Design of optimal mixing of large-scale digesters

The aim of this diploma thesis is an optimal method of mixing of the digester with consideration to the uniform mixing of the whole volume, ensuring the quality process conditions for the anaerobic fermentation and the maximum yield and quality of the produced biogas. First chapters describe the basic design parameters, general calculations and the principles for design of individual types of mixers, supplemented by practical examples of mixing large capacity tanks. The work introduces the problem of sludge formation at the sewage treatment plant with an emphasis on sludge treatment and the processes which take place inside the fermenter. Various types of design of anaerobic sludge stabilization digester were introduced. Also ways of their operation, which are necessary for the quality of the fermentation, were presented. In the next chapters, various ways of mixing high-capacity digester tanks and experience from the operation of selected treatment plants were described. According to the theoretical research part of this thesis, several types of mixing equipment was designed for the experimental digestion tank built at the Institute of Process Engineering which is used for research work with mixers. Measurement of the selected pneumatic mixing method was performed on the experimental tank and the findings were evaluated