UV disinfection of wastewater effluents for unrestricted irrigation

Abstract

Wastewater reuse in arid regions is important for the production of a water resource to be utilised for non-potable purposes and to prevent the environmental transmission of disease-causing agents. This study was conducted to evaluate the effect of water quality on the comparative disinfection efficiency of viruses, bacteria and spores by UV irradiation. Furthermore, the microbial quality of effluent produced by coagulation, high rate filtration (HRF) and either UV irradiation or chlorination was determined. Using low pressure collimated beam, a UV dose of 80 mWs/cm2 was needed to achieve a 3-log10 inactivation of either rotavirus SA-11 or coliphage MS2, whereas over 5-log10 inactivation of E. coli was reached with a dose of only 20 mWs/cm2. B. subtilis inactivation was found to be linear up to a dose of 40 mWs/cm2 and then a tailing up to a UV dose of 120 mWs/cm2 was observed. It is worth noting that effluent turbidity of < 5 NTU did not influence the inactivation efficiency of UV irradiation. Operation of a pilot plant to treat secondary effluent by coagulation, HRF and UV disinfection at a UV dose of 80 mWs/cm2 resulted in the production of high quality effluent in compliance with the Israel standards for unrestricted irrigation (< 10 CFU/100 mL faecal coliform and turbidity of < 5 NTU). Sulphite reducing clostridia (SRC) were found to be more resistant than coliphages and F coliform for UV irradiation. The results of this study indicated that UV disinfection is suitable for the production of effluents for unrestricted irrigation of food crops.

Constructed wetlands combined with UV disinfection systems for removal of enteric pathogens and wastewater contaminants

“…chloro-organic compounds) (Sun et al 2009;Zhang et al 2on), suggesting a search for a safer disinfection method is in place. UV disinfection is well established for effluent treatment in large WWTPs (Nasser et al 2006), but its use with CW effluent is much less established (Richter & Weaver 2003). Here we demonstrate the use of combined CW system and cheap, consumer level, UV disinfection systems to treat wastewater effluents, making it suitable for unrestricted irrigation.…”

Removal of pathogenic bacteria from sewage-treated effluent and biosolids for agricultural purposes

“…The effectiveness of a UV disinfection system depends on the characteristics of the effluents including the concentration of the sewage effluent, the intensity of the UV radiation and the time of the treatment (Kollu and Ormeci 2012). Nasser et al (2006) revealed that the treated sewage disinfected by UV is suitable for the unrestricted irrigation of food crops (FC < 1000 CFU/100 mL). Dungeni et al (2010) suggested UV disinfection as an additional treatment process of effluents to increase the effective inactivation and removal of pathogenic bacteria and viruses.…”

Water reuse in the Gaza Strip, Palestine

“…Rapid sand filtration is considered, with the bacl<:wash water discharged to the WWTP. • Disinfection to achieve the required level of pathogen removal to allow unrestricted reuse of effluent (Chrtek & Popp 1991;Nasser et al 2006;Oparaku et al 2on). A faecal coliform standard of 200 MPN/100 ml is to be achieved by UV lamps.…”