Economic Valuation and Effectiveness of Utilizing Electrocoagulation System in Reducing Chemical Oxygen Demand of Textile Industry Wastewater

Journal of Ecological Engineering Volume 20, Issue 8, September 2019, pages 35–43 https://doi.org/10.12911/22998993/110960 Received: 2019.06.12 Revised: 2019.07.20 Accepted: 2019.07.30 Available online: 2019.08.05 Economic Valuation and Effectiveness of Utilizing Electrocoagulation System in Reducing Chemical Oxygen Demand of Textile Industry Wastewater Elanda Fikri1*, Nita Sintawati2, Tati Ruhmawati2 Department of Environmental Health, Bandung Health Polytechnic, 40514 Cimahi Utara, Indonesia Doctorate Program of Environmental Studies, Diponegoro University, 50241 Semarang, Indonesia * Corresponding author's e-mail: 1 2 ABSTRACT Industrial activities vary greatly. The textile industry processes produce solid and liquid waste. The liquid waste comes from the process of reviewing threads, removing lubricants from synthetic fibers before weaving, and from the dyeing process. The purpose of this research is to determine the economic valuation and effectiveness of utilizing an electrocoagulation system in reducing Chemical Oxygen Demand (COD) of the textile industry wastewater. This research is a kind of an experimental study involving the pretest and posttest without control design. The research strategy consisted in 9 volt voltage and 5A electric current density with a 3 cm electrode plate distance. The container used in electrocoagulation process was made of plastic with the dimensions of 48.5×27.5×31 cm. The sampling technique was grab sampling with 3 treatments and 6 repetitions. The sample size was 45 liters. The results of this research indicate that the electrocoagulation method can reduce the level of Chemical Oxygen Demand (COD) in the textile production wastewater. The COD level before treatment was 221.5 mg/l, after electrocoagulation with 8 electrode plates dropped to 23.0–41.0 mg/l (85.26% decrease). The economic effectiveness and efficiency of the use of electrocoagulation compared to using conventional method in reducing COD level is only Rp 47.59/liter, while the conventional method reaches Rp 117.089/liter. Keywords: economic valuation, electrocoagulation, Chemical Oxygen Demand (COD), textile industry INTRODUCTION Industrial activities vary greatly. Variation in the activities of industrial sector is influenced by types of raw materials processed, types of finished goods or produced materials, production capacity, techniques or types of production processes applied. One of the main types of activities producing liquid waste that has the potential of causing pollution corresponds to the textile industry activities (Soeparman and Suparmi, 2002). The textile industry processes generate solid and liquid waste. The solid waste comes from the process of making fabrics, threads, fabric fibers, and waste from other activities that support production, while the liquid waste comes from the process of reviewing threads, removing lubricants from synthetic fibers before weaving, and from the dyeing process (Nemerow and Dasgupta 1991). The author examined the production of liquid waste by taking samples in intermediate tank that the COD content in the liquid waste was 216.5 mg/l while the permissible quality standard was 150 mg/l (According to Ministry of Environment Regulation No.5 of 2014). COD is an amount of oxygen (mg/l) needed to oxidize organic substances in 1 liter of water sample, where the K2Cr2O7 oxidizer is used as a source of oxygen. By measuring the value of COD, it is possible to determine the amount of oxygen needed for the oxidation process against the total organic compounds, both those that are easily broken down biologically and on the ones that are difficult or cannot be described biologically (Barus, 2004). The high COD concentration 35 Journal of Ecological Engineering Vol. 20(8), 2019 causes the dissolved oxygen content in the water to be low. As a result, oxygen as a source of life for aquatic creatures (animals and plants) cannot be provided; therefore, the aquatic creature dies (Monahan, 1993). PT. Garuda Mas Semesta WWTP uses Poly Aluminum Chloride (PAC) as a coagulant to bind turbidity and organic matter such as Chemical Oxygen Demand (COD) which is used in great amount in order that it can increase the value of the company’s cost. Coagulation can be obtained by chemical or electrical means. Chemical coagulation is now of lesser interest due to the high processing costs, producing large volume of mud, grouping of metal hydroxides as hazardous waste, and costs for chemicals that aid in coagulation. Chemical coagulation has been used for decades to destabilize suspensions and to facilitate deposition of dissolved metals. Alum, lime, and/or other polymers are commonly used chemical coagulants. This process, however, tends to produce large amounts of mud with a high content of water bonds which can slow down filtration and complicate dewatering. This process also tends to increase the content of Total Dissolve Solid (TDS) in the effluent; therefore, it cannot be used in industrial applications (Benefield, 1982). Electrocoagulation can often neutralize particle and ion charges; therefore, it can precipitate contaminants, reduce the concentrations lower than those that can be achieved by chemical precipitation, and can replace and/or reduce the use of expensive chemicals (metal salts, polymer). Although the mechanism of electrocoagulation is similar to chemical coagulation in the case of cation species that play a role in neutralizing surface charges, the characteristics of the floc produced by electrocoagulation differ dramatically from the floc produced by chemical coagulation. The floc from electrocoagulation tends to contain little water bonds, is more stable and easier to filter (Woytowich, 1993; Fikri, 2019). After electrocoagulation, processing can be continued with flotation. Lately, many studies have used electrocoagulation to treat synthetic wastewater as primary treatment, electrocoagulation has been chosen because it reduces the amount of sludge produced and is effective in reducing Chemical Oxygen Demand (COD); additionally, it is considered cheaper than chemical processing on primary treatment. Chemical deposition, as a preliminary treatment, 36 gives rise to large amounts of sludge. Moreover, wastewater will contain dangerous chemicals if it enters a water body (Siregar, 2005). According to Kuokkanen et al. (2013), electrocoagulation is a method of water treatment that combines the functions and advantages of conventional coagulation, flotation, and electrochemical processes. The electrocoagulation mechanism follows basic principle used in electrolytic cell systems, wherein the anode and cathode are located where the reduction oxidation reaction takes place. The electrical energy given to the anode dissolves aluminum into a solution which then reacts with hydroxy ions from the cathode to form hydroxy aluminum. Hydroxy coagulates and flocculates suspended particles so that the process of solid removal from water being (...truncated)