Interview with Bruno Burkhalter, process engineer at Wasserverbund Region Bern AG
The Wasserverbund Region Bern AG (WVRB) delivers drinking water to a quarter million people. As Process Engineer, Bruno Burkhalter is responsible for ensuring its quality. From raw water extraction to transport and eventually disinfection, he keeps an eye on all steps to ensure that only the purest water reaches the Bernese network.
We wanted to learn how he managed this task and met him for an interview at the Belpau pumping station – one of three groundwater stations where WVRB uses BactoSense to monitor the microbiology of the drinking water reliably at all times.
Dear Mr. Burkhalter, how does it feel to be responsible for the drinking water and thus the health of 250’000 people?
It is indeed a big responsibility. We have the resources and do not shy away from the costs necessary to ensure high quality. We are constantly striving to keep the water safe.
You operate a complex system with water catchments, reservoirs and an extensive network of transport pipelines. How do you ensure that everything works smoothly and safely?
We have many process controls that make our daily life easier. Our two main pumping stations (Belpau and Schönau) operate according to an energy plan. The water to fill the reservoirs is ordered the day before and distributed to the pumping stations.
For the peripheral reservoirs and pumping stations, we work with a target curve that defines the number of pumps needed to fill the reservoirs. We also have various alarms for flow rate and quality data. There is always at least one on-call person who reacts according to the priority of the alarm. Response times range from "immediately" to "6-10 a.m. the next day" to "no immediate response required".
Where do you think the greatest health risks lie?
Bacterial contamination would undoubtedly have the greatest impact on our water supply system. Other significant dangers are oil and chemical spills due to the proximity to the river. In Kiesen, there is a risk of substances getting into the water because the Aare River, feeding the groundwater, is crossed by a railway and a motorway, where hazardous substances are transported.
Where do you see the biggest challenges in your area of responsibility?
It is to interpret bad results correctly and make the right decisions for consumers' health. For example, a measure must be initiated if a limit value of the Drinking Water Ordinance (Trinkwasserverordnung - TBDV) is exceeded at one point. This could mean that follow-up checks have to be carried out on other issues. Taking an overall view and acting fast and appropriately is essential.
Years ago, a manure accident in the protection zone affected the stream near the catchment area. By chance, a sample was taken at that time, in which E. coli was detected. The water was no longer used, and emergency chlorination was initiated. The following bacteriological sample analysed was good again.
What are your critical control points, and what is measured there?
In Bern, the critical control points, according to HACCP, only concern disinfection (detected amount of energy in UV or concentration in chlorine dosing). This is because a critical control point is a step where a possible risk can be reduced to an acceptable risk.
The most crucial other control points are protection zones, measuring points during withdrawal, reservoirs and laboratory analyses from the network. Various methods are used for this purpose:
Measuring panels with temperature, pH, conductivity, redox, turbidity, spectral absorption coefficient (SAC) and partly oxygen and TCC/HNAP (flow cytometry)
Laboratory analyses: catchment to reservoir and transport pipelines between communes. The local authorities themselves monitor the municipal networks.
WVRB has been using BactoSense for two years. Where is it installed, and how do you benefit from it?
BactoSense was first installed at the central pumping station, where water is mixed and treated. Due to the routing of the pipes and pump downtimes, there was a lot of bacterial growth. BactoSense was moved to the groundwater well to improve this measuring arrangement, providing considerable insights, mainly due to the floods last year. Generally, we found good stability in the well.
The results provided by BactoSense helped us to conclude that we are well-positioned with the SAC measurement for our groundwater wells. However, since the BactoSense measures much more sensitively, using it in the transport system makes sense. We still suspect considerable dangers and hope to detect minor deviations faster and better.
What do you expect from BactoSense in the future?
We have tried multi-probe measurements with the standard method, but they did not deliver the desired results. We hope that the direct measurement principle of the BactoSense will provide us with more information about the influence of contamination and better control.
For example, contamination in the transport network could be detected by BactoSense, and the effect is then observed in the secondary network. EWB takes weekly laboratory samples, plating and total cell count. Knowing how microbiological contamination affects the distribution network, we could also better determine the reaction.
From your experience, what are the advantages of online flow cytometry compared to the classical plating method?
The fast availability of the results and the online connection facilitate the immediate detection of dangers, meaning that measures can be taken more specifically. Compared to the past, we are more sensitive to microbiological contamination.
If the total cell count (TCC) value is high, we know there may be microbiological contamination that could not have been detected with the plating method. This helps us to decide how quickly to react in the event of an alarm from the chlorine dioxide system.
“The direct availability of the microbiological measurement has a direct influence on how to react. This is because you get a result immediately and not three days later.”
Where would you like to have better control of water quality?
The current approach focuses on control at the catchment and distribution points. Part of the transportation network is still relatively unknown, and it would be nice if this could be monitored better. Measurement at the endpoint, the tap, would be desirable – if homeowners also had a self-monitoring facility. A few years ago, a property manager called me because her maintenance staff had legionellosis, and she thought the water we provided might have been bad. However, there was a problem with the plumbing of the house.
How will water quality management change in the next 20 years?
We will be confronted with more and more micropollutants. Not because they are new but because we can detect them more and more accurately. We are already in the nanoscale range, depending on the method used. This will undoubtedly change water management and may lead to groundwater treatment in several stages or to the development of a certain acceptance.
Key figures on the WVRB |
Water origin: around 99.5% groundwater and 0.5% spring water Production capacity: around 111,000 litres per minute Average daily production: 60-65'000 m³ Number of inhabitants supplied: approx. 250,000 |