Improvement of Energy Efficiency and Plant Performance in a Water Reclamation Facility in Gilbert, Arizona Using MAT2000 Online Monitoring

The City of Gilbert, Arizona Water Reclamation Facility in preparation for an ultimate expansion to 11.0 MGD had Severn Trent Services perform a plant evaluation using the MAT2000 online monitoring technology. This technology allows for a more insitu evaluation of the plant process which cannot be achieved by traditional laboratory analysis. The data can then be used to create and calibrate a computer model to help predict what process changes occur under various scenarios. Another focus of the study was to determine trends of electrical demand due to aeration and what methods could be applied to improve energy efficiency.The study revealed the variations in the load distribution between the oxidation ditches was a problem in determining the actual oxygen/energy demands and what the actual plant capacity was. Until a better understanding of the load distribution is achieved an accurate assumption of the aeration capacity cannot be made. With this in mind, a system is to be installed that monitors the dissolved oxygen, mixed liquor concentration, and level of rotor submersion and also the level of final process treatment using a ball respirometer in the clarifier splitter box. By monitoring the level of treatment using respirometric demand, ammonia levels, and dissolved oxygen concentrations inside each oxidation ditch, a regime of running all aeration rotors only during the weekend and certain times during the week lead to periods of rotors being turned off to save electrical costs.