Indian Distilleries Research Articles

Comprehensive treatment scheme for distillery wastewater targeting recovery of water, antioxidant compounds and biogas

This work integrates forward osmosis (FO) and adsorption to recover water and antioxidant compounds (melanoidins and polyphenols) from sugarcane molasses distillery wastewater prior to biogas generation by conventional anaerobic digestion (AD). FO enables water recovery with simultaneous concentration of the antioxidant compounds in the wastewater feed; the adsorption-desorption step permits recovery of the antioxidant compounds. The FO step was optimized in earlier studies and a flow rate of 1 L/min and draw solution concentration of 3 M MgCl2.6H2O was chosen. Column adsorption with XAD16 resin was tested at different flow rates and the maximum adsorption yield of 66 % melanoidins and 71 % polyphenols was obtained at 1 mL/min. While polyphenols were readily desorbed (86 % desorption with water-acidified ethanol-water), melanoidins desorption was comparatively lower (46 %). Four different treatment schemes were investigated viz. ADS1 (FO + AD), ADS2 (adsorption + AD), ADS3 (FO + adsorption + AD) and ADS4 (adsorption + FO + AD). Among these, ADS4 showed the best results with recovery of 91 % polyphenols, 72 % melanoidins, 72 % water and methane yield of 189 mL/gVSin after 37 days. While the integrated FO-adsorption process is promising and can be readily incorporated in the overall Zero Liquid Discharge (ZLD) schemes conventionally practiced in Indian distilleries, there are several aspects of the FO and adsorption steps that need further investigation.

Concentrating molasses distillery wastewater using biomimetic forward osmosis (FO) membranes

Treatment of sugarcane molasses distillery wastewater is challenging due to the presence of complex phenolic compounds (melanoidins and polyphenols) having antioxidant properties. Due to zero liquid discharge regulations, Indian distilleries continue to explore effective treatment options. This work examines the concentration of distillery wastewater by forward osmosis (FO) using aquaporin biomimetic membranes and magnesium chloride hexahydrate (MgCl2.6H2O) as draw solution. The operational parameters viz. feed solution and draw solution flow rate and draw solution concentration were optimized using 10% v/v melanoidins model feed solution. This was followed by trials with distillery wastewater. Under the conditions of this work, feed and draw flow rates of 1 L/min and draw solution concentration of 2M MgCl2.6H2O for melanoidins model solution and 3M MgCl2.6H2O for distillery wastewater were optimal for maximum rejection. Rejection of 90% melanoidins, 96% antioxidant activity and 84% COD was obtained with melanoidins model feed, with a corresponding water flux of 6.3 L/m2h. With as-received distillery wastewater, the rejection was similar (85–90%) to the melanoidins solution, but the water flux was lower (2.8 L/m2h). Water recovery from distillery wastewater over 24 h study period was higher with FO (70%) than reported for RO (35–45%). Repeated use of the FO membrane over five consecutive 24 h cycles with fresh feed and draw solutions and periodic cleaning showed consistent average water flux and rejection of the feed constituents.

Integration of poly-3-(hydroxybutyrate-co-hydroxyvalerate) production by Haloferax mediterranei through utilization of stillage from rice-based ethanol manufacture in India and its techno-economic analysis.

Haloferax mediterranei has potential for economical industrial-scale production of polyhydroxyalkanoate (PHA) as it can utilize cheap carbon sources, has capacity for nonsterile cultivation and allows simple product recovery. Molasses-based Indian distilleries are converting themselves to cereal-based distilleries. Waste stillage (14 l) of rice-based ethanol industry was used for the production of PHA by H. mediterranei in the simple plug-flow reactor configuration of the activated sludge process. Cells utilized stillage and accumulated 63 ± 3 % PHA of dry cell weight and produced 13.12 ± 0.05 g PHA/l. The product yield coefficient was 0.27 while 0.14 g/l h volumetric productivity was reached. Simultaneous lowering of 5-day biochemical oxygen demand and chemical oxygen demand values of stillage by 82 % was attained. The biopolymer was characterized as poly-3-(hydroxybutyrate-co-17.9 mol%-hydroxyvalerate) (PHBV). Directional properties of decanoic acid jointly with temperature-dependent water solubility in decanoic acid were employed for two-step desalination of the spent stillage medium in a cylindrical baffled-tank with an immersed heater and a stirrer holding axial and radial impellers. 99.3 % of the medium salts were recovered and re-used for PHA production. The cost of PHBV was estimated as US$2.05/kg when the annual production was simulated as 1890 tons. Desalination contributed maximally to the overall cost. Technology and cost-analysis demonstrate that PHA production integrated with ethanol manufacture is feasible in India. This study could be the basis for construction of a pilot plant.

