Rubber Processing Industry Effluent Treatment and Electricity Production Using Microbial Fuel Cell Technology

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1 Rubber Processing Industry Effluent Treatment and Electricity Production Using Microbial Fuel Cell Technology R.Santhosh kumar 1, M.Bindusha 2 1 Head of the Department of Civil engineering, The Kavery Engineering College, Salem 2 Master scholar, Environmental Engineering, The Kavery Engineering College, Salem Abstract: Rubber products are widely used in day to day life. So their manufacturing and processing have greater significance in the industrial world. Like any other industries, it also produces an enormous amount of effluent. Discharge of this effluent into water bodies and surroundings may adversely affect the environmental quality and leads to pollution. In this study, a dual chamber Microbial Fuel Cell was Fabricated with carbon electrodes. The experiment was carried out to study the impact of various bacterial consortiums on Chemical Oxygen Demand reduction, ph regulation and voltage generation by MFC. Industrial waste water from local rubber processing industry was used as the substrate. Microbes are isolated from bokashi culture and leachate of the waste treatment plant. The performance of MFC was studied. Results showed that a stable voltage of 820mV can be obtained with the microbial consortium from leachate of a waste treatment plant. About 93.33% of COD reduction and ph 7.2 were achieved. The biochemical s showed the presence of Lactobacillus and Pseudomonas in the microbial inoculum prepared from bokashi and the presence of Arthrobacter, Pseudomonas and Bacillus in the microbial inoculum prepared from leachate of a waste treatment plant. Keywords: Microbial fuel cell (MFC), Bokashi culture, voltage generation, COD. I. INTRODUCTION In present scenario due to the development in manufacturing and industrial field large amount of wastes are generated and a large quantity of energy is depleting. The Management of Energy and wastes are major problems that the world is facing nowadays. For the manufacturing of rubber products such as tires, foot wears, and engineering related materials, natural rubber is used as raw material. The natural rubber is taken as the latex from the tree known as Hevea brasiliensis. Then the latex is converted to rubber products. Such operations require a large amount of water. During the process, a large quantity of effluent also generated. The increase in the number of such industries causes more production of effluent. The direct discharge of this effluent to water bodies cause water pollution and eutrophication. Microbial Fuel Cell (MFC) can be used as a solution for these two problems. MFC is a device which converts the chemical energy present in the biodegradable matter into electricity by using microbes as the biocatalyst. In this conversion process, the oxidation of organic and inorganic material takes place. Electrons, protons, and energy are produced by the activity of microorganisms. Microbes present in the MFC use this energy for its growth. The electrons generated by the chemical reaction are brought to the anode and flow to the cathode through an external copperwire connected to the electrodes. The movement of protons is achieved through the salt bridge from anodic chamber to the cathode. These protons then react with the oxygen and the electrons on the cathode, produce water molecules. This is what happening in MFC.In this work, the applicability of rubber processing industry effluent in MFC operation was checked by using different types of microbial consortium and electrodes of the different surface area DOI: /IJRTER JJMVB 261

