The UN’s Intergovernmental Panel on Climate Change (IPCC) estimates that for 2030 a 60% reduction in greenhouse gas emissions is needed to achieve a goal of no more than a 3 °C increase in the earth’s global temperature level (IPCC (Intergovernmental Panel on Climate Change), 2007). The wastewater treatment industry will play an important role in achieving this ambitious objective, since in the last several decades energy consumption has grown considerably, both through increases in treated volume and the implementation of new technologies aimed at achieving higher effluent qualities (Nakagawa et al., 2006). In addition, we should not forget that reducing the WWTP carbon footprint is not just an environmental issue; there are also important economic repercussions (Ko et al., 2004; Gill et al., 2011).
In this context, several Countries are still not into line with the Water Framework Directive (2000/60/EC) which established 2015 as deadline for achieving “good status” for all waters, and with the “Urban Waste Water Treatment Directive” (91/271/EEC and 98/15/EC) , which defines strict requirements for urban waste water treatment plants and for certain industries. Italy for instance fails treatment for almost 40% of waste water (cf. Global Water Intelligence – report 2017) causing serious damage to environment and to the economy, and has already received by the Environmental Protection Agency (EPA) a number of infringement procedures in the past years for “poor “ability to treat wastewater. Other European Countries face similar problems (Spain, France, Greece, UK and Ireland, etc.). Therefore, if already the energy demand of the WWT sector is high, it is expected that in the near future, when the European Countries meet the EU Directives, this energy consumption will show a significant increase due a higher expected volume of water being treated, as well as to the adoption of new technologies aimed at yielding higher quality effluents. Furthermore, the impact of the new Priority Hazardous Substances Directive for toxic contaminants will drive energy usage significantly higher.
In order to address this challenge, the European Environmental Agency has published the following recommendations for the optimization of the wastewater treatment:
- Improve the efficiency by means of water consumption reduction, wastewater generation minimization, loss reduction, recycling, and the decentralized treatment.
- Reduce the energy consumption by means of process inefficiencies cutting, introduction of best available practices, innovative processes, automatized controls, and more efficient aeration technologies.
Taking into account that in a WWT plant between the 50% and 60% of the energy demand is produced by the aeration systems, by means of this project it is intended to contribute to the improvement and optimization of the wastewater treatment precisely by means of the improvement of the efficiency of such aeration systems in the secondary or biological stage.