Pathogen removal efficiency from UASB + BF effluent using conventional and UV post-treatment systems

Abstract

The aim of this study was to verify the efficiency of removal of microorganisms in effluents of a Wastewater Treatment Plant (WWTP) comprising an association of a UASB reactor followed by three submerged aerated biofilters (BAF) and one tertiary filter. The WWTP designed to treat domestic wastewater from a population of 1,000 inhabitants showed high removal efficiency for organic matter and suspended solids. Helminth eggs were also efficiently removed from the tertiary effluent and were found in the sludge from the UASB reactor; however, removal of bacteria in this system was very low. To enhance the efficiency of the system, the effluent from tertiary filters was submitted to UV disinfection in a real scale reactor. Our results showed that UV irradiation was very effective at lowering the concentrations of E. coli, thermotolerant coliforms and coliphages to acceptable levels for agricultural reuse. Salmonella spp. and helminth eggs were seeded into the tertiary effluent before passing through the UV reactor. Salmonella was not found in the final effluent, but helminth eggs were not completely inactivated by UV irradiation and viable eggs were detected after 28 d of incubation.

TiO2 photocatalytic inactivation under simulated solar light of bacterial consortia in domestic wastewaters previously treated by UASB, duckweed and facultative ponds

“…This effect has also been reported by other authors using UASB effluents and UV disinfection. 21 In facultative pond and duckweed pond effluents, Salmonella was completely inactivated in the absence of TiO 2 using both BLL and the solar simulator. This could be due to the low turbidity and low concentrations of organic and inorganic matter in these effluents, as well as the low initial bacterial concentrations.…”

Anaerobic Sludge Blanket Reactors

“…1.0 log 10 removal for Salmonella spp., 0.5 log 10 removal for Shigella spp., 1.0 log 10 removal for Vibrio spp in a UASB reactor (Pant and Mittal, 2007) 1.1 log 10 reduction of thermotolerant coliforms in UASB reactors (Oliveira and von Sperling, 2011) 1.0 log 10 reduction of thermotolerant coliforms in an ABR reactor (Lalbahadur et al, 2005) 0.3 log 10 removal of Cryptosporidium oocysts (Morsy et al 2007) 0.42 to 1.30 log 10 for UASBs (Keller et al, 2004;von Sperling et al, 2003;Yaya-Beas et al, 2015).…”

Sustainable Post Treatment Options of Anaerobic Effluent

“…Although the efficiency of the UASB-SABF system was satisfactory in terms of organic matter removal, the removal of the pathogenic microorganisms was very low. Keller et al (2004) investigated the combined UASB-SABF system followed by conventional and UV system to enhance the efficiency of the system to remove the pathogenic microorganisms. The results revealed that the 84% of COD (residual effluent COD of 78 mg/L), 86 % of BOD (residual effluent BOD of 26 mg/L) and 86% of TSS (residual effluent TSS of 23 mg/L) removal was achieved.…”