The increased water consumption globally, especially in urban areas, has resulted in scarcity of high-quality water resources. Environmental and economic concerns have emerged as driving forces behind wastewater reuse. Today, people use treated water as a potable and non-potable water source. According to the World Health Organization, blackwater and greywater together form the wastewater generated from a household. Blackwater contains waste from toilets and kitchens, including fecal matter with high concentrations of organic matter. Greywater, on the other hand, comes from bathrooms and laundries and has lower contamination levels. Since this water has low pathogenic contamination and nitrogen, experts recommend recycling and reuse of greywater. Reusing greywater reduces the demand for freshwater, improves public health, and reduces environmental risks.
If you are new to the system of greywater management, this blog is for you. It details out the systems of greywater management and discusses how you can reuse and save huge volumes of water throughout the year.
What Is Greywater?
Greywater, also referred to as wastewater or sullage, is the wastewater produced in homes and workplaces. It contains water from various streams other than toilet wastewater. It is called greywater because the waste generated and mixed in water gives it a cloudy look and imparts a grey colour.
Generally, the water used for baths, washing utensils, showers, sinks, dishwashers and washing machines forms the domestic wastewater or greywater. Since the water released from these activities has fewer microbes than blackwater, it is easier to treat and reuse. You can use greywater for non-potable purposes, including toilet flushing and irrigation.
However, you must consider the following concerning greywater.
- If you live in a household with conventional flushing toilets, this water constitutes about 65% of the total wastewater generated. Therefore, it is a valuable source of water that Indian households can reuse, especially for toilet flushing.
- Greywater is not completely free of pathogens. It might contain traces of human waste generated from laundering soiled clothes.
- The presence of warmth, organic matter (such as dead cells), nutrients and pathogens often deteriorate the quality of greywater when you store it and lead to bad odour.
Treating Greywater
According to statistics, around 30 to 50% of wastewater generated by Indian households is greywater. With the best wastewater treatment plants, you can efficiently recycle it. It often contains contaminants including detergent, lint, human hair, dead skin cells, and other impurities. Whether there is a presence of organic or inorganic contaminants, the best greywater recycling systems help you achieve the desired water quality.
However, greywater treatment becomes difficult when it gets mixed with blackwater because there’s a rise in the contamination level. Therefore, every establishment, whether residential or commercial, must install a greywater filtration system to reduce the burden on public sewerage systems and increase efficiency.
The greywater generated from your house undergoes treatment in a septic tank. A separate pipe is used to collect water from various sources, including the laundry, showers and bathrooms. This ensures that the water doesn’t mix with sewer or blackwater.
After collecting the water, solid waste such as hair and other particles are separated from the water. The next step involves removing the microbes, chemicals and pathogens from the water. After completion of all these procedures, the recycled water can be used for irrigation and washing purposes.
Greywater Systems: The Types
Your greywater system is an onsite wastewater system. These systems use greywater for subsurface landscape irrigation through subsurface drip irrigation fields, disposal trenches, and mulch basins. Your system filters the wastewater through a highly effective multi-stage filtration system. It removes lint, hair, and other impurities. After the treatment, the treated water gets diverted to your flower beds, and gardens, thereby creating an effective irrigation system.
Some of the most common types of greywater systems include the following:
Filtration
The process involves the removal of solid matter through physical processes and is the most common method adopted by greywater treatment systems. Usually, the filtration occurs through sand, gravel, and fine mesh among others. You can also use pine bark, activated charcoal, sand, and polyurethane foam as agents for filtering greywater. These filtering agents completely remove the phosphorus from the water and meet all the pH criteria, making the water perfect for reuse.
Constructed Wetlands
An artificially constructed wetland, using ecological technology, mimics conditions occurring in a natural wetland. With this technology, you need to adopt special flora, fauna, soil, and microorganisms that remove specific pollutants from the greywater. You can classify the wetland into three main types- subsurface flow, surface flow, and floating treatment wetland. The subsurface flow systems are the most widely used constructed wetlands that come in two technologies, horizontal and vertical flow constructed wetlands. While each of the systems combines physical, chemica,l and biological processes, the treatment efficiency depends on factors like loading rate and availability of electron acceptors. The systems are effective enough to remove BOD-suspended solids along with heavy metals like iron, zinc, and lead.