2 in two-chambered microbial fuel cell and confirms the influence of rubber processing industry effluent in MFC technology. II. MATERIALS AND METHODS 2.1 Sample collection The rubber processing industry effluent samples were collected from a local rubber processing unit in Kozhikode district, Kerala.The samples were collected in sterilized plastic canes. The effluent sample used for DO determination was taken into dark DO bottles and added few drops of manganous sulphate solution to fix dissolved oxygen. 2.2 Microbial culture /Inoculum preparation Microbes are the most important part of microbial fuel cell. Two set of different Microbial inoculums were prepared. The first set of inoculum is made by using sample taken from bokashi culture and the second set is made by using sample taken from leachate of a nearby waste treatment plant. The inoculum was prepared by adding 5 ml sample to 45 ml nutrient broth and kept for agitation overnight. 2.3 Experimental setup The experimental setup was constructed by using an inert material in order to inhibit the microbial activity. For that purpose, a glass material was used for the construction of anodic and cathodic chambers with silicone as a sealant. Two glass chambers with volume capacity three liters each were used, one constitutes anodic and the other cathodic. Solid graphite electrodes were used. For easy pouring and removal of the salt bridge, T-shaped PVC with top covering was used. A magnetic stirrer was dipped in the anodic chamber for intermittent stirring. In order to make the anodic chamber under anaerobic condition, a lid and gasket were used to completely seal the chamber. The lid has a hole in it, after the introduction of effluent and electrode wire through the hole, was sealed using silicone. 2.4 Salt bridge preparation Salt bridge was made of Agar. 300 ml of distilled water was taken in 500 ml beaker and added 8.4 g nutrient agar and 0.2g KClslowly and heated till boiling with continuous stirring. Aluminum foils were tied closely to the two side openings of the salt bridge pipe and agar solution is immediately poured into it from the middle opening and kept it undisturbed for 2-4 hours in order to solidify the agar salt bridge completely. Then the aluminum foil was removed and the salt bridge formed so was used for the experiment. 2.5 Confirmation of biodegradation and voltage generation Physico-chemical characteristics such as chemical oxygen demand (COD) and ph were analyzed. The content in the anaerobic chamber was provided with 5 minutes stirring in every 24 hours to increase the rate of reaction between microbes and the bio-degradable matters present in the effluent. Readings were taken at an interval of 3 days. The voltage was measured by using a standard multimeter of sensitivity up to 1mV. 2.6 Identification of biodegrading organism For the identification of bacteria responsible for the biodegradation in the anaerobic chamber, biochemical s were conducted after developing enough microbial colonies using pour plate method. Nutrient agar media was prepared and sterilized in an autoclave. The molten nutrient agar media was poured (approximately 15ml) into each sterilized Petri plates, and allowed to solidify. The effluent from microbial fuel cell was serially diluted and 0.1ml of the sample was inoculated on solidified agar media and was spread uniformly with the sterile spreader. These Petri plates All Rights Reserved 262

3 incubated in an incubator for 24-48h at 30 o C. The Petri plates were observed after incubation for various bacterial colonies. The different colonies were taken and subcultured separately. Using these colonies the following biochemical s were conducted. Indole, methyl red, Voges- Proskauer, citrate utilization, catalase andoxidase were conductedin order to identify bacteria responsible for bio-degradation. III. RESULT AND DISCUSSION The result obtained from the initial Physico-chemical analysis of effluent are shown in table 1 Parameter Permissible limit (as per Value obtained for Value obtained for IS:2490, Part-I-1981) sample I sample II ph Chemical oxygen demand (mg/l) Biological oxygen demand (mg/l) Table 1: Characteristics of effluent before experiment 3.1 Characteristics of effluent after using in Microbial fuel cell ph The ph of effluent before using it in the microbial fuel cell was 4.11 and 4.10 for the sample I and sample II respectively. It indicates that the samples were acidic in nature. The first trial is carried out by using microbial inoculum from bokashi culture along with the sample I. The bokashi culture had an acidic ph of 3.9 and after treatment using MFC, no increase in ph was observed (Shown in table 2).The second trial was carried out by using sample II with the microbial inoculum prepared from leachate of a waste treatment plant. After the treatment using MFC the ph tends to become neutral (Shown in table 2). Time (in days) Chemical Oxygen Demand (mg/l) % Reduction in COD ph Table2.Characteristics of treated water using microbes isolated from bokashi culture. Time (in days) Chemical Oxygen Demand (mg/l) % Reduction in COD ph Table 3.Characteristics of treated water using microbes isolated from waste treatment plant All Rights Reserved 263

