Computer aided flow investigation of liquid agricultural wastes

Abstract

Liquid agricultural wastes serve as important fertilizers in modern agriculture but pose environmental and health risks due to high nitrogen compound content. To prevent soil and groundwater contamination, ammonia separation is required before waste application on fields. Conventional separation by stripping is difficult because of column clogging by solid waste loads. This work investigates, both experimentally and numerically, the flow behaviour of liquid agricultural waste to support the development of innovative separators based on inclined plates. The measurements were carried out in a newly developed experimental setup consisting of a liquid distributor over a plate with variable inclination angles. The influence of volumetric flow rate and inclination angles on the flow topology and liquid detachment from the edge of the plate was studied. While the impact of the flow rate was significant, no influence of the plate inclination angle could be observed. A CFD model was developed to support experimental work. Its validation with experimental data was successful, yet with some systematic deviation due to the model simplifications. The developed experimental setup and CFD model offer optimization potential for separation column internals designed for liquid agricultural wastes, with experiments providing higher accuracy and simulations offering flexibility.