Compliance to zero liquid discharge norms in Indian distilleries: technical challenges and solutions

Molasses based distilleries in India are now classified as ‘Red Category’ because of the pollution caused by vinasse. The stringent norms being enforced by the pollution control authorities have posed many technical challenges and resulted in the development of advanced and cleaner technologies for effective and economical disposal of vinasse. There has been a shift from the end of pipe treatment to an integrated waste management in order to achieve zero liquid discharge. Anaerobic treatment to generate biogas, aerobic surface composting to manufacture bio-compost and reverse osmosis or multiple effect evaporation systems for concentration of vinasse are now well established. Advanced technologies such as concentrated vinasse incineration, and co-processing of vinasse in cement plants are also being investigated. This paper presents an overview of the latest technologies employed for fermentation and distillation, advantages and limitations of the various effluent treatment technologies and prospects for implementation of emerging technologies. The paper also provides recommendations for further improvement in established technologies for vinasse treatment.

Water management initiatives in sugarcane molasses based distilleries in India

Molasses based alcohol distilleries in India are one of the most polluting industries; in addition, they are high consumers of raw water. Growing scarcity of high quality freshwater as well as stringent regulatory standards is compelling these units to explore appropriate water management options. This paper provides an overview of the water use and effluent treatment status in Indian distilleries and the challenges faced by this sector. Practices adopted by progressive Indian distilleries to minimize freshwater use are illustrated through case studies. Further, the R&D focus pertaining to wastewater treatment and disposal is also summarized.

Improving industrial water use: case study for an Indian distillery

Alcohol distilleries are highly water intensive units generating large volumes of high strength wastewater that poses a serious environmental concern. This study aimed at identifying options for improved water use in this sector through a case study in a local distillery. It emerged that optimization of cooling tower operation, innovative ways to reuse wastewater streams like spent lees and spentwash and employing semi-continuous/continuous fermentation could reduce water use in distilleries.

Performance Evaluation of a Full Scale Effluent Treatment Plant for Distillery Spent Wash

Distillery spent wash can be one of the major polluting wastewaters, if discharged into water bodies without adequate treatment. Anaerobic lagooning was the only treatment option mostly practiced by distillers to treat distillery spent wash before 1980s. Thereafter, significant development in management of distillery spent wash has been achieved in this country. Today almost all distillers recover biogas from distillery spent wash through the biomethanation process. Anaerobic digesters, anaerobic fixed film systems and two-phase anaerobic treatment are some of the treatment options popularly practiced by Indian distilleries for biomethanation. Production of biogas from spent wash not only reduces the pollutional load but also reduces the payback period of the effluent treatment plant. This paper details the performance evaluation of a full-scale effluent treatment plant for distillery spent wash. In addition, the approach that included detailed biological and physico-chemical treatability studies for improvement in treated effluent quality is also discussed.

Bioremediation and decolorization of anaerobically digested distillery spent wash

A facultative anaerobic pure bacterial culture L-2 capable of growth on 12.5% (v/v) diluted digested spent wash supplemented with glucose (10 g/l) was isolated from an Indian distillery. It achieved 31% decolorization and 57% COD reduction after 7 days' incubation. The advantages of using such a culture for digested spent wash bioremediation are apparent in providing a realistic approach for decreasing its pollution potential prior to disposal.

Pilot plant studies on fixed bed reactor system for biomethanation of distillery spent wash

High strength distillery spent wash was successfully treated in fixed film fixed bed two‐staged anaerobic reactors using cheaper and abundantly available pebbles as media on laboratory scale. Encouraged with the results, further studies were carried out on pilot scale for the same reactor system installed in an Indian distillery. Optimum loading were observed as 10 Kg COD/m3.d (reactor‐I) and 3 Kg COD/m3 .day (reactor‐II) with detention period of 2.43 days with an influent COD concentration of approximately 50,000 mg/L. The overall COD removal was about 80% with a specific biogas yield of 0.30 m3CH4/Kg CODr. This paper deals with the detailed performance evaluation of the reactor system on pilot scale for biomethanation of distillery spent wash and determination of the relevant kinetic constants based on various models.