Water purification systems
from which it is pumped, via variable speed drive duty and standby feed pumps, to a Modula S-XL reverse osmosis system protected by 5 µm particle filters.
High velocity supply Permeate from the reverse osmosis modules is delivered to a NephroSAFE ultrafiltration unit and, via a PEX (crosslinked polyethylene) ring main, to the points-of-use. The supply of water into the ring main is maintained at a high velocity to discourage biofilm formation, and is typically higher than the consumption. Unused water from the ring main is recirculated through the ultra filtration module to ensure that the quality in the ring main is maintained. The NephroSAFE ensures the removal of bacteria and endotoxins from the dialysis water, and the reject water is returned to the inlet of the reverse osmosis system. The combination of reverse osmosis and ultrafiltration ensures a consistent supply of treated water to Renal Association standards, while consuming less energy than a twin-pass reverse osmosis system.
year, giving an annual saving of £7,500 over the budget estimate.
The water treatment plant, distribution ring main, and points-of-use for the new renal dialysis building – funded by the North Bristol NHS Trust, and located at Bristol’s Cossham Hospital – were supplied by ELGA Process Water.
A sanitisable system The ultrafiltration membrane is heat sanitisable, allowing the ring main and ultrafilter to be sanitised at the same time with hot water, by recirculating in the normal operational mode while the water is heated to 85˚C and maintained at that temperature for a pre-set time. The NephroSAFE incorporates a heater for this purpose. Hot water was chosen as the sanitising medium because it is safer than chemical agents.With chemical sanitisation it is not easy to be certain that the solution reaches all the points-of-use, nor that it has been completely rinsed from the system. Hot water sanitisation can be monitored by simple, reliable temperature measurements, which can be used to make the process automatic.
Factory-tested before delivery The PEX ring main was fitted out during the building works, and the renal water treatment system factory-tested prior to delivery. This meant that, when the building
was handed over, the plant could be immediately connected to the ring main, and the whole system commissioned. The result was that dialysis patients were being treated within four weeks of building handover.
Key ‘environmental features’ The water treatment system has four important environmental features aimed at minimising energy consumption and, as a
58 Health Estate Journal September 2013
result, reducing the system’s carbon footprint. Firstly, the latest generation of low pressure high flux RO membranes are used, which operate at significantly lower pressures than their predecessors, which means lower pumping energy. Secondly, the raw water feed pumps are fitted with variable speed drives, which are modulated to match output to demand, so there is no excessive pumping. Thirdly, the RO system monitors the operating parameters constantly, and adjusts the volume of water sent to drain. This not only minimises the feedwater consumption, but also keeps the amount of reject water discharged to around 15 per cent of the feedwater. Fourthly, when the system is heat sanitised, the dialysis machines and their feed hoses are included in the circuit, reducing electricity demand for heating the dialysis machines, and also ensuring that the points-of-use are kept free of bacteria.
Contributing to water conservation goals In keeping with the sustainable approach taken to the design of the Cossham Dialysis Unit, the renal systemcontributes to the overall water conservation goals by delivering the reverse osmosis reject water to a grey water recovery system, where it is used forWC flushing. The Cossham Dialysis Unit’s projectmanager, Richard McSmythurs, had anticipated 25 per cent wastewater, which is typical formany renal water systems. This would amount to some 5,000m3
each year. If this were to be
discharged to sewer it would cost about £12,000 per annum,made up ofmains water charges, treatment costs, and sewer disposal charges. In fact the ELGA Process Water systemgenerates only about 2,700m3
per year of wastewater, reducing
costs by around £5,500 per year. By re- using this wastewater in place ofmains water within the renal unit, and selling the surplus to themain hospital, the Cossham Dialysis Unit will gain a further £2,000 per
footprint targets The treated water supplied to the renal dialysis stations has consistently been fully compliant with the Renal Association’s Guidelines, and heat sanitisation has proved to be safe, effective, and environmentally friendly. The use of energy-saving techniques has helped tomeet the CosshamDialysis Unit’s carbon footprint target, as well as reducing energy costs. Wastewater recycling has reduced the Unit’s water footprint, and the cost savings
Meeting carbon
accruing fromlowermains water consumption and sewer discharge are a welcome contribution to the annual budget.
Kalpesh Shah
Kalpesh Shah, Healthcare product manager – Renal, ELGA ProcessWater, joined the Permutit Company – later to become part of ELGA ProcessWater – in 1993, after graduating from the University ofWestminster with a BEng in Mechanical Engineering. After gaining experience in design and sales of water treatment plant, he moved into project management, specialising in pure water systems for pharmaceutical applications. He then joined ELGA ProcessWater’s fledgling healthcare department as contract engineer, and, as it grew, took on the role of contracts manager in 2008. Here he developed an interest in renal water systems and, in 2009, took on his present responsibilities as product manager for the renal solutions division of healthcare operations. Kalpesh Shah is a Member of the
Association of Renal Technologists, and recently gained a Graduate Certificate in Management from Kingston University.
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