Alton WTW (2020)
Anglian Water’s Alton Water Reservoir and treatment works based near Ipswich in Suffolk was constructed and opened in 1987. Between 85-95% of the water is supplied to Ipswich and Felixstowe via the Wherstead Reservoir and the Orwell Bridge, with the remainder fed to the villages of the Shotley Peninsula and South Suffolk. The works was at high risk of experiencing a total loss of supply event to 92,214 properties. The cause being a dinoflagellate bloom triggering severe stress to the filtration process. A significant increase in bi-annual algae growth and the works inability to cope with reduced flows and potential failure of downstream plant; because of the solids contamination build up over a four year period, led this to becoming an emergency scheme.
The risk of a water quality failure and issue of a boil notice is as a result of disinfection failure due to high turbidity. The high turbidity is as a result of Alton WTW inability to treat the very high loads in varying sized algae which bloom in Alton Reservoir during the summer months. Insufficient treatment plant and possible issues with the existing processes lead to a failure to remove the turbidity throughout the treatment works.
The project team proceeded with the following initial investigative works to identify the required solutions:
- @one Alliance process engineers and Anglian Water scientists carried out extensive water quality sampling to try and understand the quality of water and the solids in the water.
- Extensive CFD and hydraulic modelling on the DAF plant to understand the capacity of the treatment works.
- Through a referral from Anglian Water CEO Peter Simpson, @one Alliance met with specialist contractor LG Sonic to discuss the requirements for the Alton Algae project. The project team needed to establish if LG Sonic could understand and meet the required contractual and safety standards and if their technology and products could help solve the algae problem at the works and contribute towards the successful delivery of the project.
The MPC-Buoy is specially designed for large water surfaces. It combines near real-time water quality monitoring, web-based software and ultrasound technology to provide cost-effective treatment against algae in drinking water reservoirs, lakes, and cooling reservoirs.
The MPC-Buoy is equipped with four ultrasonic transmitters for 360-degree algae control. Each transmitter has an ultrasonic treatment range of 500min diameter. Based on the water quality data, the system can remotely activate the right ultrasonic program. The web-based MPC-View software allows to visually track the water quality and the progress of the ultrasonic treatment.
The transmitters send ultrasonic sound waves of several specific frequencies, amplitudes, waveforms and durations into the water. These ultrasonic waves create a sound layer in the top layer of the water, which has a direct impact on the buoyancy of the algae. The algae cells sink to the bottom of the water reservoir, where they will be degraded by the bacteria present in the soil. LG Sonic devices control the growth of new algae from 70% to 90%.
The LG Sonic products are not based on cavitation; the LG Sonic technology uses low-power ultrasound to control algae growth. This prevents the release of algal toxins into the water.
MPC-View water quality software
The MPC-View software allows to visually track the water quality of a water body. The software receives its data from advanced water quality sensors that are integrated into the MPC-Buoy.
The software features a personal dashboard displaying an overview of the algae control project. The software provides insight into the water quality, algae trends, and the progress of the ultrasonic treatment. Furthermore, the software displays technical parameters, such as the status of the ultrasonic transmitters, signal strength, and battery voltage. Generated reports can be exported to Excel or converted to PDF to be shared or published.
- Monitor water quality: The MPC-Buoy provides a complete overview of the water quality by collecting the following parameters every 30 minutes: chlorophyll α (green algae), phycocyanin (blue-green algae), pH, turbidity, dissolved oxygen, and temperature.
- Predict algal blooms: The collected data is delivered in real time via 3G to a web-based software. Based on the developed algorithm LG Sonic is able to modify the ultrasonic program to the specific water conditions and predict algal blooms a few days ahead.
- Control algae: Based on the received data, the ultrasonic program can be activated according to the water conditions and type of algae present. In this way, it is possible to eliminate existing algae and prevent the growth of new algae.
- Project delivery: @one Alliance
- Ultrasonic floating buoys: LG Sonics
- Mechanical: Waveneys
- Electrical: Glasswell & Last
- Panels, modifications and software: TES
- New poly aluminium dosing package: WES
- Civils: Claret Civil Engineering
- Sludge removal plant: FLI Water
- Sub-contractor to FLI Water: Aspinals
- Scaffolding: Tubes
The initial investigative work identified the solutions and the following work was undertaken:
- Refurbishment of the flotation streams, consisting of a new sludge removal system in all four tanks (Streams A&B) including replacement spray bar, extending and modifying the baffle inside the tanks, opening up inlet orifices (from flocculation to flotation streams) from 190 to 325mm (to reduce velocity). Removal of existing header pipework and nozzles and replacement with new header pipework and nozzles. The new sludge removal system will be on variable speed drives (local panels associated with each tank).
- 4 (No.) new recirculation pumps also on variable speed drives. Modifications to saturator pipework, 2 (No.) new boll filters including modifications to pipework and amendments to software, SCADA system to be fully integrated to the DAF plant, including a new ICA section.
Poly aluminium dosing plant
- Installation of a new poly aluminium dosing plant.
- Amendments to poly dosing plant.
- Permanent installation of existing temporary chlorophyll and turbidity monitors on the raw water.
- Installation of 13 (No.) ultrasonic floating MCP-Buoys.
Installation of MPC-Buoys
The MPC-Buoys were delivered to Alton WTW from LG Sonic as flat pack, then assembled on site before being situated on the reservoir. On completion of the installation and before being placed in their final positions, the MPC-Buoys were left outside to allow the panels to charge and to check that all signals were set up correctly and connecting with the MPC-View software. The MPC-Buoys were then put into position and commissioned.
By utilising the services of LG Sonic and their MPC-View monitoring system, it is far easier to see and identify what is happening in the reservoir. When required, LG Sonic will increase the power output to the ultrasonics, which helps reduce any sudden growth and assist with keeping algae and turbidity levels down in the reservoir. Since the installation of the MPC-Buoys and ultrasonic programme, we have started to see the benefits in reduction of suspended solids coming into the works and a reduction in algae going through the works. The system supresses the algae in the reservoir, which reduces the growth of the algae.
Alton WTW had never delivered fully on their expected output of 42 Ml/d, instead the works had only achieved 36 Ml/d. After completing all works associated with this scheme, Alton WTW now delivers 42Ml/d of water.
The editor and publishers thank Andrew Hardy, Project Delivery Manager with Anglian Water @one Alliance, for preparing the above article for publication.