Comparison of EDCs removal in full and pilot scale membrane bioreactor plants: Effect of flux rate on EDCs removal in short SRT.

Currently, it is estimated that over 1 billion people are short of adequate portable water and this is expected to increase to 2.5 billion in the year 2025. Membrane Bioreactors (MBR) are now accepted as important tools to extend the availability of water by facilitating the reuse of wastewaters. Sludge Retention Time (SRT) and liquid flux rate are the two most important parameters for controlling the MBR process. In this study, the removal of selected endocrine disrupter compounds (EDCs), diltiazem, progesterone, estrone (E1), carbamazepine (Cbz) and acetaminophen (Acet), by one full scale (VRM) and one pilot scale (clear-box) MBR plants was investigated. During the study, sludge age was set at 10 days and the sludge concentration was fixed at about 5.0 g/L. The transmembrane pressure (TMP) got higher with either increasing flux or sludge concentration in the membrane chamber. Therefore, changing the flux from 13 to 30 L/m2-h in both plants caused enhancement in TMP from -25 to -300 mbar in the clear-box and from -160 to over -350 in the full scale MBRs. It was understood that flux had very little effect on the removal of EDCs at very low concentrations. Moreover, diltiazem was completely removed in the full scale whereas no removal was achieved in the pilot scale. Estrone and progesterone were completely removed by biodegradation in both plants. Acetaminophen was completely removed in the full scale plant whereas over 95% removal was achieved in the pilot scale MBR.

Removal of endocrine disrupting compounds in a lab-scale anaerobic/aerobic sequencing batch reactor unit.

The fate and removal of six selected endocrine disrupting compounds in a lab-scale anaerobic/aerobic (A/O) sequencing batch reactor (SBR), operating at 5 days, solids retention time (SRT) were investigated. A carbamazepine (CBZ), acetaminophen (ATP), diltiazem (DTZ), butyl benzyl phthalate (BBP), estrone and progesterone mix was spiked as model endocrine disrupting compounds (EDC) into domestic wastewater obtained from a nearby sewage treatment plant. The influent, effluent and sludge samples from the SBR unit were analysed by using an LC/MS/MS instrument equipped with electrospray ionization. More than 80% removal was observed for all the EDCs tested. It was found that biodegradation is the most important mechanism for BBP, ATP and progesterone. Biodegradation constants were calculated according to the simplified Monod model for these compounds. The DTZ seemed to have lower rate of biodegradation. The CBZ appeared totally resistant to biodegradation. However, it presented a high rate of sorption onto the sludge and was thereby treated. This contradicts with the literature studies.