Keywords: acclimatisation, biosorption, endosulfan, inhibition, mixed culture of bacteria, shock, pesticide contamination
Removal of endosulfan using aerobic mixed bacterial culture
With the increasing use of pesticides in modern agriculture, increased evidence of their disastrous effects on the environment has been noticed. Pesticides applied in various modes and places contaminate various parts of the environment, including groundwater sources. As pesticide problems are greater in the rural areas, the authors have developed a successful low-cost technology for rural areas with wood charcoal treated with nitric acid. As pesticides are classified as hazardous waste, the sludge resulting from their treatment has to be disposed off safely. This paper describes the removal of pesticides at a higher concentration of 24 mg/l, using a mixed culture of aerobic bacteria, and also a study of the inhibiting action of endosulfan on bacterial cells. It was found that bacteria without acclimatisation could remove 89.7% of endosulfan, and with prior acclimatisation the efficiency was 96%. It was found that removal in the initial phase is because of the hydrophobic nature of endosulfan and its affinity to sediments. The adsorbed endosulfan subsequently undergoes biotransformation, which has been confirmed by monitoring endosulfan concentrations in the bacterial sludge. Transformation was found to be significant in the acclimatised culture system. The fluctuation in bacterial performance was greater at lower concentrations of endosulfan, and overall inhibition was greater at higher concentrations.