The water we drink.

Bangalore is a city which is growing very fast, thanks to the influx of people from all over the world, for it has made a name as the Education and IT hub of the country. One can find people of all kinds of ethnicity and religion on the streets of Bangalore. And guess what, the probability of you finding a person who shares the local tongue and dialect is very less, not to mention a particular category of people who fake their ignorance of the local language.

The point I am trying to make is that being a rapidly growing city in terms of area as well as population, Bangalore has got its share of problems. Some of the problems everyone experience is traffic, then comes water, power and also the ever increasing cost of living. There are times when the water supply won’t be regular; sometimes people may have to manage without the regular water supply by the municipal body. When we face these kinds of problems, it is a natural reaction for the citizens to get angry and blame the water supply board. Even I was among one of them until recently but my views changed a bit after I visited the water treatment and pumping station run by Bangalore Water Supply and Sewage Board (BWSSB) which is the government body which is responsible for the water supply and other related operation.

The water we get in the taps is sourced from the river Cauvery which is one of the major rivers in the country and flows across the southern Deccan plateau. This water treatment and pumping station is about 85kms away from the city and the river flows another 20 -25kms away from this. The water from the river is diverted from Shiva Anicut (Dam/ reservoir) which is situated near Shivanasamudra which is known for being the first hydroelectric power station in Asia. The water diverted from there makes use of the height (head) difference and flows until it reaches the Netkal Balancing Reservoir (NBR) from where it flows to the treatment plant situated in T.K halli (Torekadahalli) which is 9kms away from the NBR. In the T.K Halli facility, they treat the raw water from the NBR and then is pumped further towards the city. This facility is the first pumping station along the supply line which is followed by 2 more pumping stations before the water reaches Bangalore. This plant has 4 stages and the 5th one is under construction. The first stage, commissioned in the year 1974 has an output of 135 MLD, the second stage commissioned in 1982 has the same output of 135 MLD. Third stage came into operation in 1993 and has the capacity of around 330-350 MLD and the most recent one being the stage 4 plant, which started in 2002 operates at 330 MLD at the moment.

I had the privilege to visit the stage 4 plant recently and was surprised to find the whole operation automated and they recover as much water as possible during the operation of this plant. The water flows in from NBR and it is subjected to aeration in a cascade aerator where the water is made to flow down stepwise and this improves the contact with the atmospheric oxygen and brings about aeration. This aerated water then flows to the next section of the plant where it is subjected to pre chlorination. The chlorine gas is mixed with liquid phase (water) and is fed to the pre chlorination section. The chlorine levels are maintained at 1 ppm in order to bring about the disinfection of water. Then the raw chlorinated water is checked for turbidity and pH. This water source is found to have a constant pH of 8, so eliminating the need to regulate the pH but still the checks are carried to for variations. The turbidity is treated by using alum as a flocculating agent. The dosage of alum depends upon the turbidity of water. Compared to summer, the turbidity will be more in rainy season. This alum brings about flocculation of the suspended solids in water and in turn undergoes sedimentation in the pulsator clarifiers where the water is retained for around 20 minutes or more depending upon the amount of suspended particles present. The clean water obtained is made to flow into the filtration section where it gets filtered in Rapid sand filters. Once the filtration is done the water flows to the pumping station from where it is pumped towards Bangalore. The sludge formed in the clarifiers are pumped into a Sludge thickener where the sludge is thickened and the remaining water is removed and pumped back to the first step of treatment process again. The filters are backwashed once after every shift using air and water at pressure from below. The plant operates round the clock with three 8 hour shifts per day.

The treated water is again recharged with chlorine and pumped using huge centrifugal pumps. The water pumped has to pass through 2 more pumping stations before it reaches the city. The water is recharged with chlorine at every station and again once in the city before distribution. The water from all the 4 stages of this plant amounting to around 950 MLD is pumped using around 20 pumps making this the main source of water for the city. Around 190 MLD is sourced from one more river Arkavathy through another 2 pumping stations situated in Hesarghatta and T.G Halli near Bangalore.

