Treatment Of Distillery Waste Water A Review Sanjay Patel

Patel and JamaluddinPolyphenols are responsible for strong inhibitory effectson microbial activity, and must be removed duringwastewater treatment, owing to the environmental andpublic health risks they pose. Humans exposed tophenol at 1300 mg/l of concentration exhibitedsignificant increases in diarrhoea, dark urine, mouthsores and burning of the mouth [31].III.ENVIRONMENTALHAZARDSDISTILLERY WASTEWATEROFThe production and the characteristics of thespent wash are highly variable and dependent on thefeedstock used and various aspects of the ethanolproduction process. Wash water used to clean thefermenters, cooling water blow down and broiler waterblow down further contribute to its variability [37]. In aDistillery, sources of wastewater are stillage, fermenterand condenser cooling water and fermenter wastewater.The liquid residues during the industrial phase of theproduction of alcohol are: liquor, sugarcane washingwater, water from the condensers and from the cleaningof the equipment, apart from other residual water.Distillery effluent has very high biological oxygendemand (BOD), chemical oxygen demand (COD) andhigh BOD/COD ratio. The amount of inorganicsubstances such as nitrogen, potassium, phosphates,calcium, sulphates is also very high. Its recalcitrantnature is due to presence of the brown polymers,melanoidins, which are formed by Maillard aminocarbonyl reaction. Table 1 gives physic-chemicalcharacteristics of distillery effluents.These compounds have antioxidant properties,which render them toxic to many microorganisms suchas those typically present in wastewater treatmentprocesses [38]. The defiance of melanoidins todegradation is apparent from the fact that thesecompounds escape various stages of wastewatertreatment plants and finally enters into the environment.Apart from melanoidins, the other recalcitrantcompounds present in the waste are caramel, variety ofsugar decomposition products, anthocyanins, tanninsand different xenobiotic compounds [39]. Theunpleasant odor of the effluent is due to the presence ofputriciable organics like skatole, indole and othersulphur compounds [40]. The molasses effluent that isdisposed in canals or rivers produces obnoxious smell[41]. Spent wash disposal into the environment ishazardous and has high pollution potential. High COD,total nitrogen and total phosphate content of the effluentmay result in eutrophication of natural water bodies [5].The highly colored components of the effluentcan block out sunlight from in rivers, lakes or lagoonswhich in turn decrease both photosynthetic activity anddissolved oxygen concentration affecting aquatic life.Kumar et al. [42] evaluated the toxic effect of distilleryeffluent on common guppy, Lesbistes reticulates andobserved remarkable behavioural changes with varying119effluent concentration. Impact of distillery effluent oncarbohydrate metabolism of fresh water fish, C. Carpiohas studied by Ramakritinan et al. [43]. Saxena andChauhan [44] investigated the influence of distilleryeffluent on oxygen consumption in fresh water fish,Labeo rohita and observed that the presence ofinorganic and organic salts in the effluent interferedwith the respiration in the fish. The coagulation of gillmucous decreased dissolved oxygen consumptioncausing asphyxiation. Matkar and Gangotri [45]observed concentration dependent toxicity of distilleryeffluent on the fresh water crab, Barythephusa guerini.Stress due to distillery effluent caused defunctrespiratory processes in the fish resulting inanaerobiosis at organ level during sub lethalintoxication. Distillery effluent disposed on land isequally hazardous to the vegetation.It is reported to inhibit seed germination, causesoil manganese deficiency and damage agriculturalcrops [46-47]. Raw distillery effluent is highly toxiceffect on the growth and germination of Vigna radiataseeds even at low concentration of 5% (v/v). Leachingof protein and carbohydrates from the seeds as well asdecrease in activities of important enzymes like alkalinephosphatase and ATPase was also observed [48].Application of distillery effluent to soil without propermonitoring, perilously affects the groundwater qualityby altering its physicochemical properties such as color,pH, electrical conductivity (EC), etc. due to leachingdown of the organic and inorganic ions [49]. In a studyconducted by Ramana et al. [29] the germinationpercent in five crops decreased with increase inconcentration of the effluent. The germination wasinhibited in all the five crops studied with concentrationexceeding 50%.At the same time, organic wastes contained indistillery effluent are valuable source of plant nutrientsespecially N, P, K and organic substrates if properlyutilized [50]. For instance, distillery effluent incombination with bioamendments such as farm yardmanure, rice husk and Brassica residues was used toimprove the properties of sodic soil [51]. The use offungi for bioconversion of distillery waste intomicrobial biomass or some useful metabolites has beenrecently reviewed by Friedrich et al. [52]. The endproducts of bioconversion are fungal biomass, ethanol,enzymes etc. and substantially purified anddecolourized effluents. Recently enhanced productionof oyster mushrooms (Pleurotus sp.) using distilleryeffluent as a substrate amendment have been reported[53].IV. DISTILLERY WASTEWATER TREATMENTWastewater treatment methods aim at the removal ofunwanted compounds in wastewater for safe dischargeinto environment.

