Abstract:
River Bank Filtration (RBF) has been proved to be an efficient water treatment process in European countries, United States as well as in India. Many cities and towns in India are situated on the river bank and have favourable hydrogeological conditions, these can also benefit from River Bank Filtration technology, as RBF is a low cost and efficient water treatment process. Due to a combination of inadequate sewage disposal practices, industrial wastes and mixing of fertilizers and chemicals from non point sources, many river systems have been polluted.
In this work, an attempt has been made to extract water of good quality from a highly polluted river Kali in the state of Uttar Pradesh through RBF. The site was selected near Samli bridge downstream of Kali River at Muzaffar Nagar. The study includes the collection of water samples from the river, a pumping well adjacent to the river and ground water samples near Samli Bus-Stand from March to November' 2006. Two monitoring wells were drilled to study soil characteristics and also to monitor the quality of bank filtrate abstracted. On site field experiments were performed to determine ready to measure water quality parameters, such as pH, dissolved oxygen, specific conductance, water temperature, alkalinity and turbidity on monthly basis. Major cations and anions, and bacteriological indicator parameters were analysed in the laboratory.
The results show that the variation in parameters investigated for pumping well water are within permissible limits for drinking water according to WHO and BIS 10500 (1991). In the filtrate, indicator bacteria such as total coliform and faecal coliform were removed by 98 to 99%, including even under low flow conditions in the river, when the number of total coliform was 93-2400 counts/100 mL of sample, and faecal coliform was 23-70 counts/100 mL of sample. The number of total coliforms in water from pumping wells was observed from 2-28 counts/100 ml of sample and faecal coliform was not detected. Total coliforms were observed at 0-2 counts/100 ml of sample and faecal coliform was not detected in ground water.
The turbidity was reduced by up to 99.7%. The turbidity was observed in the range of 0.26-1.97 NTU in ground water. The dissolved oxygen in river water ranged between 0.0 to 1.05 mg/L. It has been observed that during summer the dissolved oxygen is reduced down to 0.0 mg/L which shows the poor health of the river, while in case of wells it is 0.0 to 1.0 mg/L. Dissolved oxygen was not detected in ground water. The specific conductance of water from the pumping well was observed always higher than that in the river. But the ground water had very high specific conductance value 1788-1990 pS cm-1. The sulphate content in river water has been slightly above in comparison to the well water. The sulfate content in ground water was observed in the range of 99-110 mg/L. Though the total dissolved solids and especially the hardness increase during RBF, they are within permissible limits. The total dissolved solid were observed in the range of 915-995 mg/L, which is above than the permissible value.
It has been observed that the ground water is hard water but the pumping well water was superior in quality. Thus RBF may be helpful in extracting better quality of water in extreme environmental conditions also.
