What Is Grey water Management: A Practical Example

Waste water management is a must for reducing pollution as well as for sustainable development. Do you know that 60 per cent of domestic wastewater is grey water (water that does not contain faecal matter) that can be reused for irrigation, gardening and toilet flushing after proper treatment. Let’s deep dive into grey water management treatment methods and also look at an example of a village that has installed grey water management systems.

What Is Grey Water?

Grey water refers to wastewater from households or offices without faecal matter. All water streams from domestic uses except water from toilets comes under grey water. The source of grey water includes water from the bath, washing machine, sinks or dishwash. Grey water constitutes around 60% of domestic water, which is a good amount. This can be reused after proper treatment for agricultural and toilet flushing purposes.

What Does Grey Water Constitute?

The content of grey water varies from place to place or house to house according to the products they use for washing, bathing and in sinks. Generally grey water constitutes hair, lint, fats, body oils, grease, chemicals from soap, toothpaste, detergents, shaving creams and cosmetics. Grey water also contains microbial elements such as bacteria, viruses and parasites. The main pollutant of grey water is detergents that are high in Sodium and Phosphorus. So as grey water has harmful chemicals and pathogens it cannot be directly reused. It has to be managed properly, using a grey water management system.

Grey Water Management System

The grey water is treated using a greywater management system before the reuse or final disposal. Through the greywater management system the contaminants and pathogens in the water are reduced. Grey water should be treated fastly as time progresses the microbes in grey water increases and grey water may become sewage.

The grey water treatment is done to remove harmful substances for human health, hazardous to soil, environment and irrigation system. Mainly two types of grey water management can be adopted. The primary diversion system and the secondary treatment system.

Grey Water Management Treatment Method

Primary diversion systems-

This system uses filtration or sedimentation to remove oil/grease and solid matters and the water is used for land applications. In this method the grey water is not stored. The wastewater mainly from laundry applications are simultaneously filtered and is utilised for land applications or gardening purposes.

Secondary treatment system

Secondary treatment of grey water is used to remove more solids, greece, oils and organic materials. This allows secondary treated greywater to be irrigated via micro-drip or surface irrigation methods. The secondary treatment method removes pathogens and inorganic substances in the grey water. Secondary treated grey water is more healthier than primary for human contact. The secondary treated grey water can be used for toilet flushing and irrigation.

There are health risks in using grey water. Even the treated grey water may contain pathogens that affect human health. While installing the domestic user should take care that the grey water should not contain faecal matters, and solid food wastes for a better and healthier usage. And grey water should not be stored for long for treatment purposes. The grey water treatment should be done immediately, otherwise it may become sewage water with more concentration of pathogens and foul smell.

A Successful Story Of Greywater Management At Pappankuzhi Village

With the efforts of community members and government officials, Pappankuzhi village has successfully implemented a grey water management system. Individual and community grey water management system has been installed in the village. Ninety three individual and three community grey water management systems are installed. The installed system effectively treats about 42,000 litres of grey water that is generated per day in the village.

Proper guidelines were given to the people in the village for proper usage of grey water management systems. Swachhagrahi, A. Sarla Devi played a crucial role in creating awareness on the importance of water management and grey water systems.

Grey Water System In Pappankuzhi Village

Individual soak pits are simple to construct with locally available materials. It contains a collection pipe where greywater in households is collected and filtered in an inspection chamber. The soak pit consists of a concrete tub where the suspended particles settle, allowing greywater to overflow into the filter media where it percolates into the ground.

Community Soak Pits : Horizontal and vertical type soak pits are constructed at the discharge points of the drainage systems. Drainage systems have been built in Pappankuzhi Village up to the grey water disposal point. The horizontal soak pits are suitable for places with high water table where the treated water can be recovered and reused for agricultural activities. Two horizontal systems are constructed in Pappankuzhi village.

The vertical soak pits require less land area when compared to horizontal type soak pits and are constructed in areas with a low water table, where the treated water will help replenish the groundwater table. Pappankuzhi has one vertical soak pit.

This is a practical example that may inspire students on the need of water conservation and why we study water conservation.