Water and Effluent Treatment Magazine
Issue link: https://read.utilityweek.co.uk/i/867569
between them throughout the day to ensure both streams remain in active service. The streams are also able to operate in parallel to provide a peak output of 12m3/hr as and when required. The two water supplies are mixed in a buffer tank, and pumped to duty/ standby XL360/1000 so eners, each capable of supplying both deionisation streams. The MegaRO reverse osmosis units (one per stream) remove up to 98% of dissolved inorganics and more than 99% of dissolved organics, colloids and particles, providing 75% recovery with a permeate flow of 8.6m3/h. The water then passes on to the CEDI- VNX 50-2 units – each containing a bank of ion selective mem- branes and ion exchange resins – which also pass a small electrical current across the stacks. A central motor control centre housing a Siemens S7-300 PLC interface handles power distribu- tion and system control, and pro- vides a Profibus DP communica- tion link to connect with the site's building management and dis- tributed control systems. Monitoring The combined borehole and mains water supply leads to vari- able input water quality, requir- ing a number of precautions to be built into plant operations to ensure consistent performance. These measures include the addi- tion of small doses of sodium bisulphite prior to RO to remove any residual free chlorine that could damage the membranes, with continuous redox monitor- ing to raise an alarm in the event of high free chlorine levels at the RO unit inlet. Small doses of sodium hydrox- ide (NaOH) can also be added at this stage if the feed water pH is low, to avoid reduced plant per- formance due to the presence of free carbon dioxide (CO2). A clean-in-place (CIP) system was added for both the RO and CEDI units. Once purified, the outlet water from CEDI units is pumped to two exchangeable IHF mixed bed cyl- inders for final polishing, ensur- ing that the total silica specifica- tion is maintained regardless of variations in the raw water com- position. This set-up minimises the use of strong chemicals, bulk chemical storage and the need for effluent neutralisation. By investing in this project, FM1 now operates a high quality, reliable water treatment system that ensures consistently high performance is maintained over a wide range of flows and raw water compositions, while mini- mising chemical consumption. SEPTEMBER 2017 WET NEWS 15 ThE coNcEpT • The custom system combines chemical-free membrane technologies with mixed bed polishing cylinders • The custom solution provides two streams each designed for an output flow of 8m3/h • The resulting high purity water is pumped to two exchangeable IHF mixed bed cylinders for final polishing • A central motor control centre housing a Siemens S7-300 PLC interface handles power distribution and system control NEED To KNoW 1 Key goals included improving effluent neutralisation to comply with industry regulations 2 FM1 uses a range of fuels from various municipal, commercial and industrial sources across Yorkshire and the wider region 3 Hitachi Zosen Inova's (HZI) is an EfW engineering, procurement and construction contractor ThE VERDIcT The design and build of the new water treatment system provides a number of benefits for FM1, including shorter delivery, site commissioning and testing times, and effective removal of larger particulates using multiple cartridge filter elements (10μm). FM1 works in a similar manner to an existing coal-fired power station on the site When pumping station equipment gets older the risk of breakdowns and disruptions increases, switching out your old pumps to the submersible sewage pump type ABS XFP is easy with the Sulzer adapter bracket which fits to the existing guiderail. Choosing the XFP also means lower energy consumption with the Premium Efficiency IE3 motor that comes as standard, and reduced maintenance costs and blockages delivered with the versatile range of Contrablock Plus impellers. For more information, www.sulzer.com/timeforchange Time for Change