Stuart Rice of Te-Tech Process Solutions looks at improving the performance of wastewater treatment works.
Like all industries, wastewater treatment can do its part to become “greener” by increasing efficiency and reducing both energy consumption and reliance on chemicals. But the sector is challenged with highly variable influent streams, ever-tightening discharge consents and climate change. Extreme weather events and increasingly drier summers and wetter winters cause huge variations in flow and quality both seasonally and diurnally. Continuous optimisation of wastewater treatment assets can tackle these dramatic fluctuations in influent conditions and ensure that treatment works are operating at peak efficiency all the time. This can be achieved by using an intelligent control system.
Intelligent control systems are able to provide 24/7 management and optimisation of wastewater treatment assets. Learning from historical data and analysing real-time data feeds of process parameters, an intelligent platform can support or directly enact decisions to maximise process performance. Some systems are capable of predictive responses; they can anticipate changes in influent characteristics and prepare a response before they happen. Not only destined for new builds, intelligent control systems are able to improve legacy systems by optimising their performance and extending the life of existing assets.
Dealing with industrial effluents
The Aigües de Manresa municipal wastewater treatment plant at Sant Fruitós De Bages-Narvarcles-Santpedor in North East Spain has to deal with consented industrial effluents leading to variable high nitrogen inlet loads. The works consists of two plug flow aeration lanes with variable speed blowers and flow control valves. Historically control was by means of a fixed pressure set point in the main air manifold and a fixed dissolved oxygen set point in the aeration lanes. Under these operating conditions, the plant frequently failed to meet the 15mg/l total nitrogen discharge consent, especially during winter periods.
ACA, the Catalan Water Authority finances improvement projects such as this, and Aigües de Manresa decided to install a new control intelligent platform, with modules for aeration optimisation including denitrification cycles, sludge recycling and sludge age. As well as utilising existing instrumentation, they also added new ammonia and nitrate specific ion analysers and optical MLSS probes.
The intelligent control system has ensured not only that the treated effluent quality is always met, but has also allowed the works to handle an increase of 30% in total nitrogen load whilst using fewer resources and reducing carbon footprint. Since installing the system, the Sant Fruitós De Bages-Narvarcles-Santpedor works has reduced energy consumption by 15% per m3 of raw sewage treated and 49% per kg ammonia removed.
“The results of implementing the intelligent platform have gone over and beyond our expectations, allowing us to meet nitrogen discharge limits without the need to make any significant investment in the plant”, says Antoni Ventura, Aigües de Manresa’s General Manager. “All in all, this not only resulted in increased treatment capacity and energy efficiency, but also in optimal process stability and sludge quality.”
The benefits to the water industry of asset optimisation using intelligent control are clear: ensuring compliance with effluent standards whilst improving sustainability and reducing costs. Not surprising, then, that wastewater treatment facilities around the world are turning to intelligent control systems.
The control system installed at Sant Fruitós De Bages-Narvarcles-Santpedor is the CREA® intelligent control platform. It provides real-time control and decision making, and improves plant efficiency and process reliability whilst ensuring compliance with consent limits. With modules to control aerobic and anaerobic biological processes, chemical dosing, sludge age, recycling and sludge thickening, dewatering and digestion, this platform is highly flexible and can be installed on any size of works, process configuration or aeration technology.
Te-Tech Process Solutions is offering the CREA® intelligent control platform as part of their end-to-end Asset Optimisation service for wastewater treatment processes, which includes system integration, installation of real-time data monitoring, intelligent control platforms, and in-house panel design and fabrication.
Tel: 023 8235 1600