Sandeep Sarkar

Treatment of cosmetic effluent in different configurations of ceramic UF membrane based bioreactor: Toxicity evaluation of the untreated and treated wastewater using catfish (Heteropneustes fossilis).

Extensive usage of pharmaceutical and personal care products (PPCPs) and their discharge through domestic sewage have been recently recognized as a new generation environmental concern which deserves more scientific attention over the classical environmental pollutants. The major issues of this type of effluent addressed in this study were its colour, triclosan and anionic surfactant (SDS) content. Samples of cosmetic effluent were collected from different beauty treatment salons and spas in and around Kolkata, India and treated in bioreactors containing a bacterial consortium isolated from activated sludge samples collected from a common effluent treatment plant. Members of the consortium were isolated and identified as Klebsiella sp., Pseudomonas sp., Salmonella sp. and Comamonas sp. The biotreated effluent was subjected to ultrafiltration (UF) involving indigenously prepared ceramic membranes in both side-stream and submerged mode. Analysis of the MBR treated effluent revealed 99.22%, 98.56% and 99.74% removal of colour, triclosan and surfactant respectively. Investigation of probable acute and chronic cyto-genotoxic potential of the untreated and treated effluents along with their possible participation in triggering oxidative stress was carried out with Heteropneustes fossilis (Bloch). Comet formation recorded in both liver and gill cells and micronucleus count in peripheral erythrocytes of individuals exposed to untreated effluent increased with duration of exposure and was significantly higher than those treated with UF permeates which in turn neared control levels. Results of this study revealed successful application of the isolated bacterial consortium in MBR process for efficient detoxification of cosmetic effluent thereby conferring the same suitable for discharge and/or reuse.

Potential of ceramic microfiltration and ultrafiltration membranes for the treatment of gray water for an effective reuse

Abstract Gray water may serve as a water resource for agricultural uses due to their high nutrient content. In this study performance evaluation of indigenously developed low-cost ceramic membrane was investigated for treatment and reuse of high organic loaded gray water. The efficiency of microfiltration (MF) and ultrafiltration (UF) process was studied individually and as a two-stage treatment involving MF followed by UF. Effect of time was observed on reduction of chemical oxygen demand (COD) in the permeate stream and permeate flux in different processes. Depending on the variation in feed loading, about 73–90% COD reduction was achieved in the single-stage UF at 30 min of filtration with operating pressure of 2 bar, which was about 84–94% for two-stage treatment. Permeate quality in terms of organic loading, oil and grease and coliform concentration were found suitable according to the discharge norms for agricultural reuse of water. The effect of untreated, MF- and-UF treated wastewater was observed...

Development of hydrophobic clay–alumina based capillary membrane for desalination of brine by membrane distillation

Abstract Clay–alumina compositions of 0, 20, 40 and 55 weight percent (wt%) clay and rest alumina were maintained in porous support preparation by extrusion followed by sintering at 1300 °C for 2.5 h to obtain 3 mm/2 mm (outer diameter/inner diameter) capillary. 1H,1H,2H,2H-perfluorodecyltriethoxysilane (97%) (C8) was used to modify the capillary surface of all compositions without any intermediate membrane layer to impart hydrophobic characteristics and compared in terms of contact angle produced by the capillaries with water and liquid entry pressure (LEPw). FTIR analysis showed that the hydrophilic surface of the capillary membranes was efficiently modified by the proposed grafting method. Capillary with 55 wt% clay produced a pore size of 1.43 micron and was considered as an ideal candidate for grafting with C8 polymer to impart surface hydrophobicity. The contact angle and LEPw value obtained for this modified membrane (C-55-M) were 145° and 1 bar, respectively. The modified capillary membrane was applied for desalination of brine by air gap membrane distillation (AGMD) at a feed pressure of 0.85 bar. Maximum flux obtained for C-55-M membrane was 98.66 L/m2 day at a temperature difference of 60 °C with salt rejection of 99.96%. Mass transfer coefficient of C-55-M was 16 × 10−3 mm/s at feed temperature of 70 °C.

Process for Preparation of Low Cost Clay-Alumina Multichannel Ceramic Membrane for Liquid Filtration Application

A low cost 21 channel ceramic membrane was developed by extrusion and sintering process by mixing cheap natural mineral, clay, with alumina. Two types of ceramic paste were prepared for preparation of multichannel tubes for comparative study. Paste 1 was prepared from alumina and organic binder, methocel, along with water, and paste 2 was prepared from clay and alumina along with methocel and water. Both the pastes were extruded through multichannel die by plunger type hydraulic extruder to prepare 21 channel green tubes. The green tubes were dried in a conventional way by drying it over alumina channel for 72 h, and in a controlled atmosphere by rotating it over a roller at 18 rpm inside a closed chamber kept at 70% relative humidity and 40°C for 48 h. Both the dried alumina and clay-alumina tubes were sintered in (a) vertical hanging, (b) horizontal and (c) angular supported conditions in top hat furnace and the final tubes were compared and inspected for physical defects, viz. cracks and warps to find the optimum processing conditions. The average pore size and porosity of alumina tube, fired at 1600°C, were found to be 2.5 µm and 42%, whereas those for clay alumina tube, fired at 1450°C, were 1 µm and 39% respectively. Maximum pure water flux obtained were 756 and 462 L.m–2.h–1 at 1 bar for alumina and clayalumina tubes respectively.

Preparation and Characterization of Single Layer Ultra Filtration Alumina Membrane Directly over Porous Clay-Alumina Tubular and Capillary Support for Textile Effluent Treatment

Clay-alumina porous tubular supports of 8/6 mm for outside diameter/inside diameter (OD/ID) were prepared by extrusion and sintering at 1450°C for 110 min to obtain an average pore size of 1 µm and porosity of 40%. Slip casting slurry was prepared by peptization of boehmite (AlO(OH)) powder with 1.5 N nitric acid and mixing it with γ-Al2O3 powder of 40 nm particle size along with PVA and PEG in determined weight percentage. Clay alumina porous support tubes of 3.1/1.9 and 8/6 mm (OD/ID) were coated with the slip casting slurry and sintered at 550°C for 60 min to obtain γ-alumina membrane directly over the supports in a single step. The membrane layer prepared over both the support tubes were without any intermediate layer. The membranes presented a pore diameter distribution centered at 7.0 nm on 3.1/1.9 mm (OD/ID) and 5.5 nm on 8/6 mm (OD/ID) supports, which was in ultrafiltration (UF) range. The prepared UF membranes were studied for treatment of bio-treated synthetic and real textile effluent in the side stream mode. About 98% decolorization of synthetic dye solution and 95.6% colour removal of real textile effluent were obtained by the combined effect of UF membrane and bioreactor.