Fungal Problems in Wastewater Treatment Works

Fungi in UK Treatment Works

Over the past decade, Aqua Enviro has carried out microscopic analysis on thousands of biomass samples from both municipal wastewater treatment works and industrial effluent treatment plants.  This information is used to monitor, troubleshoot and optimise the process.

The samples have shown a range of operating problems such as the filamentous bulking, foaming, dispersed growth and toxicity.  However, in the past 12 months we’ve been commissioned to specifically investigate problems of fungal growth in a range of treatment systems.  These have been in activated sludge plants (ASP’s) and biological aerated flooded filter plants (BAFF) treating sewage and in biofilters treating distillery and brewery effluent.

Fungus is not usually observed in significant quantities in aerobic treatment systems but given the right set of growth conditions, fungi can proliferate out of control with detrimental consequences on treatment and effluent quality.

Understanding Fungal Growth

Fungi are a Kingdom of eukaryotic microorganism which includes the yeasts and moulds.  They are typically filamentous organisms that reproduce by sporulation and the spores are produced on specialised structures or in fruiting bodies.  Like bacteria, Fungi decompose organic matter and have significant roles in nutrient cycles.  Most yeast and fungal species thrive in warm, sugary, acidic and aerobic conditions; however they can grow under a wide range of environmental conditions.

Their growth follows the general growth curve with a lag phase, exponential growth phase, deceleration phase, stationary phase and a autolysis (death) phase.  During exponential growth one cell produces two cells, two cells produce 4 cells etc.  This will continue until either some environmental factor becomes limiting (such as carbon or nitrogen source) or a metabolic by product accumulates to inhibitory levels (such as pH or secondary metabolite).   In order to control fungal growth it is essential to understand what factors (i.e. ph, temperature, substrate, oxygen) are allowing it to out-compete the normal bacterial species.

Tackling the Problem

Our normal approach to tackling these issues is as follows:


  1. Identify the species of fungimicroscopic analysis is carried out.  Samples may need culturing on agar plates to encourage the fungi to produce their fruiting bodies or spores to allow identification
  2. Tackle Growth Conditions – Plant process data is reviewed and changes are recommended to remove the growth conditions that favour the fungal species. On site process investigation is carried out if required
  3. Pilot Plant Testing – Prior to implementing the process changes, pilot plant tests may be required to check the effectiveness of the control measures and to ensure this can be carried out whilst maintaining consent compliance

This methodical approach allows the necessary changes to be made to provide rapid process improvements without risking further deterioration in effluent quality.  In conclusion:

 Fungal Growth Elimintaion = Improved Effluent Quality + Reduced Operating Costs

For further information of our process optimisation and troubleshooting services please contact us at


Posted 16th June 2010
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