| Title | Comparison of fine bubble scouring, backwash, and mass air load supply for dynamic membrane maintenance and steady operation in SFD MBR for wastewater treatment |
| Abstract | The self-forming dynamic membrane bioreactor (SFD MBR) is an evolution of the conventional ultrafiltration-based MBR where filtration occurs through a cake layer (dynamic membrane, DM) supported by a filtration net. The effluent quality levels that may be achieved through this technology are comparable to those of conventional MBR and suitable for effluent reuse, as shown in previous research. In addition, SFD MBR are more sustainable, both in terms of investment costs (filtration net materials are cheaper than UF membranes), and operation. Indeed, the typical operating pressure of these systems is below 100 mbar, thus compatible with gravity-driven operation. Nevertheless, as all membrane-based processes, also SFD MBR require periodic maintenance cleaning of the supports holding the filtering layers, in order to ensure high and constant effluent quality and steady operation. In this paper, different strategies for continuous or temporized cyclic DM maintenance aimed at limiting the frequency of on-site manual cleaning interventions are compared. In particular, five tests were performed at the bench scale adopting the same process conditions except for the type of DM maintenance strategy. Continuous fine-bubble air scouring of the membrane surface was compared with two intermittent cyclic procedures based on backwash with permeate (with and without simultaneous air scouring) and mass air load supply (with two cycles of different durations), respectively. The results have confirmed the overall high performance of this technology under all the tested conditions, with COD removal efficiencies always exceeding 86 %, effluent turbidity values normally well below 5 NTU (and often much lower), complete nitrification and partial nitrogen removal. Furthermore, the comparison among the different DM maintenance strategies has shown that the mass air load supply is the most efficient approach towards sustainable operation. In particular, shorter mass air load cycles provided the best performance in limiting the manual cleaning needs, which under this condition were as low as once every 3 weeks. The key finding of this study is the demonstration of cyclic air mass load as an effective preventive cleaning strategy allowing good performance of a bench-scale SFD MBR, strongly reducing the manual maintenance requirements. More experiments are required to confirm these results in larger scale installations. |
| Source | Journal of Water Process Engineering 53 |
| Keywords | Dynamic membraneWastewaterSFD MBRFiltration |
| Journal | Journal of Water Process Engineering |
| Editor | Elsevier, Oxford/England, |
| Year | 2023 |
| Type | Articolo in rivista |
| DOI | 10.1016/j.jwpe.2023.103846 |
| Authors | Salerno C.; Berardi G.; Casale B.; Pollice A. |
| Text | 482307 2023 10.1016/j.jwpe.2023.103846 Scopus 2 s2.0 85160280896 Dynamic membrane Wastewater SFD MBR Filtration Comparison of fine bubble scouring, backwash, and mass air load supply for dynamic membrane maintenance and steady operation in SFD MBR for wastewater treatment Salerno C.; Berardi G.; Casale B.; Pollice A. IRSA CNR, Viale F. De Blasio 5, Bari, 70132, IRSA CNR, Viale F. De Blasio 5, 70132 Bari, Italy, , Italy The self forming dynamic membrane bioreactor SFD MBR is an evolution of the conventional ultrafiltration based MBR where filtration occurs through a cake layer dynamic membrane, DM supported by a filtration net. The effluent quality levels that may be achieved through this technology are comparable to those of conventional MBR and suitable for effluent reuse, as shown in previous research. In addition, SFD MBR are more sustainable, both in terms of investment costs filtration net materials are cheaper than UF membranes , and operation. Indeed, the typical operating pressure of these systems is below 100 mbar, thus compatible with gravity driven operation. Nevertheless, as all membrane based processes, also SFD MBR require periodic maintenance cleaning of the supports holding the filtering layers, in order to ensure high and constant effluent quality and steady operation. In this paper, different strategies for continuous or temporized cyclic DM maintenance aimed at limiting the frequency of on site manual cleaning interventions are compared. In particular, five tests were performed at the bench scale adopting the same process conditions except for the type of DM maintenance strategy. Continuous fine bubble air scouring of the membrane surface was compared with two intermittent cyclic procedures based on backwash with permeate with and without simultaneous air scouring and mass air load supply with two cycles of different durations , respectively. The results have confirmed the overall high performance of this technology under all the tested conditions, with COD removal efficiencies always exceeding 86 %, effluent turbidity values normally well below 5 NTU and often much lower , complete nitrification and partial nitrogen removal. Furthermore, the comparison among the different DM maintenance strategies has shown that the mass air load supply is the most efficient approach towards sustainable operation. In particular, shorter mass air load cycles provided the best performance in limiting the manual cleaning needs, which under this condition were as low as once every 3 weeks. The key finding of this study is the demonstration of cyclic air mass load as an effective preventive cleaning strategy allowing good performance of a bench scale SFD MBR, strongly reducing the manual maintenance requirements. More experiments are required to confirm these results in larger scale installations. 53 Published version https //www.sciencedirect.com/science/article/pii/S2214714423003653 utm_campaign=STMJ_AUTH_SERV_PUBLISHED utm_medium=email utm_acid=79415456 SIS_ID= dgcid=STMJ_AUTH_SERV_PUBLISHED CMX_ID= utm_in=DM376211 utm_source=AC_ Articolo in rivista Elsevier Journal of Water Process Engineering Journal of Water Process Engineering alfieri.pollice POLLICE ALFIERI giovanni.berardi BERARDI GIOVANNI carlo.salerno SALERNO CARLO |
