Recycled water is the process of converting wastewater into water that can be reused for other purposes e.g. irrigation, toilet flushing, laundry and car wash for both private home owners and/or commercial/industrial properties.
Recycling water is the way of the future, we don't have a choice anymore, not with our global water resources worsening. A United Nations report states that 2.7 billion people will face water shortages by 2025, which means almost half of the total population of the world will be affected by this problem. For too long people have been too ignorant around water, especially in our semi-arid country, South Africa.
By using recycled water instead of freshwater is a water-saving measure. When recycled water is eventually discharged back into natural water sources, it can still have benefits to ecosystems, improving streamflow, nourishing plant life and recharging aquifers, as part of the natural water cycle.
Greywater makes up about 65% of the total wastewater produced by an average household and is a good source of water for reuse. Greywater is all wastewater generated in households or office buildings from hand wash basins, showers, baths and clothes washing machines. It does not include kitchen sinks, dishwashers, toilets, urinals and bidets. Domestic greywater can be recycled directly within the home, garden or company and used either immediately or processed and stored. If stored, it must be used within a short time or it will begin to putrefy due to the organic solids in the water. Recycled greywater of this kind is never safe to drink, but a number of treatment steps can be used to provide water for washing, flushing toilets and irrigation.
The application of greywater recycling provides substantial benefits for both the water supply system as well as the wastewater treatment system.
The treatment process, from biological systems such as wetlands and bioreactors or more compact systems such as membrane bioreactors or mechanical systems eg sand filtration and UV radiation, depends on the end application.
Some greywater recycling benefits:
- Reduces freshwater extraction from rivers and aquifers
- Reduces pressure on wastewater treatment plants
- Reduces energy use and chemical pollution from treatment
Greywater Recycling for Irrigation:
Greywater makes up about 65% of the total wastewater produced by an average household and is an excellent alternative source of water for irrigation. Greywater should be applied below the surface where possible e.g. subsurface or surface drip irrigation (on top of the soil, under mulch or in mulch-filled trenches) and not sprayed, as there is a danger of inhaling the water as an aerosol. All our installations are designed by our expert team, ensuring you of a quality and aesthetically pleasing installation.
With any greywater system, it is important to try and use eco-friendly detergents as far as possible. Most of these are easily available, if not, we can supply these with all installations.
Greywater Recycling for Toilet Flushing:
It is completely unnecessary to use clean drinking water for toilet flushing. Recycled greywater is a perfect alternative for this purpose. Greywater from showers, baths, hand wash basins and clothes washing machine can be reused instead of just being sent to the drain.
Such a system could save approx. 30% of water in an average household. We have a few different recycling options for toilet flushing, preferably treating the water so it can be stored for a certain period, but in certain dwellings where potable water is not required it can be reused without treatment.
It is also great to combine greywater recycling with rainwater which is already fairly clean to begin with and/or has not been polluted with non-degradable chemicals such as non-natural soaps. It is not recommended to use water that has been in the greywater filtration system for more than 24 hours or bacteria builds up, affecting the water that is being reused, unless treated extensively. We have installed many different greywater recycling systems and are sure to design and install a system that suits your need and budget.
Greywater Recycling for Laundry:
Only if the pathogen filled greywater is treated extensively (pre-filtration, biological degradation and ultra-fine membrane) can it be reused for laundry purposes. Unfortunately this is not always financially viable, especially for the private home owner, BUT to be able to turn unclean/unclear greywater into clear re-usable water is indeed water conservation at its best. We usually recommend combining this recycled system with another source of water e.g. rainwater harvesting during the rain season and municipal water during the dry season. Sometimes we exclude greywater generated by clothes washing machines for this application, it depends on the end use. This recycled greywater can be stored indefinitely.
Also refer to our Wetlands system for this application.
Wastewater reuse is a long-established practice used for irrigation, especially in arid or semi-arid countries like South Africa. Reusing wastewater is part of sustainable water management and is an alternative water source. Recycling blackwater reduces water scarcity and alleviates pressures on groundwater and other natural water bodies.
When greywater is mixed with toilet wastewater and/or kitchen sinks, it is called sewage or blackwater and is treated onsite sewage facility (septic system). Water from kitchen sinks and/or dishwashers contains fats, oils and grease. It undergoes preliminary treatment to remove these substances before discharging it into a grey water tank.
Blackwater Recycling for Irrigation:
Sometimes it is not viable to separate greywater outlets from blackwater outlets/sewer. Although it is easier and cheaper to treat and recycle greywater than blackwater (sewage), because of lower levels of contaminants, it is not impossible. Blackwater reuse is a long-established practice used for irrigation, especially in a semi-arid country like South Africa.
The treatment process is purely the biological breakdown of organic solids entering the treatment plant. This process incorporates the advantages of fixed film technologies and combines it with fine bubble diffused aeration techniques. Its main components; the bio media and fine bubble diffused aeration grid.
The Biological Breakdown Process:
- Primary treatment takes place in septic tanks/anaerobic reactors. The septic tank size is determined by the number of people in the household. This process requires at least 24hrs but should be retained for at least 48hrs. The longer retention time, the higher quality effluent. It then flows into the biological reactor for secondary treatment.
- Secondary treatment is done in the Aerobic Biological Reactor. Here air (oxygen) is pumped into the reactor to mix and supply air to the waste water. This allows the waste water to circulate between an aerobic zone and an anoxic zone to facilitate the de-nitrification process. Fixed film (specifically designed for waste water treatment) process is when immobilized media has been provided for microorganisms to attach and grow on.
- The last,Tertiary treatment process is a disinfectant/sterilizing process as a precaution against pathogens that may have passed on from the second stage. Contact period should be at least 30 minutes.
Blackwater recycling provides water for your garden all year round; 24/7, 365 days a year. This is saving water at it's best without you having to change your lifestyle in any way whatsoever.
Pool Backwash Recycling:
Under no circumstances should backwash wastewater be directly discharged to the environment or to the stormwater system, it HAS to go into the sewer system (South African Council Regulations). The wastewater is extremely harmful to the environment and promotes weed growth in natural bushland areas.
The backwash wastewater can be reused for topping up of your pool again. It is a very simple system and we often install it at cost to clients who install any one of our other systems; greywater recycling and/or rainwater harvesting. Remember; every drop matters. If you can install a small rainwater harvesting tank to take care of the evaporation loss over the hot summer months and reuse your backwashed water, you can take care of your pool top-up water over the hot summer months.