WATER EFFICIENCY | GREYWATER RECYCLING outlets as possible, so it could collect from stacks of the central villas. The collected greywater is pumped through a disk pre-filter system and dosed with a small amount of chlorine before entering ultrafilters. The ultrafiltration system is a hollow-fibre membrane with automated integral backwash that yields water to near drinking-water standards. The treated water is then stored, ready for use, in a separate tank and pumped, as needed, to provide flushing for 88 toilets. The estimated greywater yield per day is just more than 3,000 litres when the development is fully occupied. The ultrafiltration and treatment of the water ensures it is cleaned to a very high standard, even though its primary purpose is to flush toilets, says Honey. It also ensures that no particles remain to damage valves on the system it serves. Filtration and monitoring SAM BURGESS is a water reuse manager at SDS References: 1 CLEAN Combined with cloud-based data monitoring and control, the GWOD system can feed back a wide variety of data to meet the operators specifications and optimise the efficiency of the system. Data collected could include flowrates, temperature, and level information, and alarms can be set up if data goes outside of predetermined limits, so anomalies can be identified quickly for action. The system can display information via an onsite interface, and be integrated into the operators own BMS. Remote monitoring is also enabled for swift identification of any requirement for maintenance visits or servicing in real time. The scalability of the GWOD system means recycled water can be provided from when the first residents move into the building. It then adapts to increasing demand as more people move in, reusing just enough water and delivering it throughout the building as needed. The system is scalable simply by adding additional filters, which increases the skid footprint only slightly. It also operates at a high treatment flowrate for the footprint, compared with an MBR system. The only practical way to expand an MBR system to treat more greywater is to add reactor tanks, that takes up floor space and requires additional pipework and infrastructure on site. On-demand systems also have a much quicker start-up and shutdown procedure than MBR systems. So, for example, if buildings are vacant as happened during the Covid-19 pandemic the system can be shut down, then restarted immediately when required. SDS is installing its GWOD technology sometimes with rainwater harvesting systems at several sites in London, including residential projects, commercial offices and hotels. It has also installed systems in Europe, Mexico and the Middle East. There will be an increasing need to introduce rainwater reuse and greywater recycling systems to bring down consumption of treated mains water, says Honey. CJ The stainless steel fitting with a permanent press joint. Material grade 316L suitable for Potable, Hydronic heating, Cooling and Di-ionised water. Flame-free, no hot works permit required. Pressing indicator assists identification of un-pressed joints. Maximum operating temperature: 110 C at 16 bar. WRAS approved. Suitable for use with stainless steel tubes to EN 10312 Series 1 & 2. Available from 15 to 54 mm. For more information email cpd@ibpgroup.com 68 October 2021 www.cibsejournal.com CIBSE Oct21 pp67-68 Greywater recycling.indd 68 24/09/2021 17:44