Simple Gravity Flow System
This system does not require the use of electricity or pumps. Instead, you can send the greywater from your laundry or bath directly into the garden. Alternatively, you can also use a storage tank to store and use the greywater. Never keep the greywater stored for more than 24 hours. When you use a storage tank, the water from your household flows into the tank and finally into the irrigation system or your yard. Ensure to place the tank below your house and above the areas that you want to irrigate. During the storage, do not forget to chlorinate the water, as it prevents bacterial growth. Your tanks will require a tight-fitting lid along with a gasket and associated piping and valves. Do not forget to mark greywater on them, labeling them unsafe for drinking.
The ‘Laundry to Lawn System’ is an ideal example of the system. The system comes with a valve switch that allows the input of greywater and othe utput of treated water to the sewer. The best part of this system is that it doesn’t require any plumbing alterations.
Pumped System
If you live in an uphill area that requires irrigation with treated greywater, a pumped system is the best method. You can pump up the water into a holding tank and then release it into the landscape. The system uses a pump to pressurize and push the greywater to the desired irrigation areas. However, the system requires using electricity for the functioning of the pump.
Sand Filter-to-Drip Irrigation
This is one of the most intricate systems where you need to pump the treated and stored greywater into a holding tank through a special line. These are completely automated and highly water-efficient systems. The systems can automatically clean the filters by sending pressurized potable water back through the filter. It helps in removing the debris and supplement greywater with municipal water when required.
Your house water recycling system usually has a unit installed outside your home. You will find the unit connected to your various household appliances and home irrigation systems. Each time you use your appliances or take a shower, the used water flows into the unit. Here it undergoes filtration by removal of impurities without any chemical use. The filtered and treated water then collects into the irrigation system where you store it for future use.
Benefits of Greywater Management
Enlisted are the top benefits of greywater management.
Conserves the Environment
The water generated by various appliances such as washing machines and dishwashers forms a substantial portion of household wastewater. With the greywater treatment system, both residential and commercial establishments can reduce the pressure on local water supplies and sewage systems. The environmentally conscious approach helps conserve freshwater resources. Moreover, it reduces the burden on wastewater treatment plants.
Cost-Effective Solution
Have you experienced a surge in your water bill? Are you looking for a smart way to reduce cost on water bills? Greywater treatment at home is the only answer to this problem. When you reuse the treated water, you significantly cut down on the consumption of fresh and potable water. The reduction in freshwater demand reduces utility costs, thereby benefitting homeowners and nature.
Reduces Pressure on Sewage Systems
Traditional sewage systems bear a huge burden with excessive loads. It often results in system inefficiencies and environmental hazards. However, with on-site treatment and reuse of greywater, you can divert a good amount of your household wastewater away from the sewage system. It prevents incidents like overflowing, reduces treatment costs and boosts the longevity of the system.
An Eco-Friendly Practice
When you embrace greywater treatment, you contribute to sustainable and eco-friendly practices. Besides, you align yourself with the global initiative to reduce water scarcity and minimize environmental impacts. These practices resonate positively with conscious homeowners, attracting more people to your commercial or residential establishment.
Heat Recuperation
Often most people use hot water for bathing, cleaning utensils and other activities. Each time you use hot water, it incorporates thermal energy, which ends up in the drain. However, if you have a greywater recycling system installed in your home, the warm water collects in the system. The system uses thermal energy to warm the cold water approaching the system. This way you can use approximately 60% of your energy.
Challenges of Greywater Management
Besides the benefits, installing greywater management systems come with numerous challenges. These include the following:
Lack of Awareness and Education
Most Indians have limited knowledge and awareness about the benefits associated with greywater management. Left untreated, the wastewater from households poses serious threats which most homeowners are unaware of. Moreover, people have limited knowledge about the possibilities of recycling and reusing the greywater for non-potable usage such as flushing toilets and irrigation.
Infrastructure Facilities
Greywater management requires specific infrastructural facilities that most Indian homes lack. There is absence of infrastructure for the collection, treatment and reuse of greywater. Many urban and rural areas even lack proper public sewage and drainage systems. Therefore, the wastewater generated from homes discharge directly into the nearby water bodies, resulting in pollution and health hazards.
Technological Challenges
Most parts of India follow traditional water management practices as adopting advanced technologies pose many challenges. Financial constraints and lack of technical expertise are the primary reasons behind the issue. Experts must implement simple and affordable technologies that would suit the local contexts and encourage widespread adoption.
Conclusion
Factors like population explosion and climate change result in water scarcity. The amount of water required per person is also increasing drastically. India must address these challenges by implementing a comprehensive and integrated approach. Besides receiving government support, organizing public awareness campaigns, capacity building and technological innovations are the need of the hour. Moreover, promoting research and development for implementing sustainable and affordable greywater management technologies will improve water conservation and reduce pollution in the country.