Study of the adaptation of an MBR system to double the wastewater purification capacity of the barranco seco ii treatment plant

Abstract

This paper considers the problem of an urban wastewater treatment plant which has no land available for expansion but whose capacity needs to be increased from its current 52,000 m3 /d. To increase capacity, adaptation to the purification process was proposed of a membrane bioreactor (MBR) system with ultrafiltration (UF) membranes submerged in the biological reactor. The experimental study gave biomass concentrations of between 15,000 and 20,000 mg/L. Mass load was chosen as operating and control parameter of the MBR system, which ranged between 0.02 and 0.16 (kg BOD5 /d/kg of mixed liquor volatile suspended solids) with an optimum value between 0.12 and 0.13. This study shows that MBR systems are able to process wastewaters at biomass concentration levels as claimed by the manufacturer, operating in conditions similar to those of prolonged-aeration-type activated sludge systems, with a high quality water product. The feasibility is shown of doubling plant capacity with the MBR system as it is possible to work with biomass concentrations between 5,000 and 6,000 mg/L compared with the 2,500–3,000 mg/L of the biological reactor without the proposed MBR system.