Ecology, Environment and Conservation Paper

BIOGAS SPARGING (BUBBLING) AS A SCOURING TOOL FOR FOULING MITIGATION IN VACUUM-DRIVEN SUBMERGED ANAEROBIC MEMBRANE BIOREACTOR (SANMBRS): EVALUATION OF ITS EFFECT ON BIOGAS ESCAPE FROM BIOREACTOR

Mohammad Mehdi Amin, Yaghoub Hajizadeh, Ali Ghanbari, Bijan Bina, Afshin Ebrahimi and Reza Ghanbari

Abstract

The objective of this study was to investigate the possibility of biogas escape from Submerged Vacuum driven Anaerobic Hollow Fiber Membrane Bioreactor (SAnMBR) while biogas sparging was applied for membrane fouling mitigation. SAnMBR was made of polypropylenes hollow fiber membranes with the module area of 0.1 m2 and has the working volume of 6.75 to 7 L. Reactor was operated with water in both modes (biogas sparging and without biogas sparging) in mesophilic temperature (35±1 °C), and in two conditions (continuous vacuum and step method). Finally effects of biogas sparging and gas flow rates on the TMPs were also analyzed on real mixed liquor (after 120 day of operation), which three biogas sparging rates were used for this SAnMBR; 1.5 L/min, 3.5 L/min and 6.5 L/min. Average flux, volume of permeates and TMP by applying biogas spargingin all the tests were lower than those without applying biogas, which shows suction of biogas. For examples cumulative permeate by applying biogas in step method was reduced from 2410 cc to 1981cc (17.8 %). Final TMP in real mixed liquor was -0.638 bars for biogas sparging rate of 1.5 L/min, and were -0.48 bars and -0.418 bars for the biogas sparging rates of 3.5 L/min and 6.5 L/min, respectively. There is a possibility for biogas escapes as the mixture of biogas and permeate from submerged hollow fiber AnMBRs under vacuum pressure while biogas sparging was applied as a scouring tool.