COAGULATION AND FLOCCULATION TREATMENT OF WASTEWATER IN TEXTILE INDUSTRY USING CHITOSAN

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December 2010, Volume 1, No.2 International Journal of Chemical and Environmental Engineering Improvement of Coagulation-Flocculation Process for Treatment of Detergent Wastewaters Using Coagulant Aids A. Ayguna, T. Yilmazb a Department of Environmental Engineering, Selcuk University, Konya, Turkey, ahmetaygun@selcuk.edu.tr b Kocaeli Provincial Department of Environment and Forestry, Kocaeli, Turkey, tuba.ertugrul@gmail.com Abstract In this study, coagulation-flocculation process was used to treat detergent wastewater with ferric chloride as coagulant. The improvement of the process by using polyelectrolytes and clay minerals (montmorillonite and bentonite) as coagulant aids was also investigated. The results of the wastewater characterization showed that the concentration of organic matter expressed as che mical oxygen demand (COD) was as high as 24.3 g/L while the biochemical oxygen demand was low. Chemical treatment can be considered as a suitable option for treatment of detergent wastewater due to the low ratio of BOD5/COD. Coagulation/flocculation and precipitation studies were performed in a conventional jar-test apparatus. The coagulant dosage of ferric chloride ranged between 0.5 g/L and 3 g/L, whereas the concentrations of polyelectrolyte and clay minerals varied between 5-75 mg/L and 25-750 mg/L, respectively. The optimal condition was obtained at the dosage 2 g/L ferric chloride at pH 11 with the COD removal efficiency of 71%. Addition of coagulant aids provided higher removal efficiencies. Using clay minerals at the dose of 500 mg/L with ferric chloride provided 84% of COD removal and the removal efficiency of COD increased with using polyelectrolyte, resulting in an efficiency of 87%. The maximum removal efficiency was obtained with the addition of polyelectrolyte and it was found that the ferric chloride combination with coagulant aids, at certain pH and agitation speed, provided higher removal efficiencies compared to coagulation with ferric chloride alone. Key Words: coagulation-flocculation, detergent wastewater, ferric chloride, polyelectrolyte, clay minerals 1. Introduction Detergent wastewater discharge can cause serious environmental problems because detergent product and its ingredients can be relatively toxic to aquatic life [1]. Anionic and nonionic surfactants are major components of synthetic detergents. In order to protect the water environment, an efficient treatment process must be applied [2]. Due to its complexity, detergent wastewater is very difficult to treat [3]. Methods for removal of surfactants involve processes such as chemical and electrochemical oxidation, membrane technology, chemical precipitation, photocatalytic degradation, adsorption and various biological methods. Each of them has limitation and some drawback in application [4]. Treatment of surfactant wastewaters by biological processes such as activated sludge is problematic due to the low kinetics of degradation and foam production [5]. Hence, among the currently employed chemical unit processes in wastewater treatment, coagulationflocculation has received considerable attention because of high impurity removal efficiency. Coagulation/flocculation is a commonly used process in water and wastewater treatment in which compounds such as ferric chloride and/or polymer are added to wastewater in order to destabilize the colloidal materials and cause the small particles to agglomerate into larger settleable flocs [6]. FeCl 3 is an important coagulant in wastewater treatment and can be used for color removal [7-8], organic matter removal in leachate [9], solid removal from fisheries wastewaters [10], treatment of municipal wastewater [11], surfactant removal from microelectronic plant wastewater [4]. Abdulhassan et al, [4] found that coagulationflocculation process using FeCI 3 can be used effectively for removal of surfactants and COD from microelectronic plant wastewater and the removal efficiencies of 99% and 88% were obtained, respectively. Also they found that the rate of COD removal decreased if the pH was lower than 7 or higher than 9. High operating costs due to the use of chemical substances and high amount of sludge and its disposal costs are shown as the important disadvantages of chemical treatment [12]. Therefore, researchers have focused on new alternative methods to reduce chemical usage by improving discharge standard with adding low cost natural substance. Clay minerals are natural substances used in wastewater treatment and have high ion exchange 2.1Experimental Procedure capacity, absorption, and catalysis properties as well as natural and low-cost materials [13]. Some researchers reported that clay minerals can be preferable coagulant aid for removal of toxic compounds, pesticide, herbicide, heavy metals and color removal [14]. It is clear that all treatment methods in use have some drawbacks, and there is a need to look for other alternative methods. In the literature, there is some evidence that clay minerals, when used in conjunction with coagulants result in improved COD removals, as compared to used alone [15]. However, there are no detailed studies in the literature about the comprehensive investigation of using clay minerals in coagulation process for treatment of detergent wastewater. The aim of this study is treatment of detergent wastewater by coagulation-flocculation process using ferric chloride as coagulant. And also, improvement of process performance is investigated by using polyelectrolytes and clay minerals as coagulant aids in flocculation step. Coagulation-flocculation and precipitation studies were performed in a six-place conventional jar-test apparatus, equipped with 6 beakers of 500 mL volume. Before coagulation/flocculation process, wastewater sample was thoroughly shaken to avoid possibility of settling solids. The experimental process consisted of the initial rapid mixing stage that took place for 5 min at 150 rpm, the following slow mixing stage for 30 min at 30 rpm and the final settling step for 1 h. After 1 hour settling period, samples were withdrawn from supernatant for analyses. Process performance was monitored by using COD values. Table 2.Chemical analyses of the clay minerals used in this study Properties Unit By Mass SiO2 Al2O (%) (%) (%) (%) (%) (%) (%) (%) (%) 52.69 12.19 8.63 6.15 4.15 1.92 0.11 0.46 13.86 Specific Surface Area (m2/g) 538.72 >45 µm (%) 12.56 >10 µm (%) 28.82 >2 µm (%) 48.67 3 Fe2O 3 CaO MgO TiO2 K2O Na2 O Loss on Ignition 2.Materials and Methods Wastewater sample was collected from outfall of a recycling plant located in Dilovası Organized Industrial Zone, Kocaeli city, Turkiye. In the recycling plant, IBC tanks, used for storage and transport, are brought for cleaning of detergent residues before they are used again. Cleaning is carried out by using high pressurized water and after cleaning, wastewater containing detergent has to be treated before it is discharged to sewage system. The average flow rate of wastewater is about 25 m 3/day. Wastewater sample