In order to be ready for the future, the Integrated Wastewater Purification Installation (IAZI) has to measure and analyze substances in the wastewater even more thoroughly. In recent times, mussels have been helping to do this. It’s a proven method that, thanks to technology developed in house and a fruitful collaboration, has now also been made suitable for wastewater – a first in the Netherlands!
Mussels react to even very slight deviations
Drinking water companies, including WML (the Limburg Water Supply Company), have already been using Mosselmonitor® for decades. The technology is simple, but incredibly effective and reliable. “Mussels react directly to deviations in the quality of the water by closing their shells,” explains Compliance Officer and Lab Expert Ger Notermans. “Mosselmonitor® uses a sensor to measure the distance between the mussel’s shell edges from minute to minute. As soon as seven of the eight mussels have been closed for a certain time, an alarm is sounded in the measuring room. The measurements take place in ‘real time’, so we know about it as soon as it happens. This allows us to react at an early stage in the process. What’s great is that the mussels react before the water quality actually drops down into the danger zone.”
The right choices thanks to thorough research
As early as summer 2016, the IAZI, in collaboration with the Centre of Expertise Water Technology (CEW) and the research laboratory WLN launched a research project to investigate whether this technology for monitoring drinking water quality could also be applied to purified industrial wastewater (effluent). “Crayfish were setting off false alarms too often, so we ultimately settled on mussels,” Notermans explains. Over time, the mussels acclimatize to the effluent, potentially slowing their reaction speed. “Which is why the mussels are switched out every six to eight weeks,” says Notermans. “We cultivate the freshwater mussels that we use for this ourselves.”
Developing a unique cooling system
For them to survive, the effluent from IAZI that flows over the mussels must have a certain oxygen content and must remain cooler than 24˚C. “Our wastewater is warmer in the summer, meaning it has to be cooled,” says Ron van Laarhoven (Senior Analytics Engineer Sitech). “We have developed a unique cooling system, which we commissioned SPIE to manufacture.”