Patel and JamaluddinThis can be achieved by using physical, chemical andbiological treatment of distillery effluent is eitheraerobic or anaerobic but in most cases a combination ofboth is used. Physical treatment methods such asmembrane filtration processes (nano-filtration, reverseosmosis, electro-dialysis) and adsorption techniques.Chemical treatment methods such as coagulation orflocculation combined with flotation and filtration,precipitation flocculation with Fe(II)/Ca(OH)2, electroflotation, electro-kinetic coagulation, conventionaloxidation methods by oxidizing agents (ozone),irradiation or electrochemical processes etc., removetoxic material and colloidal impurities. Melanoidins, thecomplex bio-polymer of amino–carbolyl compoundsare very recalcitrant in nature and exists extensively notonly in foods but also in wastewaters released fromvarious agro-based industries as sugarcane molassesbased distillery and fermentation industries and keepingin view the hazardous nature of melanoidins, itschemical and microbial degradation has been attemptedto reduce its pollution load and also to characterize itschemical structure so that better strategies could bemade for its degradation and decolourization.A. Physico-chemical Treatment technologies fordistillery wastewaterRemoval of melanoidin from distillery effluenthas been attempted, but with limited success so far [54,13]. Physiochemical treatment processes such asadsorption, oxidation process, coagulation andflocculation. Table 2 have been used for removal ofmelanoidins from treated effluent. However, theseprocesses still have disadvantages due to the highoperation cost, high consumption of chemical agent,fluctuation of color removal efficiency, high volume ofsolid waste produced, formation of hazardous byproducts and intensive energy requirements.Adsorption. Activated carbon is a well knownadsorbent due to its extended surface area, microporusstructure, high adsorption capacity and high degree ofsurface reactively. Among the physicochemicaltreatment methods, adsorption on activated carbon iswidely employed for removal of color and specificorganic pollutant. Bernardo et al. [55-56] investigateddecolourization of synthetic melanoidin usingcommercially available activated carbon as well asactivated carbon produced from sugarcane bagasse. Theadsorptive capacity of the different activated carbonswas found to be quite comparable. Chemically rochloride and 3-chloro-2-hydroxypropyltrimethylammonium chloride was capable of decolorizingdiluted effluent [57]. 0.6 g of chemically modifiedbagasse in contact with 100 ml 1:4 (v/v) effluent: watersolution resulted in 50% decolourization after 4 hcontact with intermittent swirling. Significantdecolourization was observed in packed bed studies on120anaerobically treated effluent using commercialactivated charcoal with a surface area of 1400m2/g [58].Almost complete decolourization ( 99%) was obtainedwith 70% of the eluted sample, which also displayedover 90% BOD and COD removal. In contrast, otherworkers have reported adsorption by activated carbonto be ineffective in the treatment of distillery effluent[59-60]. Adsorption by commercially availablepowered activated carbons resulted in only 18% colorremoval, combined treatment using coagulationflocculation with polyelectolyte followed by adsorptionresulted in almost complete decolourization [59]. Lowcost adsorbents such as pyorchar (activated carbon bothin granular and powdered form, manufactured frompaper mill sludge) and bagasse flyash have also beenstudied for this application. Ramteke et al. [61] reportedcolor removal up to 98% with pyorchar.However, to achieve the same level of colorremoval, larger doses of the indigenously preparedpowdered and granular pyorchar were required incomparison to commercial activated carbon. Mall andKumar [14] compared the color removal usingcommercial activated carbon and bagasse flyash. 