collected from the plant was placed in plastic containers to be transported to the laboratory and stored at 4 0C in a refrigerator. The composition of the detergent wastewater is presented in Table 1. .Experimental studies carried out in three steps. In the first step, optimum pH for the treatment was determined. The study was carried out between the pH values of 4-12. Desired pH values of wastewater were adjusted by using 6N and 0.1 N H2SO4 and NaOH. In the second step coagulation-flocculation was performed between ferric chloride concentration of 0.5-3 g/L and optimum concentration was investigated. In the last step polyelectrolyte and clay minerals were added as coagulant aids for improving process performance and the most efficient coagulant aid was determined. The concentrations used in this step were between 5-75 mg/L for polyelectrolyte and 25-750 mg/L for clay minerals. Table 1.the composition of detergent wastewater Parameter Value pH 12.31 24.3 Chemical oxygen demand (COD) (g/L) Biochemical oxygen demand (BOD5) (g/L) 3.2 BOD5/COD 0.05 In this study, two kinds of coagulant aids were used. One of them was polyelectrolyte (anionic 1858 S) whereas the other was clay minerals. The clay minerals used in this study were collected from an area in Ermenek, Konya City (Turkey). Chemical analyses of the clay minerals are illustrated in Table 2. pH, COD, BOD5 were analysed in the laboratory according to the methods given in the Standard Methods. pH measurements were done by using the WTW Multiparameter 340i. Closed reflux colorimetric method (Method 5220 C) was used for COD analysis and BOD 5 was analysed (Method 5210) as dictated by Standard Methods [16]. 3.Results and discussion Coagulation-flocculation process was conducted for the treatment of the detergent influent. Numerous jar tests were carried out in order to establish a practical understanding of the coagulation performance and to find optimum pH, coagulant dosage and coagulant aid dosage. 3.1 Effect of pH on Coagulation In the coagulation–flocculation process, pH is very important since the coagulation occurs within a specific pH range for each coagulant. In this study, a wide range of pH between 4-12 was selected. 98 The results of the study showing the effect of pH on COD removal efficiencies and effluent COD concentrations when FeCl3 was used as a coagulant are presented in Figure 1. To determine optimum pH value, FeCl3 dosage was constant at 1.5 g/L. When pH increased from 4 to 11, COD removal efficiency increased from 34% to 57% and COD concentration of effluent was 10560 mg/L. At higher pH value, COD removal efficiency decreased. It is clear that optimum pH was 11 for the coagulation-flocculation process at 1.5 g/L FeCl 3 dosage. pH is an important parameter for coagulation process since it controls hydrolysis species. When a coagulant such as aluminum or ferric salt is added to water, a series of soluble hydrolysis species are formed. These hydrolysis species have positive or negative charges depending on the water pH. They are positively charged at low pH (< 6) and negatively charged at high pH. The positively charged hydrolysis species can absorb onto the surface of colloidal particles and destabilize the stable colloidal particles. This mechanism is called ‘charge neutralization’. A precipitate of aluminum or ferric hydroxide is formed at sufficiently high coagulant dosage. These precipitates can physically sweep the colloidal particles from the suspension. This mechanism is called ‘sweep-floc coagulation’ [17]. In this study, after FeCl 3 addition as a coagulant, mechanism of coagulation showed properties of sweep-floc coagulation due to the high pH in operation. leading to total COD removal of 47%. Mahvi et al. [2] reported that when lime, alum and ferric chloride were used as a coagulant, COD removal resulted in 21%, 37% and 89%, respectively. This results shows that ferric chloride can be noteworthy option and provide higher removal efficiencies than lime, alum and their combinations. Figure 2. Effect of FeCl3 dosages on the effluent COD and COD removal efficiency 3.3 Effect of Polyelectrolyte Polyelectrolytes are commercial coagulant aids. Synthetic polyelectrolytes are currently the most widely used chemicals in the treatment of industrial wastewaters. Generally, a little amount of polyelectrolyte dosage is enough to reach high efficiency. Because of they have some advantages including the possibility of structuration in response to specific requirements, greater purity, higher quality, stability and greater efficiency [19]. With polyelectrolytes as coagulant aids, the metal coagulant dosage can be reduced without cutting down the performance [20]. Yu et al, [21] reported that the charge density and molecular weight of polyelectrolyte play important role in the coagulation. Effluent COD and COD removal efficiencies versus different polyelectrolyte dosages are given in Figure 3. At the lowest concentration of polyelectrolyte, COD removal efficiency was 74% and effluent COD concentration was 6.4 g/L . With increase in polyelectrolyte concentration, removal efficiency increased up to 87%. At a higher concentration than 50 mg/L, effluent COD decreased thus 50 mg/L polyelectrolyte dosage was accepted as optimum dosage. Optimum concentration of polyelectrolyte forms a bridge between particles and cause good flocculation. However high concentration of polyelectrolyte forms an envelope on the suspending particles and causes them to remain in suspension thus removal efficiency decreases [18]. Similar result was obtained from this study and when the polyelectrolyte concentration was increased, process performance was decreased. Figure 1. COD removal efficiency and effluent COD concentrations at different pH values 3.2 Determination of the optimal coagulant dosage Effect of FeCl3 dosages on the COD removal efficiency is shown in Figure 2. Coagulation-flocculation was performed between ferric chloride concentrations of 0.5-3 g/L. At a concentration of 2 g/L, removal efficiency was 71% that was accepted as the optimum dosage. COD removal efficiency decreased by increasing FeCl 3 concentration. At high coagulant doses, metal hydroxides are produced and organic substances are removed by incorporation into or sorption onto hydroxide flocs [18]. According to the study of Papadopoulos et al. [3] use of 1.5 g/L lime in coagulation-flocculation process provided COD removal efficiency of 29%, combination with 1.5 g/L alum improved COD removal up to 18%, 99 Figure 3. Effect of polyelectrolyte dosages on the effluent COD and COD removal efficiency Figure 4. Effect of clay minerals dosages on the effluent COD and COD removal efficiency 3.4 Effect of clay minerals on coagulation Clay minerals may be used as coagulant aids in flocculation step of binding already formed small flocs into larger particles when aluminum or iron salts have been used as the primary coagulant. Coagulation with clay minerals followed by sedimentation can clean up industrial effluent when the flocs formed are dense enough [22]. Effect of clay minerals dosages on the effluent COD and COD removal efficiency is illustrated in Figure 4. When clay