My glass of used water please!

Thursday, 31 July 2014 00:00 -     - {{hitsCtrl.values.hits}}

Water, water, everywhere, not a drop to drink – a sailor may lament when drifting across the sea minus his craft. Today technology is advanced and commonly available, thus freeing ships of the need to dock at a harbour to take in water. Countries need not divert rivers to meet needs but process sea water, especially in coastal areas. Desalination is a technology serving many a nation and we too use the technology in coastal holiday resorts as well as in major thermal power plants, Lakvijaya at Norochcholai being an example. Reverse osmosis units are also being used in areas where the CKDU (chronic kidney disease of unknown etiology) prevails though this is questionable from the point of view of the retentate (high salinity stream) discharge. In a coastal system this can be thrown back to the ocean while in the interior additional management is necessary and it is not quite clear how that is being managed at present. However, one aspect still irks the user – the technology is energy intensive and when the cost of energy is high, this is a problem to the user as process economics are always important. Middle Eastern countries with energy available cheaply have no major issue in processing sea water for their daily needs. A major research thrust is there to identify ways and means of bringing down costs and improving performance of membrane based systems. If the energy costs across comes down making desalination a feasible option with current technology, one has to understand water is not going to be an issue. Thus the power of energy on resolving the ‘water’ issue. This was first articulated by Prof Smalley of Rice University, USA. He was looking towards carbon nanotubes fulfilling this promise and today some promising work is happening.    

Reusing used water

There is also another way to ensure that you have adequate quantities of water. Why not reuse used water? Used water can imply many things and definitely sewage is also used water as it has a high percentage of water. Remember that in washrooms we use at times more than six litres to flush away a few millilitres of matter and liquids! If one closes this loop, it is easy to understand the volume that can add to the feed system. With advanced technologies, reclaiming used water to serve as quality water is possible and we have excellent examples for these practices too. Water is a necessity and a must have for life. Thus while economics may dictate process preferences the need to have adequate supplies can never be compromised. Vandana Shiva, the eco-warrior from India, has famously written on ‘water wars’. Some predict that in the 21st century water may eclipse oil in importance.    


In a recent seminar on wastewater strategies for Sri Lanka held at the auditorium of the Central Environmental Authority, a visiting Singaporean water professional, Prof. Wun Jern was quite eloquent on their way of using water. Singapore has always had a problem with availability of water. Having faced drought, floods and pollution in the early years, but overcoming all odds in a 30-year period to turn all economic tables upside down, it is a little wonder that what once was an issue is no longer an issue to this tiny island state. As a small nation state they have started purchasing water from Malaysia after the separation and still do so to a much lesser degree. As the economy grew and Singapore became an affluent country, the question of water security is always an important question to answer. How can a country be run based on water bought from elsewhere? Today when you land in Singapore and drink a glass of water, it is quite likely that you will be drinking recycled wastewater. Spare a thought on your act, based on this information the next time round in Singapore. It is not quite easy and palatable to state that recycled sewage is an excellent choice for drinking, but Singapore knew in advance that this is the way to go. Innovative use of science and technology has transformed the water sector in Singapore like all other sectors. The innovative developments and use of membrane technologies alongside UV disinfection had been the way. The 2007 Stockholm Industry water prize was bestowed on Singapore’s Public Utility Board for the sterling efforts in water resource management. The present vision in Singapore is set on becoming a global hydro hub. A hub status Sri Lanka should have imagined being, as a pioneer in irrigation and water management of ancient times. Listening to the Professor, this vision too appears to be within reach. The technology reach of the university research arm appears to be truly amazing. Before their address in Colombo, the Singaporean team from the Nanyang Environmental & Water Research Institute (NEWRI) had handed over a wastewater treatment system to the Sri Dalada Maligawa in Kandy working alongside the University of Peradeniya.    


Recycling wastewater to return as potable water is practiced in Singapore and in fact it is one of the main sources of water to them today. More than 30% of the Singapore water is supplied from this base – they term this as one national water tap. Highly purified reclaimed water is known as NEWater. Singapore is also one of the leading countries in utilising urban storm water runoff too. Not having much land to capture rain, they have resorted to multitude of ways. As per Prof. Jern, it is important to condition the population as communication matters a lot in building perceptions. Pure scientific reasoning may not bring about the desired change with the general population. In Singapore the education system had worked systematically on ensuring that the word ‘used water’ is the word commonly employed. Systematic expunction of the word sewage had taken place and as per him no textbook of a child carried the word sewage and no discussion as such in a school either. The word used water has got stuck and then it is a couple of process steps away from becoming potable water. He took great pains in stating the process performance assurance as even a simple breakdown by way of wastewater coming into the product side can significantly damage the reputation.    

Sri Lanka

Water as we know is circulated through the hydrological cycle. For Sri Lankans it is rain that matters. We never produce any water and we are stuck with the quantity that we have. It is the distribution that challenges us as well as the quality. Adverse weather, as well as climate change, can drastically redistribute the availability pattern. Wet areas can get wetter and dry areas much drier. Facing another El Nino period, Sri Lanka should try to understand this possibility again. When these extreme events take place, life as we know is subjected to severe stress. An interesting ‘water availability map’ for 2025 has come from UN from their CEO Water Mandate, after a detailed modelling study. In that Sri Lanka stands out as the only country that is not going to face an economic water scarcity. All the surrounding nations to Sri Lanka are shown to face severe water shortages. Though as a country the modelling may have revealed this particular result, we know local variations can exist. A country is said to be facing a serious water crisis when available water is lower than 1,000 cubic metres per person per year. When a scarcity happens, the impact is not only lack of water. Economic development and health too are seriously affected, thus compounding the situation. It is perhaps good news as well as bad news for Sri Lanka when one contemplates the concept of water wars and geopolitics. Otherwise, you can perhaps make an economic killing via the Sri Lankan bottled water trade. May be we should start branding Sri Lankan water right now! Water, however, does need not be considered in so much of a commodity mindset due to its life-serving properties and culture-bound nature. [The writer is Professor of Chemical and Process Engineering at the University of Moratuwa, Sri Lanka. With an initial BSc Chemical engineering Honours degree from Moratuwa, he proceeded to the University of Cambridge for his PhD. He is the Project Director of COSTI   (Coordinating Secretariat for Science, Technology and Innovation), which is a newly established State entity with the mandate of coordinating and monitoring scientific affairs. He can be reached via email on]

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