| Share facebook | RSS

0
Comments

World Report View

Water quality in Chennai

by | 15-11-2014 16:43 recommendations 0

The National Environmental Engineering Research Institute, Nagpur in 2002 had carried out water quality checks at all the stages namely source, treatment level, service reservoir level and at the consumer level during the monsoon, summer and winter seasons. Water samples from sources viz. Poondi lake, Cholavaram lake, Chembarambakkam lake, Red Hills lake and Porur lake were monitored once for all water quality parameters. Samples were also collected from service reservoirs and analysed for residual chlorine and bacteriological contamination. Both the treatment plants were evaluated unit wise on three different dates at various stages of treatment system. The parameters analyzed wereTurbidityTotal ColiformsTotal Faecal ColiformsSource LevelThe water quality of Cholavaram, Poondi, Porur and Chembarampakkam lakes are within desirable limits for all parameters except for TC and TFC. Both these are present in large amounts during all the three seasons. The graph below depicts the concentration of TC in the lake water.concentration of TC during summer, monsoon and winter in Poondi, Porur and Chembarambakkam lake is so large that the concentration has been designated as ?too numerous to count?. So the columns depicting the concentration of the above mentioned samples have been shown with a black bar . The concentration of TFC during the three seasons for Poondi, Porur and Chembarambakkam lake have been depicted in Figure-4.As for surface water source, Dissolved Oxygen (DO) and Chemical Oxygen Demand (COD) have been considered for the lakes. DO is an important characteristic depicting the oxygen concentration present in a water body required for sustaining aquatic life. The permissible limit for DO is 4 milligrams per litre (mg/l).On the other hand COD values indicate the amount of oxygen required to disintegrate all the organic mater (carboneous and non carboneous) into carbon dioxide and water. As the water from the source is treated and disinfected before being supplied as drinking water, it is equivalent to Class C water body (drinking water source after conventional treatment and disinfection). Thus, according to World Health Organization (WHO) guideliness, the COD permisible level should be 10 mg/l.Treatment Levelspecification for drinking water except for bacterial parameters. It has been observed that 3 out 4 samples taken from the Red Hills plant are contaminated with bacteria but only 1 out of 4 water samples from the Kilpauk plant is contaminated. Figures 7 and 8 below show the level of TC and TFC in the treated water for the three seasons. The permissible level of TC and TFC in drinking water sample should be 0 mg/100 ml.Apart from bacterial contamination, two out of three outlet water samples from the Red Hills plant during the winter season have shown high TDS level of 570 mg/l and 505 mg/l against the desirable limit of 500 mg/l.Service reservoir levelAt the service reservoirs level the presence of bacteria depends on the amount of residual chlorine present. Some samples having residual chlorine concentration well above the minimum limit of 0.2 mg/l and have shown the presence of TC and TFC. The following map highlights the areas receiving contaminated water during different seasons.Also the population of people receiving bacterial contaminated water differ during the three seasons. In summer 6 out of 16 zones with a population of 29 lakhs out of 50 lakhs are receiving contaminated water, while in winter 7 zones (population 16 lakhs) and during the monsoons only 2 zones (population 6 lakhs) receive contaminated water. So the percentage of population receiving contaminated water in summer and winter is higher than during the monsoons.The water from the service reservoir is then distributed to the consumer end through pipelines. The above graph (Figure 11) shows that 59% of places are receiving contaminated water in summer and monsoon while only 54% of places are affected in winter. Thus in all the seasons more than half of the city is receiving contaminated water.Apart from the bacterial contamination, the quality of drinking water is within permissible limits of BIS drinking water standard IS 10500.

no image

  • Dormant user
  • recommend

0 Comments

Post a comment

Please sign in

Opportunities

Resources