minerals used as a coagulant aids in the range of 25-500 mg/L, effluent COD value decreased from 24.3 g/L to 6.08 at minimum clay concentration and to 3.84 g/L at maxium clay concentration Maximum removal efficiency was 84% and obtained at the concentration of 500 mg/L which was accepted as the optimum dosage. Although COD removal was slightly higher at 750 mg/L, the difference was only 1% that can be accepted insignificant. In addition to this, Dilek and Bese [15] reported that the clay addition during alum coagulation had a positive effect on the dewaterability of the sludge in treating pulp-and-paper industry wastewaters. This improvement was more pronounced in combinations with higher clay dosages. In this study, removal efficiencies of clay minerals and polyelectrolyte were similar to each other. Clay minerals are natural and local sources, so when clay minerals and polyelectrolyte used as coagulant aids, if the removal efficiency of each coagulant aid is close to each other, the operation cost of treatment with clay minerals may be lesser than polyelectrolyte. In the study of Demirci et al. [18], the results were shown clearly and the cost of the annual waste water treatment of 2.16x106 m 3 using the common coagulant alum together with clay or polyelectrolyte was calculated. The results indicated that the cost in the treatment with clay was about 50 000 dollars whereas it was about 1 600 000 dollars in the treatment with polyelectrolyte. 4. Conclusion In treatment of detergent wastewater that contains relatively high COD and low BOD, coagulation process can be used as a pretreatment process. In this study, FeCl3 had the lowest COD removal efficiency when it was used alone and it was determined that addition of polyelectrolyte and clay minerals to FeCl 3 as coagulant aids, improved the COD removal efficiency. The highest removal efficiency was obtained from the combination of FeCl3 with clay minerals. Comparing all the results and possibilities, using clay minerals as coagulant aid accompanied with FeCl3 can be advisable and more economical option for the treatment of detergent wastewater since it has similar removal efficiency compared with polyelectrolyte and more economic. REFERENCES [1] Kowalska I., Kabsch-Korbutowicz, M., Majewska-Nowak, K., Pietraszek, M., Removal of Detergents from Industrial Wastewater in Ultrafiltration Process, Environment Protection Engineering, Vol.31, No. 3-4, pp. 207-219, 2005. [2] Mahvi, A.H., Maleki, A., Roshani, B., Removal of Anionic Surfactants in Detergent Wastewater by Chemical Coagualation, Pakistan Journal of Biological Sciences, Vol. 7, No. 12, pp. 22222226, 2004. [3] Papadopoulos, A., Savvides, C., Loizidis, M., Haralambous, K.J., Loizidou, M., An assessment of the quality and treatment of detergent wastewater, Water Science and Technology, Vol. 36, No. 2-3, , pp. 377-381, 1997. [4] Aboulhassan, M. A., Souabi, S., Yaacoubi, A., Baudu, M., Removal of surfactant from industrial wastewaters by coagulation flocculation process, International Journal of Environmental Science and Technology, Vol. 3, No. 4, pp. 327-332. 2006. [5] Dhouib, A., Hamad, N., Hassaïri, I. and Sayadi, S., Degradation of Anionic Surfactants by Citrobacter Braakii, Process Biochemistry, Vol. 38, pp. 1245-1250, 2003. 100 [6] Amuda, O.S., Amoo, I.A., Coagulation /flocculation Process and Sludge Conditioning in Beverage Industrial Wastewater Treatment, Journal of Hazardous Materials, Vol. 141, No. 3, , pp. 778-783, 2007. [7] Papic, S., Koprivanac, N., Bozic, A. L., Removal of Reactive Dyes from Wastewater Using Fe(III) Coagulant, Coloration Technology, Vol. 161, No. 11, pp. 352–358, 2000. [8] Errais, E., Duplay, J., Darragi, F., Textile Dye Removal by Natural Clay – Case Study of Fouchana Tunisian Clay, Environmental Technology, Vol. 31, No. 4, pp. 373-38, 2010. [9] Yilmaz, T., Apaydin, S., Berktay, A., Coagulation-Flocculation and Air Stripping as a Pretreatment of Young Landfill Leachate, The Open Environmental Engineering Journal, Vol. 3, pp. 42-48, 2010. [10] Genovese C.V., González, J. F., Solids Removal by Coagulation from Fisheries Wastewaters, Water SA, Vol. 24, No. 4, pp. 371372, 1998. [11] Odegaard, H., Optimised Particle Separation in the Primary Step of Wastewater Treatment, Water Science and Technology, Vol. 37, No. 10, pp. 43-53, 1998. [12] Alpaslan, M.N., Dolgen, D., Akyarli, A., Liquid Waste Management Strategies for Coastal Areas, Water Science and Technology, Vol. 46, No. 8, pp. 169-175. 2002. [13] Ingram, D.S., Vince-Prue, D., Gregory, P.J., Science and the Garden: The Scientific Basis of Horticultural Practice. Blackwell Science Ltd., Oxford, 2003. [14] Hascakir, B., Dolgen, D., Utilization of Clay Minerals in Wastewater Treatment: Organic Matter Removal with Kaolinite, Ecology, Vol. 66, pp. 47-54,2008 [15] Dilek, F.B., Bese, S., Treatment of pulping effluents by using alum and clay-Colour removal and sludge characteristics, Water SA, Vol. 27, No. 3, pp. 361-366, 2001. [16] APHA, AWWA, WEF, Standard Methods for the Examination of Water and Wastewater (21th edition) Washington: APHA, AWWA, WPCF, 2005. [17] Kim, S.H., Moon, B.H., Leeb, H.I., Effects of pH and Dosage on Pollutant Removal and Floc Structure During Coagulation, Microchemical Journal, Vol. 68, No. 2-3, pp. 197-203. 2001. [18] Demirci, S., Erdogan, B., Ozcimder, R., Wastewater Treatment At The Petroleum Refinery, Kirikkale, Turkey Using Some Coagulants And Turkish Clays As Coagulant Aids, Water Research, Vol. 32, No. 11, 3495-1499, 1998. [19] Aguilar, M.I., Saez, J., Llorens, M., Soler, A., Ortuno, J.F., Meseguer, V., Fuentes, A., Improvement of Coagulation– Flocculation Process Using Anionic Polyacrylamide as Coagulant Aid, Chemosphere, Vol. 58, No. 1, pp. 47-56, 2005. [20] Bolto, B., Abbt-Braun, G., Dixon, D., Eldridge, R., Frimmel, F., Hesse, S., King, S., Toifl, M., Experimental evaluation of cationic polyelectrolytes for removing natural organic matter from water, Water Science and Technology, Vol. 40, pp. 71–79, 1999. [21] Yu, J., Wang, D., Ge, X., Yan, M., Yang, M., Flocculation of kaolin particles by two typical polyelectrolytes: A comparative study on the kinetics and floc structures, Colloids and Surfaces A: Physicochemical and Engineering Aspects, Vol. 290, No. 1-3, pp. 288-294. 2006. [22] Ozacar, M., Sengil, I.A., The Use of Tannins from Turkish Acorns (Valonia) in Water Treatment as a Coagulant and Coagulant Aid, Turkish Journal of Engineering & Environmental Sciences, Vol. 26, pp. 255-263, 2002. 101