That was a detailed description of the things I managed to remember, and the engineer there also made it a point to inform us that in case if they have to carry out any maintenance work, the plant has to be shut for a day or so, and this leads to a drastic reduction in the amount of water pumped and hence the interruption of regular supply of water in many areas of Bangalore.

But can’t we make use of the recycled/treated water from many sewage treatment plants set up in and around Bangalore to meet our non-potable requirements and reduce the demand thereby conserving water and saving the energy required to purify and pump water from far off places?? Think about it and work towards it.

Water, water, everywhere, Nor any drop to drink.

"Day after day, day after day,

We stuck, nor breath nor motion;

As idle as a painted ship

Upon a painted ocean.

Water, water, everywhere,

And all the boards did shrink;

Water, water, everywhere,

Nor any drop to drink."

These are few lines out of 'The Rime of the Ancient Mariner' (The full poem can be read in the next post) by an English poet Samuel Taylor Coleridge. There is water everywhere in the ocean not of any use for it is too salty to be drunk. But the times are changing and it is possible that the water we drink in the future has to come from these oceans itself.

Water, its importance, the impending water crisis and few possible solutions were discussed in the 'International Summit on Water' held recently in Bangalore which I had the privilege to attend and here follows the overview of what I saw there.

Everyone knows that water is one of the most essential resources on this earth and it is very much required to sustain life on this planet. More than 70% of our planet surface is covered by water giving the name ‘Blue Planet’ to Earth. Out of this 70% of the total water, 97% is in the oceans and the remaining 3% is fresh water out of which 1% is available for use and the other 2% is locked in the glaciers and icecaps. The amount of fresh water is limited but whereas the demand for the same is growing in an exponential rate with the increase in the population and industrialization. Satisfying the demand is a major concern and over that, the sources of fresh water are constantly being polluted by the careless actions of man. The rapid rate of industrialization, urbanization and ever increasing population is the main reason for it.

The present day scenario calls for drastic steps to be taken in order to maintain the availability of water to everyone and also to conserve this precious resource. At this rate it is said water will switch places with petroleum to be called as ‘liquid gold’ in the near future and the most probable cause for the next world war will be water. To prevent this situation, we have to divert our attention towards the methods and possibilities of making efficient use of the scientific and natural resources available and come up with come answer and the solutions we have come up with are desalination and waste water treatment. There are many technologies being developed and few of them are already operational.

The International Water Summit 2011 is an initiative which provided the platform for the people working with these technologies can come together, exchange the thoughts, ideas, research work and also to create awareness among the people. This summit was organized by Indian Water Works Association [IWWA] which is a voluntary body of professionals who are concerned and connected with water supply for municipal, industrial, agricultural uses and treatment and disposal of waste water along with MECON which is a premier engineering company, a Government of India PSU who are also responsible for the construction of a 100 MLD desalination plant in Chennai in collaboration with ADECO.

International Summit on Water was a 2 day event held in NIMHANS Convention Centre, Bangalore on the 11^th and 12^th of February 2011. This summit focused on the 2 major areas of Desalination and Waste water treatment. This summit had more than 20 delegates from different institutes and organizations from across the globe presenting their papers.

There were many papers on Desalination technology and the projects being underway in various parts of the world, including the methods being utilized in the construction of the sea water Reverse Osmosis System to obtain desalinated water and also different purification and pretreatment methods studied in order to cater the demand during the upcoming Olympics in London. There were also representatives from the companies like Hyflux who manufacture equipments for SWRO plants discussing about the various pretreatment methods being used which is generally ultra filtration and the various types of filter cartridges available along with their lifespan. Mr. Dong Fei Li also compared the different types of desalination technologies used namely SWRO, MSF (Multistage Flash Distillation) and MED (Multiple Effect Distillation) and reasoning why SWRO is better than the other 2 process in terms of energy consumption and material costs. The plants having largest desalination capacity are situated in Asia at present and one such plant is SingSpring plant situated in Singapore which was presented as a case study.

The Desalination processes consumes a lot of energy and minimizing the energy consumption as much as possible makes the process more economical and in order to minimize the energy consumption, energy recovery devices like pressure exchangers (PX) are used. These PXs are installed in the flow system and it utilizes the energy from the high pressure reject steam to pressurize the cool inlet stream. The principle of working of these Energy Recovery Devices (ERD) and the various models available were made known by Mr.Madurakavi Kumar from Energy Recovery Inc.

