Optimization of the design and operation of sewage treatment systems by activated sludge for future water resource recovery facilities

Abstract

This research aims to produce elements for the evaluation of the feasibility of adding new technologies to a sanitary sewage treatment plant through the activated sludge process. The study will be developed on a full scale at the Itatinga ETE, located in the Municipality of São Sebastião in the State of São Paulo. In subproject 1, biological nitrogen removal via simultaneous nitrification and denitrification will be studied, controlling the sludge age and the air supply system using dissolved oxygen (DO), ammonia nitrogen (N-NH4+) and nitrate sensors. (N-NO3-), and oxide-reduction potential installed in the aeration tanks. The process control will include determinations of rapidly biodegradable COD, nitrogen, volatile suspended solids (VSS), molecular biology for groups of nitrating, nitrating and denitrifying bacteria and phosphorus accumulators, among other variables. This subproject is expected to contribute to the development of a differentiated form of operational control that leads to energy savings for aeration and that results in the important benefit of removing nitrogen from the sanitary sewage. Subproject 2 consists of the biological removal of side-flow phosphorus added to simultaneous nitrification and denitrification (NDSRP). This subproject is expected to evaluate the alternation conditions necessary for the removal of nitrogen and phosphorus and the main operational conditions for the possibility of nitrification, denitrification and removal of phosphorus in a single biological system. This alternative has shown promise in studies in Europe to face the usual challenges of conventional phosphorus removal processes. Subproject 3 will address the sludge treatment line of the same WWTP, seeking to determine the best conditions for chemically assisted gravitational densification of the excess activated sludge. Tests for the application of polymers will be carried out, having as reference the content of solids to be obtained in the dewatered sludge in centrifugal decanters. These sludge from the centrifuges will be applied in greenhouses, whose experimental design was defined to determine the best operational conditions for obtaining a sludge with a substantially higher solids content. Thus, the final volume to be transported and disposed is smaller, reducing operating costs. In addition, the fact that this additional treatment will result in class A sludge according to CONAMA Resolution 375/2006 will be investigated, making it suitable for agronomic use. (AU)