K. Swaminathan

Decolorization and degradation of H-acid and other dyes using ferrous–hydrogen peroxide system

In this study, advanced oxidation process utilizing Fentons reaction was investigated for the decolorization and degradation of two commercial dyes viz., Red M5B, Blue MR and H-acid, a dye intermediate used in chemical industries for the synthesis of direct, reactive and azo dyes. Effect of Fe2 +, H2O2, pH, and contact time on the degradation of the dyes was studied. Maximum color and COD removal was obtained for Red MSB, H-acid and Blue MR at 10-25 mg/l of Fe2+ dose and 400-500 mg/l of H2O2 dose at pH 3.0. The initial oxidation reaction was found to fit into first order rate kinetics and the rate of oxidation of H-acid was higher than the other dyes. Release of chloride and sulfate from the Fentons treated Red M5B dye and sulfate from H-acid and Blue MR indicates that the dye degradation proceeds through cleavage of the substituent group.

Ozonation of reactive dye, Procion red MX-5B catalyzed by metal ions

Ozonation of aqueous solution of Procion red MX-5B, a commercial azo reactive dye was investigated. The effect of various experimental variables on decolorization and degradation of the dye has been studied. Color removal was faster than organic removal. Dye mineralization was evident by the generation of sulphate, chloride, nitrate, oxalic and acetic acid during ozonation. The decolorization and organic removal followed pseudo-first-order kinetics. Among the metal ions studied, manganese catalyzed ozonation showed better decolorization and organic removal. Fourier transform infrared (FTIR) spectroscopy results indicated the disappearance of bands for aromatics and appearance of bands due to carboxylic acids in the ozonated samples. Acetyl benzoic acid, diethyl phthalate and phthalic anhydride were identified as intermediates by gas chromatography mass spectra (GC/MS). Based on these findings a tentative pathway for the degradation MX-5B was postulated.

Degradation of resorcinol in upflow anaerobic filter

Abstract Biodegradation of resorcinol was studied in upflow anaerobic filter (UAF). Substrate and total organic carbon (TOO removal efficiencies above 90% were achieved when substrate loadings were increased from 0.38 kg to 2.07 kg/m3/d. Gas yield was around 0.54 m3/kg COD removed. The system remained unaffected even at an influent resorcinol concentration of 2000 mg/1. Decrease in hydraulic retention time (HRT) upto 16 h did not influence the performance of the filter. Low effluent suspended solids (< 50 mg/1) indicated that solids washout was minimum and the system operated at high solids retention time (SRT).

Migration of Organic Contaminants from an Abandoned Hazardous Waste Dumpsite — A Case Study

The indiscriminate disposal of wastes on land is causing a serious threat to the environment. The present study aims to assess the leaching potential of industrial waste and possible ground water contamination. Sludges generated from the treatment of wastewater from basic organic chemical industry manufacturing chloro and/or nitro aromatics were subjected to Toxicity Characteristic Leaching Procedure (TCLP). The leachates were extracted with methylene chloride and, after passing through anhydrous sodium sulphate and concentration, were subjected to gas Chromatographic analysis. The gas Chromatograph used was Perkin Elmer Sigma 3B. The operating conditions of GC were, column: 1% SP-1240 DF 100/120 Supelcoport, oven temp : 100|C, injector and detector temp : 150|C, N2 flow rate: 40 ml/min. The detector used was Flame Ionization Detector.

Reclamation of site used for impoundment of wastewater from a pesticide industry ‐ a case study

Abstract Wastewater generated from a pesticide industry containing 15 to 20% HCl was neutralised and stored in three solar evaporation ponds (SEP)lined with Flexible Membrane Liner(FML). Characteristics of the pond water showed the presence of high concentration of dissolved solids which were mainly due to salts such as chloride and sulfate of calcium and sodium. High performance liquid chromatographic (HPLC) analysis of pond water did not indicate the presence of sevin. A variation in the chemical composition of the sediment samples was observed from top to bottom layers. The study revealed that the salts and organics were retained mostly in the upper portion of the pond sediment thus indicating remote possibility of percolation. The possible treatment alternatives/remedial measures to be adopted for cleanup of the ponds are discussed.