Pneumatically Agitated High-Density Polyethylene Mesh–Based Bioreactor Developed for Wastewater Treatment

Abstract

The use of woven and nonwoven fibers and meshes in membrane bioreactors (MBRs) has enhanced the study of the development of dynamic membranes, which aid to a large extent in overcoming the traditional problem of fouling associated with MBRs. The present study reports the mixing characteristics and the gas–liquid mass transfer characteristics of a pneumatically agitated high-density polyethylene (HDPE) mesh–based bioreactor developed for wastewater treatment. The HDPE mesh is not a material traditionally used in MBRs. The pore size of the mesh used in the study, 2 mm, has not been reported on for the development of self-forming dynamic membranes. The reactor was configured in a novel way by integrating the mesh into the reactor. Aeration was provided at the bottom for meeting the oxygen requirements and obtaining maximum mixing. The mixing characteristics and the mass transfer coefficients were determined at various superficial air velocities. The reactor exhibited excellent mixing characteristics at a superficial air velocity of 3.79 cm/min and possessed the optimum gas–liquid mass transfer coefficient. The reactor was modeled to tanks-in-series and extended tanks-in-series models. The reactor was then used for nitrification of ammonia wastewater. The treatment efficiency was recorded to be around 98%.