AQUALOOP Water Treatment for Greywater
At ECOVIE, up until now we have focused our water management efforts on application of rainwater collection (see all other blogs pieces!). Now, with our relation with Intewa GMBH, we have the opportunity to expand our process design know-how into other areas. One of these is the area of greywater recycling using Intewa’s AQUALOOP technology. We are excited about the possibilities and have already found a lot of interest in this technology for residential and commercial applications.
In our experience, there are a lot of building types that generate a lot of grey water that can be reused* to reduce sewer outfall and demand for incoming water from municipal sources, wells, or captured rainwater while also reducing sanitary sewer outfall. Grey water is water sourced from inside a building from showers, sinks, and laundry, can be a very viable water source for a variety of uses depending upon the level of treatment it is given. As an example, a typical family of four may generate around 40,000 gallons of treatable grey water per year from showers and laundry (assuming 7 minute showers and 1 load of laundry per day). Dorms and apartment buildings may have similar per capita grey water generation, but obviously a higher total amount. Hotels generate a much higher amount of grey water due to high laundering water use for washing linens and towels. Indeed, many grey water systems are dedicated to hotel laundry water reuse.
Recycling greywater on site has the obvious impact of reducing municipal water demand while also reducing sanitary sewer outfall which helps reduce the risk of environmental contamination from events like combined sewer overflows. So, regardless of location, there is a clear impact of conserving fresh water supplied while managing wastewater better. The financial returns to property owners can compete very well with captured rainwater use, especially for new construction projects.
Greywater use makes sense especially in areas with low rainfall and where there are threats of losing fresh water supplies. Drought stricken California and the western US in general are particularly good examples. Even in wetter climates like the Southeast US, greywater recycling makes a lot of sense for new construction projects in order to save on water and sewer bills and reduce other wastewater treatment needs.
Taking advantage of these potentially large water sources requires matching end water quality needs to treatment requirements and greywater quality. Simply put, greywater is contaminated by whatever its prior use was. Shower water has soaps, dirt, and other contaminants from showering. Laundry water has the same. Variability of these contaminants may be a concern. With very little treatment, just a simple bag filtration for example, greywater can be used for some limited things like subsurface irrigation and possibly flushing toilets. You may be familiar with “laundry to landscape” greywater use which is an example of very simple recycling. However, such systems require that filtered water be used within 24 hours or else the water quality degrades to become black water. A more robust greywater system requires treatment that will allow extended water storage. AQUALOOP treatment provides this type of robust treatment.
Grey water treated with an AQUALOOP systems can be used for a variety of purposes including:
1. Toilet flushing – This is one of the most common uses of recycled greywater. It is quite easy to store and use treated grey water for this
2. Broadcast and drip irrigation – While most simple grey water systems are relegated to subsurface drip only, AQUALOOP produces water clean enough to spray in normal irrigation spray heads. Typically, water is used for irrigation after all indoor uses have been met. Some local jurisdictions may not have caught up to this technology and prohibit broadcast spray thinking it is from a simple filtration system without disinfection. It is our goal to educate to have local codes reflect existing technology.
3. Laundry – AQUALOOP treated greywater is clean enough for laundry use. Especially for hotels with a lot of whites to launder, recycling laundry water is a high growth market and there are many grey water systems in use in hotels. As with broadcast irrigation, local codes may not have caught up with the technology but this is changing.
How Does AQUALOOP Work?
AQUALOOP for greywater reuse consists of a two tank system. One tank collects pre-filtered water and houses a fluidized bed bioreactor and ultrafiltration membranes. The other tank stores clean water for pumping to its end use. The size depends upon the amount of water being treated and recycled. A single family home may have a compact system in their basement utility room that looks like this:
A larger system which treats greywater up to around 80 inhabitants may look like this:
AQUALOOP treatment is scalable to any water supply/demand situation. Here is how the AQUALOOP process works. It consists of three basic steps:
1. Prefiltering to remove large contaminants like hair and other things that may go down the drain. In this case, we can use a PURAIN pre-filter sized for incoming flow.
2. Fluidized bed reactor – A support medium for bacteria and intense aeration controlled by the membrane station and blower achieve biological treatment. Support media help grow beneficial aerobic bacteria to treat water by consuming contaminants and food for growth of bacteria (BOD).
3. Ultrafiltration – Backwashing modules filter water to 0.2 microns before pumping to the clear water holding tank. Find more details of the membrane technology here.
AQUALOOP claims a 6 log (99.9999%) removal of bacteria and 99.7% virus removal. See our case study and the website for more details on water quality capabilities.
AQUALOOP is BS 8525 certified and testing for NSF 350 is underway which will make AQUALOOP one of the only greywater treatment systems with this level of certification.
We really look forward to your questions and comments on this development and talking to you about specific applications you may see. AQUALOOP has also been used for rainwater treatment, wastewater treatment and a host of other applications.
*Reuse applies to water that is recycled before being released to nature. This may include on site recycling like we are covering here or water that goes to a municipal scale treatment plant for use in “purple pipe” reclaimed water systems. Water that is released to nature and then used by humans at a later date is typically not classified as reuse water. Examples include water that comes from wells or reservoirs. Although we all know that all water is used over and over again through the hydrological cycle, we tend to not think of water that come out of a tap in this way. Rainwater is not reuse water by this definition since it is coming from nature and has not been “used” by humans since it entered nature from wherever it came (let you imagination run wild here). This is a common misclassification and misunderstanding in the general public and even among water professionals. The term reuse should never be used when referring to captured rainwater.