TREATMENT OF INDIGO CARMINE DYE BEARING WASTE WATER BY E LECTROCOAGU LATION

Abstract

The treatment of waste water from industries before discharge to fresh stream of water is of environmental concern. Wastewaters from dying and finishing processes in textile industry are characterized by intense color, high levels of Chemical oxygen demand (COD) and dissolved solid, and highly fluctuating pH. The consumption of dyes is about 80% in the textile industry with its use in other paper, tannery, plastic, pharmaceutical and food industry. Presence of dyes in waste water is of primary concern and a very small amount of dye in water (10-20 mg 1-1) is highly visible and affects water bodies. . The color of the effluent discharged into receiving waters affects the aquatic flora and fauna, and causes many water borne diseases. Many dyes are toxic and are generally, stable to light, oxidizing agents and heat, and their presence in wastewaters offers considerable resistance to their biodegradation, and thus upsetting aquatic life. Ludhiana, Panipat, Pali, Bichbhri, Patancheru, Jetpur, Ahmedabad, Surat and Tirupur are some of the country's most polluted zones. Conventional methods for dealing with textile wastewater consist of various combinations of biological, physical and chemical method which include adsorption, coagulation, chemical oxidation, photochemical, electrochemical technique, chlorination, ozonation, irradiation, ion exchange, reverse osmosis, membrane separation, biological treatment, etc. Electrocoagulation was found to be an empirical water treatment technology that has ability to treat variety of contaminants including dyes, metals, suspended solids, oils and organics present in the industrial waste water. The technique combines all the primary and secondary treatment together producing a lower quantity of sludge than other methods allowing for low disposal cost. The process has many different applications over the last century and has proven its viability by removing a wide range of pollutants. The objective of this study is to investigate the feasibility of aluminium electrodes for the removal of Indigo Carmine dye, which is commonly used in textile industry as well as food industry, from aqueous solution. The experiments were carried out to study the effect of pH, inter electrode distance, current density, voltage and iii initial concentration on the removal of Indigo Carmine from aqueous solution by batch process. It was found that for an initial concentration of 100 mg 1-' the percent removal was about 88% when electrocoagulation time was 5 min. The dye solution decolorized more efficiently when the initial pH was 3 that is in acidic medium the color removal efficiency was good. Aluminium electrodes with an effective area/volume ratio of 25.6m2 m-3 were optimized at a voltage of l 1 V with an operating current density of 10.7Am2. iv