The denitrification efficiency of the new effluent in zin conference centre constructed wetland

Wetland is a natural system of water treatment. It has been used as waste water treatment system in many countries in Europe. The vertical flow constructed wetland of different water level are efficient in removing Nutrients, TSS, heavy metals and toxic compounds from waste water. Nutrients are effectively removed from domestic wastes through microbial nitrification-denitrification path way. Excess nitrogen in water bodies are the major causes of Eutrophication. The aim of this study is to optimize the nitrogen removal efficiency of vertical flow wetland using different water levels from Zin conference centre wetlands. The samples were collected from influents and two effluents- old and new for COD, BOD, NH4-N, NO3-N, TKN and TN analysis. The data were analyzed using SPSS to see the significance between factors. Results showed that the average NO3-N in the effluent is 0,17+ 0,23 mg/L but  in the old and new  effluents are 55+12,3 mg/L  and 46,5+12,7 mg/L  respectively. The NH4-N concentration was significantly decreased from influent 62,8 + 17 mg/L  to effluents  0,21+ 0,2 mg/L and 2,75+ 4,6  mg/L in the old and new effluents respectively.  The COD concentration was significantly decrease from 379+130 mg/L in the influent to 38+11,7  mg/L  and 35,3+22,0 mg/L in the old and new effluent respectively. The shortage of COD in the effluent affects the denitrification and nitrification processes in the wetland. Keywords: Key words: Domestic wastewater, Microbial Nitrification-denitrification, Water levels, Nitrogen removal efficiency, Eutrophication

Nano Fe3O4–graphite paste modified electrochemical sensor for phosphatic pesticide -chlorpyrifos

A sensitive, cost effective and selective electrochemical sensor has been developed by exploiting iron oxide nano-particles as modifier in the paste of graphite powder. Cyclic voltammetric (CV) and differential pulse voltammetric (DPV) working parameters have been standardized and used practically for the determination of chlorpyrifos (O, O-diethyl O-3, 5, 6-trichloropyridin-2-yl phosphorothioate) pesticide from its aqueous solutions. Both techniques were deployed to investigate the electro-chemical interactions between chlorpyrifos and modified carbon paste sensor along with the redox characteristics at analyte/ sensor interface. The significant enhancement in peak current signals and the improved magnitude of the redox peak potential indicated the awe-inspiring facilitation of the electron transfer process by the modifier at the sensor/ analyte interface. The difference in the redox -potential (ΔEp) and peak current ratio (Ipc/Ipa) have revealed a notable surface enhancement characteristic of the modifier that responds the higher concentration gradient of pesticide at the interface. In lower analyte’s concentration range i.e. from 1.0 to 100μM, the peak current varies directly to the pesticide concentration with detection limit of 2.8 x10-6 mol/L. The relative stability of the modified sensor is fine and the reproducibility of the results is up to 98%, even after a gap of two months. The proposed analytical method is quite successful when applied for the quantification of chlorpyrifos from its aqueous samples. The electrochemical sensing/ detection of the pesticide chlorpyrifos is confirmed by its two electrons redox behavior and the same have been explained by suitable reaction scheme as:Keywords: Nano-iron oxide, Chlorpyrifos, Modified graphite paste, Voltammetry, Electrochemical metho

Antibacterial Activity of Ag-Doped TiO2 and Ag-Doped ZnO Nanoparticles

We report in this paper antibacterial activity of Ag-doped TiO2 and Ag-doped ZnO nanoparticles (NPs) under visible light irradiation synthesized by using a sol-gel method. Structural, morphological, and basic optical properties of these samples were investigated using X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray (EDX) spectrum, and UV-Vis reflectance. Room temperature X-ray diffraction analysis revealed that Ag-doped TiO2 has both rutile and anatase phases, but TiO2 NPs only have the anatase phase. In both ZnO and Ag-doped ZnO NPs, the hexagonal wurtzite structure was observed. The morphologies of TiO2 and ZnO were influenced by doping with Ag, as shown from the SEM images. EDX confirms that the samples are composed of Zn, Ti, Ag, and O elements. UV-Vis reflectance results show decreased band gap energy of Ag-doped TiO2 and Ag-doped ZnO NPs in comparison to that of TiO2 and ZnO. Pathogenic bacteria, such as Staphylococcus aureus, Pseudomonas aeruginosa, and Escherichia coli, were used to assess the antibacterial activity of the synthesized materials. The reduction in the viability of all the three bacteria to zero using Ag-doped ZnO occurred at 60 μg/mL of culture, while Ag-doped TiO2 showed zero viability at 80 μg/mL. Doping of Ag on ZnO and TiO2 plays a vital role in the increased antibacterial activity performance