In the wake of severe water scarcity in several districts of the country, its high time urban residents who are the largest consumers of the freshwater resources, got conscious of recycling of Grey water
According to a recent World Bank study, India – a home to 17 percent of world’s population, holding about 4 percent of the world’s freshwater resources is already the largest consumer of freshwater in the world. Annually, it is consuming freshwater to the tune of 750 billion cubic metres and it is estimated that the demand would double to 1.5 trillion cubic metres by 2030. For a country that has been battling a near drought like situation virtually every year, the World Bank figures definitely warrants some serious thinking about ways and means the country could bridge the widening gap between the water ‘haves’ and ‘have nots’.
Why is Waste water recycling a neglect in India?
Undoubtedly, waste water treatment plants and restructuring of sewerage system is a costly proposition. Considering the magnitude of waste water generated across India, it ought to be processed on a day-to-day basis. Creating such an infrastructure by the government alone without any support from private sector and individual residents is simply impossible. Moreover, non-availability of land in the urban areas to create zone-wise centralised recycling systems makes the project virtually impossible to undertake.
What is Grey Water recycling?
Used water from bathroom sinks, showers, tubs, washing machine, etc. that has not come in contact with faeces from the toilet, is called Grey water. It may look dirty and may contain food, grease, hair and certain household chemical, yet it is considered safe and beneficial source of water for irrigation and various household purposes like flushing toilets.
Why reuse Grey water?
Often, Grey water is directly released into existing water bodies. Grey water released directly into rivers, lakes or ponds leads to pollution of potable water owing to presence of chemical nutrients. On the contrary, we can use the same polluting chemicals as growth promoters (i.e. fertilizer) making them beneficial for the plants. Importantly, reuse of Grey water especially in the urban ghettos would not only help check the ever swelling sewer or septic system, but to a great extent solve food shortage issues and also turn the surroundings clean and green.
Which technology is best suited for you?
Individual households should always try sticking to low-tech simple design while recycling Grey water using gravity wherever possible, instead of using costly pumps and filtration techniques. The entire focus should be on making optimal use of Grey water for development of food and a green ecosystem. However, if the system is being designed for the entire residential or commercial complex, it is advisable to engage an engineer or water expert to design a system that is capable of treating and reusing large volumes of water. Undoubtedly, a complex system would work out to be a bit expensive, as it may require a good amount of space and also involve heavy pumps and modern filtration systems.
Word of Caution!
In case you are planning an independent Grey water recycling system here are some issues that you need ponder about:
- Storing Grey water: As plants have to be watered at regular intervals, a basic storage system ought to be in place. Ensure that you don’t store Grey water for more than 24 hours, as the nutrients in it will start to break down, creating bad odour.
- Avoid physical contact: One cannot entirely rule out pathogen contamination, especially if someone in the family is infected or sick, so ensure that the Grey water directly soaks into the ground and people or animals come in its direct contact.
- Optimal use: While using Grey water for irrigation, ensure that plants are optimally watered and there is no run-off or pool-up. Pooling of Grey water could be breeding grounds for mosquitoes and run-off water could infect households.
- Managing excess water: In case the Grey water generated is in excess of what’s required for irrigation of plants, then it is sensible to let the excess Grey water into the sewer/septic system. Here a valve system could be used to switch the excess flow into the sewer system.
- Keep it simple: Always go for a recycling system that would last longer, require less maintenance, require less energy and cost less money. As far as possible try avoiding pumps in favour of gravity, and use a filtration system that is simple, manageable and cost effective.
-Manoj Mahanta
Team, ScienceNow
