GDM is a relevant and adequate approach to produce safe drinking water due to low operation requirements and marginal need for external energy inputs. An important advantage of GDM is that these systems decrease the concentration of biodegradable compounds in the permeate, in comparison to conventional ultrafiltration (UF). These characteristics are not only of major interest for community scale systems, but also for centralized systems. For instance, enhancing the removal of biodegradable compounds is one of the first objective of reverse osmosis pre-treatment step, given that they are major membrane foulants. Yet, a principal limitation for GDM applicability in centralized systems is the higher footprint and associated capital costs caused by higher membrane surface requirements, due to lower fluxes than achieved with conventional UF.
Since 2019, we actively work on approaches that could increase GDM fluxes and reduce space requirements by replacing flat-sheet with hollow fiber membranes. Using our new GDM platform (picture), we successfully proved that GDM filtration is feasible with hollow fiber (HF) membranes operated in inside-out mode. The implementation of a backwash allows maintaining high fluxes despite the low space availability for biofilm growth in the lumen of the fibers, as discussed in Stoffel et al., (2021). With this project, we showed that the GDM step footprint could be decreased by up to 20 times, when implementing HF membrane operated in inside-out mode with low cost maintenance instead of GDM systems equipped with non-maintained flat sheet membranes.
Our current activities focus on assessing procedures to lowering the capital costs and optimizing the operation.