Wastewater treatment is a critical yet inefficient process in the European Union: it takes in large amounts of energy, and releases a lot of emissions. It currently accounts for around 3 % of the electrical consumption in developed countries, and the typical energy efficiency of treatment plants in Europe is under 50 %. A whole load of harmful gases are also pumped out into the atmosphere at various stages of the process: from either the energy use, chemical consumption, disposal of unwanted effluent or management of sewage sludge. “Wastewater treatment plants are a significant anthropogenic source of greenhouse gas emissions; these include carbon dioxide, methane and nitrous oxide (N20), with the last two causing 25 and 265 times more harm than CO2 in a 100-year period, respectively,” says Professor Andreas Andreadakis, from the Department of Water Resources at the National Technical University of Athens and C-FOOT-CTRL project coordinator. Redesigning plants – or the way they operate – could begin to treat this sordid situation. C-FOOT-CTRL is a Horizon 2020-funded project creating a software tool to kickstart the process. C-FOOT-CTRL is an online monitoring system for treatment plants, which can accurately predict and record the emission of gases and pick out the worst sources of pollution and inefficiency. It then suggests where improvements could be made to reduce the carbon footprint.
Measuring the carbon footprint
The C-FOOT-CTRL team created a novel gas analyser to monitor emissions and log the information online. “Particular emphasis has been given to the online N2O measurement,” says Prof. Andreadakis. Almost 8 % of global anthropogenic GHG emissions are N2O, and wastewater treatment plants contribute 3.2 % of this. The tool accurately records and tracks emissions at the source in real time, and initiates mitigation processes when necessary. Meanwhile, the system reveals which activity in particular was causing the problem. The C-FOOT-CTRL tool includes three basic components: databases, online measurements and a dynamic computer model, which determines the carbon footprint. A user interface communicates the results of the monitoring system back to the plant operators. The innovative software is designed to be a low-cost and flexible system based on integrated sensor networks, for monitoring and ‘supervising’ activities aimed at reducing GHG emissions. In revealing structural weaknesses, it should also spur new designs. “C-FOOT-CTRL will encourage water utilities to increase efforts and place new technologies at the heart of their innovation strategies, based on the analysis of the performance of their wastewater treatment plants,” says Prof. Andreadakis. The tool was tested successfully in two different treatment plants in Greece and the United Kingdom. “A series of mitigation strategies for GHG emissions and studies on the effects of their implementation in wastewater treatment plants have been developed by using the C-FOOT-CTRL tool,” says Prof. Andreadakis.
The tool and its resulting impacts will help in the fight against climate change and energy inefficiency across the EU. It will also improve the day-to-day operation of plants – which should lead to a higher quality of life for local communities. Decreasing the carbon footprint of wastewater treatment plants can also have positive implications for water tariffs, explains Prof. Andreadakis: “C-FOOT-CTRL tool and the implementation of appropriate GHG mitigation strategies can result in lower energy consumption within the plant. As a result, the service of wastewater management can become cheaper and this can be reflected in the water bills of customers.” This research was undertaken with the support of the Marie Skłodowska-Curie programme.
C-FOOT-CTRL, greenhouse gas, GHG, wastewater treatment plant, energy, consumption, water, carbon footprint, climate change, water bill