Removal of pathogenic microorganisms in pilot-scale uasb-septic tanks and albireh urban wastewater treatment plant in Palestine subhi

Abstract

Inadequate wastewater treatment facilities and a general lack of data on hygienic aspects of treated wastewater have hampered the successful implementation of effluent reuse schemes at the national level; in addition, illegal irrigation practices with partially treated effluent impose serious health hazards and environmental problems. The main objective of this research is to investigate the pathogens removal in Upflow Anaerobic Sludge Blanket (UASB)-septic tanks and Albireh wastewater treatment plant (AWWTP). The UASBseptic tanks, located at AWWTP, were fed continuously with raw municipal wastewater from the aerated grit chamber of AWWTP. The two pilot scale UASB-septic tanks (R1 and R2) were operated at two different hydraulic retention times (HRT) of 2 and 4 days for R1 and R2, respectively. At AWWTP, as an extended aeration system with aerobic sludge stabilization, the HRT was about one day. Both raw wastewater and treated effluent were tested for microbial pathogens, including indicator bacteria, protozoa and trophozoite using microscopic and specific culture media. The removal efficacies of R1 and R2 were 15.5% and 15% for fecal coliform and 6.9% and 11% for fecal streptococcus, respectively, while the removal efficacy of the oxidation ditch was 38% for fecal coliform and 16% for fecal streptococcus. Though Salmonellae was detected in 30% of analyzed influent samples, it was not detected in any sample of the effluent of both treatment systems. Also, the treated effluent of R1, R2 and oxidation ditch was parasite- (cysts or trophoziote) free. This information can assist municipalities and village councils in the implementation of rational and efficient treatment strategies for sustainable effluent reuse. Finally, the installation of post treatment stages, including filtration and disinfecting units, is recommended in order to comply with prescribed national guidelines for effluent reuse.