Ergin Taskan

Bio-reduction of tetrachloroethen using a H2-based membrane biofilm reactor and community fingerprinting.

Chlorinated ethenes in drinking water could be reductively dechlorinated to non-toxic ethene by using a hydrogen based membrane biofilm reactor (H2-MBfR) under denitrifying conditions as it provides an appropriate environment for dechlorinating bacteria in biofilm communities. This study evaluates the reductive dechlorination of perchloroethene (PCE) to non-toxic ethene (ETH) and comparative community analysis of the biofilm grown on the gas permeable membrane fibers. For these purposes, three H2-MBfRs receiving three different chlorinated ethenes (PCE, TCE and DCE) were operated under different hydraulic retention times (HRTs) and H2 pressures. Among these reactors, the H2-MBfR fed with PCE (H2-MBfR 1) accomplished a complete dechlorination, whereas cis-DCE accumulated in the TCE receiving H2-MBfR 2 and no dechlorination was detected in the DCE receiving H2-MBfR 3. The results showed that 95% of PCE dechlorinated to ETH together with over 99.8% dechlorination efficiency. Nitrate was the preferred electron acceptor as the most of electrons generated from H2 oxidation used for denitrification and dechlorination started under nitrate deficient conditions at increased H2 pressures. PCR-DGGE analysis showed that Dehalococcoides were present in autotrophic biofilm community dechlorinating PCE to ethene, and RDase genes analysis revealed that pceA, tceA, bvcA and vcrA, responsible for complete dechlorination step, were available in Dehalococcoides strains.

Chlortetracycline removal by using hydrogen based membrane biofilm reactor.

In the last years, increasing attention has been paid on the presence of antibiotics in aqueous environments due to their ecological damage and potential adverse effects on organisms. Membrane biofilm reactors (MBfR) have been gained a significant popularity as an advanced wastewater treatment technology in removing of organic micro-pollutants. In this study, the performance of H2-MBfR for simultaneous removal of nitrate and chlortetracycline, formation of transformation products and community analysis of the biofilm grown on the gas permeable hollow fiber membranes was evaluated by considering effect of the hydraulic retention time, surface loadings of target pollutants and H2 pressure. The results showed that the simultaneous chlortetracycline (96%) and nitrate removal (99%) took placed successfully under the conditions of 5h HRT and 2psi H2 pressure. It has been determined that the main elimination process was biodegradation and Betaproteobacteria species was responsible for chlortetracycline degradation.

The production of electricity from dual-chambered microbial fuel cell fueled by old age leachate

ABSTRACT In this study, electricity production from old age landfill leachate was investigated using dual chambered microbial fuel cell with Ti-TiO2 electrodes. The effect of organic loading rate on microbial fuel cell performance was examined by changing the hydraulic retention time and leachate chemical oxygen demand (COD) concentration. Microbial diversity at different conditions was studied using PCR-DGGE profiling of 16 sRNA fragments of microorganisms in the liquid media of the anode chamber and of the biofilm on the anode electrode. Both COD removal and current density were positively affected with increasing organic loading rate. The highest microbial fuel cell performance was achieved at hydraulic retention time of 0.5 day and organic loading rate of 10 g COD/L.day. The performance of the microbial fuel cell reactor decreased when hydraulic retention time was reduced to 0.25 day. The investigation of the microbial dynamics indicated that abundance of bacterial species was considerably dependent on the operational conditions. The microbial fuel cell reactor was mainly dominated by Geobacter, Shewanella, and Clostridium species, and some bacteria were easily washed out at lower hydraulic retention times.

Usage of Ti-TiO2 Electrode in Microbial Fuel Cell to Enhance the Electricity Generation and its Biocompatibility

Microbial fuel cell (MFC) provides the generation of electricity as bacteria on anode electrode oxidize organic content present in wastewater. This study presents simultaneously the electricity generation from two different synthetic wastewater mixtures using a new electrode in both anode and cathode compartments. Results showed that power output increased excessively in the case of Ti-TiO2 electrode. MFC reactors were mainly dominated by Geobacter, Shewanella, Pseudomonas and Clostridium species. The molecular results also demonstrated that Ti-TiO2 electrode is biocompatibility and able to be used in MFC because these species are electricity producing bacteria.

Combination of a novel electrode material and artificial mediators to enhance power generation in an MFC.

This study focuses on two main aspects: developing a novel cost-effective electrode material and power production from domestic wastewater using three different mediators. Methylene blue (MB), neutral red (NR) and 2-hydroxy-1,4-naphthoquinone (HNQ) were selected as electrode mediators with different concentrations. A tin-coated copper mesh electrode was tested as anode electrode. Maximum power density of the microbial fuel cell (MFC) with 300 μM MB was 636 mW/m². Optimal mediator concentrations with respect to the achieved maximum power output for MB, NR and HNQ were 300 μM, 200 μM and 50 μM, respectively. The results demonstrate that tin-coated copper mesh showed a higher biocompatibility and electrical conductivity.