58%color removal was reported with 30 g/l of bagasseflyash and 80.7% with 20 g/l of commercial activatedcarbon. Since the bagasse flyash has high carboncontent and the adsorbed organic material furtherincreases its heating value, the spent adsorbent can beused for making fire briquettes. Yet another adsorbentthat has been examined is the natural carbohydratepolymer chitosan derived from the exoskeleton ofcrustaceans. Lalov et al. [62] studied the treatment ofdistillery wastewater using chitosan as an anionexchanger. At an optimum dosage of 10 g/l and 30 mincontact time, 98% color and 99% COD removal wasobserved.Coagulation and flocculation. Coagulation isthe destabilization of colloids by neutralizing the forcesthat keep apart. The optimum dosage of lime was foundto be 10 g/l resulting in 82.5% COD removal and67.6% reduction in color in a 30 min period. Thesefindings are in disagreement with those of Migo et al.[63] used a commercial inorganic flocculent, a polymerof ferric hydroxysulfate for the treatment of molasseswastewater. The treatment resulted in around 87%decolourization for biodigested effluents; however, anexcess of flocculent hindered the process due toincrease in turbidity and total organic carbon (TOC)content. FeCl3 and AlCl3 were also tested fordecolourization of biodigested effluent and showedsimilar removal efficiencies. About 93% reduction incolor and 76% reduction in TOC were achieved wheneither FeCl3 or AlCl3 was used alone. The process wasindependent of chloride and sulfate ion concentrationbut was adversely affected by high fluorideconcentration.

121Patel and JamaluddinTable 2: Physicochemical methods employed for distillery wastewater treatment.TreatmentAdsorptionChitosan, a biopolymer was used as anion exchanger% COD removal% Color 95Flocculation of synthetic melanoidins was carried out by various inorganic ionsPolyferric hydroxysulphate (PFS)NRNRFerric chloride (FeCl3)9596Ferric sulphate (Fe2 (SO4 )3)NR95Aluminium sulphate (Al2(SO4)3)Calcium oxide (CaO)NRNR8377Calcium chloride (CaCl 2)NR46Chemically modified bagasseDEAE bagasseCHPTAC bagasseActivated carbon prepared from agro industrial wastePhosphoric acid carbonized bagasse was usedCommercially available activated carbonAC (ME)AC (LE)Coagulation-flocculation[60]Different inorganic ions and waste water from Iron pickling and Titanium process industry were used as coagulants. Addition ofpolyelectrolyte percol 47 reduced their dosageFerrous sulphate (FeSO4)78987796Ferric sulphate (Fe2 (SO4)3)AlumIron pickling waste waterTitanium processing waste waterIron chloride coagulationIron chlorideAluminium chlorideCalcium oxide (CaO)Ferric chloride (FeCl3)Aluminium chloride (AlCl 3)Polyaluminium (PAC)Oxidation processesFenton's oxidationOzonationElecrochemical 2838692[38]8815-259980[64][65]Graphite electrodes80.695.6Lead dioxide coated on titanium90.898.5Ruthedium dioxide coated on titanium92.199.5Electrocoagulation and electro Fenton92.6[61][62][63][66][67]Membrane technologiesReverse osmosis99.9Nanofiltration97.1However in the presence of high flocculentconcentration (40 g/l), addition of 30 g/l CaO enhancedthe decolourization process resulting in 93% colorremoval. This was attributed to the ability of calciumions to destabilize the negatively charged melanoidins;further, formation of calcium fluoride (CaF2) alsoprecipitates the fluoride ions.Almost complete color removal (98%) of biologicallytreated distillery effluent has been reported withconventional coagulants such as ferrous sulfate, ferricsulfate and alum under alkaline conditions [39]. The[27]100best results were obtained using Percol 47, acommercial organic anionic polyelectrolyte, incombination with ferrous sulfate and lime. Thecombination resulted in 99% reduction in color and 87and 92% reduction in COD and BOD, respectively.Similar findings have also been reported by Mandal etal. [60]. Coagulation studies on distillery effluent afteranaerobic–aerobic treatment have also been conductedusing bleaching powder followed by aluminum sulfate[71].

