1.0 INTRODUCTION 

1.1 Preamble 

Water is a precious commodity. Most of the earth water is sea water. About 2.5% of the water is fresh water that  does not contain significant levels of dissolved minerals or salt and two third  of that is frozen in ice caps and glaciers. In total only 0.01% of the total water of the planet is accessible for consumption. Clean drinking water is a basic human need. Unfortunately, more than one in six people still lack reliable access to this precious resource in developing world.   India accounts for 2.45% of land area and 4% of water resources of the world but represents 16% of the world population. With the present population growth-rate (1.9 per cent per year), the population is expected to cross the 1.5 billion mark by 2050. The Planning Commission, Government of India has estimated the water demand increase from 710 BCM (Billion Cubic Meters) in 2010 to almost 1180 BCM in 2050 with domestic and industrial water consumption expected to increase almost 2.5 times. The trend of urbanization in India is exerting stress on civic authorities to provide basic requirement such as safe drinking water, sanitation and  infrastructure. The rapid growth of population has exerted the portable water demand, which requires exploration of raw water sources, developing treatment and distribution systems.  

 The raw water quality available in India varies significantly, resulting in modifications to the conventional water treatment scheme consisting of aeration, chemical coagulation, flocculation, sedimentation, filtration and disinfection. The backwash water and sludge generation from water treatment plants are of environment concern in terms of disposal. Therefore, optimization of chemical dosing and filter runs carries importance to reduce the rejects from the water treatment plants. Also there is a need to  study the water treatment plants for their operational status and to explore the best feasible mechanism to ensure proper drinking water production  with least possible rejects and its management. With this backdrop, the Central Pollution Control Board (CPCB), studied water treatment plants located across the country, for prevailing raw water quality, water treatment technologies, operational practices, chemical consumption and rejects management.  

This document presents study findings and views for better management of water treatment plants.  

1.2 Methodology  

 The methodology consists of three phases, as below:  

1. Questionnaire survey 

2. Field studies (dry and wet studies) and 

3. Compilation of informations 

1.3 Questionnaire Survey   

Preliminary survey for population, source of water, type of water treatment schemes and capacity of water treatment plants at Class I towns were done by questionnaire survey. A copy of the questionnaire is given at  Annexure 1. Subsequently, State Pollution Control Boards and State Public Health Engineering Department were also approached for obtaining informations. As a result some of the towns, which were not listed, also responded.  Finally, 126 towns responded against  targeted 229 Class I towns and in addition 76 other towns were also responded. In total 202 received responses are summarized at Annexure 2, which reveals that in many of the cities, the water source remain surface water. 

1.4 Field Studies  

In the filed studies, 52 water treatment  plants in various parts of the country from East to West and North to South were visited. Detailed information on raw water quality, treated water quality, organizational structure for Operation and Maintenance (O&M) of water treatment  plants, operational status / problems, and information on mode of disposal of filter backwash waters & clarifier sludge was collected. In the study, all the  metropolitan of the country have been covered. Apart from geographical location, the size of water treatment plant and type of treatment units were also taken  into account while making selection of water treatment plant for visits. 

 Water treatment plants up to Jammu in North, up to Thiruvananthapuram in South, up to Kolkata in east and up to Mumbai in west have been visited. 

During the detailed study, samples of filter backwash water and clarifier sludge 2had been collected from 30 plants, which are listed in Annexure 3.  Plants for fluoride and arsenic removal have also been covered in the study. These water treatment plants not only cover different capacities but also different technologies. The details obtained during the visits and also from wet analysis are discussed at appropriate chapters.