Elena Ferrer, bioindication and bio control tech at the Northeast Tenerife Wastewater Treatment Plant.
The ecosystem created by wastewater and the microorganisms in it, is called activated sludge or mixed liquor. It consists mainly of bacteria, protozoa, metazoans, and fungi. All these beings work together dynamically, creating a true microsociety.
Bioindication encompasses all the information we can extract from the presence or absence of these microorganisms in our mixed liquor. Many of them are closely related to specific environmental variables, such as the physicochemical characteristics of the influent water (BOD, %soluble COD…), the physicochemical characteristics of our mixed liquor (temperature, %volatiles…), and operational characteristics (organic load, sludge age…).
It is a highly effective tool to understand the state of our process and the conditions of our sludge in real-time. Additionally, it helps us prevent and predict potential concerns, such as filamentous bulking or foaming.
We gather information through macroscopy and microscopy. Macroscopy is based on direct observation of both the biological reactors and our sludge in the V30 analysis; we look for the presence of foams, odors, solid loss, waxy layer formation, settling speed, clarified water turbidity, and more.
Microscopy allows to closely watch a fascinating microcosm.
With just a drop of mixed liquor, we can obtain a lot of information about the operation of our plant. Among other things, we will find out if we are conducting proper nitrification, if the organic matter in the wastewater is being removed, if we are injecting enough oxygen, if the sludge age is high, or if we have an overgrowth of filamentous bacteria. All of this is thanks to our bioindicator microorganisms.
Each treatment plant is unique and has its own identity because it is influenced by its particular characteristics, the habits of the population it caters to, and the type of process used. All these factors provide specific conditions for the development of different populations of microorganisms.
We are currently preparing a meeting between various lab techs and plant managers at Sacyr Water to share this knowledge and potentially bring bioindication techniques to many more facilities.