Journal of Chemical and Natural Resources Engineering, Vol.4(1):43-53 FKKKSA, UNIVERSITI TEKNOLOGI MALAYSIA COAGULATION AND FLOCCULATION TREATMENT OF WASTEWATER IN TEXTILE INDUSTRY USING CHITOSAN MOHD ARIFFIN ABU HASSAN1, TAN PEI LI1, ZAINURA ZAINON NOOR1 ABSTRACT Aluminum sulfate (alum), ferrous sulfate, ferric chloride and ferric chloro-sulfate were commonly used as coagulants. However, a possible link of Alzheimer’s disease with conventional aluminium based coagulants has become an issue in wastewater treatment. Hence, special attention has shift towards using biodegradable polymer, chitosan in treatment, which are more environmental friendly. Moreover, chitosan is natural organic polyelectrolyte of high molecular weight and high charge density which obtained from deacetylation of chitin. Experiments were carried out on textile industry wastewater by varying the operating parameters, which are chitosan dosage, pH and mixing time in order to study their effect in flocculation process by using chitosan. The results obtained proved that chitosan had successfully flocculated the anionic suspended particles and reduce the levels of Chemical Oxygen Demand (COD) and turbidity in textile industry wastewater. The optimum conditions for this study were at 30 mg/l of chitosan, pH 4 and 20 minutes of mixing time with 250 rpm of mixing rate for 1 minute, 30rpm of mixing rate for 20 minutes and 30 minutes of settling time. Moreover, chitosan showed the highest performance under these conditions with 72.5% of COD reduction and 94.9% of turbidity reduction. In conclusion, chitosan is an effective coagulant, which can reduce the level of COD and turbidity in textile industry wastewater. Keywords: 1.0 Chitosan; textile wastewater; coagulation; flocculation; wastewater treatment. INTRODUCTION Textile dyeing processes are among the most environmentally unfriendly industrial processes, because they produce colored wastewaters that are heavily polluted with dyes, textile auxiliaries and chemicals [1]. Besides, textile finishing’s wastewaters, especially dye-house effluents, contain different classes of organic dyes, chemicals and auxiliaries. Thus they are coloured and have extreme pH, COD and BOD values, and they contain different salts, surfactants, heavy metals, mineral oils and others. Therefore, dye bath effluents have to be treated before being discharged into the environment or municipal treatment plant [2]. Textile dyes are structurally different molecules themselves with low or no biodegradability. The removal of color is associated with breakup of the conjugated unsaturated bonds in molecules. For this reason, many chemical treatment processes have been used extensively to treat textile wastewaters. Most of the studies, such as chemical precipitation, adsorption by activated carbon photocatalytic oxidation, ozonation and Fenton’ oxidation focusing on color removal although effective, are 1 Department of Chemical, Faculty of Chemical and Natural Resources Engineering, Universiti Teknologi Malaysia, 81310 UTM Skudai, Johor, Malaysia. Correspondence to : Mohd. Ariffin (m.ariffin@fkkksa.utm.my) MOHD. ARIFFIN, TAN PEI LI, ZAINURA expensive or can cause further secondary pollution [3]. In most water treatment plants, the minimal coagulant concentration and the residual turbidity of the water are determined by the Jar-Test technique. Besides, physical-chemical treatment allows reducing dissolved, suspended, colloidal and non settable matter as well as colouring from dyes. Depending on the wastewater characteristics, COD of a textile effluent can be reduced between 50% and 70% after optimizing the operating conditions such as pH, coagulant and flocculants concentrations [2]. Coagulation or flocculation process was conducted for the treatment of industrial wastewater to achieve maximum removal of COD, TP and TSS. Therefore, Amudaa and Amoob [4] investigated the effect of coagulant dose, polyelectrolyte dose, pH of solution and addition of polyelectrolyte as coagulant aid and found to be important parameters for effective treatment of beverage industrial wastewater. Colloid particles are removed from water via coagulation and flocculation processes [5].Besides, Guibal and Roussy [6], pointed that the coagulation and the flocculation of suspended particles and colloids result from different mechanisms including electrostatic attraction, sorption (related to protonated amine groups) and bridging (related to polymer high molecular weight). Aluminum sulfate (alum), ferrous sulfate, ferric chloride and ferric chlorosulfate were commonly used as coagulants [7]. Additionally, high COD removal capacities have been observed during the combined action of alum and lime for the treatment of stabilized leachates. However, it has been stated out recently that there may be a possibility for aluminium-based coagulants to link with Alzheimer’s disease [8]. Hence, a special attention has been given to the environmental friendly coagulant or flocculent, chitosan. Chitin is cellulose like biopolymer widely distributed in nature, especially in marine invertebrates, insects, fungi, and yeasts. Its deacetylated product, chitosan, is readily soluble in acidic solutions, which makes it more available for applications. Chitosan is a biodegradable, non-toxic, linear cationic polymer of high molecular weight. Besides, chitosan was an effective agent for coagulation of suspended solids from various food processing wastes [5]. Moreover, chitin extraction also does not cause any disturbance to the ecosystem, its embraces all advantages provided by polysaccharides, considering it as the source of chitosan, and both are biocompatible biopolymers for animal tissues with low toxicities and significant biomedical applications [9]. Chitosan coagulation produced flocs of better quality, namely larger flocs and faster settling velocity. The effectiveness of chitosan for coagulating mineral suspensions was improved due to the presence of inorganic solutes or due to addition of materials extracted from soils at high pH [5]. Apparently, no major studies have been done to clarify the textile wastewater by using chitosan in coagulation and flocculation process. Therefore, this study was carried out to analyze the effect of chitosan in clarifying textile wastewater in flocculation process in different experimental conditions. The optimum pH, dosage and mixing time needed to achieve the best performance of chitosan in flocculation process were determined. 2.0 EXPERIMENTAL 2.1 Sample collection and materials Sample of textile wastewater was collected from a textile company which is situated in Kulai, Johor Bahru. The sample had been stored in the refrigerator in order to 44 COAGULATION AND FLOCCULATION TREATMENT OF WASTEWATER minimize the changes in the characteristics of wastewater sample since it may vary from day to day. Chitosan was purchased in the form of white fine powder from Agros Company. The Chemical Oxygen Demand (COD) reagent vials in high range (0 to 15 000 mg/l) were purchased from Hach Company. 2.2. Coagulant preparation Stock solution of chitosan should be prepared before starting the experiment. 3g of chitosan which purchased in form of white fine powder was used. Then, 96g of distilled water and 1g of acetic acid were added in order to dilute the chitosan powder. Pinotti et al. [3] pointed that chitosan solutions were prepared by dissolving the chitosan in 1% acetic acid solution during continuous agitation for several hours. According to Guibal and Roussy [6], chitosan dissolved in acetic acid, was used in the coagulation and flocculation processes. Besides, Pan et al. [5] pointed that chitosan is soluble in acidic solution, which makes it more available for application. Therefore, acetic acid needs to be added in order to dilute the chitosan powder. 