4 3.1.2 Chemical oxygen demand (COD) The chemical oxygen demand (COD) is an indicative measure of the amount of oxygen that can be consumed by reactions in a measured solution. The higher COD indicates that the water is highly polluted. Treatment of effluent by using microbes from bokashi culture results in the reduction of COD about to 66.67%. The sample II with microbes from the leachate caused COD reduction up to 93.33%. The reduction in COD values might be due to the presence of higher amounts of nutrients in the form of dissolved ions and it might have helped the growth of bacteria. The comparison of COD values shown in Figure % Reduction in COD Bokashi culture leachate microbes Time (days) Fig.1 Comparison of COD after treatment 3.2 Voltage Generation Using graphite electrodes of different surface area Trial I: Using graphite electrode of rod shape having a surface area of 75cm 2 was taken. Initial COD of the sample was taken as 12000mg/l and about 1500ml volume of effluent was taken for the trial I. The voltage generation is mentioned in table 4. Time is taken in days Voltage (Mv) Table 4.Trial I result Trail II: Using graphite electrode of bar shape having surface are of 180cm 2. Other parameters are taken as the same in trial 1. The voltage generation is mentioned in table 5 Time is taken in days Voltage (Mv) Table 5. TrialII All Rights Reserved 264

5 Comparison of voltage generation obtained from trail I (Using rod-shaped graphite electrode) and trail 2(Using bar-shaped graphite electrode) is shown in the graph Voltage (mv) Time (days) rod bar Fig 2.voltage generation by using two types of graphite electrodes Using different types of microbial consortium Trial I: Voltage generation by using microbes from bokashi culture The Initial COD of the sample was mg/l. About 1500ml volume of the sample was taken for the trial. The initial ph was observed as The readings were taken in the interval of 3 days. Table 6 shows the measurement of generated voltage. Time (in days) Voltage (m V) Table 6. TrailI result Trial II: Voltage generation by using microbes from leachate of waste treatment plant The initial COD of the effluent sample is 84000mg/L. It is very high COD compared to the permissible limit. The ph of the sample was About 1500 ml of effluent sample was taken for the trial. The readings obtained were shown in table All Rights Reserved 265

6 Time (in days) Voltage (m V) Table 7.Trial II result Voltage (mv) Time ( days) bokashi microbes leachate microbes Fig 5. Comparison of voltage generation 3.3 Identification of microbes The microbes were identified through biochemical s such as indole, methyl red, VogesProskauer, citrate utilization, catalase, and oxidase.the result obtained from the biochemical is shown in the table given below. Sl.No. indole methyl red Voges- Proskauer citrate utilization catalase oxidase bacteria Microbial colonies isolated from bokashi culture Pseudomonas Lactobacillus Microbial colonies isolated from the leachate of waste treatment plant Pseudomonas Arthrobacter Bacillus Table 8.Biochemical All Rights Reserved 266

7 This table shows that the microbial inoculum prepared from bokashi contains the Lactobacillus and Pseudomonas microbial inoculum prepared from leachate of waste treatment plant contains Arthrobacter, Pseudomonas and Bacillus IV. CONCLUSION According to the experiments carried out in a dual chamber microbial fuel cell(mfc) with graphite electrodes indicates that, by using MFC with a microbial inoculum prepared from leachate of waste treatment plant can reduce the chemical oxygen demand up to 93.33% and produce a voltage of 820 mv. Also, this system can alter the acidic ph (4.11) of rubber processing industry effluent into neutral or permissible limit (7.2). The responsible bacteria for the degradation were identified as Pseudomonas, Arthrobacter, Pseudomonas and Bacillus By using the microbes(pseudomonas, Lactobacillus )isolated from bokashi can cause a reduction in COD up to 66.67%. But there is no effective change in the ph of effluent from MFC. A voltage of 638 mv was produced by it. The increase in surface area of the electrode produced a better result in voltage. ACKNOWLEDGMENT The authors would like to express our sincere gratitude to principal and other staffs of Kavery Engineering College, Salem and Corevalleys herbal technologies, Mini industrial estate, Nalllalam, Kozhikode, for providing the necessary infrastructure for conducting the study. REFERENCES [1]. GokulRamanan et al, Treatment of Waste Water from Natural Rubber Processing Plant, IJSER, Volume 4 Issue 7, July [2]. Zhenglong Li et al,electricity generation using a baffled microbial fuel cell convenient for stacking, Bio resource Technology, Volume 99, issue 6, All Rights Reserved 267