Abstract
The aim of this study was to develop a gravity feed column set-up and to set the flow parameters based on experimentally measured flow rates and pressure drops. Prior to the present study the authors used a column set-up in which acid mine drainage was pumped through pervious concrete filled columns. However, power outages due to load shedding often disrupted the experiments. As such, the gravity feed set-up was designed to overcome the need to rely on electrical power supply. The study describes the design set-up of four gravity columns. The design requirements comprised determination of appropriate column sizes, pressure heads and hydraulic gradients required to produce a low flow rate of about 1 mL/min at outlets of the columns filled with pervious concrete media. Of special interest is the hydraulic gradient being responsible for continuous flow in each column. Following completion of the design set-up, continuous flow rates of 0.60 to 0.80 mL/min were attained with a Reynolds number of about 4.0 in the columns filled with pervious concrete. Further research is in progress involving employment of the gravity-feed system for acid mine drainage treatment investigations.