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

Abstract

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 (MgCl.6HO) 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 MgCl.6HO for melanoidins model solution and 3M MgCl.6HO 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/mh. With as-received distillery wastewater, the rejection was similar (85-90%) to the melanoidins solution, but the water flux was lower (2.8 L/mh). 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.

Permeation of greywater constituents in an aquaporin based biomimetic forward osmosis membrane process: experimental performance and modeling

“…where n is the number of species that the solute dissociates into; C is the solute molar concentration (mol L -1 ); R is the gas constant (R = 8.314 kPa·L (K mol) −1 ), and T is the absolute temperature of the solution (K). Based on the classical solution-diffusion model 27,28 and according to the model proposed by Jin et al, 17 when the active layer of the membrane is facing the FS, pollutant flux (J p ) through FO membrane is expressed as Eqn (5).…”

“…However, ICP at low FS concentration (i.e. C1 level) was reduced and the FS was severely concentrated during the filtration process 5 . Thus the true solute concentration in the FS (C' F,p ) was much higher than the initial FS concentration (C F,p ) after 2 h of filtration.…”

“…Forward osmosis (FO) is recognized as an emerging membrane separation technology which has the advantages of low energy consumption and high rejection of a broad range of pollutants . FO uses the osmotic pressure gradient as the driving force for the transport of water across the semi‐permeable membrane from a relatively low concentration feed solution (FS) to a concentrated draw solution (DS) and consequently resulting in concentration of the FS and dilution of the DS . A good FO membrane should have excellent water flux, high salt rejection and superb membrane stability simultaneously …”

“…[1][2][3] FO uses the osmotic pressure gradient as the driving force for the www.soci.org C Wang, Y Li transport of water across the semi-permeable membrane from a relatively low concentration feed solution (FS) to a concentrated draw solution (DS) and consequently resulting in concentration of the FS and dilution of the DS. 4,5 A good FO membrane should have excellent water flux, high salt rejection and superb membrane stability simultaneously. 6 Aquaporins are ubiquitous biological membrane proteins acting as selective water channels through the membrane.…”

Catalytic Wet Air Oxidation Using Supported Pt and Ru Catalysts for Treatment of Distillery Wastewater (Cognac and Sugarcane Vinasses)

“…However, the presence of compounds resistant to treatment (phenols, melanoidins, sugar decomposition products) can be toxic or inhibitory to anaerobic microorganisms. Physical processes (adsorption, nanofiltration, reverse osmosis) [21,22], chemical treatments such as coagulation-flocculation [23,24], and oxidation (such as Fenton oxidation [24,25], ozonation [26-28] photocatalysis [29,30], electrochemical oxidation [31], ultrasound [32,33], and certain combinations of these technologies) have been applied for the treatment of the distillery effluents. These processes may be employed after a primary aerobic or anaerobic treatment in order to further reduce the COD or eliminate color [34,35].Among the various treatment processes suggested, catalytic wet air oxidation (CWAO) has proven to be a feasible technology for the removal of organic compounds from wastewater streams [36][37][38].…”