Prototyping a spinning adsorber submerged filter for continuous removal of wastewater contaminants

Abstract

Adsorption process is widely used for the removal of wastewater contaminants. Classic adsorption units are fixed beds and membrane filtration systems. In this work a novel configuration of a bench scale spinning adsorber submerged filter is proposed. Different prototypes of cylindric, truncated cone or prismatic spinning adsorbers were studied using activated carbon of different particle sizes GAC (1.5 mm, Granulated), μGAC (0.475 mm, microGranulated), and cPAC (0.237 mm, coarse Powder) as adsorbent, and azorubine as model adsorbate. High maximum azorubine adsorptions per unit mass of adsorbent of 214, 225 and 275 mg/g for GAC, μGAC and cPAC, respectively, were obtained using the Langmuir isotherm adsorption model. Batch adsorption followed pseudo-second order kinetics, and adsorbate uptake rate increased with decreasing adsorbent particle size. Best adsorption unit was a tank equipped with a spinning rectangular prism adsorber prototype all made of stainless-steel woven wire filter of 180 mesh size. Running at 600 rpm and filled with a high cPAC concentration (25 g/L), adsorber can remove azorubine at similar rates that the use of free moving cPAC. Adsorber unit can run in continuous mode and works even better as a novel spinning submerged filter where filtered flow exits from a central pipe axis. This integrated adsorption-submerged filtration operation mode offer the possibility of adding a high initial dose or a continuous dosing of adsorbent in the tank, increasing the adsorbent concentration of the unit. This system can also offer novel opportunities for wastewater contaminants removal using different adsorbent materials located separately.