There are more than 30 000 urban wastewater treatment plants in the EU. Some 80% of these have secondary treatment processes using activated sludge. An increase in the toxic load of urban wastewater reduces the cleaning capacity of the bacterial culture. Such increases come from uncontrolled discharges with excess toxic loads and are often seasonal, coinciding with activities of certain industrial processes such as wine production or the canning sector.
When a treatment plant operator detects that the organic or nutrient removal performance is decreasing, most of the biomass has already been damaged; the usual procedure to resume normal activity consists of increasing the air supply to the bioreactor, with a consequent increase in energy consumption and costs. Depending on the type and size of the process, aeration systems may account for about 50-70% of a plant’s total energy consumption.
In May 2016, wastewater treatment plants at Pinedo and Quart-Benàger in Spain suffered non-identified spills which seriously affected the microbiological communities of their activated sludge treatment systems for more than a month. This led to the discharge of wastewater that exceeded legal limits into the Albufera National Park, part of the Natura 2000 network of protected areas, and the Mediterranean Sea. In particular, the events affected the flooding schedule of the park’s rice fields.
Life BACTIWATER aims to demonstrate an innovative and more energy-efficient solution to reduce the environmental impact of failures and malfunctions of biological units after unexpected spills. For this, the project will demonstrate an innovative biological treatment, consisting of the culture and inoculation of microbial communities specially selected to speed up the recovery of the treatment process when disrupted by uncontrolled spills. Tests will be carried out at a demonstration plant, in which the microbial communities developed in the laboratory will be inoculated and different types of scenarios will be tested. A protocol will then be developed for recovering the biological process after a failure event involving the death of microorganisms. The system proposed by the project has high potential for replication.
The specific project objectives are to:
The project is fully in line with the Urban Waste Water Directive and its objective of protecting the environment from the adverse effects of wastewater discharges. The project will also contribute to the implementation of the Water Framework Directive, the goal of which is a good status for all EU water bodies.