Resource recovery from wastewater for nutrients, water, energy, and other value added products is growing around the world. The high density of pathogenic microorganisms, the energy intensive processes associated with wastewater treatment, and emerging contaminants of concern such as antibiotic resistant bacteria (ARB) and antibiotic resistant genes (ARG), present challenges with wastewater reuse. Greywater, a type of wastewater from decentralized systems at households which typically includes effluent water from laundry, sinks, and showers, has smaller amounts of fecal sources than sewage. Greywater reuse, therefore, is attractive given the reduced reduced health risks over sewage associated with illness from diseases from fecal origins. Not surprisingly, greywater is reused in many countries for irrigation, dust suppression, and toilet flushing. Greywater reuse is utilized mostly in arid areas such as the Middle East, Australia, or areas with fluctuating water demands associated with seasonal changes and urbanization such as Singapore. Greywater reuse can also be considered for arid or semi-arid regions in sub-Saharan Africa or islands of the Caribbean. In this research, ARG from bacteria have been detected and quantified in greywater from five recirculating vertical flow constructed wetlands (RVFCW) located in single family households in Midreshet Ben Gurion in the Negev desert, Israel. Polymerase chain reaction (PCR) and quantitative polymerase chain reaction (qPCR) were used to detect and quantify antibiotic resistant genes (blaCTX-M-32, qnrS, and sul1), bacterial gene (16S rRNA) and mobile genetic element gene (intI1). Results show that all genes except blaCTX-M-32were reduced approximately 2-3 log by RVFCW treatment. Genes for 16S, intI1 and sul1 were relatively abundant while blaCTXM and qnrS were less abundant in treated and untreated greywater. Extended spectrum beta-lactamases (ESBL) positive bacteria were enumerated using spread-plate methods. The RVFCW has shown consistent performance with significant reductions in TSS, BOD, and turbidity (90%, 95%, and 93% respectively). Total nitrogen was reduced 42% and total organic carbon was reduced 62%. There were no significant changes to pH and conductivity before and after treatment in the RVFCW. Identification of bacterial strains and communities will be completed using sequencing of 16S PCR products and next generation sequencing.

Assessment of greywater treatment systems for the removal of antibiotic resistant genes and bacteria

2019 Fall National Meeting

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