Aeration is the prime contributor to energy costs in wastewater treatment plants. Therefore, process performance depends strongly on how the external aeration is operated. The incorporation of aeration control strategies appears essential to reduce energy costs while guaranteeing effluent quality.

Previous projects lead by our team and recent studies in this field support and provide evidence on the cost-benefit of monitoring the efficiency of wastewater aeration using the off-gas technique.

Relying on the experience of DRH2O’s founder and head Dr. Diego Rosso, who has been studying aeration systems since 2000, we developed a real-time off-gas analyzer coupled with a software interface that calculates the real-time aeration cost based on the actual power tariff or contract of our clients. This hardware+software system, called DROTE+ is the last evolution of our off-gas analyzers already developed and demonstrated for years in several wastewater treatment plants.

The DROTE+ measures the oxygen content of the off-gas and reference air, and the off-gas flow. With these measurements, the instrument is able to calculate the OTE, OUR, OTR, blower power, and alpha factor (when clean water data are available).

The actions that the DROTE+ software prompts, based on historical data and process analysis, empower plant engineers and operators with quantitative metrics to set their process control to target minimum energy consumption and power demand reduction, or total energy costs, depending on their preference.

Integration with process controls will be possible in the future, but in the current configuration the DROTE+ aims at informing the plant personnel about the implications of their process actions and about the monetary incentives available to them.



Power demand in wastewater treatment is a dynamic response to the societal need for immediate and rapid treatment of their liquid discharge. This is marked for municipalities, since the population at large relies on the wastewater infrastructure to maintain the society functioning. Being municipal wastewater treatment a non-for-profit operation, the reduction of power demand costs is crucial to maintain at curb treatment costs while meeting environmental stewardship targets. Industrial wastewater has a different way of being viewed, for its treatment needs to be rapid to maintain productivity, with less priority on the treatment cost. Our extensive experience in this field has currently lead to a project award by Southern California Edison on real-time off-gas analysis for power demand reduction at wastewater treatment facilities (DRx24).


Direct and indirect greenhouse gas (GHG) emissions are associated with process operations for water and wastewater treatment, and are currently under the spotlight (e.g., the Paris COP21 Agreement). Moreover, as we increase our understanding of these emissions and their importance in the specification and selection of process options and operation control, they are becoming an integrating part of the decision-making process for utilities. It is therefore of crucial importance to quantify these direct and indirect emissions in a carbon footprint analysis. Our participation in the European Union’s Horizon 2020 project C-FOOT-CTRL (Developing on line tools to monitor, control and mitigate GHG emissions in WWTPs) is an example of our commitment to environmental impact analysis.