Assessment of UV Pre-Treatment to Reduce Fouling of NF Membranes

Reducing the Impacts of Biofouling in RO Membrane Systems through In Situ Low Fluence Irradiation Employing UVC-LEDs

“…Comparing the fluence to the study of Jarvis et al [112], who reported an inactivation rate of 0.171 cm 2 •mJ −1 for MS2 phages using a 275 nm LED with an irradiance of 4.9 mW•cm −2 , this would result in a log removal of 0.35. The applied fluence of 2 mJ•cm −2 is 10 or more times lower compared to the fluences applied for UV disinfection as biofouling control previously reported in the literature [58][59][60][61]. For a setting of 180 mA, no actinometry was performed.…”

“…In particular, RO feed water is usually pretreated to a great extent, and hence, it commonly exhibits high UV transmissions, making it ideal for UV disinfection. Studies investigating the potential of UV-disinfection pretreatment used low or medium pressure lamps, with fluences of 20–400 mJ∙cm −2 [ 58 , 59 , 60 , 61 ]. In several studies, it could be demonstrated that the UV-disinfection is delaying the build-up of the biofilm in NF or RO membrane systems using river or groundwater as feed in a full-scale application [ 58 , 59 , 60 ].…”

“…Studies investigating the potential of UV-disinfection pretreatment used low or medium pressure lamps, with fluences of 20–400 mJ∙cm −2 [ 58 , 59 , 60 , 61 ]. In several studies, it could be demonstrated that the UV-disinfection is delaying the build-up of the biofilm in NF or RO membrane systems using river or groundwater as feed in a full-scale application [ 58 , 59 , 60 ]. Furthermore, biofilms grown during a defined period of time exhibited a lower dry weight and cell number as well as a reduced ATP, protein and polysaccharides content [ 60 ].…”

“…So far, UV irradiation as a pretreatment strategy for high-pressure membrane applications has not been examined in great depth, probably because UV disinfection of the feed stream has no residual effect on the downstream biofilm [ 42 , 64 ]. Yet, it is not clear if the observed changes in the biofilm, such as lower EPS production per biovolume [ 58 ], are only linked to a delay of the biofilm formation, as experiments were frequently terminated after a defined period of time [ 58 , 59 , 60 ] rather than a function of biofouling development.…”