WET News

ONSITE XXXXXXXXXX 14 WET NEWS JUNE 2015 A water treatment plant faced closure due to a spike in pesticide concentration found in the raw water supply entering the works. Due to tough constraints on allowable pesticide concentrations, which have to be below 0.1μg/l, the site was nearing an enforced shutdown. Transvac provided and installed a TransPAC carbon dosing system when the pesticide concentration spike was detected. The project required a quick reaction from all teams involved to complete the system installation with rapid mobilisation of commissioning engineers to get the kit up and running at the ailing site. The unit was collected from Transvac by Hiab lorry and positioned at the site on the same day. As soon as water, a dosing line and power was provided to the unit, the system was ready for testing. Unlike installing traditional Granulated Activated Carbon (GAC) plants, this project did not require ground or construction works prior to relocation of the unit. This meant the project had a lower carbon footprint compared to building multimillion-pound GAC plants that can take years to design and build. The TransPAC was delivered, commissioned and running within three days. Allowable limits Water treatment works are regularly faced with problems with contamination to the raw water supplies that feed into their works' inlet. Chemicals like pesticides, put on fields by farmers to treat crops, o‡en get washed into ground water by heavy rainfall. This finds its way to lakes, rivers and reservoirs. Some pesticides can be notoriously difficult to remove from water, requiring high levels of processing and additional treatments, which uses extra energy and valuable resources. One of the most efficient ways of removing pesticides from water is by adding Powder Activated Carbon (PAC) into treatment works. PAC adsorbs the chemicals out of the water safely and is removed at flocculation stage as part of the process sludge. Transvac developed a way of adding PAC into the raw water supply. The system doses the exact amount required to remove the pesticide without the need for large batch mixing tanks and multiple pumps. TransPAC, a compact packaged system, has been developed to include a bulk bag handling frame, carbon transfer equipment, booster pump, header tank, control panel and ejector skid all within a 20' steel shipping container. A simple HMI control panel runs the system with the only input being the flow rate of carbon, set by the operator as required. The system features an automated control sequence that transfers carbon from a half-tonne bulk-bag to an intermediate storage hopper which is then dosed at a set rate into a wetting hopper above a custom designed Transvac Ejector. This Ejector is designed to take a fixed motive water flow from the booster pump and entrain the carbon slurry, sending it along dosing pipes to the point of application, normally at the Dissolved Air Flotation (DAF) plant inlet. As PAC is a difficult substance to handle, Transvac's design team developed its system to transfer the carbon with the minimum human intervention and wastage. A custom bulk-bag handling split frame has been designed to be removable from the container via a fork li‡ truck for easy and safe bag loading. In an industry where Mobile dosing saves time • Transvac has installed its TransPAC mobile carbon dosing systems at a failing water treatment works. Lilly Smith explains why the move was so crucial. ONSITE wATEr TrEATmENT NEED TO KNOW 1 The site was nearing an enforced shutdown due to tough constraints on allowable pesticide concentrations 2 This project did not need any ground or construction works prior to relocation of the unit 3 Powder Activated Carbon (PAC) is difficult to handle 4 House the system within a shipping container meant it could be lifted from one site to another 5 Some pesticides can be difficult to remove from water 6 The project had to involve a quick response THE VERDICT • "A quick reaction was key to the success of this project, with priority given to get the system into place. Once this was complete, the works had a rig that was practically custom- made for them." David moss Housing the system within a shipping container means it can be lifted from one site and delivered to another within a day efficient use of resources is key, the sealed transfer system and accurate dosing ensures that no carbon is wasted. The system also has the added flexibility to accept a carbon feed from a silo, which the site operator can do in minutes. Action A low m aintenance control philosophy means that the system washes all dosing lines clean between treatment episodes. With only clean water passing through the booster pump, the seals have been shown to last for years without the need for replacement. With the system only being switched on when necessary it does not use any resources when action is not required and can easily be put into storage for later use. In order to make installation as easy as possible, the idea to house the system within a shipping container meant it could be li‡ed from one site to site and delivered to another within a day. The strong structure means water companies do not need to dig up or otherwise disrupt the site, provided suitable hard standing is available. David Moss, senior commissioning engineer at Transvac, says: "A quick reaction was key to the success of this project, with priority given to get the system into place. Once on site, the main challenges included getting the rig integrated with the facility's systems so that continuous dosing could be maintained from the control room. A few modifications were required to gearbox ratios and instrument sensitivity to tailor the dose rate to the site requirements. Once this was complete, the works had a rig that was practically custom- made for them." n Lilly Smith is technical sales engineer at Transvac. TransPAC include a bulk bag handling frame, carbon transfer equipment, booster pump, header tank, control panel and ejector skid all within a 20' steel shipping container TECHKNOW • The TransPAC carbon dosing system is a compact packaged system • The system includes a bulk bag handling frame, carbon transfer equipment, booster pump, control panel and ejector skid • The system doses the exact amount required, and does not need large batch mixing tanks and multiple pumps • The Ejector is designed to take a fixed motive water flow from the booster pump pROjECTs spECs • Provide and install a carbon dosing system • Carry out onsite training • Integrate the dosing technology with existing systems

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