There were papers which dealt with the recent trends and the development of the desalination technology in India and with specific reference to a MED plant in Gujarat and also the projects being undertaken by WABAG INDIA in Chennai. Indira Gandhi Centre for Atomic Research, Kallapakam is a Nuclear Installation under the Department of Atomic Energy, GOI and they have also set up a hybrid SWRO/MSD desalination plant to meet their year round requirement of fresh water and also make use of the high temperature steam generated by the power plant.

There are various programs which are designed for automation and monitoring of the SWRO plants which make the maintenance of these plants easier thereby making it possible to keep it operational round the year except for periodic maintenance when required. And the maintenance and automation solutions are supplied by ABB through their OPTIMAX Membrane Performance solutions.

It is a well known phenomenon that as the pressure decreases, the boiling point of the liquids will also decrease and by making use of this phenomenon the people at National Institute of Ocean Technology, Chennai have come up with an efficient plan of desalinating sea water. Now coming to industries, boilers are an integral part of many industries and these boilers need feed water , and for continuous operation they need hundreds of gallons of water free from salts as the salts may lead to scaling in the boilers and procuring fresh water from natural sources is not always a viable option so in order to overcome this, BHEL, Ranipet has set up a RO-DM plant to treat the agricultural runoff water and utilize it as feed water for boilers thus cleaning up the Agricultural run-off water which will be having high levels of colloids, minerals, pathogens along with fertilizers and pesticides and also making efficient use of the water resources. Here they pump and store the agriculture run-off water in a pond and later is subjected to a series of operations which include clarifying and filtering through a series of Pressure Sand Filters (PSF) and Activated Carbon Filters (ACF) and later subjecting it to RO process and further treatments.

The Desalination plants do have few effects on the ecosystem and nature due to the production of heat as well as concentrated brine which is again let out to the sea which causes variations in the density, temperature and salinity of the sea water in those areas of discharge which needs to be evaluated and corrective measures taken.

As the population increases the amount of sewage produced also increases and it is necessary to treat the sewage and make use of the treated water for indirect potable use and Pall has come up with Aria series of microfiltration modules which has been approved by the California Health Dept and is being used for municipal water recycling. Right now this process is in place in the state of California, USA and the water produced is used of irrigation, as boiler feed and also supplied to University of California, Davis for various needs. MF procedure is also used for secondary treatment of waste water before letting it out into the rivers. This is found to be a very cost effective procedure.

Steel industry is one of the biggest consumers of industrial water and as the supply of fresh water is drying up, the steel industry is now facing the dual challenge of increasing production and reducing consumption of water. This is only possible when wastewater is recycled after treatment and near-zero discharge level is achieved and consumption of water per unit of steel production is minimized. These challenges can be effectively addressed by properly using existing knowledge of water and wastewater treatment and simultaneously adopting emerging technologies.

Along with these there were also discussions and presentations regarding the studies and steps taken by BWSSB for monitoring and removal of Endocrine Disrupting Chemicals (EDC) present in water by adsorption, advanced chemical oxidation and other membrane processes. The initiative taken by the Jayadeva Institute of Cardiology to use treated water wherever possible by setting up a treatment plant in their backyard was also one of the interesting topic.

The new thing under development in the process industries is known as ZLD or Zero Liquid Discharge processes, which are being developed and studied by various industries in India and around the world. Apart from all these, there were also discussions regarding the recent emerging trends in the field of municipal waste water treatment, reducing the production of waste water by making use of water efficient systems in day to day life and also usage of modern nanofiltration techniques for water purification and various methods for recovery of certain metals and also petroleum residues from the waste water.

This summit addressed almost all the major water issues being faced at present and near future and also the steps that has to be taken in order to prevent the water crisis. Apart from desalination and waste water treatment, using water judiciously and conserving it will solve half of the problems regarding water shortage.

Now, I did learn something or rather many things out of this summit. Should make it a point to attend more of these kind of things.