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Equipment to control (Private) Water Quality

Kennet Water, part of the Pollet Water Group, offers a wide range of equipment for water professionals and installers. Our products include solutions for arsenic reduction, pH adjustment, iron and manganese removal, nitrate filtration, sediment removal, color control, organic scavengers, carbon filtration, UV treatment, and more.

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Equipment to control (Private) Water Quality

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  1. Equipment to control (Private) Water Quality Neil Grant Kennet Water Components

  2. Background • Me – MSc in instrumentation and analytical science, 3 years at WRc, 15 years at Severn Trent (municipal), 8 years at Kennet (Private/industrial) water • Kennet Water - Part of the Pollet Water Group Supplier of equipment to the Water professionals/installers (rather than end users) • Products for PWS treatment • Arsenic reduction, pH, Iron & Manganese, Nitrate, Sediment, Colour, Organic Scavengers, Carbon, Sediment, UV, Filters • Reverse osmosis • Components – vessels/valves/media • Member of UKWTA

  3. Equipment to control PWQ Questions we need to ask What is the application how much water what is the source water any special site info

  4. Applications Drinking water (private supply) Domestic municipal drinking water improvements Process water Swimming Pools Not Municipal Water Treatment

  5. Private Water Treatment Layout

  6. Chemical Parameter Limits • Laid down by European Union • UK: Private Water Supplies Regulations 2009, • Covers microbial and chemical parameters • Different sampling regime for small and large supplies but basically the same chemicals are covered

  7. Typical treatments in PWS • Private water supplies often treated differently to Municipal Water supplies due to size and use and number of users. Municipal works use coagulation, flocculation, chlorination PWS typically use filtration, ion exchange, Ultraviolet

  8. Common chemical parameters • Depends on where in the country (different rock strata) • South West : iron, manganese, arsenic • East : nitrates, hardness • North England: iron, manganese, arsenic • Scotland: colour (tannins), pH • Wales: Manganese, pH • Pollution • Mine runoff, road runoff, oils, fertilisers, pesticides • Recycled water • Organics, sediment Arsenic bearing rocks

  9. Water sources • Also depends on type of water source • Borehole • Often more consistent quality • Iron, manganese, arsenic, • Surface • Often flashy • Natural colour, sediment, nitrates • Recycled water • Organics, sediment • Infrastructure: • Pipes, tanks (lead,copper)

  10. Chemical Mitigation Methods • Nothing works better than stopping it getting into the PWS in the first place • Treatment/mitigation methods • Filter housings • Manual/backwashing filter systems • Ion Exchange Medias • Reverse Osmosis • Chemical dosing

  11. Borehole Pumps & Pressure Tank • Borehole pump: - Down to you ! • Pressure Tanks • reduce the on/off cycling of pumps • Steel or plastic • Single flow/flow through

  12. Filters & Filter housings • How does it work • Water passes through a filter housing and is trapped by a sediment filter or other media (carbon, nitrate reduction) • Advantages • Simple, • Cheap • Easy to maintain • Disadvantages • Ideal breeding ground for bacteria • Can restrict the flow • Easily blocked

  13. Filters & Filter housings • Sizes • 10”, 20”, 30” and 40” • Slim, Big • Flow rates • 0-20 m3/hr • Types of sediment filters • Spun • Wound • Pleated • Bag • Antibacterial

  14. Filter systems What are they used for and trade names • Iron & Manganese Birm, Aquamandix, Filox, Greensand, Pyrolox • Sediment Sand, Turbidex, Filter Ag, Glass • Arsenic Bayoxide • pH Juraperle, Corosex, pHlocrite • Organics/pesticides Carbon (many variations)

  15. Filter systems How does it work • Water passes through a filter and impurities are trapped or adsorbed. In many instances they can be backwashed away.

  16. Example: Arsenic Reduction • Legal limit for Arsenic in water is 10ug/l (10 parts per billion) • Can Cause • Cancers, linked to cardiovascular disease • Media used is Bayoxide • Regulation 31 approved – used by Severn Trent, UU • Arsenic reduction system on Transition list of approved products PWS • Arsenic is absorbed by the media and held • Eventually the media becomes saturated and needs replacing.

  17. Example: Arsenic Reduction • How to size a unit • Service flow rate max: 20m/hr, Backwash rate: 25 m/hr • Working pH range 6.8 to 9.5 • Raw water must contain less than: • 200ug/l PO4, 200ug/l Fe, 50ug/l Manganese, 10 mg/l suspended solids • For waters with over 50ug/l a lead lag (dual) system will be needed

  18. Ion-exchange systems What are they used for and trade names • Iron & Manganese Crystal Right • Nitrate A520E • Softening Purolite C100E, Dowex • Natural colour organic scavenging, • Demineralisation MB400, NRW3240

  19. Ion-exchange systems How does it work • Water passes through the media where certain ions are exchanged in the resin for other ions eg calcium (scale) is held and exchanged for sodium. Periodically the resin is regenerated eg with salt (sodium chloride)

  20. Ion exchange systems Advantages • Normally automatic, • Can be targeted to the chemical pollutant • Can be sized accurately • Disadvantages • Adds chemicals to the water • Need to be specified correctly • Need maintenance

  21. Example: Nitrate Reduction • Legal limit for Nitrate in water is 50mg/l (50 parts per million) • Can Cause • Methaemoglobinaemia (blue baby syndrome) • Media used is Nitrate reducing resin eg Purolite A520E • Regulation 31 approved – used by Anglian, Thames, … • Nitrate is absorbed by the media and chloride is exchanged • Chloride limit is 250 so normally adding say 50 to a background level of 80 is no a problem. It can be blended with raw water. It is regenerated with salt – sodium chloride

  22. UV Disinfection

  23. UV Disinfection UV systems from 5 l/min to 1000 m3/hr

  24. Domestic (post Municipal) Treatment Taste (chlorine) Particles Mineral Reduction (RO)

  25. Industrial Process Water Depends On Process Large volume sediment reduction Pure Water (Revers Osmosis) Chemical Dosing

  26. Reverse Osmosis • To remove chemicals such as Sulphate and sodium Reverse osmosis means the permeation of liquid through a semipermeable membrane caused by a pressure exceeding osmotic pressure.

  27. Reverse Osmosis

  28. Dosing systems What are they used for and trade names • Chlorine Sodium/calcium Hypochlorite • pH sodium bicarbonate, sodium hydroxide • Scale Reduction Ortho/poly phosphates • Advantages • Often automatic, • Can use feedback from sensors to be accurate • Disadvantages • Add chemicals to the water • Need a lot of maintenance • Can block

  29. Swimming Pool Water Treatment • Chemical dosing (Chlorine/pH) • Often automatic, • Sediment Filtration • Requires variable speed pumps • Low pressure manual sand filters • Top up water • Depends on source water

  30. Conclusions Bacterial contamination normally more of a health issue than chemical problems (Pragmatic approach) Different from municipal treatment because of size Many variations which often look similar Work well if specified and maintained properly Shouldn’t be used as a sticking plaster (stop the chemicals getting in in the first place before chemical mitigation)

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