The effects of biodiscs rotation in a new Rotating Bed Biofilm Reactor for the removal of Hydrogen Sulphide

This paper focuses on the effects of biodiscs rotation in terms of biomass detachment in a prototype of a new Rotating Bed Biofilm Reactor (RBBR). The prototype was implemented as pretreatment before chemical scrubbers in the actual gas treatment train of a tannery wastewater treatment plant (WWTP). The RBBR treats an average of 8000 m3 h-1 of gaseous effluent (20% of the total gaseous flow rate treated in the plant) with variable hydrogen sulphide concentrations (10-400 mg S m-3) in the influent. The prototype was able to remove up to 20 Kg d-1 of H2S, and about 80% of the total load, allowing to save a corresponding dosing of chemicals (NaOH) of about 600 Kg d-1. A characterization of the biomass in the biodiscs was performed through bio-molecular analysis. Among the different operating conditions tested, the biodiscs rotation frequency was demonstrated to be a fundamental parameter for biofilm thickness, pH in the solution and solids retention time control and, thus, to optimise hydrogen sulphide removal as well as mitigation of pressure head loss increase.