Water & Wastewater Treatment Magazine
Issue link: https://fhpublishing.uberflip.com/i/1202034
www.wwtonline.co.uk | WWT | FEBRUARY 2020 | 31 Digestion tends to be applied ahead of chemical treatment, which then reduces phospho- rus to lower levels (below 1.0 mg/L). Chemical methods usually involve dosing water with metallic salts which react with dissolved phosphate to pro- duce solid precipitates. Com- monly used salts include ferric chloride, ferrous chloride, fer- ric sulphate, ferrous sulphate, aluminium sulphate (alum), sodium aluminate and calcium carbonate. A solids separation process such as clarification or filtration is used to remove the precipitated materials. If ultra- low phosphorus levels are needed, a membrane filtration system may be considered. Alternative technologies As a result of the challenges posed by reduced discharge limits, phosphorous removal has been a focus for innova- tion during AMP6 and a series of trials of alternative tech- nologies has been supervised by the EA and with support from UK Water Industry Research (UKWIR). These trials have introduced some interesting new technologies most of which however still require chemical dosing, albeit at reduced levels. Packaged systems for dosing tests If a site's dosing needs are unknown, testing is needed. Short-term hire of a dosing rig is an economical way to gain a full picture of the upper and lower dosing limits, rather than just a jar-test snapshot. A small and simple pack- aged system consisting of a DosingCube and an IBC (in- termediate bulk container) of chemical, sitting on a double IBC bund. Larger options in- clude a self-contained system within a waterproof enclosure with a 1,000-litre storage tank and a DosingCube. Container- ised systems can offer greater size and functionality, with a storage tank, duty and standby pumps and a local control panel. Tests are typically run in real time over a hire period of between four and 12 weeks. Dosing flow requirements established for small sites tend to be very low, which can create difficulties in system design. With the benefit of extensive field experience, WES has engineered those problems out of its temporary and permanent packages. WES offers a range of compact packages, designed for easy transport and installa- tion. A typical storage capacity is 1,500 litres – enough to refill from an IBC without having to interrupt dosing. The package can be supplied complete with a fill point panel, pipework, connectors, a set of duty and standby pumps, safety features and a proprietary or client-compliant control system. Storage tanks of up to 7,500 or even 10,000 litres can be accommodated, and space for extra pumps can be added to any package. ENSURING A SECURE SUPPLY OF WATER FOR FUTURE GENERATIONS HEAR the water industry's global ambitions for water security for future generations FIND OUT how regional plans and the National Framework will impact you COLLABORATE with your peers to tackle supply, demand and water quality ONLY HERE CAN YOU: BOOK NOW wwt.events/watersecurity2020 FOLLOW US @WWTLive #watersecurity2020 WATER SECURITY IN A CHANGING ENVIRONMENT 6 MAY 2020 | BIRMINGHAM SUPPORTED BY WWT-WaterSecurity20-HPHad.indd 1 14/01/2020 11:45