PROTOFILWW: insights in the ecology of activated-sludge systems

Abstract

Treatment of wastewater by activated sludge processes represent s a component of the largest biotechnology in the world. Yet activated sludge system s correspond to microbial ecosystems complex enough to discourage most microbial ecologis ts. The importance and the role of the protozoa and little metazoa community in the pu rification process of activated- sludge plants are well established. Even though, very few studi es have established reliable relationships between the microfauna and the operational condit ions or physical-chemical parameters [1,2]. Another component that deserves particular in terest by managers and technicians is the excessive growth of filamentous bacteria, ca using the known phenomena of bulking and foaming. The present investigation being carried on aims at the identifi cation of the microfauna (protozoa plus small metazoa) and filamentous bacteria on a wid e set of activated-sludge wastewater treatment plants (WWTP), working on different region s of Portugal, under different operational and physical-chemical conditions in order to allow for the establishment of consistent relationships between the former and the latter. Each of the WWTP will be studied several times allowing for the identification of the causes and for the answer of questions such as Why do different filame ntous or microfauna species appear in similar conditions? Do the WWTP tend to maintain the same populations or do these changes often? Are the changes cyclic or occasional? One of the most important objectives of the present proposal is the implementation of molecular techniques to allow for the confirmation of the ident ifications of the filamentous bacteria: the identification by morphological features can be p roblematic and erroneous.