Fouling and mitigation mechanisms during direct microfiltration and ultrafiltration of primary wastewater

Reclamation of Nutrient Solution from Membrane-Based Microalgal Harvesting Processes for Cultivation of Vegetables in Hydroponic Systems

“…This implies that 15 min of water flushing may not offer sufficient cleaning effectiveness for the accumulated foulants after 45–90 min filtration, possibly due to their relatively dense nature. As a result, the residual cake layers could be further compacted, which may greatly contribute to irreversible fouling during the following filtration cycle. , …”

“…In particular, high-temperature water flushing greatly facilitated the reducing cake layer fouling for both solutions and the irreversible fouling for AS2; it also slightly alleviated irreversible fouling during the filtration of AS1 (Figure b,c). In our previous studies on the crossflow filtration of primary wastewater, , it was observed that high-temperature water flushing mitigated both cake layer and irreversible fouling compared to wastewater flushing because elevating the temperature increased the solubility of organic/inorganics in the foulants, allowing them to be readily detached from the membranes. It was noted that AS1 with more organics could potentially block more membrane pores, displaying a higher irreversible fouling resistance (Figure b).…”

“…As a result, the residual cake layers could be further compacted, which may greatly contribute to irreversible fouling during the following filtration cycle. 14,15 To explore this hypothesis, further shortening filtration and water flushing durations (i.e., 15 min filtration−5 min water flushing) were performed under the same duration for the ratio of filtration and water flushing. Clearly, increasing the cleaning frequency greatly reduced the TMP increase (Figure 4a), and as a result, led to a lower cake fouling resistance (Figure 4c).…”

“…To promote membrane-based microalgal harvesting techniques, several membrane fouling control strategies have been attempted, such as pretreatment of the feed water (i.e., microalgal suspension), improvement of membrane properties, and enhancement of hydrodynamic conditions. − It has been reported that the effective hydrodynamic-based fouling mitigation approaches (such as increasing the crossflow velocity, using gas sparging, and vibrating membranes) could be beneficial for inducing a stronger shear force on the membrane surface, alleviating concentration polarization, and reducing cake accumulation. , Furthermore, in our previous studies on direct membrane filtration of municipal wastewater, it was found that periodic high-temperature (50 °C) water flushing − and ultrasonication , could effectively alleviate membrane fouling. This allows us to investigate the feasibility of using high-temperature water (Icelandic natural resource) and ultrasonication methods for periodically cleaning the membranes during membrane-based microalgal harvesting processes.…”

Reduction of Ultrafiltration Membrane Fouling by the Pretreatment Removal of Emerging Pollutants: A Review

“…The thickness of the filter cake layer shows a “V” trend with increasing amount of flocculating agent. Warm water is usually used to clean the UF membrane to enhance the release of pollutants in the filter cake layer, and the additional heat supply will increase the cost by at least 0.126 RMB/ton [ 34 , 150 , 151 , 152 ]. The cost of water purification with inorganic coagulants is almost the same as that of AOPs, and nearly half of the total cost is saved compared with PAM [ 153 ].…”