Máté Váczy-Földi PhD StudentEmail: m.vaczy-foldi@qmul.ac.ukProfileProfileProject Title: Predator-prey interaction in activated sludge reactors Summary: Activated sludge (AS) systems for wastewater treatment is the world’s most widely used biotechnological process. There is a strong interest in improving their environmental sustainability due to their high energy consumption. The AS systems include hyper-diverse communities of bacteria and their protozoan predators. While there is research showing that the efficiency of AS systems critically depends on the diversity and function of bacteria, we know little about the interaction between protozoa and bacteria, and its effect on efficiency. It was recently shown that protozoan predation has strong effects on bacterial diversity and treatment quality in AS reactors. My PhD will build on this initial study and aim to establish the critical interaction links between bacteria and protozoa in AS systems and examine how the dynamics of these communities affect treatment efficiency. We will collect samples from AS reactors to characterise and quantify the protozoa and bacteria to uncover the predator-prey interactions. We will use ecological network approaches to determine the effect of predation on treatment efficiency and define operational conditions that maximise it. We will test these newly defined conditions using lab-scale reactors with a focus on nitrogen removal. This study will inform the protozoan predation-bacteria relationship in AS systems and provide a tool for managing AS system efficiency at microorganismal level. Supervisor: Dr Ozge Eyice Research