Water recycling technology tipped to deliver savings

A next-generation water recycling system, unveiled by water infrastructure systems specialist SDS, is promising to boost efforts to save water by offering improved investment returns.

The SDS Greywater on Demand (GWOD) system is described as the ‘flagship’ technology of the company’s water reuse product range, following its acquisition of the water recycling business of Waterscan last year.

SDS said the GWOD uses ultrafiltration technology together with smart controls to deliver a ‘space-saving, low-energy and responsive’ water reuse system. It is also one of the first to be equipped with SDS’s SYMBiotIC automated smart controls incorporating cloud-based monitoring to ensure process performance is optimised.

The GWOD’s small footprint, together with its ability to provide, ‘on-demand, quality recycled water whenever needed’, makes it capable of improved investment payback when compared to conventional Membrane Bioreactor (MBR) greywater systems, especially for larger-scale systems, SDS explained.

The company’s water recycling specialist Kevin Reed said, “In the past, MBR systems have tended to be the technology of choice. Our ultrafiltration system typically processes water at about 2m3 per hour per filter, compared to an MBR system which processes at about 4m3 per day per membrane. As a result of the faster treatment, the storage volume, and therefore the tank size, is considerably smaller than for a typical MBR system.  

“Using ultrafiltration also makes the system responsive to demand at peak times. Unlike MBR, our system does not depend on having to build up a biomass of bacteria for peak operation. 

“High quality water is available immediately on start up. This also means that the system can be shut down when not in use, for example in an office block at weekends or holidays. In this way the system saves energy, too.” 

SDS added that the Greywater on Demand system can pay back in as little as seven years, although actual return on investment will depend on the size of the system and the local water company charges. 

In the GWOD system, greywater is collected and then pumped through a disk pre-filter system and dosed with a small amount of chlorine before entering the ultrafilters. The treated water is then stored, ready for use, in a separate tank and pumped, as needed, around the building.

Greywater is waste water, for example, from baths, showers and handbasins, that can be filtered, treated and then reused for non-drinking purposes such as toilet flushing, laundry or garden irrigation.  SDS said the principle is already being ‘widely adopted’, especially by hotels and large office blocks.  In London, where planning laws encourage water recycling, up to 20% of new buildings include greywater reuse systems.

 Kevin Reed added, “With the impact of climate change, increased periods of drought and water stress are predicted. So, it will be imperative for sustainable buildings to adapt and install water saving measures as standard. 

“Up to 60% of the water used in commercial buildings, such as office blocks or hotels, is highly-treated drinking water that is used, wastefully, to flush toilets or irrigate gardens, where the level of treatment is simply not needed. More cost-efficient reuse of water will benefit water companies by decreasing the demand on an already stressed supply network.

“Any technology must first demonstrate it is commercially viable, before its environmental benefits can be exploited. New technologies like ultrafiltration and smart controls can lead the change, by making water reuse systems more accessible and attractive commercially.”