General research interests:
- Microbial drinking water quality, biological filtration, water treatment processes
- Microbial ecology, 'omics.
- Interdisciplinary and multi-stakeholder approaches to solve environmental problems.
- Microbial drinking water quality, biological filtration, water treatment processes
- Microbial ecology, 'omics.
- Interdisciplinary and multi-stakeholder approaches to solve environmental problems.
Optimizing Filter Operation in an Ozone-Biofiltration Plant to Reduce Selection for Opportunistic Pathogens in Drinking Water Production (Univ. of Michigan, City of Ann Arbor, Water Research Foundation).
Non-tuberculous mycobacteria (NTM), some of which are opportunistic human pathogens, are frequently detected in drinking water systems. There is growing evidence that drinking water disinfectants select for NTM. An important, but mostly unexplored area is the selection for NTM during biofiltration, which has become a popular technology in centralized drinking water treatment plants (DWTPs) in North America. Few if any studies have evaluated the impact of disinfectant exposure during backwashing on the selection for NTM in biologically active carbon (BAC) filters. We hypothesize that reducing disinfectant exposure of the microbial communities in BAC filters promotes more diverse biofilm communities with microbial populations that effectively outcompete pathogens, while achieving the same or better filtration performance. We are evaluating this hypothesis using a combination of full-scale and pilot-scale investigations at the Ann Arbor DWTP, with culture-independent, high-throughput microbiology. Specifically, we propose to test the impact of dechloraminating the backwash supply on filter microbial communities, focusing on whether this strategy reduces NTM levels. This research will result in strategies for utilities to reduce the levels of disinfectant-resistant, opportunistic pathogens in biological filters and thereby lower the likelihood of seeding the distribution networks with these microbes. While this work focuses on the Ann Arbor DWTP, it will be applicable to other utilities that practice biofiltration, especially those that pre-ozonate and use disinfectants in their backwash water.
Towards a predictive framework for microbial management in drinking water systems (Univ. of Glasgow, Scottish Water).
This project focused on the characterization of the microbial ecology of full-scale drinking water (DW) systems using DNA sequencing-based approaches. Multiple full-scale DW systems in Scotland were sampled, in order to elucidate the impacts of: (i) methodological variation and (ii) system properties on DW microbial communities, using a combination of bioinformatics and molecular microbial ecology. Regarding methodological variation, I elucidated the impacts of sample replication, PCR replication, sample volume and sampling flow rate on the structure and membership of DW microbial communities. Regarding system properties, I showed that microbial communities in DW distribution systems (DWDSs) undergo diurnal variation (and therefore are linked to water use patters/hydraulics in the systems), and that sampling location shapes the microbiome at small scales in the distribution system (i.e. nearby locations within a distribution zone). An assessment of the impact of source water type and treatment processes showed that disinfection is a key treatment step for community composition and functional potential, and that several genes related to protection against chlorine/oxygen species are overabundant in chlorinated and chloraminated systems, compared to disinfectant residual-free systems.
Previous research
Previously I worked on: (i) estimating the impact of climate change on water availability of two reservoirs in the UK (operated by Severn Trent Water), and (ii) an estimation of environmental flows in the Yuna River Basin, Dominican Republic, using indicators of hydrologic alteration.