Patel and JamaluddinThe optimum dosage was 5 g/l bleaching powderfollowed by 3 g/l of aluminum sulfate that resulted in96% removal in color, accompanied by up to 97%reduction in BOD and COD. Non-conventionalcoagulants namely wastewater from an iron picklingindustry which is rich in iron and chloride ions andtitanium ore processing industry containing significantamounts of iron and sulfate ions have also beenexamined [39]. The iron pickling wastewater gavebetter results with 92% COD removal, combined withover 98% color removal. Though the titaniumprocessing wastewater exhibited similar color removallevels, the COD and BOD reductions were perceptiblylower.Oxidation process. Ozone destroys hazardousorganic contaminants and has been applied for thetreatment of dyes, phenolics, pesticides, etc. [68].Oxidation by ozone could achieve 80% decolourizationfor biologically treated effluent with simultaneous 15–25% COD reduction. It also resulted in improvedbiodegradability of the effluent. However, ozone onlytransforms the chromophore groups but does notdegrade the dark colored polymeric compounds in theeffluent [68, 72]. Similarly, oxidation of the effluentwith chlorine resulted in 97% color removal but thecolor reappeared after a few days [60]. Ozone incombination with UV radiation enhanced spent washdegradation in terms of COD; however, ozone withhydrogen peroxide showed only marginal reductioneven on a very dilute effluent [73]. In another study,Sangave and Pandit [74] employed sonication ofdistillery wastewater as a pre-treatment step to convertcomplex molecules into a more utilizable form bycavitation. Samples exposed to 2 h ultrasoundpretreatment displayed 44% COD removal after 72 h ofaerobic oxidation compared to 25% COD reductionshown by untreated samples. These results are contraryto those of Mandal et al. [60] who concluded ultrasonictreatment to be ineffective for distillery effluenttreatment.A combination of wet air oxidation andadsorption has been successfully used to demonstratethe removal of sulfates from distillery wastewater.Studies were done in a counter current reactorcontaining 25 cm base of small crushed stonessupporting a 20 cm column of bagasse ash as anadsorbent [75]. The wastewater was applied from thetop of the reactor and air was supplied at the rate of 1.0l/min. The treatment removed commercially availablepowdered activated carbons resulted in only 18% colorremoval; however, combined treatment usingcoagulation–flocculation with polyelectrolyte followed57% COD, 72% BOD, 83% TOC and 94% sulfates.Wet air oxidation has been recommended as part of acombined process scheme for treating an-aerobicallydigested spent wash [76]. The post-anaerobic effluentwas thermally pre-treated at 150 C under pressure inthe absence of air. This was followed by soda-limetreatment, after which the effluent underwent a 2 h wet122oxidation at 225 C. 95% color removal was obtained inthis scheme. Another option is photo catalytic oxidationthat has been studied using solar radiation and TiO2 asthe photo catalyst [77]. Use of TiO2 was found to bevery effective as the destructive oxidation process leadsto complete mineralization of effluent to CO2 and H2O.Up to 97% degradation of organic contaminants wasachieved in 90 min. Pikaev et al. [78] studied combinedelectron beam and coagulation treatment of distilleryslops from distilleries processing grain, potato, beet andsome other plant materials. Humic compounds andlignin derivatives constitute the major portion of thisdark brown wastewater. The distillery wastewater wasdiluted with municipal wastewater in the ratio of 3:4,irradiated with electron beam and then coagulated withFe2(SO4)3. The optical absorption in UV region wasdecreased by 65–70% after this treatment. The cost wasfound to be less than the existing