Water is the primary need of any living creature on the planet. With the growing population and urbanization, the availability of the consumable water is diminishing. The growth of the economy or the population cannot be controlled. But with change in sensitivity towards the consumption of water, we can meet the present demands and optimum use of the same can help to save our future generations.
The quality and the quantity of the available water is depleting due to population and pollution which is driving the governments to set the laws for conservation of the water resources and greywater management system is one of the significant methods to achieve the same.
Greywater is the reclaimed water that has been used once in domestic, commercial or industrial activities and can be reutilized after treating up to standard limits for certain tasks.
This greywater can be treated through various technologies depending on the nature of reuse for further applications like car washing, irrigation, toilet flushing or street cleaning.
The current Indian scenario
Water is becoming a rare resource in the world. In India, it has been projected by International water management institute that by 2025, one third of the population will live in complete water scarcity.
With the rapid increase in the population and demand for fresh water the available resources are depleting day by day. The per capita surface water, which was available at 2300 m3 (6.3 m3/day) in 1991 has depleted to 1980 m3 (5.7 m3/day) in 2001 and is projected to deplete to 1191 m3 by 2050. And the water requirement is projected to 1450 Km3 in 2050 as compared to 1086 Km3 presently. Hence, it is very crucial to reduce the use of surface and groundwater in all sectors, find alternatives to fresh water reuse option for optimization of the available water. The alternatives include rainwater harvesting and greywater management system and reutilization for meeting the projected deficit.
The wastewater is generated from various activities like washing, laundry, bathing, mopping, flushing, cooking, etc. This water is categorized into three types depending upon the level of contaminants present in the source. They are black water, dark grey water and light grey water. Black water is generated from the flush and are high in disease causing microorganisms. Dark grey water is the water that originates from the kitchen sink, which also contains disease causing germs and organic contaminant from food waste and grease or oils. Light-greywater is originated from bathroom sink, tubs, showers and laundry. This water also contains disease causing microorganisms but in lower number as compared to the other two types. The level of organic contaminants is also less in this type of water. The figure shows how much water is discharged as wastewater in regular household activities.
Benefits of greywater reuse
- The first and the foremost reason of greywater management and reuse is to replace or conserve the freshwater for other potable uses.
- The greywater is rich in nutrients like phosphorus and nitrogen that are present in detergents, which are good for the plants. The water generated from laundry if used appropriately can help in good vegetation and plant growth.
- Reduces the cost incurred in sewage treatment. Greywater when treated and used within the area minimises the wastage through sewer lines and cost incurred in its treatment at sewer cleaning facilities.
- Usually the reutilization of the greywater require no or minimal treatment before use.
- Greywater can help to supply most of the water needs for irrigation purposes.
These various methods can be used to treat the same from low level of complexities for basic uses like gardening or flushing to high level of treatments to remove sediments, oil and grease, chemicals, odour and other impurities depending upon the nature of reuse.