project

Food and temperature

Water lice and Aeromonas

Expert(s):
Nikki van Bel PhD, Kimberly Learbuch MSc, Anthony Verschoor PhD MSc

  • Start date
    01 Jan 2018
  • End date
    01 Mar 2019
  • Principal
    Bedrijfstakonderzoek
  • collaborating partners
    Evides, Oasen, De Watergroep, WMD (via WLN)

Drinking water contains a large variety of nutrients which (harmless) bacteria can use to grow. These bacteria could in turn serve as a food source for water lice, for instance. We still do not know much about the lifecycle and the food source of water lice in the drinking water system. The presence of water lice might possibly lead to complaints about water quality, so that efforts are being made to prevent the survival of the water louse in the drinking water distribution system.

Because of climate change it is expected that the temperature of drinking water will increase. Higher temperatures could possibly lead to the growth of the Aeromonas bacterium in the distribution system. Aeromonas is not a threat to public health, but these exceedances are not desirable and the water utilities would gladly prevent them. Over the last few years it has become clear that Aeromonas growth in the drinking water distribution system is connected with several factors, the most important of which being the water temperature and the quantity and type of nutrients present in the water.

Impact of higher temperatures on Aeromonas growth and the effect of sediment on the survival of water lice in water

The impact of higher temperatures on the growth of Aeromonas is still not known. To prepare for a future with higher drinking water temperatures, this research will therefore study the impact increased temperatures will have on Aeromonas growth.

In order to formulate (precautionary) measures against water lice, we need to know more about their lifecycle. Laboratory tests will be done to see whether they can survive in water and sediment taken from various sites, and to discover which substances in the water and/or sediment can favour their survival and which not.

Breeding water lice and testing effect of different water types and sediment

Tests will be conducted, using flasks with water from different drinking water distribution areas, to determine how well Aeromonas grows at temperatures from 5°C to 30°C. This will be done through an Aeromonas bacterial count in the water every day or every other day. This will clearly show whether Aeromonas grows more at different temperatures, and whether it depends on the water used in the test.

Voedingsbodem met bacteriekolonies van Aeromonas

Growth medium with Aeromonas bacterial colonies

A literature study will be done to collect knowledge on the lifecycle and food source of water lice. On this basis, a breeding system for water lice will be set up in the laboratory. Using these water lice, experiments will be done employing water and sediment from different drinking water distribution areas to determine whether water lice survive better on different types of sediment and water, and which substance or substances account for this.

Control measures for water lice and Aeromonas growth

Once we know how the sediment affects the survival of water lice in the drinking water system, we could take targeted measures to prevent the survival of water lice in the system.

Moreover, insight into the impact of the temperature and the water type on Aeromonas growth in drinking water will allow us to take possible precautionary measures to prevent the effects of climate change on the microbial quality of drinking water.

Waterpissebed op een esdoornblad waarop ze gekweekt worden in het laboratorium

Water louse on a maple leaf, upon which it is being bred in a laboratory