mixing characteristic improvement of a wastewater treatment plant anerobic digester using cfd analysis

In this paper the influence of the operational and geometrical parameters on the mixing and flow uniformity within an anaerobic digester is investigated. anaerobic digestion is classified as single or multiphase flow reactor to produce biogas from processed organic waste. within the digesters, mass transfer is a key component to obtain an optimal process which is highly dependent on uniformity and turbulence of the flow. two quantitative mixing criteria namely uniformity index and turbulence intensity are assessed to investigate the possibility of improving mixing characteristics of an operating digester. the effect of inlet velocity, draft tube flow presence, draft tube velocity magnitude and direction and inlet tube position have been investigated and compared to a validated base case. according to the finding both inlet velocity and inlet pipe position can noticeably affect the operation of the digester and proper tuning of the inlet velocity and also optimized pipe position can enhance the uniformity of the flow while inducing high turbulence within the digester. furthermore, by adjusting the inlet pipe position, it is possible to improve the uniformity index and turbulence intensity by 44% and 40% respectively.