Greywater utilisation

Advantages of grey water recycling:

- Patented design guarantees safety
- Reduction of drinking water consumption by up to 70% by the combined use of rainwater and treated grey water
- Particularly efficient for premises with high water consumption and small rainwater collection area
- High operational safety and low operating costs thanks to intelligent control
- Compact design and underground installation, requiring no extra space in the house
- No noise in the building
- Suitable for remote control

1. Grey water tank for biological treatment (900 litres) 2. Grey water inflow 3. Grey water overflow 4. Sewage system 5. Grey water system ventilation 6. Ultrafiltration module / sterilisation 7. Fresh water inflow 8. Rainwater / fresh water tank 2400 liters 9. Ventilation unit 10. Domestic water supply 11. Submersible pump 12. Biovitor 13. Rainwater inflow 14. Drinking water feed 15. System control 16. Soak-away 17. Rainwater / fresh water overflow 18. Soak-away ventilation

* at 330 days per year production;   ** at € 5,- water costs (Drinking water supply and waste water costs combined)

Principle function diagram for indoor grey water recycling unit with up to 900 liter/day production

1. Grey water tank

2. Aeration pump

3. Grey water

4. Membrane filter compact unit (50l/h production) 

5. Clear water pump E, integral automatic switching with dry running protection

6. Emergency overflow

7. Free outlet

8. Drinking water make-up feed with solenoid valve

9. Clear water / water for services

10. Clear water tank




Principle components and connections for a 500l/day system

This layout has been designed as a 3 tank system with identical 500l tanks sized 1.650 mm height and 650mm diameter. Please note that the first tank works in this configuration as a buffer tank to handle a high inflow as it happens in the peak hours morning and evenings. To assist an initial purifiaction process the buffer tank (1st tank on the left) has been equipped with an additional active aeration. The control unit has been adapted to handle an extra component. The main benefit is that we can achieve a higher recycling rate by simply adding a buffer tank.

Principle layout of an implemented indoor grey water recycling system in Germany (2000l/d)

Larger systems for grey water recycling are available upon request. The capacity of 6m³/d of recycled grey water is the recommended maximum limit for preconfigured systems incl. all tanks ex Germany. For the export of grey water recycling systems a detailled training and installation is strongly recommended since local materials like tanks could be used.

Any systems larger then 10m³/d capacity requires a detailled planning process.

4000 l/d outdoor system

Application chart of a grey water recycling system for 4,000 litres per day installed indoors
Size and space requirement of a grey water recycling system for 4,000 litres per day indoor (top view)

Example of a "running" system in Aachen/Germany

A number of grey water recycling systems have been installed for clients worldwide. With an installation in China where valuable lessons have been learned to the recent installation for a residential house in Aachen/Germany.  In this particular installation in Aachen, rainwater harvesting has been combined with grey water recycling technology.

One outdoor tank is used to collect the grey water from the house. The other tank collects the rain water along with the treated grey water/ process water which is again being reused in the house for toilet and washing machine. Through an aerated ultra filtration system grey water is being treated into high quality process water free of bacteria and other impurities. 

In the basement of the house are all the necessary installations. The special feature of the electronic control unit is that on a regular basis (up to every minute) every parameter of the whole system is being monitored and transferred via modem to a central location for further analysis or active access into the running system. Not only the parameters are being check but also an automatic alarm at the central control can be generated and the system can be switched off automatically. Even some data are being monitored that could indicated a problem into the future. Preventive Servicing is the key objective.

Left: Tanks into the earth
Middle: Aerated ultrafiltration
Right: Indoor control with remote sensing
Left: Grey water
Right: Hygienically safe process water

Ultrafiltration performance analysis for rainwater, grey water/sewage treatment

* The oxidation has to be controlled in respect to the materials of the pipes. In the practical use of rainwater, so far no corrosion could be observed. ** CFU = colony forming units; *** when filling bottles, **** n.m. = not measurable
Key component is the submerged ultrafiltration module directly into the raw water producing germ free and clear water
Ultrafiltration Membrane with pore size of 50nm