2.3 Jar test A conventional jar test apparatus was used in the experiments to coagulate sample of textile wastewater by using chitosan. It was carried out as a batch test, accommodating a series of six beakers together with six-spindle steel paddles. Besides, the sample of wastewater was adjusted from the initial pH 12.99 to pH 4 in the experiments due to chitosan is soluble in acidic aqueous phases, but insoluble in basic aqueous phases. The pH was controlled by adding either strong acid (HCl) or strong base (NaOH). Before fractionated into the beakers containing 500mL of suspension each, the samples of textile wastewater were mixed homogeneously. Then, the samples ought to be measured for turbidity and COD for representing an initial concentration. After the desired amount of chitosan was added to the suspension, the beakers were agitated at various mixing time and speed, which consist of rapid mixing (250 rpm) for 10 minutes and slow mixing (30 rpm) for 20 minutes. After the agitation being stopped, the suspension was allowed to settle for 30 minutes. Finally, a sample was withdrawn using a pipette from the top inch of supernatant for turbidity and COD measurements which representing the final concentration. All tests were performed at an ambient temperature in the range of 26-30°C. In the experiment, the study was conducted by varying a few experimental parameters, which were chitosan dosage (12-66 mg/l), pH (2-10) and mixing time (10-30 minutes) in order to study their effect in flocculation and obtain the optimum condition for each parameter. 2.4 Analytical analysis The COD test was performed by colorimetric method using Spectrophotometer HACH Model DR/2000. It is used to measure the oxygen demand for the oxidation of organic matters by a strong chemical oxidant which is equivalent to the amount of organic matters in sample. Moreover, turbidity was measured by using HACH Ratio/XR Turbiditimeter which the sample was filled into a sample cell and put into the cell holder for measurement. While the pH of wastewater was measured by using a digital Horiba pH meter F-21. The pH meter was calibrated by using buffer solutions of pH 4.0 and pH 7.0 before starting the experiments. 45 MOHD. ARIFFIN, TAN PEI LI, ZAINURA 3.0 RESULTS AND DISCUSSION Studies on the effects of chitosan dosage, pH and mixing time are the experiments which were conducted in order to investigate the sorption capacity of chitosan in flocculation process. Since the Chemical Oxygen Demand (COD) level in wastewater from textile industry is considered as the most important parameter, so it has been used as the indicator on the sorption capacity of chitosan in these experiments by supporting with other parameter which is turbidity. The characteristics of the wastewater from petroleum refinery were as follow: 3.1 Effect of chitosan dosage Dosage was one of the most important parameters that been considered to determine the optimum condition for the performance of chitosan in coagulation and flocculation. Basically, insufficient dosage or overdosing would result in the poor performance in flocculation. Therefore, it was crucial to determine the optimum dosage in order to minimize the dosing cost and obtain the optimum performance in treatment. The effect of dosage was analyzed at pH 4, 250 rpm of mixing rate for 10 minute and 30 rpm of mixing rate for 20 minutes and 30 minutes of settling time for a range of chitosan dosage which varied from 12 mg/l to 66 mg/l. Besides, the sample of wastewater was adjusted from the initial pH of 12.99 to pH 4 due to chitosan was soluble in acidic aqueous phases [5]. Moreover, Domard et al.[10] pointed out that there were 90 % of the functional group of NH2 on chitosan surface has been protonated at pH 4. The pH was controlled by adding either strong acid (HCl) or strong base (NaOH). The results were presented in Figure 1(a) which showed the effects of chitosan dosage on COD level and the percentage of COD levels reduction by using chitosan. While Figure 1(b) showed the effects of chitosan dosage on turbidity levels and the percentage of turbidity levels reduction by using chitosan. From the jar test experiment, the curves for the both graphs were in the U-shape form for the condition of COD level and turbidity level versus chitosan dosage. While for the condition of percentage of COD and turbidity levels reduction, the curves for the both graphs were in “N” shape [11]. Besides, it was observed that the trends for all parameters were almost identical but with different percentage of reduction for particular chitosan dosage. For the optimum chitosan dosage of 30 mg/l, chitosan recorded the highest reduction of parameters, which were the reduction of 94.90% and 72.50 % for turbidity and COD respectively. Therefore, the optimum chitosan dosage in this research was 30 mg/l. From the dosage 12 mg/l to 30 mg/l, the percentage of reduction for COD and turbidity was increased and these were presented in Figure 1(a) and 1(b). This phenomenon could be explained based on charge density. If compared to the other coagulants, chitosan has a high charge density [12]. Moreover, the charge density of the polymer increased when polymer adsorption increased [13]. Therefore, this signifies the rapid destabilization of the particles. In other word, it can be defined as chitosan, a coagulant which has a high charge density require less amount of the coagulant to destabilize the particles. 46 1600 80 1400 70 1200 60 1000 50 800 40 600 30 400 20 200 10 0 % Reduction COD (mg/l) COAGULATION AND FLOCCULATION TREATMENT OF WASTEWATER 0 12 18 30 42 57 66 Chitosan Dosage (mg/l) (a) 70 100 90 60 80 70 60 40 50 30 40 30 20 % Reduction Turbidity (NTU) 50 20 10 10 0 0 12 18 30 42 57 66 Chitosan Dosage (mg/l) (b) Figure 1 Effects of chitosan dosage on (a) COD level and the percentage of COD level reduction (b) turbidity level and the percentage of turbidity level reduction by using chitosan. -■-, COD level; -♦-, % COD level reduction; ● -, turbidity level; -■-, % turbidity level reduction There was a drastic drop for the percentage of reduction for COD and turbidity when the chitosan dosage concentration was in the range of 30 mg/l to 66 mg/l. This poor performance was due to the phenomenon of excess polymer is adsorbed on the colloidal surfaces and producing restabilized colloids. Thus, there were no sites available on the particle surfaces for the formation of interparticle bridges. The restabilized colloidal particles can become positively charged and cause the electrostatic repulsion among the suspended solids. 