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Dye effluents pose severe environmental hazards. Devising cost-effective and eco-friendly techniques for treating wastewater containing dye effluent is the need of the day. The intention of the present study is to expose a technique for decolorizing the dye effluents, for degrading the contaminants present in the effluent and for minimizing the COD below standard limits. The dye effluent samples collected for the present study characterize a high COD of 972 mg/L, pH 8.6 and highly objectionable color (990 Hazen Units). The predominant indigenous organisms present in the samples were isolated and identified as Aspergillus niger and Aspergillus flavus. Potential exogenous organisms Trichoderma viride and Aspergillus fumigatus were obtained, and these organisms were used to conduct treatability studies. An up-flow immobilized column reactor (UFICR) was designed and used to treat the textile effluent. The shaker flask trials give maximum decolorization efficiency of 91% and COD reduction of 84%. The reactor studies showed elevated efficiencies of 92.7% and 93% efficiency in decolorization and COD reduction, respectively. The present study is developed as an efficient strategy to replace the less eco-friendly physicochemical approaches and also to provide a better insight into the field of bioremediation and its role in the treatment of dye effluent. [ABSTRACT FROM AUTHOR]

Effluent collected from a dye industry in Tirupur, Tamilnadu, India, was screened for potential indigenous micro-organisms to treat remazol dyes and dye effluents. Out of sixty strains isolated, four strains were found to be potential in degrading the dye effluent and various remazol reactive dyes. The physicochemical characterisation of the dye effluent showed quite high values. Decolourisation studies were performed for two different effluents (I & II) and observed maximum decolourisation of 76.4% at 120 h (Effluent I) and 79.9% at 96 h (Effluent II) by the organism EI25. The synthetic dyes Remazol Red RGB (RR-RGB), Remazol Red RR (RR-RR), Remazol Yellow RGB (RY-RGB) and Remazol Yellow RR (RY-RR) showed complete decolourisation (100%) after 24–72 h by two potential strains (EI05 and EI25). EI25 have shown the maximum efficiency of 87.2, 95.1, 89.4 and 84.4% decolourisation for RR-RGB, RR-RR, RY-RGB and RY-RR, respectively, within a 24 h time period. Morphological characteristics and biochemical screening tests identified the organisms to beClostridium butyricumandClostridium acetobutylicum.C. acetobutylicum(EI25) was found to be the most potential strain isolated. Biodegradation of remazol dyes was characterised by spectral analysis using UV–Visible spectroscopy and FTIR spectroscopy. The peak disappearance in UV spectrum is at theλmax519 nm for RR-RGB and RR-RR; whereas, 410 nm for RY-RGB and 419 nm for RY-RR stands as the proof of decolourisation. In the FTIR spectrum, the shift of several important peaks responsible for the functional groups N=N, S=O and phenolic O–H corresponding to the structure of remazol group of dyes and appearance of new peaks indicating the degradation metabolites observed in the decolourised samples ensures biodegradation. Further, EI25 have also shown marked reduction in the basic wastewater characteristics like COD, BOD, TDS, EC and pH. Thus it is concluded that theClostridiumspecies on further studies can be well developed into a biological method of textile effluent treatment process. [ABSTRACT FROM PUBLISHER]

A simple process, vacuum distillation, was utilized for purification of methyl orange (MO) as dye effluent. The dye effluent characteristic of high chemical oxygen demand (COD) value and high chromaticity is difficult to treat for the industrial wastewater treatment. In our work, the effect of some factors on the distillation efficiency (DE), including pressure, concentration and the surfactant based on the optimal conditions was evaluated. The results showed that the COD removal for 99.57% was obtained when the concentration of MO is 2000 mg l-1 at the pressure of 0.070 MPa. Moreover, the polyacrylamide (cationic) used in initial concentration of 500 mg l-1 show satisfactory removal efficiency in the further test. [ABSTRACT FROM AUTHOR]

Using DMAc as solvent, water as non-solvent, modified poly (vinylidene fluoride) (PVDF) ultrafiltration membranes (PSi, PA, PS) were prepared by precipitation phase inversion, blending with nano-silica (SiO2), polyvinyl alcohol (PVA), and styrene maleic anhydride. The physical-chemical properties and morphology of PVDF membranes were characterized by FT-IR, water contact angle (WCA), swelling index, scanning electron microscopy, atomic force microscopy, etc. Considering reactive black 5 and congo red as the representatives of dye effluent pollutions, the filtration behavior to dye wastewater of four different types of PVDF UF membranes was discussed. Experimental results showed that, compared with original PVDF UF membrane, for three kinds of modified membrane, the first bubble pressure and strength (S) fell off to a certain extent, and the membrane surface roughness increased. Additionally, the cross-sectional macroporous and pure water flux (J) all increased. Especially, owing to the addition of PVA and SiO2, the WCA and the adsorption amount (Q) of PA and PSi membranes were reduced extraordinarily, and flux recovery rate increased obviously. As a result, the hydrophilicity of PVDF membrane was improved significantly. Moreover, the rejection (r) to two dyes was also remained well, which showed a better anti-fouling ability. [ABSTRACT FROM AUTHOR]