Mike Weeks

Arthropod Ecophysiology Group

Climate change, arthropod overwintering and pest outbreaks

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Insect infestations in water treatment processes

Mike Weeks

I graduated from Cardiff University in 2002 with a degree in Zoology, having taken several modules involving invertebrate biology and pest management, which fuelled my interest in these areas. My final year research project investigated the possibility of detecting slug proteins in starling faeces using monoclonal antibodies.

My PhD is on the control of invertebrate infestations in carbon filters used in the treatment of potable water.

Current research

Aquatic invertebrates can infest various stages of the modern surface water treatment process. One stage that is particularly suitable for the establishment of large populations of invertebrates is the granular activated carbon (GAC) stage. In water treatment the GAC is usually immediately before the final treatment stage, which is disinfection with chlorine, and so any invertebrates that are resistant to the chlorine dose can potentially pass into distribution.

Paratanytarsus grimmii

Previous aesthetic problems have been caused by GAC filters that were heavily infested with chironomid midges, such as Paratanytarsus grimmii, which are resistant to high doses of chlorine. As pesticides cannot be added to the water while it is being treated and because methods of controlling invertebrates within mains are laborious, costly and wasteful, it was necessary to develop novel methods for controlling pests present in GAC. Anaerobic treatment, which involves stopping the flow of water through the filters to allow microorganisms to use up the available oxygen so that the midges suffocate, was developed to solve the midge problem. However the current anaerobic treatment programme does not appear to work on two other organisms that are known to be capable of infesting GAC and have been found to be resistant to doses of chlorine greater than that used in water treatment, the prosobranch snail Potamopyrgus jenkinsi and the water louse Asellus aquaticus. The aim of this project is to develop new control methods or modify existing control methods, such as anaerobic treatment or backwashing, to target these organisms.

Asellus aquaticus

The current work involves continuous sampling of the GAC filters to track the population densities of the snails and measurements of the sizes of all snails found to build a picture of the change in the snail population’s age structure throughout the year. This information will be useful for deciding the most suitable time of year for applying a particular control measure to control these snails.

Potamopyrgus jenkinsi

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