Water and Effluent Treatment Magazine
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16 WET NEWS JUNE 2014 With total expenditure (totex) expected to play an important role in the next AMP cycle, companies will have to ensure treatment opportunities are not missed. Siltbuster Pro- cess Solutions' Rich Matthews reveals why. The challenge: Getting 'money smart' over existing assets INSIGHT WATER TREATMENT The DAF in use at a water treatment works. The equipment provides a large treatment capacity within a small footprint W ith AMP6 fast ap- proaching, everyone is looking at how they can use their money smarter – and make the most of their ex- isting assets. The challenge is to consider total expenditure (to- tex) solutions within the agreed programme, without compro- mising site compliance. Furthermore, the investment on existing sites to enhance or increase the capacity, has to be achieved within the site con- straints, where space is o en at a premium. Undertaking improvements to existing processes can be viewed as presenting both a high risk to compliance and cre- ating additional programme challenges. This can shi peo- ple towards more of a capex rather than an opex focus, and as a result opportunities to max- imise asset life can be missed. To combat this, companies need to look wider than the con- ventional tried and tested solu- tions and seek alternative tech- nology that has already been adopted as good practice in other sectors. The availability of mobile packaged treatment plants may not be an innovative concept, but implementing a wider range of these technologies will pro- vide the flexibility and reliabil- ity to maintain compliance and allow more opex solutions to be considered. DAF (Dissolved Air Flotation) technology has a proven track record and has been around for some time. Whilst DAF is com- monly used in industrial and potable water treatment, it is seldom used in municipal wastewater treatment. The use of mobile DAFs pre- sents a way to provide treatment capacity during upgrade works and ensure compliance is maintained. DAFs can offer short-term solutions for water companies, buying them valuable time to consider the optimal long-term options in terms of plant upgrade. They can also be used as a permanent installation to enhance existing site capacity. Siltbuster Process Solutions is seeing more and more requests for assistance from water companies to work with them to build in such innovative solutions into their mainte- nance programmes. As such the use of DAFs is being seen in wastewater as well as water treatment. SPS has seen a significant interest in the mobile lamella DAFs that offer a large treatment capacity within a small footprint. The units adopt a plug and play approach that allows for flexibility in managing pro- grammes, site constraints and compliance risks in either undertaking capex or opex focused solutions. THE CONCEPT • DAF technology works by removing suspended solids such as organic matter, algae, colour, FOGs from wastewater • Using proven solids / liquid separation technology, the DAF units create white-water 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 • The solids are thickened by natural de-watering and removed by means of an automated mechanical scraper • DAF technology has applications across several sectors including food and drinks production effluent; raw water or backwash water from potable water applications; • Municipal wastewater streams (eg. activated sludge and tertiary solids removal) and water from environmental remediation THE VERDICT • Kelda Water Services: The ability to deploy such a large treatment capacity from a Hiab is proved critical in providing clients with a flexible fast response and worked within the site constraints • Anglian Water: The 2.4m wide x 6m long DAF unit was used to treat a peak flow rate of up to 144m 3 /h which, in combination with a small amount of flocculent, was able to reduce the discharge solids concentra- tion to less than the 5mg/l • Southern Water: Since installation, the D100 DAFs have achieved the required suspended solids reduction that also ensured compliance with the total iron and phosphorus limits • NEED TO KNOW 1 Alternative technology should be sought that has already been adopted as good practice in other sectors 2 Companies are seeking innovative solutions to their maintenance programmes 3 Investment on existing sites to enhance or increase the capacity must be achieved within site constraints 4 Implementing a wider range of technologies will provide flexibility and reliability 5 Totex solutions must be considered without compromising site compliance 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