WET News

JUNE 2014 WET NEWS 17 An alternative approach to enhancing capacity and ensuring compliance during treatment plant upgrades. Rich Matthews explains A solution: DAF ensures compliance D AF technology works by removing suspended sol- ids from wastewater. Us- ing proven solids / liquids sepa- ration technology, the DAF units create white-water by dissolving air under pressure and then re- leasing it to form micro fine air bubbles. The solids then attach themselves to the air bubbles, which rise to the surface. The solids are then thickened by natural dewatering and removed by means of a mechani- cal scraper. The first DAF installation of this kind developed by SPS was for Anglian Water, at Cottesmore WwTW. Here the DAF provided solids removal instead of two continuous backwash sand fil- ters, which were struggling to achieve suspended solids consent. The SPS range of lamella DAF units are perfect for this type of application as the addition of lamella plates to a DAF allows a relatively high flow rate to be treated by a very compact unit. At Anglian Water the 2.4m wide x 6m long unit was used to treat a peak flow rate of up to 144m3/h which, in combination with a small amount of flocculent, was able to reduce the discharge solids con- centration to less than 5mg/l. SPS also supplied two D100 lamella DAF units to Southern Water and contractor BTU for final effluent polishing applica- tions at two separate wastewater treatment works. Both of these • Total ammonia • Free ammonia • Chloramine • Final effluent monitor • Chloramination control • Inlet monitoring w w w. a t i u k . c o m F O R WA S T E WAT E R A N D P O TA B L E WAT E R A P P L I C AT I O N S Tel: 0800 8046 062 sales@atiuk.com On Line Ammonia monitor F O R WA S T E WAT E R A N D P O TA B L E WAT E R A P P L I C AT I O N S Very low running costs Simple electrochemical sensing technique Ammonia Advert (WITH QR CODE):ATi 27/9/12 15:18 Page 1 Fed up with digging in the wrong place? The HL5000-H2 will pin-point leaks with a mimimum of fuss and maximum accuracy. SebaKMT · Archcliffe Road, Dover, CT17 9EN T: 01304 501 101 - F: 01304 502 307 E:uksales@megger.com· W: www.sebakmt.com/en installations helped to reduce the risk to compliance, where the suspended solids limit was a concern. At one Southern Water site the requirement was slightly dif- ferent. Although the primary concern was maintaining solids consent, the high proportion of iron in the solids meant that the concentration of solids in the treated water discharge needed to be maintained at a low level. Iron is added at the works to ensure compliance with a tight phosphorous consent. Compliance This iron can be bio-accumu- lated into the biological growth in the trickling filters. Over time the percentage of iron in the bio- mass increases, hence when the biomass comes off (sloughs), the solids discharge limit is put at risk. More importantly the iron limit is also put at risk and if exceeded would push the treat- ment plant into 'failed works' status, seriously affecting the water company's serviceability targets. The iron can also cause the solids to become finer and hence affect normal solids compliance as well. Southern Water consid- ered using drum filters but the footprint required would be too large and units were not available. Since installation, the D100 DAFs have achieved the required suspended solids reduction that also ensured compliance with the total iron and phosphorus limits. The project at Kelda Water Services' RMB Chivenor in North Devon was different again. The project involved providing a temporary solids / liquid sepa- ration system whilst the existing final settlement tank was refurbished. Normally solids liquid / sep- aration on an Activated Sludge Plant is carried out using a final settlement tank. However, as this was only a temporary installation SPS pro- vided Kelda with one of its D100 portable Dissolved Air Flotation units as a compact alternative. Whilst the use of DAF for sludge thickening applications is well documented, they are still relatively unused on municipal sites, but the potential for their use here is huge in addressing dif- ferent maintenance challenges. n Rich Matthews is delivery manager at Siltbuster Process Solutions. www.siltbuster.com SAPPEL is becoming Diehl Metering Sappel - Diehl Metering offers systems with high-quality metering, low starting flows and a large dynamic range. Metering and data collection systems can be used in all field configurations. With fixed, mobile and M-Bus networks, our radio reading systems are efficient, scalable and switching from mobile reading to fixed network is seamless. More information: www.diehl.com/metering Contact: Diehl Metering Ltd. 22C Salmon Fields Business Village, Royton Oldham OL2 6HT | Tel. +44 (0) 161 6209593 ALTAIR and HYDRUS Smart solutions for water metering White-water is created by dissolving air under pressure and then releasing it to form micro fine air bubbles. The solids attach themselves to the air bubbles, which rise to the surface

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