14th September, 2018.- The Life Celsius Project, designed to demonstrate the viability of a wastewater purification system with lower energy costs and less CO2 emissions to the atmosphere, completes its three-year course of testing at the WWTP in Archena (Murcia).
Led by Acciona Agua, with the support of the EFE News Agency and financed by the Life programme of the European Commission, the initiative has integrated two innovative processes that incorporate a type of bacteria that do not need oxygen for their metabolism and that take advantage of the heat environment of the area for its development.
The latter, which in fact is the premise for deciding the location of the pilot plant, has explained María del Mar Micó, chemical engineer at Acciona Agua and project director, was due to the fact that in the region of Murcia, the influent reaches the treatment plant at around 15 to 25 degrees Celsius.
Two innovative processes
The Celsius plant corresponds to the second phase of a project, led by Acciona Agua, that began with the installation in the Archena WWTP of an anaerobic membrane digester for the elimination of organic matter without oxygen supply and without the need for an external heat source.
However, the high concentration of sulfate in the influent that reaches the wastewater treatment plant forced to replace the anaerobic AnMBR system of organic matter removal by an aerobic one.
This first stage was the result of the OptiAnMBR project, supported by the then Ministry of Economy and Competitiveness and developed by Acciona Agua, Esamur (Regional Sanitation and Wastewater Treatment Entity of the Region of Murcia) and Cetenma (Technology Center for Energy and the Environment).
The second stage started with the implementation of partial nitrification in the pilot plant, for which bacteria from Archena’s own wastewater treatment plant were inoculated, and the anammox phase, with the contribution of microorganisms from other Acciona Agua plants, which adapted perfectly to the climate and type of influence and in a short time demonstrated considerable activity, with higher rates than usual in similar processes.
The advantages of partial nitrification
In conventional nitrification, two types of bacteria work together: ammonium oxidants, which convert ammonium into nitrites, and nitritoxidants, which convert it into nitrate, and both need oxygen for their metabolic functions.
“In our partial nitrification we want ammonium oxidants to survive above nitritoxidants and we achieve this by reducing aeration as much as possible”, explained Micó, while in another reactor the anammox combine ammonium with nitrate and convert it into nitrogen gas without the need for oxygen; the combination of both “implies an important saving in aeration”.
The project director stressed that “although in partial nitrification we still have to make efforts to improve it, the anammox process has been very positive and we have very good prospects for converting the whole process into a complete technology that can replace the traditional water treatment systems based on aerobic processes”.
The objective of the project was that the combination of both stages would save 60 percent of the energy required in the main wastewater treatment processes, which would result in a significant decrease in greenhouse gas emissions.
Briefly, benefits for the environment beyond those derived from conventional treatment, in which “the most conflicting elements of wastewater” are eliminated, such as organic matter and nitrogen compounds, which “when they are not well treated can cause problems of eutrophication and hypopsia in the environment, “she added.
The Acciona Agua expert has assured that this technology “it will be especially interesting in areas of warm weather, such as the Mediterranean Basin, Latin America or Africa, as it will benefit from the temperature of the influent in these areas, slightly higher than in other regions.”
María del Mar Micó has praised the Life programme, “crucial as an economic support for projects related to the environment and nature and as a promotion of collaboration between different entities and companies in Europe”.
“The aim is to generate knowledge that contributes to improving tools and achieving better practices in waste treatment, water, etc., which will ultimately lead to better management of the environment,” she explained.
Traducción: Carmen Gilson