5 minute read
Sludge Management
The D:Max by CDE is the latest addition to Qualitech’s range of services
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Industrial cleaning and waste management specialist Qualitech has launched a new tank cleaning service for the utilities sector, following an investment in the latest screening and classification technology from wet processing industry experts CDE.
CDE’s D:MAX is a mobile, trailer-mounted screening and classification system which efficiently removes grit, rag and other troublesome solids from the water and wastewater treatment process. Its mobility enables flexible processing of waste across a range of industries as it can be transported between sites to process material closer to the source, therefore eliminating the need to haul waste at high cost to a central processing facility. Qualitech spokesperson Bob Currie said: “We have identified a clear gap in the market in our region for a tank cleaning contract service of this kind, and it’s an area where we see great potential for future growth.” “Although this is our first project with the team at CDE, we have long been familiar with their technology and credentials in this space. From the moment we observed the D:MAX solution in operation and witnessed firsthand the results it was delivering we knew it had the potential to play a key role in our business.”
Qualitech’ s new D:MAX will be used to process a variety of waste materials from digesters at wastewater treatment sites at a rate of 120m3/hrat 6% dry solids (DS) content. With the D:MAX, Qualitech can eliminate plastics, rag, grit and other solids passing through pumps, tanks and centrifuges which can reduce capacity and adversely impact efficiency due to their wear on downstream processes. By removing these highly abrasive materials the D:MAX minimises avoidable and costly downtime for maintenance, while recovering capacity within the process where solids build-ups have occurred resulting in increased operational efficiency. CDE Business Development Manager Fergal Campbell added: “Qualitech has developed an impressive network in its 10-year history, providing coverage throughout the north and south of England. The solution will play an important role in advancing the circular economy in the region by recovering dewatered grit, with opportunities for applications in construction, and allowing retained sludges to be recovered for energy generation that will produce high quality cake free from solids contamination for agricultural uses”
A key advantage of the D:MAX is that it has the potential to divert high tonnages from waste for landfill and can recover significant volumes of recycled grit and aggregates suitable for a variety of applications. This material represents an unknown proportion of the volume of sludge that could potentially be removed and transported offsite at significant cost. By utilising the D:MAX only the solids contamination is removed, resulting in considerable reductions in disposal costs, reducing carbon footprint and minimising environmental impact. In addition to recovering materials for future use, screened organics can be used in electricity and energy generation while screened sludge can be used for composting and agriculture. For more information about CDE and the D:MAX, visit CDEGlobal.com
Sludge cake to liquid in minutes
Yorkshire Water Knostrop is a large wastewater treatment plant servicing a growing population of 800,000 people. The decision was taken to rebuild the works with standard digestion and a Combined Heat and Power (CHP) plant. The contract was given to build a facility to process indigenous sludge and imported dewatered sludge cake.
SEEPEX had previously installed 12 large progressive cavity pumps on site, pumping sludges to an incinerator which had come to the end of its asset life. Over many years these pumps had proven to be reliable, and SEEPEX had built a well-established relationship with both the end user and their logistics hub.
Reliable operation under extreme conditions
Knostrop is a sludge treatment centre that not only produces indigenous sludge but also receives five daily loads of dewatered sludge by truck five days a week from satellite sites in West and North Yorkshire. Each load had to be processed in under an hour to prevent vehicle backup. The application required a pump to receive imported dewatered sludge from a large reception belt facility and process 28 tonnes of 30% DS cake with high grit and rag content into a 6% DS homogenous mixture. The resultant total volume after mixing was 150m3/h which was then fed to the digesters. The pump had to run up to eight hours a day, achieve a constant dry solids mix and operate reliably under these extreme conditions.
Perfectly mixed for optimised digestion
SEEPEX calculated the total pumped volume of sludge cake plus dilution liquid, using a combination of application experience, pump selection software and algorithms. Choosing the correct amount of dilution/side stream liquid to thin the cake is important to achieve the 6% DS required to optimise digestion. Two large TVE open hopper pumps with an auger feed screw were selected, these were fed from the imported sludge reception facility. Each pump was designed to handle a capacity of 150m3/h of back mixed sludge and pump 30% DS dewatered sludge cake in the absence of dilution liquid. A homogenous mix was achieved within the pump hopper by the auger feed screw and appropriately positioned dilution connections. A reliable 6% DS mixture was delivered by monitoring the pump’s speed and discharge pressure by controlling the amount of dilution liquid being added to the pump hopper. To assist with maintenance, the pump was fitted with rotor joint access (RJA) enabling the pump’s compression zone to be moved over the stator. This allows access to the rotor universal joint and gives the ability to remove debris without involving extensive maintenance work, e.g. removing pipework and the pump’s stator.
SEEPEX maintenance-in-place technology enables the removal of blockages and simplifies maintenance SEEPEX pumps back mix 30% DS dewatered sludge into 150m3/h 6% DS homogenous mixture in under 1 hour
Reliable operation and good service life
Since their installation in June 2018, the pumps have performed as per the predicted KPIs related to parameters such as flow, pressure, speed, kW and amps. The processed sludge is pumped without interruption. And there has been no reported failure or performance drop. The removable compression zone significantly reduces downtime as blockages caused by large debris can be removed and the pump put back in operation within hours without dismantling the pump and extensive downtime.
The solution delivered by SEEPEX is a more cost-effective alternative to the traditional multi-step back mixing approach which would involve further tank storage, additional pumps and blending.
seepex.com
