Bacterial community and groundwater quality changes in an anaerobic aquifer during groundwater recharge with aerobic recycled water

Abstract

Managed aquifer recharge offers the opportunity to manage groundwater resources by storing water in aquifers when in surplus and thus increase the amount of groundwater available for abstraction during high demand. The Water Corporation of Western Australia (WA) is undertaking a Groundwater Replenishment Trial to evaluate the effects of recharging aerobic recycled water (secondary treated wastewater subjected to ultrafiltration, reverse osmosis, and ultraviolet disinfection) into the anaerobic Leederville aquifer in Perth, WA. Using culture-independent methods, this study showed the presence of Actinobacteria, Alphaproteobacteria, Bacilli, Betaproteobacteria, Cytophaga, Flavobacteria, Gammaproteobacteria, and Sphingobacteria, and a decrease in microbial diversity with an increase in depth of aquifer. Assessment of physico-chemical and microbiological properties of groundwater before and after recharge revealed that recharging the aquifer with aerobic recycled water resulted in elevated redox potentials in the aquifer and increased bacterial numbers, but reduced microbial diversity. The increase in bacterial numbers and reduced microbial diversity in groundwater could be a reflection of an increased denitrifier and sulfur-oxidizing populations in the aquifer, as a result of the increased availability of nitrate, oxygen, and residual organic matter. This is consistent with the geochemical data that showed pyrite oxidation and denitrification within the aquifer after recycled water recharge commenced.

Microbial community changes induced by Managed Aquifer Recharge activities: linking hydrogeological and biological processes

“…These results suggest that P8 denitrification processes occur below the basin even when it is empty, indicating that 4 months is not enough time to revert back to natural conditions at this sampling point. This assumption is consistent with nitrate isotopic data presented in Grau-Martínez et al (2018) and is also in agreement with the study of Rodriguez-Escales et al (2016) in which biomass decay acted as an endogenous carbon source for respiration once the input carbon was reduced, maintaining denitrification rates.…”

“…Biodegradation of EOCs strongly depends on redox conditions (Barbieri et al, 2011;Maeng et al, 2010). In this regard, it has been shown that MAR is a feasible technique capable of partially degrading some of these contaminants (Hellauer et al, 2017;Massmann et al, 2008), particularly when bioprocesses are enhanced (Grau-Martínez et al, 2018;Schaffer et al, 2015). Infiltration through the soil intrinsically leads to two main consequences in groundwater recharge:…”

Microbial community changes induced by Managed Aquifer Recharge activities: Linking hydrogeological and biological processes

“…As for microbial MAR field studies, most relevant research is limited to well injection systems (Ginige et al, 2013;Reed et al, 2008;Zhang et al, 2016) or riverbank filtration conditions (Huang et al, 2015). Onesios-Barry et al (2014) compared results from a column experiment and soil samples in a MAR site in the US, focusing on the micro-30 bial populations linked to pharmaceutical and personal care products removal, and concluded that microbial composition and structure of both systems were comparable.…”

Water Recycling via Aquifers for Sustainable Urban Water Quality Management: Current Status, Challenges and Opportunities

“…Aquifers harbour diverse microbial communities which can facilitate the natural attenuation of nutrients through microbial metabolic processes [63,64]. Microbial processes that facilitate nitrogen removal include aerobic ammonia oxidation, denitrification and anaerobic ammonia oxidation (Anammox) [65,66].…”

“…As part of Perth's Groundwater Replenishment Scheme, Ginige et al [64] characterised the bacterial community within the anaerobic Leederville aquifer being recharged with aerobic reclaimed water using culture-independent molecular methods (clone library and QPCR of 16S rRNA genes) and flow cytometry. The study revealed that bacterial numbers increased and diversity decreased as a result of the aquifer recharge.…”