Mughal emperor Akbar built a majestic fort at Sikri near Agra, India and named it ‘Fatehpur Sikri’ (City of Victory) after Emperor Babur’s victory over Rana Sanga. It was his headquarters for just 14 years from 1571 until 1585. Ironically, the fort built after victory in battle was abandoned due to lack of water and Akbar relocated to Agra Fort near the Yamuna River. Similarly, Kampuchea’s civilization of Angkor Wat thrived on an elaborate water storage and supply system; but collapsed when it broke down a few centuries later.
We take water for granted; not surprisingly, the terms ‘On Tap’ for ‘freely available’ and ‘Down the Drain’ for ‘sheer waste’ originated from the unlimited availability of water. Our water supply and sewage systems are based on the premise that freshwater sources and wastewater sinks are infinite. Wasteful habits and mental inertia create pollution and shortages. Although water is essential for life, there is neither punishment for wasting nor incentive for saving it. Users are unaware of its true worth as purification and supply are subsidized by taxpayers’ money and its environmental impact cannot be quantified.
We rely on rainwater stored in dams, lakes, underground aquifers, etc for the year’s supply. Underground aquifers are depleted faster than natural percolation can replenish them and the limited capacity of lakes is reduced by silting.Shrinking glaciers reduce the summer flow of perennial rivers. Climate change creates problems of too much, too little or untimely precipitation (that affects food production).
A fast growing population needs more and better quality freshwater; however, water sources are limited. Mumbai gets over 3000 MLD of water and its requirement may increase to 6300 MLD by 2021. 20 – 50 liter packs of drinking water sell for Rs 40 – 200 each and tankers supply water worth Rs 3600 Crores a year. Saudi Arabia may run out of groundwater in the next 13 years.
Old houses in Rajasthan collect rooftop rainwater in underground tanks for the year’s drinking and cooking needs. However, Rainwater Harvesting is possible only during the monsoon and limited to storage and treatment facilities. Rainwater is almost like distilled water and requires little treatment. The Bishnois of Rajasthan have established a sustainable way of life in the deserts by conserving water, flora and fauna that is worth emulating.
Sustained Special Forces operations in inhospitable deserts are constrained by the limited water that can be carried. We have sometimes cooked food with smelly water from pits in dry jungle stream beds. A survival method uses a clear plastic sheet to trap warmth and moisture by day and collect dew at night.
Indus Valley civilization had a commendable drainage system, but we cannot use water like our ancestors did long ago. The use of water produces effluents and one liter of sewage pollutes eight liters of water. Polluted water requires increased effort for purification and supply. It is imperative to segregate, reuse and recycle wastewater. Drainage and plumbing should segregate the following:
- Organic biodegradable matter from the kitchen and bathroom is bio-filtered through reed-beds and reused for irrigation and flushing. A separate facility will work for WCs.
- Water containing chemicals for complete recycling.
RENEWATE is a water recycling system (patent applied for vide 1186/MUM/2010 dated 09 April 2010) based on low-temperature vacuum-aided evaporation and condensation. It works as a heat pipe (super conductor of heat) for rapid heat exchange with a warm evaporator and cool condenser (hermetically sealed with internal vacuum). A small-scale model has proved the concept and given valuable lessons. It can work better than ‘Atmospheric Water Generator’ and ‘Seawater Greenhouse’.
Low-grade waste heat and wastewater require considerable energy for disposal/ recycling. Central AC plants and chillers need cooling towers that consume about 1000 KwH of electricity per day. An effluent treatment plant for 300 KL of wastewater costs about Rs 4000/- per day. With cost-cutting, it is possible that some effluents are released without complete treatment. RENEWATE is powered by low-grade waste heat or solar heat, which is used up. Cooling towers and ETPs become redundant; and power saved is power generated. It recycles wastewater/ seawater into pure water and concentrated residue. Very little energy is needed to create conditions that keep it working as long as waste heat maintains a temperature differential. In principle, it is similar to water condensing inside PET water-bottles over a day/ night cycle and outside single-sheet glass windows of AC rooms when relative humidity outdoors is high.
RENEWATE revolutionizes the concept of water purification, cooling towers, radiators and effluent treatment. It can dispose of waste-heat and waste liquids with minimal power; generate a continuous supply of freshwater in a ship; and act as a common heat sink for multiple cooling appliances in a green building. RENEWATE would reduce pressure on traditional water sources; prevent pollution by zero-discharge of effluents and save energy. Its potential benefits are difficult to quantify; like the value of a head load of water carried by women in water deficient areas. Environmental degradation must stop for our own survival. It is not whether we can afford ‘sustainable methods’, but whether we can afford to ‘not employ them’.
Lt Col Satish M Vaidya (Retired) has considerable experience as a Paratrooper (Special Forces) officer of the Indian Army. His second innings with a hotel chain involved security and loss prevention for 10 years and Six Sigma/ change management for two years (where he got a Green Belt). His main interest lies in environment and resources conservation. In his current third innings, he has completed Masters in Environmental Science and Six Sigma Black Belt. He is working on a system that purifies liquids, works on low-grade waste heat, can conserve energy & prevent water pollution. Over the last 3 ½ years he has established a wet-waste composting system, which can help large scale solid waste management. He actively campaigns for a clean environment and writes regularly.