நீரியல்: தற்போதைய ஆராய்ச்சி

Present study was conducted to evaluate the impact of ozonation on the quality improvement of Secondary Treated wastewater at Varanasi, in India. Physico- chemical parameters such as BOD, COD, TOC, UV254, color and microbiological parameters such as E. coli, fecal coli. & total coliform disinfection parameters were used to evaluate the efficiency of ozone to upgrade secondary effluent quality. Experimental results revealed that 10 mgL-1 O3 for 5 minutes exposure duration was found most suitable dose and contact time for the significant reduction of physicochemical parameters of secondary treated wastewater such as BOD, COD, TOC, UV254 and color i.e. 30%, 14.3% 45% & 60% respectively as well as it enhanced the biodegradability more than 50% in the treated water. Our data also revealed that this applied dose and exposure time is responsible for the highest degradation of microbiological parameters i.e. >98%. Other than this the toxic response of test species was influenced mainly by the dose and exposure time. The acute toxic effect after ozonation was observed on V. fischeri and found that toxic effect of the secondary effluent was decreased after applied dose and exposure duration. Results supported the expectation that the process of Ozone might enhance the overall treatment efficiency of secondary effluent treatment.

The degradation of diluted textile effluent was studied by electrochemical technique. For electrochemical degradation, the graphite carbon electrodes were used as anode and cathode. Electrochemical behavior of effluent was performed with cyclic voltammetry in different pH 1 to 11 using pencil graphite as working electrode. The potentials selected for the dyes were in the range +0.8 V to -0.4 V. The voltammetric curve of effluent at pH 1 shows cathodic peaks at +0.3365 V and +0.0613 V and anodic peaks at +0.396 V and +0.689 V. During electrochemical degradation, the chromoporic groups and aromatic rings were destroyed. Decolourisation and degradation of the effluent was followed using UV-vis spectroscopy, LC-MS and COD measurements. The dyes present in the textile effluent were completely oxidised and degraded with graphite electrodes. The effect of initial pH, supporting electrolyte and current density on the degradation of textile effluent was discussed.

The present study presents the sono-degradation petroleum refinery effluent and the influence of addition activated carbon and hydrogen peroxide on sonolysis. The sonolytic degradation was analyzed for the reduction in % COD of the effluent and the results showed that the combination of activated carbon and hydrogen peroxide gave better results. The effect of key operating parameters, such as sonication time and pH on % COD reduction were studied. Experiments were carried out at initial concentrations of activated carbon (0.5, 1, 1.5 and 2 gm) and activated carbon (2 gm) with hydrogen peroxide (50,100,150 and 200 mg/l) on sonochemical degradation of effluent at pH 10. This study showed that % COD remaining was found to be found that the activated carbon at 2 grams a better read, therefore, adopted with the added along with 50,100,150 and 200 mg/l hydrogen peroxide respectively. Degradation was found to increase with increasing sonication time. In addition, as the concentration is increased. At the end of 90 min of sonication, the % COD remaining was increases when the recycling of activated carbon increases.

First time in India, the present study was investigated the efficiency of electron beam to hygienise and oxidise the wastewater and focus on new technologies and processes. The use of electron beam accelerator to disinfect sewage water is gaining a great importance. The current emphasis on environmental health and water pollution issue are that, there is an increasing awareness in the process of disposing the waste water supply as well as beneficially. EB treatment of the waste water has found to be very effective in reducing the pathogens as well as BOD and COD load, indicating an increased in bio-degradability of waste water. EB dose of 1.5 kGy was sufficient for complete elimination of total coli forms. The experimental results elucidated that the percentage of reduction of BOD was 14 more as well as 32 % of reduction in COD with respect to increasing of irradiation doses(0.45 -6 kGy). So the irradiated sewage water can find its application either in agriculture for irrigation or in industry sector for cooling purpose or in both the sectors after flocculation treatment. Irradiation with electron beam is an unconventional to chlorination of municipal sewage water to provide disinfection.

A carboxylic acid group containing resin with cation exchange capacity, 12.67 meq/g, has been used to remove Cu2+, Co2+ and Ni2+ ions from dilute aqueous solution. The resin had Cu2+, Co2+ and Ni2+ removal capacity, 216 mg/g, 154 mg/g and 180 mg/g, respectively. The selectivity of the resin for Cu2+ over Co2+ and Ni2+ was investigated in the presence of 1.0 M or 0.5 M sodium chloride. The resin was found to offer high capacity and selectivity for Cu2+. The sorbed metal ions (Cu2+, Co2+ and Ni2+) were easily stripped with dilute HCl. The sorbed Co2+ and Ni2+ could also be stripped with 1.0M NaCl.