UBC Theses and Dissertations

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UBC Theses and Dissertations

Intermittent operations of passive membrane systems Baskar, Varshini


Passive membrane systems are ideal for use in small and remote communities; they are operated under a low permeate flux, thereby requiring limited energy, they have few passive fouling control measures, leading to limited mechanical complexity, and are relatively easy to operate. Their operation depends on the formation of a structurally loose and permeable biofilm on the membrane surface, which helps stabilize the permeate flux and aids the removal of organic material and other material of concern. However, their application is potentially hindered by intermittent loading conditions caused by periods of no inflow demand, a characteristic of small and remote systems. Periods of no inflow could stress biofilm in passive membrane systems and affect the overall system stability and performance. The current study investigated the impacts of the periods of no inflow on the throughput and in organic material removal the passive membrane systems. Passive membrane systems operated with various periods of no inflow were considered and compared to a passive membrane system operated with continuous inflow. The periods of no inflow considered were 3 hours per 24 hours, 8 hours per 24 hours and 2 days per week. For the passive membrane systems operated with periods of no inflow, both conditions with no permeate recycling (i.e., no flow through system) and permeate recycling (i.e., flow maintained through system by recycling permeate) were considered. Results indicate that the periods of no inflow do not negatively impact the performance of passive membrane systems. Rather, periods of no inflow could lead to better performance. The results also provided insight on the relationship between the length of the periods of no inflow, the recycling of the permeate during periods of no inflow, and the overall performance of passive membrane systems. In small and remote communities, the financial investment in equipment and operations for permeate recycling during periods of no inflow might be outweighed by the increased water production when operated with permeate recycling. Hence, for small and remote communities, operation of PGDMF systems without permeate recycling during the periods of no inflow is ideal.

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