The pollution of natural water resources poses a serious threat to life on earth. This problem has increased in developing countries where population growth and industrialization are the major reasons behind inefficient treatment of effluents (Elhassadi, 2008). Nowadays, researchers have shifted their interests in reuse or recycling of wastewaters (Vourch et al., 2005). In physico-chemical processes reagent costs are high and the soluble COD removal is low (Demirel et al., 2005). Chemical treatments could induce other forms of pollutants in treated water.
Electrocoagulation is an electrolytic process that has been used for the treatment of various liquid wastes. Current is imposed on soluble anodes like Al, Fe or their alloys in an electrochemical cell. It acts as a reactor for the experiment. During electrocoagulation, the coagulants are obtained in situ by the dissolution of the anode (Mollah et al., 2001). Industrial activities cause serious pollution problems (Rameshraja and Suresh, 2011). Electro-coagulation (EC) is clean water technology for the removal of toxic heavy metals containing solutions (Picard and Galhalifaud-Feuiltade, 2000). Electrocoagulation is an alternative technology and most effective. Electrocoagulation emerges as one of the promising techniques for the treatment of effluents. Many researchers consider it as an effective tool for treatment of wastewaters with high removal efficiency.
1.1.1 Advantages of Electrocoagulation:
1) Electrocoagulation addresses any size of suspended solids.
2) Electrocoagulation requires no filters.
3) EC requires simple equipment.
4) It gives clear and odorless water.
5) Sludge is readily settable.
6) Flocs are larger and contain less bound water.
7) It produces effluent with less TDS content.
8) No chemicals are required.
9) The gas bubbles carry pollutants to the top of solution.
1.2 Powdered Activated Charcoal:
Industrial wastewater is often contaminated with various compounds (Okafor and Aneke, 2006). The most important technologies to treat wastewaters include coagulation/flocculation process (Amuda et al., 2006), membrane filtration (Galambos et al., 2004), oxidation process (Peres et al., 2004). These methods are generally expensive and require skilled personnel. Low cost and non-conventional adsorbents include agricultural by products such as nut shells, wood, bone, peat which are processed into activated carbons (Bansode et al., 2004; Nomanbhay and Palanisamy, 2005). Activated charcoal absorbs toxins quickly which is made from carbon and ground into very fine granules. It works like sponges. Activated carbon is widely used for the purpose of adsorption (Barret et al., 1951) as a result of its high degree of micro porosity. It has a high adsorption capability. The presence of activating agents and carbonization conditions influenced the development of pore structures (Sricharoenchaikal et al., 2007). The materials are specified by large specific surface areas and tunable surface containing functional groups (Rezaee, et al., 2008).
Adsorption process is a fundamental process in treatment of municipal wastewater. Advantages include potential for significant heavy metal removal and superior removal of organic wastes (Musa et al., 2008). Activated carbon treatment is useful and effective process for the removal of heavy metals. The adsorption efficiency is determined by pore size of adsorbent and chemical structure, which effects its interaction with polar or non-polar adsorbates and active sites which determine chemical reactions (Onundi et al., 2010).
1.4 Significance of Study:
Benefits of this project include:
1) Steel, cooking oil industrial effluent and diluted spent wash having complicated wastes were characterized and studied in detail by electrocoagulation treatment by using Al-Al, Fe-Fe and Fe-Al; Rods and Plates.
2) The effluents were treated by using powdered activated charcoal prepared by using five different woody plant materials namely Walnut, Pine, Mango, Litchi and Sagwan. The treatment was given to effluents under various concentrations of the charcoal.
3) Standard operating condition especially time, current and voltage for various effluents were identified to get maximum reduction in parameters of interest.
Fig. 1.1: Benefits of Electrocoagulation
Our studies are based on following hypothesis
1) There is need for treatment of industrial effluents by using advanced treatment technology which will reduce the intensity of the effluents.
2) Electrocoagulation is in use since last few decades and is a better way to treated effluents with complicated wastes.
3) Electrocoagulation has ability to treat complicated and highly concentrated wastewaters.
4) Powdered activated charcoal is with high capacity to adsorb pollutants and effectively treat the wastewaters.
5) There is need to prepare powdered activated charcoal from various plant materials and to find out the potential of the various plant species to treat the wastewaters.
1) To characterize the effluents of three different industries namely diary, textile and distillery.
2) To find out the effect of various operating conditions namely pH, quantity of effluent, current, voltage, inter electrode distance, time, pretreatment of effluent etc. on efficiency of electrocoagulation.
3) To develop a laboratory scale treatment unit/model by using innovative technique of electrocoagulation and low cost ecofriendly materials for the treatment of effluents.
4) To find out the standard operating conditions to get maximum efficiency of electrocoagulation of the selected effluents.
5) To find out toxicants of scientific interest and parameters before and after treatment of electrocoagulation by using standard operating protocols and instrumentation techniques.
For convenience and presentation, the dissertation has been divided into different parts. ‘Chapter 1’ covers ‘Introduction’ related to the electrocoagulation, biosrobents and powdered activated charcoal. A brief literature survey is carried out in Chapter 1′. The materials obtained and the methods followed for this investigation have been described in ‘Chapter 3’ ‘Materials and Methods’. The important findings of the investigation have been critically discussed in the light of recent literature in the form of research articles, reviews, books etc. in the ‘Chapter 4’ as ‘Results and Discussion’. The significant findings of the investigation have been added in ‘Chapter 5’ as ‘Summary Conclusion and Recommendations’. The last part of the work includes the references (research papers, books, reviews and monographs) used for discussion, which have been listed alphabetically in ‘Bibliography’.