Effect of the mixed liquor suspended solid on permeate in a membrane bioreactor system applied for the treatment of sewage mixed with wastewater of the milk from the dairy industry

Abstract

The performance of a bench-scale submerged membrane bioreactor (MBR) equipped with ultrafiltration membranes (ZENON) was investigated at different mixed liquor suspended solid (MLSS) concentrations (3069, 4314 and 6204 mg/L). The pilot plant was located in the wastewater treatment plant of the city of Granada (Puente de los Vados, Granada, Spain), which receives the wastewater of the milk from the dairy industry of Granada. The results showed the capacity of the MBR systems to remove organic material (COD and BOD₅), suspended solids, turbidity, color and microbial indicators such as E. coli and coliphages. Therefore, the results suggest that the transmembrane pressure (TMP) was influence by the MLSS concentration assayed. However, an increase in the MLSS concentration increases the nitrification processes and consequently the amount of NO₃ ⁻ in permeate.

Keywords:

• Membrane bioreactor
• sewage
• treatment
• re-uses
• wastewater treatment
• ultrafiltration
• activated sludge
• MLSS

Acknowledgment

This study was supported by a grant from the Ministry of Science and Technology, Spain (reference REN2002-04293-C02). J.M. Poyatos and M. Molina-Muñoz were supported by a PhD scholarship from the Ministry of Education and Science (PFPI, MEC, Spain).