Determining the influence of wastewater hydrodynamics in bioreactors on the process of mass transfer

Abstract

The anaerobic method of treating wastewater from biotechnological and economic industries has great prospects for the development of a renewable energy source. Biogas released during the operation of the bioreactor can be used as an energy source for the generation of electricity and heat. This paper reports the design of an apparatus for wastewater treatment with microorganisms immobilized on inert carriers. The original substrate supplied to the bioreactor is heated by thermostating. The temperature of the original substrate is controlled using an electronic temperature meter. Temperature in the bioreactor is also controlled; maintaining the methane growth of microorganisms in the range of 35–37 °C is enabled by a temperature sensor. The gas that is released during the experiment is collected in a gas collector, where its volume is measured, owing to the torn cylinder connected to the gas collector. Additionally, a temperature sensor is installed in the gas collector to determine the mass of the biogas collected in the experiments. Owing to the high-speed camera connected to a computer, the process of formation and separation of gas bubbles from the biofilm is recorded, as well as the thickness of the biofilm on flat carriers. To determine the effect of hydrodynamics under a laminar mode of wastewater supply, in the bioreactor channels, a peristatic dosing pump is used in the experimental installation. In the experiments, the thickness of the biofilm changed in the range from 10-3 m  to 4.8·10-3 m and, because of this, the width of the channel along which the substrate flow moved changed accordingly. Experimentally, it was established that the volume of biogas released increases with an increase in the rate of wastewater in the bioreactor channels. Based on the experimental results, a criterion equation was built using which can determine the coefficient of mass yield