**Wrexham**: Engineers at Five Fords Wastewater Treatment Works have successfully enhanced efficiency through cutting-edge techniques, achieving £3.5 million in savings. The project, led by Mott MacDonald Bentley and Dŵr Cymru Welsh Water, improves treatment capacity for over 130,000 residents amid growing demands.
Engineers in North Wales have implemented innovative techniques to enhance the efficiency of wastewater treatment at the Five Fords Wastewater Treatment Works (WwTW), situated near Wrexham. This project, orchestrated by Mott MacDonald Bentley (MMB) in collaboration with Dŵr Cymru Welsh Water, has reportedly resulted in savings estimated at £3.5 million compared to traditional methods.
The Five Fords facility plays a vital role in treating sewage for over 130,000 residents. To accommodate a growing population and the increased demands from new anaerobic digestion plants, MMB was tasked with augmenting the treatment capacity of the plant’s three activated sludge process (ASP) lanes. However, it quickly emerged that the plant’s current layout presented challenges with flow distribution that hindered efficiency.
Jack Jones from MMB explained that the differing flow rates into each ASP lane were evident in the varying levels of dissolved oxygen measurements. “One of the lanes, for example, was operating in a super-critical condition, whilst another was sub-critical,” he noted, indicating significant process control challenges.
The complications were compounded by existing structural issues, including a large 800mm relief pipe discharging a mixture of returned activated sludge (RAS) and overspill into the main inflow channel. Earlier modifications to the plant involved replacing flumes with weirs to enhance capacity, but the necessity for further modifications posed considerable logistical constraints. Traditional methods, such as electromagnetic flowmeters, which typically require a full pipe for accurate measurement, were deemed impractical due to associated installation costs and potential operational downtime.
Consequently, MMB conducted a series of internal discussions with hydraulic, mechanical, and process engineers to explore alternative solutions. The favourable option involved using three actuated penstocks, which would regulate flow into each channel, while the fourth could be isolated for future use. However, reliable measurement of the flow downstream of the penstocks remained a considerable challenge.
MMB turned to NIVUS, a specialist in flow measurement technology, to implement their cross-correlation flow meters. This innovative method employs ultrasonic reflection to measure velocities continuously at various levels within the flow, producing detailed flow profiles in real-time, even under challenging conditions.
Josh Sparks, MMB’s Contracts Manager and EICA Regional Practice Lead, discussed the importance of this technology, stating that it operated effectively in heavily polluted applications, accommodating various influencing factors related to flow computation.
Initial installations of the NIVUS flow meters took place before the penstock implementation to assess flow variations. Following the deployment, MMB reported that initial concerns regarding the reaction speed of the penstocks to changes in flow were resolved, allowing for smooth and consistent flow distribution among the ASP lanes. This success was reflected in a satisfactory 28-day proving phase, after which the system showed no issues and continued to perform well.
The project’s outcome met its goal of equalising flow rates within the ASP lanes, thereby improving treatment efficiency and capacity. The overall expenditure for MMB’s solution was projected at around £1 million, substantially less than the £4.5 million estimated for conventional modifications involving a new distribution chamber.
The financial savings realised under the Welsh Water Alliance’s contract have provided financial benefits not only to MMB but also to Dŵr Cymru Welsh Water and its customers. As a result of the success of this project, MMB has initiated internal webinars to disseminate the benefits of this technology to engineering colleagues globally. Looking ahead, the NIVUS cross-correlation flow measurement technology is set to be employed in future wastewater projects and other applications, such as pump management and potable water flow measurement.
Summarising the project’s successes, Josh Sparks expressed satisfaction with the results, stating, “Cross-correlation flow measurement turned out to be the key that unlocked the financial, time, and carbon savings that have been achieved.” The proactive approach taken at Five Fords sets a precedent for future endeavours in wastewater treatment efficiency.
Source: Noah Wire Services
Subscribe to Industry Updates
