What’s the problem?
The recent climate strikes and extinction rebellion actions have shown that the world is becoming increasingly aware of the devastating effects of our changing climate. Thus, social pressure on governments and businesses is growing to reduce their own carbon footprint. The water industry plays a double role here: on the one hand it has to deal directly with the effects of climate change (often presenting themselves as water issues, i.e. floods or droughts), and – sometimes under difficult circumstances – continue to deliver clean drinking water and process wastewater. On the other hand, the water industry also feels the pressure to reduce its own carbon footprint in order not to contribute to the problem any further.
This has led to a serious dilemma for wastewater utilities. On the one hand, wastewater utilities strive to achieve ambitious climate goals, but on the other hand, they are faced with an increasing need to expand their treatment systems in order to remove e.g. pharmaceuticals and pesticides more effectively before discharging the effluent into surface waters. Sophisticated treatment systems for the removal of complex chemical structures (e.g. advanced oxidation or membrane filtration techniques) often require considerable amounts of energy, so it seems that these two goals are incompatible with each other.
However, we at Sensileau think it must be possible to solve this complex issue.
What can be done about it?
We have started to develop a decision support tool that will allow for the comparison of various monitoring and treatment scenarios in terms of costs, carbon footprint and water quality (expressed as ecotoxicity). This Water Impact Forecast calculator (in short: Wat-IF) helps wastewater utilities to assess the benefits and climate impact of various treatment optimisation strategies, so that a decision for the best possible option can be made.
How does it work?
Wat-IF calculates the benefits resulting from the implementation of sensor technologies in wastewater processes using a utility’s own characteristics, as shown in the picture above. In the first version of this calculation tool, users provide the volume of wastewater of their utility (in terms of cubic metres per day or as per-capita equivalents) and, if available, information on influent nutrient and BOD levels. If these figures are not available, general default values can be used. Next, four different scenarios are compared:
- current situation, no changes
- current situation + active sludge treatment optimisation using oxygen, nitrate and ammonia sensors
- current situation + additional (4th) treatment step to remove organic micropollutants using powdered active carbon
- current situation + active sludge treatment optimisation using oxygen, nitrate and ammonia sensors + additional (4th) treatment step to remove organic micropollutants using powdered active carbon
Benefits are expressed as:
- improved water quality
- reduction in carbon footprint
- reduced ecotoxicity
- reduction in energy-consumption or chemicals dosing
These indicators allow the user to make a thorough assessment of the impact of various activities, thereby taking into account not only improved water quality and cost savings, but also climate impact. The outcomes can be used when preparing a business case for optimisation processes.