the electrolytic generation of H2 at the cathode. Genes associated with phosphate metabolism and membrane proteins were also differentially expressed. Keywords: electric current induced gene expression
2008-02-12 | GSE5192 | GEO
Project description:The disinfection of helminth eggs and Escherichia coli contaminated aqueous solutions, was studied using an electro-Fenton reactor equipped with a polarized activated carbon (AC) packed bed and two chambers loaded with cation exchange resins. Experiments using different arrangements and operation conditions, revealed that effective elimination of Escherichia coli takes place in all electrochemical disinfection tests. For the more resistant helminth eggs however, adsorption, electro-oxidation and electro-Fenton experiments showed retention within the reactor and pathogen inactivation values of 0, 16, and 25%, respectively. Using helminth eggs concentration data in different sections of the reactor, optical microscopy analysis and an exploratory computer simulation, differences in the disinfection performance were explained and new recirculation and flow direction and polarization switching operation schemes were defined. The corresponding experiments revealed that the effective coupling between adsorption and electro-Fenton phenomena, all along the AC packed bed compartment, results in 100% inactivation of helminth eggs.
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Project description:The control of cellular processes by direct electronic interface will facilitate the development of biosensors, synthetic biology, and nanobiotechnology by providing the means to pass information from synthetic to living elements of hybrid systems. To investigate the potential of manipulating cellular gene expression by means of electric current, Escherichia coli cultures were screened for electric current inducible genes using global gene expression profiling. Cells in stationary phase were subjected to a DC current density of 2.5 mA/cm2 for 2 min after which the cells were lysed and the total RNA extracted. Of the 4290 expressed genes in E. coli , 432 genes were found to be significantly differentially expressed at an effective alpha value of 5.8 X 10-6. Of these, 333 genes were induced and 99 repressed. Several genes were verified as differentially expressed by quantitative real-time RT-PCR. The set of differentially expressed genes were examined for the presence of regulatory factors, subsidiary regulon genes, and biological function, particularly redox functions. Transcripts for the regulatory proteins fnr, sspB, soxS, oxyR, creB and yeiL were found to be up-regulated, and crp was down regulated. While soxS and oxyR were up-regulated, the downstream genes controlled by these regulatory proteins were not differentially expressed, suggesting that the oxidative stress level of low-current electric exposure is small. Genes controlled by FNR and CRP, many of which have redox function, were found to be differentially expressed suggesting modulation by direct reduction that can only be partially explained as a response to the reducing environment created by the electrolytic generation of H2 at the cathode. Genes associated with phosphate metabolism and membrane proteins were also differentially expressed. Three biological replicates were exposed to electric current along with three biological replicate controls.
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Project description:Human noroviruses are excreted in feces from infected individuals and included in wastewater. It is critical to remove/inactivate them in wastewater treatment processes, particularly in the disinfection step, before release to aquatic environments. However, the high mutation rates of human noroviruses raise concerns about the emergence of strains that are less susceptible to disinfectants and can survive even after wastewater treatment. This study aimed to demonstrate the strain-dependent susceptibility of norovirus to free chlorine. A population originated from the murine norovirus strain S7-PP3, a surrogate for human noroviruses in environmental testing, was exposed to free chlorine and then propagated in a host cell. This cycle of free chlorine exposure followed by propagation in cells was repeated 10 times, and populations with lower susceptibility to free chlorine were obtained from two independent trials of chlorine exposure cycles. Open reading frame 2 (ORF2) and ORF3 of the murine norovirus genome were analyzed by next-generation sequencing, and a unique nonsynonymous mutation (corresponding to a change from phenylalanine to serine) at nucleotide (nt) 7280 in ORF3, which encodes the minor capsid protein VP2, was found in chlorine-exposed populations from both trials. It was confirmed that all of the clones from the chlorine-treated population had lower susceptibility to free chlorine than those from the control population. These results indicate that exposure to free chlorine and dilution exert different driving forces to form murine norovirus (MNV) quasispecies, and that there is a selective force to form MNV quasispecies under free chlorine exposure.IMPORTANCE This study showed that free chlorine disinfection exerted a selection pressure for murine norovirus (MNV). The strain-dependent viral susceptibility to the disinfectant elucidated in this study highlights the importance of employing less susceptible strains as representative viruses in disinfection tests, because the disinfection rate values obtained from more susceptible strains would be less useful in predicting the virus inactivation efficiency of circulating strains under practical disinfection conditions.
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