47 MOHD. ARIFFIN, TAN PEI LI, ZAINURA 3.2 Effect of pH The pH will not only affects the surface charge of coagulants, but also affects the stabilization of the suspension. Besides, the solubility of chitosan in aqueous solution is influenced by pH value. Therefore, the study of pH was essential to determine the optimum pH condition of the treatment system. The effect of pH was analyzed at optimum dosage, 30 mg/l, with 20 minutes of mixing time, 250 rpm of mixing rate for 10 minutes and 30 rpm of mixing rate for 20 minutes and 30 minutes of settling time for a range of pH which varied from pH 2 to pH 10. The results were presented in Figure 2(a) which showed the effects of pH on COD level and the percentage of COD level reduction by using chitosan in flocculation. Figure 2(b) showed the effects of pH on turbidity level and the percentage of turbidity level reduction by using chitosan. From the jar test experiment, the curves for the both graphs were in the U-shape form for the condition of COD level and turbidity level versus pH. While for the condition of percentage of COD and turbidity levels reduction, the curves for the both graphs were in “N” shape [11]. Moreover, it was observed that the trends for all parameters were almost identical but with different percentage of reduction for particular pH. By analyzing every curve in Figure 2(a) and 2(b) which for COD and turbidity reductions respectively; it can be stated that the pH of textile wastewater has an influence on coagulation using chitosan. Furthermore, the figures demonstrate that over 72.5 % COD reduction and 94.9 % turbidity reduction can be achieved at pH 4. Therefore, the optimum pH condition of the treatment system was pH 4. This was supported by the statement of the sorption capacity of chitosan was optimum at pH 4 – 5 when it interacts electrostatic with anions in solution [14]. Domard et al. [15] pointed out that there are 90 % of the functional group of NH2 on chitosan surface has been protonated at pH 4, and gradually reduced to about 50% as pH increased to 6. Therefore, the positive charges on the chitosan surface will significantly decrease as solution pH increased, so the contribution by the charge neutralization of the chitosan to destabilize the particles becomes less important as pH increased. The properties of chitosan, including its cationic behavior and molecular weight, may be used both for charge neutralization (coagulating effect for anionic compounds) and for particle entrapment (flocculating effect). Moreover, based on observation, the floc produced by chitosan appears rapidly at pH 4 and form a large size, which can be easily settled. The operating pH of 4.0 could influence the chitosan behavior. In acidic solution, the amino groups of chitosan were protonated. Besides, chitosan would be expected to exhibit behavior typical of a polyelectrolyte when under these conditions. Polyelectrolyte act as coagulant aids in the treatment of water and wastewater; they may also be used as primary coagulant for the same purpose. Many polyelectrolytes are advantageous over chemical coagulants because they are safer to handle and are easily biodegraded. The removal of COD and turbidity increased with increasing dose of polyelectrolyte [4]. Moreover, the protonation of amino groups of chitosan in solution makes chitosan positively charged which act as cationic polyelectrolyte. Since the particles in textile suspension was negatively charged, chitosan was very attractive as coagulant by allowing the molecule to bind to negatively charged surface via ionic or hydrogen bonding. This will further reduce or neutralize the particles surface charge. Therefore, the particles destabilization by chitosan could be explained by charge neutralization mechanism. 48 900 80 800 70 700 60 600 50 500 40 400 30 300 200 20 100 10 % Reduction COD (mg/l) COAGULATION AND FLOCCULATION TREATMENT OF WASTEWATER 0 0 2 4 6 8 10 pH (a) 70 100 90 80 50 70 40 60 50 30 40 20 30 20 10 10 0 0 2 4 6 8 10 pH (b) Figure 2 Effects of pH on (a) COD level and the percentage of COD level (b) turbidity level and the percentage of turbidity level reduction by using chitosan. -■-, COD level; -♦-, % COD level reduction; -●-, turbidity level; -■-, % turbidity level reduction Takahashi et al. [16] proved that the solubility of chitosan decreases as the pH varies towards the basic condition. Chitosan dissolves in aqueous solution at pH less than 6.0. Over pH 6.0, it becomes insoluble in solution and exists as solid particles. This statement was supporting the obtained results in this experiment which the performance of chitosan in flocculation was worse in basic medium than acidic medium. Besides, Roussy et al. [1] also proved that chitosan at alkaline pH shows very low efficiency and required high concentration of chitosan to achieve the required treatment levels. This confirmed that, at least partial, protonation of chitosan amino group was required to achieve efficient coagulation of these organic suspensions. 49 % Reduction Turbidity (NTU) 60 MOHD. ARIFFIN, TAN PEI LI, ZAINURA 3.3 Effect of Mixing Time Besides the effect of chitosan dosage and pH, mixing time also play an important role on flocs formation and growth in flocculation process. Polymeric flocculent disperses throughout the medium and adsorbs on the colloidal particle surfaces for interparticle bridging or charge neutralization during the mixing period. Besides, longer mixing time will lead to an increase in flocs breakage. Hence, it decreases the flocculation rate. On the other hand, if the mixing time is too short, the collisions between the flocculants and colloids are not efficient to precipitate suspended solids in wastewater. Thus, the flocculation rate is not optimum under this condition. Therefore, a study was conducted on the effect of mixing time in flocculation. The effect of mixing time was analyzed at optimum dosage, 30 mg/L and optimum pH, pH 4, 250 rpm of mixing rate for 10 minutes and 30 rpm for 20 minutes and 30 minutes of settling time for a range of mixing time which varied from 10 minutes to 30 minutes. The results are presented in Figure 3(a) and 3(b) which shows the effects of dosage on the percentage of COD and turbidity levels reduction by using chitosan in flocculation respectively. Besides, the curves for the both graphs are in the U-shape form for the condition of COD and turbidity versus mixing time. Moreover, it was observed that the trends for all parameters are almost identical but with different percentage of reduction for particular mixing time [17]. By analyzing every curve in the Figure 3 (a) and 3 (b) which for COD and turbidity reductions respectively; it can be stated that the mixing time of textile wastewater has an influence on coagulation using chitosan. Furthermore, the figure demonstrates that over 70.9 % COD reduction and 93.3 % turbidity reduction can be achieved at pH 4. Therefore, the optimum mixing time condition of the treatment system is 20 minutes [11]. Mixing period is very crucial for polymeric flocculent on their performance in flocculation. The trends that had been illustrated at Figure 3 showed that the longer or shorter agitation time would result in the poor performance of chitosan for binding and bridging [11]. At lower agitation time (i.e. 10 minutes), the collisions between the flocculants and suspended particles are low and lead to the lower flocculation rate. On the other hand, if the mixing time is too long, the flocculate chains tend to break and limiting the size of the flocs formed. The small size flocs are not dense to settle down in wastewater and thus, indirectly cause the sample to be turbid again. This phenomenon was observed in the Figure 3 which showed the lower percentage of reductions at longer mixing time (i.e. 30 minutes). 