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Department of Chemistry, National Institute of Technology, Kurukshetra-136 119, Haryana, India E-mail : shaguftaajabin@gmail.com Department of Civil Engineering, Lingaya’s University, Faridabad-121 002, Haryana, India Manuscript received online 28 August 2014, revised 05 April 2015, accepted 16 April 2015 Food industry is a major source of waste water pollution. Several techniques are available to remove pollutants from food industry waste water. One of the promising technologies for the removal of pollutants from food industry waste water is coagulation and flocculation. In the present work, various coagulants like lime, alum and ferrous sulphate were applied on waste water to select the suitable one with optimum removal efficiencies for further treatment with polyelectrolytes. Parameters such as turbidity, Total suspended solids (TSS), Chemical oxygen demand (COD), Biological oxygen demand (BOD) and oil and grease content were evaluated. On the basis of results, lime was proven to be the most efficient inorganic coagulant for further treatment. It could remove 55.2% turbidity, 51% TSS, 49.6% COD, 51% BOD and 51% oil and grease at its optimum dosage of 50 mg/L. Generation of sludge in the coagulation-flocculation process was also studied. The volume of sludge was 22.5 mg/L at the optimum dosage of lime. Further cationic polyelectrolyte Organopol 5470C and anionic polyelectrolyte Chemfloc 430A were also studied in conjunction with lime. Organopol 5470C in conjunction with lime showed better result because of low dosage, maximum pollutant removal and minimum quantity of sludge generation. It could remove 94% turbidity, 95.5% TSS, 83.5% COD, 89% BOD and 92.5% oil and grease; whereas Chemfloc 430A in conjunction with lime could remove 91.2% turbidity, 90% TSS, 77.8% COD, 83% BOD and 86.8% oil and grease. The volume of sludge produced while using polyelectrolyte and lime together was much lower than using lime alone. The amount of sludge produced in case of Organopol 5470C and lime together is 8.9 mg/L, while sludge generation by Chemfloc 430A in conjunction with lime is 10.4 mg/L. |
