Membrane bioreactors for water reclamation

Abstract

Singapore has been using dual membrane technology (MF/UF RO) to produce high-grade water (NEWater) from secondary treated sewage. Membrane bioreactor (MBR) has very high potential and will lead to the further improvement of the productivity and quality of high-grade water. This study was focused on the technical feasibility of MBR system for water reclamation in Singapore, making a comparison between various membrane systems available and to get operational experience in terms of membrane cleaning and other issues. Three MBR plants were built at Bedok Water Reclamation Plant with a design flow of 300 m3/day each. They were commissioned in March 2003. Three different types of submerged membranes were tested. They are Membrane A, plate sheet membrane with pore size of 0.4 microm; Membrane B, hollow fibre membrane with pore size of 0.4 microm; and Membrane C, hollow fibre membrane with pore size of 0.035 microm. The permeate quality of all the three MBR Systems were found equivalent to or better than that of the conventional tertiary treatment by ultrafiltration. MBR permeate TOC was about 2 mg/l lower than UF permeate TOC. GC-MS, GC-ECD and HPLC scan results show that trace organic contaminants in MBR permeate and UF permeate were in the same range. MBR power consumption can be less than 1 kwh/m3. Gel layer or dynamic membrane generated on the submerged membrane surface played an important role for the lower MBR permeate TOC than the supernatant TOC in the membrane tank. Intensive chemical cleaning can temporarily remove this layer. During normal operation conditions, the formation of dynamic membrane may need one day to obtain the steady low TOC levels in MBR permeate.

Waste Management Methods and Sustainablity

“…Thus, treatment with MBR produces a highly clarified effluent that can be more easily disinfected and can be ideally used for producing non-potable water. MBR must be followed by RO and UV treatment for the purpose of reclaiming potable water (Tao et al 2005(Tao et al , 2006. Advances in Reverse Osmosis technology include improved membranes and configurations, more efficient pumping and energyrecovery systems, and the development of process technology, such as membrane distillation (Kim et al 2008).…”

Untitled

“…Uma vez que todos constituintes rejeitados pela membrana permanecem no reator biológico para um determinado TRS, estes compostos podem ficar por períodos de tempos mais longos do que em sistemas convencionais, dando-lhes mais tempo para ser degradados (NG e Hermanowicz, 2005;Masse et al, 2006; Dong e Jiang, 2009). Outra possibilidade, conforme sugerida por Tao et al (2005), é a redução do poro efetivo da membrana causada pela camada de depósito na sua superfície (denominada também como camada gel). O autor encontrou que a remoção de COT pelo BRMs foi drasticamente reduzida após a realização da limpeza química com hipoclorito de sódio, indicando, assim, que a formação da camada gel na superfície das membranas em um BRMs pode elevar a remoção de macromoléculas orgânicas.…”

État actuel des connaissances des procédés de bioréacteur à membrane pour le traitement et la réutilisation des eaux usées industrielles et urbaines

“…En effet, VAN BENTEM et al (2007) VAN BENTEM et al, 2007). Cependant, TAO et al (2005) ont observé un ratio air/perméat plus élevé pour des BRM pilotes immergés opérés en configuration "outside", comparativement au BRM immergé fonctionnant en configuration "inside" (Tableau 2). Ces auteurs ont également observé une réduction de 8 % des coûts énergétiques dans la configuration "inside".…”