4.0 CONCLUSIONS The characteristic of wastewater discharged from textile industrial activities was strictly controlled by Department of Environment. This was basically due to the wastewater from textile industry was contaminated with a complex set of oxygen demanding materials and poses a great problem to natural environment. Besides, the conventional aluminium-based coagulants have a possible link to Alzeimer’s disease while chitosan was more favourable in wastewater treatment due to its environment friendly characteristic. As a result, the wastewater from textile industry was treated by using chitosan via coagulation and flocculation processes. 50 COAGULATION AND FLOCCULATION TREATMENT OF WASTEWATER 460 73 450 COD (mg/l) 430 71 420 70 410 400 69 390 68 380 % Reduction 72 440 67 370 360 66 10 15 20 Mixing Time (min) 25 30 25 100 90 20 80 70 60 15 5 50 40 30 20 0 10 0 10 10 15 20 25 30 Mixing Time (min) (b) Figure 3: Effects of mixing time on (a) COD level and the percentage of COD level reduction (b) turbidity level and the percentage of turbidity level reduction by using chitosan. -■-, COD level; -♦-, % COD level reduction; -●-, turbidity level; -■-, % turbidity level reduction ACKNOWLEDGEMENTS The authors gratefully acknowledge the financial support received in the form of research grant (Vote No. 78121) from Research Management Centre (RMC), Universiti Teknologi Malaysia. 51 % Reduction Turbidity (NTU) (a) MOHD. ARIFFIN, TAN PEI LI, ZAINURA REFERENCES [1] [2] [3] [4] [5] [6] [7] [8] [9] [10] [11] [12] [13] [14] [15] [16] Roussy, J., Vooren, M. V., Dempsey, B. A. and Guibal, E. (2005). “Influence of Chitosan Characteristics on the Coagulation and the Flocculation of Bentonite Suspensions.” Water Research. 39. 3247-3258. Vera, G., Aleksandra, V. and Marjana, S. (2005). “Efficiency of the Coagulation/Flocculation Method for the Treatment of Dye Bath Effluents.” Dyes and Pigments. 67. 93-97. Pinotti, A., Bevilacqua, A. and Zaritzky, N. (1997). “Optimization of the Flocculation Stage in a Model System of a Food Emulsion Waste using Chitosan as Polyelectrolyte.” Journal of Food Engineering. 32. 69-81. Amudaa, O. S. and Amoob, I. A. (2007). “Coagulation/Flocculation Process and Sludge Conditioning in Beverage Industrial Wastewater Treatment.” Journal of Hazardous Materials. 141. 778-783. Pan, J. R., Huang, C. P., Chen, S. C. and Chung, Y. C. (1999). “Evaluation of a Modified Chitosan Biopolymer for Coagulation of Colloidal Particles.” Colloids and Surfaces A. 147. 359-364. Guibal, E. and Roussy, J. (2007). “Coagulation and Flocculation of DyeContaining Solutions Using a Biopolymer (Chitosan).” Reactive and Functional Polymers. 67. 33-42. Amokrane, A., Comel, C. and Veron, J. (1997). “Landfill Leachates PreTreatment by Coagulation Flocculation.” Water Research. 31. 2775–2782. Mohammad Sayem Mozumder, A. S. (2004). “Amphiphilic Polyelectrolytes: Characterization and Application in Coagulation/Flocculation.” King Fahd University of Petroleum & Minerals: Thesis Master. Lima, I. S. and Airoldi, S. (2004). “A Thermodynamic Investigation on Chitosan–Divalent Cation Interactions.” Thermochimica Acta. 421. 133-139. Domard, A., Rinaudo, M. and Terrassin, C. (1989). “Adsorption of Chitosan and a Quarternized Derivative on Kaolinite.” Journal Applied Polymer Science. 38: 1799-1806. Mohd Ariffin, A. H. and Liew, L. L. (2007). “Wastewater Treatment at Petroleum Refinery by Using Chitosan in Flocculation.” Universiti Teknologi Malaysia: Thesis Degree. Ahmad, A. L., Sumathi, S. and Hameed, B. H. (2006). “Coagulation of Residue Oil and Suspended Solid in Palm Oil Mill Effluent by Chitosan, Alum and PAC.” Chemical Engineering Journal. 118. 99-105. Ariffin, A., Shatat, R. S. A., Nik Norulaini, A. R. and Mohd Omar, A. K. (2005). “Synthetic Polyelectrolytes of Varying Charge Densities but Similar Molar Mass Based on Acrylamide and Their Applications on Palm Oil Mill Effluent Treatment.” Desalination. 173. 201-208. Guzman, J., Saucedo, I., Revilla, J., Navarro, R. and Guibal, E. (2003). “Copper Sorption by Chitosan in the Presence of Citrate Ions: Influence of Metal Speciation on Sorption Mechanism and Uptake Capacities.” International Journal of Biological Macromolecules. 33. 57-65. Hao, Y., Yang, X. H., Zhang, J., Hong, X. and Ma, X. L. (2006). “Flocculation Sweeps a Nation.” Pollution Engineering. 38. 12-13. Takahashi, T., Imai, M. and Suzuki, I. (2005). “High-potential Molecular Properties of Chitosan and Reaction Conditions for Removing p-quinone from the Aqueous Phase.” Biochemical Engineering Journal. 25. 7-13. 52 COAGULATION AND FLOCCULATION TREATMENT OF WASTEWATER [17] Mohd Ariffin, A. H. and Mohd Hafiz, P. (2007). “Pre-Treatment Of Palm Oil Mill Effluent (Pome): A Comparison Study Using Chitosan And Alum.” Universiti Teknologi Malaysia: Thesis Master. 53
Research Methodology / Research Methodology (BNE) Module Code: MHK220882 / MHH124269 CRITICAL EVALUATION OF JOURNAL PAPER Student Number: Programme: Title of Journal Paper: Author(s) : Journal / Conference: Volume / Issue: Critical Evaluation done by: Pages: Student Name DISSECTION OF PAPER Section 1. Abstract (read the abstract and answer the following questions) 1. What is the objective of the paper? The objective is to in light the people of the effects of the wastage done by the industrial water. 2. What are the contributions from the authors? The damage and the solutions. 3. What are the main results mentioned in the abstract? The use of organic polymer. 4. Does the abstract serve as a summary of the paper, presenting the objective, scope and results? Yes it does, it is pointing out the issues and the treatment for it. Section 2: Introduction (read this section and answers the following questions) 1. What ‘research problem’ is discussed in the paper? 2. What rationale is given by the authors, attributing importance to the research problem? 3. How many earlier works are cited by the authors and what are the perceived drawbacks of these earlier works? 4. How and why the authors claim to have a better technique or approach? Section 3: Methodology 1. What methodology is used by the authors to address the research problem? 2. In what way the methodology used by the authors is relevant to the methodology you proposed to adopt? Section 4: Results and Conclusions 1. List the results obtained by the authors. 2. What are the conclusions drawn by the authors from the study. Research Methodology / Research Methodology (BNE) Module Code: MHK220882 / MHH124269 Write a critical analysis of the paper (about 200 words)

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School: Boston College

Second Article-confirm

Journal of Chemical and Natural Resources Engineering, Vol.4(1):43-53
FKKKSA, UNIVERSITI TEKNOLOGI MALAYSIA
COAGULATION AND FLOCCULATION TREATMENT OF WASTEWATER
IN TEXTILE INDUSTRY USING CHITOSAN
MOHD ARIFFIN ABU HASSAN1, TAN PEI LI1, ZAINURA ZAINON NOOR1

ABSTRACT
Aluminum sulfate (alum), ferrous sulfate, ferric chloride and ferric chloro-sulfate were
commonly used as coagulants. However, a possible link of Alzheimer’s disease with
conventional aluminium based coagulants has become an issue in wastewater treatment.
