Water and Effluent Treatment Magazine
Issue link: https://fhpublishing.uberflip.com/i/340814
16 WET NEWS JULY 2014 The upgrade at Taunton include an increased treatment capacity requirement and a tightening of the consent ONSITE Energy e ciency by the N-RTC (Nitri cation Real Time Controller) are mainly based on the Activated Sludge Models of the International Water Association. The N-RTC also constantly reads the NH4-N concentration at the outlet of the aeration lane. This value provides a feed- back control loop and ensures that the DO concentration is ne tuned to achieve the desired ammonium set point at the end of the ASP. In this way, the N-RTC control module combines the advantages of feed forward and feedback control, which are (1) rapid response, (2) set point accuracy and (3) robust compliance. Aeration to achieve the bio- logical oxidation of ammoniacal compounds to nitrate is the most energy intensive process at activated sludge plants because blower power consumption can represent more than 50% of total costs at some plants. However, in addition to the advantages of the process opti- misation system, four new Sulzer high speed HST-20 turbo- compressors are being installed by Nomenca, following trials on similar units by Wessex Water. These machines employ a con- trol system that manages both the number of blowers to run, and the speed of the blowers, which will further improve energy eŽ ciency. Summarising, Orford says: "Wessex Water has an ambi- tious long-term objective of car- bon neutrality, and these improvement works projects provide us with useful opportu- nities to make a signi cant con- tribution to that goal." calibration-free and dri• -free measurements. Once the construction work is complete there will be four new lanes, each with three zones, so a total of 12 LDO probes will monitor dissolved oxygen. In addition, two SOLI- TAX ts line dip probes will measure Mixed Liquor Sus- pended Solids (MLSS) content in the aeration lanes and the solids content of the Returned Activated Sludge. The RTC at Taunton will also control sludge retention time, which enhances plant eŽ ciency. The suspended solids probes employ a patented dual scat- tered light method with a built- in wiper, to provide colour-inde- pendent measurement of solids without a requirement for calibration. Ammonium measurements will be undertaken at both the entrance and exit of the aera- tion lanes with two AMTAX sc instruments; high-precision analysers that continuously col- lect samples via an air-bubble cleaned lter probe. The ammo- nium analysers will be mounted directly over the lters to mini- mise the distance travelled by samples. The RTC is implemented on an industrial PC that communi- cates with an sc controller net- work and the local PLC. The RTC system determines the most eŽ - cient aeration level and continu- ously feeds DO set points to the PLC which controls the blowers. This means that under RTC, DO set points are no longer xed, instead they š oat according to the load. Energy intensive The RTC modules continuously deliver set points to the PLC, which applies them to the pro- cess. This ensures that response to changing conditions is imme- diate. The algorithms employed The AMTAX, seen here installed at Holdenhurst, is a high-precision analyser that continuously collects samples via an air-bubble cleaned € lter probe SHARE YOUR OPINION... yoursayWN@fav-house.com Twelve LDO sc probe, seen here with separated cap, will monitor dissolved oxygen, while SOLITAX sc probes will measure Mixed Liquor Suspended Solids Try Grundfos pumps free for up to 90 days Grundfos SE/SL pumps with the new S-tube® impeller deliver world-class hydraulic efficiency and reduced clogging. In fact, we are so confident in the effectiveness and efficiency of the new Grundfos SE/SL pumps that we are willing to let you put them to the test, without any cost to you, for 90 days. It's our way of standing behind the quality of our pumps. We call it "Try Before You Buy". Contact your local Grundfos office today to order your trial pump. NO COMPROMISE InTroduCInG TrY Before You BuY See more at uk.grundfos.com/no-compromise.html Grundfos Pumps Ltd Grovebury Road Leighton Buzzard Beds LU7 4TL, UK Tel: 01942 263899 ukwater@grundfos.com Grundfos Merrywell Business Park Ballymount Road Lower Dublin 12, Ireland Tel: 01-4089088 info-ie@grundfos.com 100348_GFS_TRY BEFORE YOU BUY_AD_GB_WetNEWS_ART01_JW.indd 1 6/12/14 2:55 PM