method wherein theeffluent was transported about 20 km via pipeline to afacility for biological treatment followed bysedimentation. The treatment cost was 0.45–0.65US /m3 which dropped to 0.25 US /m3 using combinedelectronic-beam and coagulation method.Other treatments. Pikaev et al. [78] applied radiationtechnology for treatment of distillery waste. The studyinvolved a combined treatment of electron beam (dose20 kGy) and coagulation using Fe2(SO)3 which resultedin a decrease in optical absorption in the uv region by65–70% in the treated effluent. Ultrasound technologywas also applied for the treatment of distillery effluent.Studies were carried out to find out the efficacy of theultrasonic irradiation as a pre-treatment step and theresults indicated that ultrasound treatment enhanced thebiodegradability of the distillery waste water [74].Chaudhari et al. [79] proposed a novel catalytic thermalpre-treatment or catalytic thermolysis (CT) to recoverthe majority of its energy content with consequent CODand BOD removal. They found that the initial pH (pH)had profound impact on the efficiency of thermolysis inCOD removal. At 140 C with 3kgm 3 catalyst loadingand pH 2 (optimum value), they observed a maximumof 60% COD removal. The CT process resulted in theformation of settleable solid residue and the slurryobtained after the thermolysis exhibited very goodfiltration characteristics. At 140 C and pH 2, the solidresidue had a C:H atomic ratio of 1:1.08 with a heatingvalue of 21.77MJ kg 1. The residue can be used as afuel in the combustion furnaces and the ash obtainedcan be blended with organic manure and used inagriculture/horticulture. Kannan et al. [80] adoptedelectro coagulation technique with addition ofindigenously prepared areca nut carbon (AAC) fortreatment of distillery effluent. This study, for a periodof 1 h, resulted in almost colourless effluent with 89.7%BOD and 80% COD removal. This process resulted inthe formation of settleable solid residue and the slurryobtained after the thermolysis exhibited very goodfiltration.

Patel and JamaluddinIt can be used as a fuel in the combustion furnaces andthe ash obtained can be blended with organic manureand used in agriculture/horticulture. Various physicochemical methods such as adsorption, coagulationflocculation and oxidation processes like Fenton’soxidation, ozonation, electrochemical oxidation usingvarious electrodes and electrolytes, nonofiltration,reverse osmosis, ultrasound and different combinationsof these methods have also been tested for the treatmentof distillery effluent. As mentioned above, sugarcanemolasses wastewaters have been reported to bedecolorized by various physico-chemical methodswhich are summarized above.Physico-chemical treatment methods areeffective in both color and COD removal. Neverthelessthe drawbacks associated with these methods are excessuse of chemicals, sludge generation with subsequentdisposal problems, high operational cost and sensitivityto variable water input [81]. Considering the advantagesand the disadvantages of different treatmenttechnologies, no single technology can be used forcomplete treatment of molasses wastewater. Hence,there is a need to establish a comprehensive treatmentapproach involving several technologies sequentially.B. Biological/microbial TreatmentMicroorganisms due to their inherent capacityto metabolize a variety of substrate have beenutilized since long back for biodegradation of complex,toxic and recalcitrant compounds which cause severedamage to environment. Thus, these organisms

Sanjay Patel and Jamaluddin Department of Biological Sciences, RD University, Jabalpur (Madhya Pradesh), India. (Corresponding author: Sanjay Patel) (Received 17 January 2018, Accepted 27 March, 2018) (Published by Research Trend, Website: www.researchtrend.net)