Hence, special attention has shift towards using biodegradable polymer, chitosan in
treatment, which are more environmental friendly. Moreover, chitosan is natural
organic polyelectrolyte of high molecular weight and high charge density which
obtained from deacetylation of chitin. Experiments were carried out on textile industry
wastewater by varying the operating parameters, which are chitosan dosage, pH and
mixing time in order to study their effect in flocculation process by using chitosan. The
results obtained proved that chitosan had successfully flocculated the anionic suspended
particles and reduce the levels of Chemical Oxygen Demand (COD) and turbidity in
textile industry wastewater. The optimum conditions for this study were at 30 mg/l of
chitosan, pH 4 and 20 minutes of mixing time with 250 rpm of mixing rate for 1 minute,
30rpm of mixing rate for 20 minutes and 30 minutes of settling time. Moreover,
chitosan showed the highest performance under these conditions with 72.5% of COD
reduction and 94.9% of turbidity reduction. In conclusion, chitosan is an effective
coagulant, which can reduce the level of COD and turbidity in textile industry
wastewater.
Keywords:

1.0

Chitosan; textile wastewater; coagulation; flocculation; wastewater
treatment.

INTRODUCTION

Textile dyeing processes are among the most environmentally unfriendly industrial
processes, because they produce colored wastewaters that are heavily polluted with
dyes, textile auxiliaries and chemicals [1]. Besides, textile finishing’s wastewaters,
especially dye-house effluents, contain different classes of organic dyes, chemicals and
auxiliaries. Thus they are coloured and have extreme pH, COD and BOD values, and
they contain different salts, surfactants, heavy metals, mineral oils and others.
Therefore, dye bath effluents have to be treated before being discharged into the
environment or municipal treatment plant [2].
Textile dyes are structurally different molecules themselves with low or no
biodegradability. The removal of color is associated with breakup of the conjugated
unsaturated bonds in molecules. For this reason, many chemical treatment processes
have been used extensively to treat textile wastewaters. Most of the studies, such as
chemical precipitation, adsorption by activated carbon photocatalytic oxidation,
ozonation and Fenton’ oxidation focusing on color removal although effective, are
1

Department of Chemical, Faculty of Chemical and Natural Resources Engineering,
Universiti Teknologi Malaysia, 81310 UTM Skudai, Johor, Malaysia.
Correspondence to : Mohd. Ariffin (m.ariffin@fkkksa.utm.my)

MOHD. ARIFFIN, TAN PEI LI, ZAINURA
expensive or can cause further secondary pollution [3]. In most water treatment plants,
the minimal coagulant concentration and the residual turbidity of the water are
determined by the Jar-Test technique. Besides, physical-chemical treatment allows
reducing dissolved, suspended, colloidal and non settable matter as well as colouring
from dyes. Depending on the wastewater characteristics, COD of a textile effluent can
be reduced between 50% and 70% after optimizing the operating conditions such as
pH, coagulant and flocculants concentrations [2].
Coagulation or flocculation process was conducted for the treatment of
industrial wastewater to achieve maximum removal of COD, TP and TSS. Therefore,
Amudaa and Amoob [4] investigated the effect of coagulant dose, polyelectrolyte dose,
pH of solution and addition of polyelectrolyte as coagulant aid and found to be
important parameters for effective treatment of beverage industrial wastewater. Colloid
particles are removed from water via coagulation and flocculation processes
[5].Besides, Guibal and Roussy [6], pointed that the coagulation and the flocculation of
suspended particles and colloids result from different mechanisms including
electrostatic attraction, sorption (related to protonated amine groups) and bridging
(related to polymer high molecular weight).
Aluminum sulfate (alum), ferrous sulfate, ferric chloride and ferric chlorosulfate were commonly used as coagulants [7]. Additionally, high COD removal
capacities have been observed during the combined action of alum and lime for the
treatment of stabilized leachates. However, it has been stated out recently that there
may be a possibility for aluminium-based coagulants to link with Alzheimer’s disease
[8]. Hence, a special attention has been given to the environmental friendly coagulant
or flocculent, chitosan.
Chitin is cellulose like biopolymer widely distributed in nature, especially in
marine invertebrates, insects, fungi, and yeasts. Its deacetylated product, chitosan, is
readily soluble in acidic solutions, which makes it more available for applications.
Chitosan is a biodegradable, non-toxic, linear cationic polymer of high molecular
weight. Besides, chitosan was an effective agent for coagulation of suspended solids
from various food processing wastes [5]. Moreover, chitin extraction also does not
cause any disturbance to the ecosystem, its embraces all advantages provided by
polysaccharides, considering it as the source of chitosan, and both are biocompatible
biopolymers for animal tissues with low toxicities and significant biomedical
applications [9]. Chitosan coagulation produced flocs of better quality, namely larger
flocs and faster settling velocity. The effectiveness of chitosan for coagulating mineral
suspensions was improved due to the presence of inorganic solutes or due to addition
of materials extracted from soils at high pH [5].
Apparently, no major studies have been done to clarify the textile wastewater
by using chitosan in coagulation and flocculation process. Therefore, this study was
carried out to analyze the effect of chitosan in clarifying textile wastewater in
flocculation process in different experimental conditions. The optimum pH, dosage and
mixing time needed to achieve t...

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