Global NEST Journal

In this study, the application of Sn/Sb/Ni-Ti electrodes for the treatment of waste streams were investigated which is promising for ozone production by electrolysis of water because of their stability and high potential for ozone evolution reaction. These series of anodes have a high electrochemical ozone generation potential at ambient conditions (approximately up to 40% current efficiency). But using and testing of these novel anodes for real wastewater are too limited in the literature. Titanium mesh substrate coated with Sn/Sb/Ni-Ti alloy was used as anode immersed in wastewater at room temperature with platinized titanium cathode. These electrodes used for COD and color removal from OID wastewater in Inegol, Bursa, Turkey. Five operational parameters were evaluated for electrochemical COD and color removal processes, such as pH, salt content, applied voltage/current, current efficiency and contact time. Experimental results showed that after 30 min the electrochemical oxidation efficiency of COD and color could reach up to 98% and 99% respectively at pH 8.2 and temperature of 25°C as the optimum conditions. Current density observed as the most effective parameter for COD and color removal efficiencies. The lowest energy consumption was between 10-25 mA cm-2 of current density with only 0.6 kWh gCOD−1, while the highest energy consumption was 100 mA cm-2 of current density with 9.12 kWh gCOD−1 . The optimum current density value has been found as 50 mA cm-2 with 4.05 kWh gCOD−1 . These results were also supported with ANOVA test.

The urge of environmental friendly techniques in textile processing is gaining much attention due to high risks of effluent load causing eco-imbalance. For the present study, the cotton fabric and Reactive Violet H3R dye solution were treated with microwave radiation for 2, 4, 6, 8 & 10 min. at different powers (low, medium & high). Dyeing was performed using un-irradiated (NRC) and irradiated cotton (RC) with un-irradiated (NRS) and irradiated dye solution (RS). Different dyeing parameters were optimized and ISO standard methods for color fastness were employed to rate the color change before and after irradiation. It is found that microwave irradiation for 8 min. at high power has given good colour strength. When 60 mL irradiated dye solution of 7.5pH containing 8g/L of salt as exhausting agent is used to dye irradiated fabric at 60^oC for 55 min. ISO standards for colorfastness employed at various shades have shown that microwave irradiation has improved the rating of fastness properties. It is concluded that microwave irradiation has a promising potential to improve the color strength and dyeing properties under mild conditions.

Presence of sulfide in the environment represents huge concerns to biological life. The high costs and low safety of chemical and physical removal strategies lead to finding alternative strategies. Sulfur-oxidizing bacteria (SOB) are consider a promising alternative strategy, where they play a critical role in removal of such compounds from water and soil environments, as well as, they maintain the sulfur balance during natural sulfur cycle. The main objective of this study was to isolate sulfur oxidizing bacteria (SOB) from sulfide polluted water. In addition screening for sulfide oxidase producer bacteria was performed. Twenty isolates of sulfur oxidizing bacteria were isolated from eight different sulfide polluted water sources. During testing the isolates on thiosulfate broth medium, it was observed that, eleven isolates could efficiently reduce the pH of the media from 7.5±0.2 to 5.0 ± 0.5 as a resulting of the oxidizing of sulfides to sulfate ion. The concentration of produced sulfate ion ranged from 76 to 155 mg mL^-1. The sulfur oxidase activity of the tested isolates ranged between 2.68 to 5.23 U mL^-1. The bacterial isolates were identified as Bacillus spp., Pseudomonas spp. and Klebsiella spp. based on their morphological and biochemical characterization.

The objective of the study is to determine accumulation and translocation of heavy metals from soil to paddy straw irrigated with urban sewage wastewater in peri-urban region of Girudhumal subbasin area in Madurai. The soil samples were collected in seven locations irrigated with treated and untreated wastewater and analyzed for physical properties like pH, EC, bulk density, soil type, major (N,P,K) and micronutrients (Fe, Mn, Cu, Zn) and heavy metals Ni, Cd, Pb. SEM analysis showed that soil structure is significantly influenced by wastewater irrigation. It confirms that the wastewater irrigation disturbs soil structure and affecting the plant growth in long run.  Pb content was higher than the prescribed safe limits in S5 and S6 location, similarly, Ni also was higher than the safe limit in all the locations. Pollution Load Index values are in the range of 0.08-0.56 for all sites, and it indicated that chance of heavy metal contamination is less. The EF values show moderate enrichment to Ni and Zn, Significant enrichment for Cd and Cu, Extremely high for Pb and deficiency for Mn. All these results confirmed that there is no immediate risk of heavy metal pollution, however with respect to Pb and Ni the plant tissues are showing higher values. The transfer factor for heavy metals from soil to paddy straw is less than 0.5 for Cd and for others is more than 0.5 indicated greater chances for heavy metal contamination.