Applications of the results of the laboratory kinetic batch experiments and mathematical modelling to improve the operation of WWTP with nutrient removal
Prof. Ing. Jiří Wanner, DrSc.
The theoretical part deals with basic biological principles of processes occurring in wastewater treatment plants for biological nutrient removal – carbon, nitrogen and phosphorus removal. There is a short summary of basic mathematical models describing activated sludge process in the thesis. The background research of most typical software packages used for mathematical modelling of biochemical processes was performed.
The aim of the work is to create mathematical models of observed wastewater treatment plants on the basis of laboratory analysis of activated sludge and wastewater and by using the data, which were obtained from plant operators. Each mathematical model was verified using dynamic simulations. Another aim of the work was to optimize the methodology for more detailed description of activated sludge biocenosis and to compare the commonly used equations for describing the activated sludge behaviour in secondary settling tanks.
The experimental part deals with the methodology of parameter estimation of activated sludge and wastewater using either laboratory analysis of activated sludge processes or mathematical modelling. There is also a short description of both evaluated wastewater treatment plants – WWTP Havlíčkův Brod – Perknov a WWTP Domažlice together with their schemes in the thesis. Another part of this chapter describes the performed dynamic simulations.
The main conclusions are:
- Main kinetic and stoichiometric constants of activated sludge and wastewater were evaluated. Some discrepancies and disturbances during parameter estimation were observed. Certain optimalizations were suggested in the determinations by using laboratory measurement and/or mathematical modelling.
- The results of batch tests served for the creation of mathematical model. Calibration of the steady – state was then verified by using dynamic simulations.
- WWTP Havlíčkův Brod was retrofitted and the reconstruction was controlled using mathematical modelling and laboratory analysis.
- Respirometric measurement of nitrification rate was studied by using different media. Any of media used (tap and distilled water, effluent from treatment plant and mineral medium) didn’t affect nitrification rate markedly.
- The hydraulic stability of both wastewater treatment plants was investigated using model influent patterns (adopted for our plants) simulating different weather conditions (dry, rainy and storm weather). There were no evident unexpired consequences of these applications in the behaviour of activated sludge plant.
- The most commonly known equations characterizing activated sludge behaviour in secondary settling tanks were compared. Takács double – exponential equation was evaluated as the best fitting using statistical analysis for equation comparison. The worse results were observed for the equation suggested by Cho.