Abstract 2020 is the year of wildfire records. California experienced its three largest fires early in its fire season. The Pantanal, the largest wetland on the planet, burned over 20% of its surface. More than 18 million hectares of forest and bushland burned during the 2019–2020 fire season in Australia, killing 33 people, destroying nearly 2500 homes, and endangering many endemic species. The direct cost of damages is being counted in dozens of billion dollars, but the indirect costs on water‐related ecosystem services and benefits could be equally expensive, with impacts lasting for decades. In Australia, the extreme precipitation (“200 mm day −1 in several location”) that interrupted the catastrophic wildfire season triggered a series of watershed effects from headwaters to areas downstream. The increased runoff and erosion from burned areas disrupted water supplies in several locations. These post‐fire watershed hazards via source water contamination, flash floods, and mudslides can represent substantial, systemic long‐term risks to drinking water production, aquatic life, and socio‐economic activity. Scenarios similar to the recent event in Australia are now predicted to unfold in the Western USA. This is a new reality that societies will have to live with as uncharted fire activity, water crises, and widespread human footprint collide all‐around of the world. Therefore, we advocate for a more proactive approach to wildfire‐watershed risk governance in an effort to advance and protect water security. We also argue that there is no easy solution to reducing this risk and that investments in both green (i.e., natural) and grey (i.e., built) infrastructure will be necessary. Further, we propose strategies to combine modern data analytics with existing tools for use by water and land managers worldwide to leverage several decades worth of data and knowledge on post‐fire hydrology.
There is widespread speculation that sewage treatment plants (STPs) and aquatic environments in general may be breeding grounds for antibiotic resistant bacteria. We examine the question of whether low concentrations of antibiotics in STPs can provide or contribute to a selective pressure facilitating the acquisition or proliferation of antibiotic resistance among bacteria in the receiving environment. Examination of available literature suggests that relative levels of antibiotic resistance may be increased during sewage treatment processes. However, it is unclear whether this may be partially the result of horizontal gene transfer or entirely due to clonal propagation. While there is circumstantial evidence that the presence of antibiotics or other related genetic promoters in STP wastewaters may contribute to selective pressures for these processes, a definite role is yet to be demonstrated. Future researchers would benefit from the application of non-culture-based techniques because culture limits the possible observations to a small subset of STP microbial diversity.
A pilot-scale plant was employed to validate the performance of a proposed full-scale advanced water treatment plant (AWTP) in Sydney, Australia. The primary aim of this study was to develop a chemical monitoring program that can demonstrate proper plant operation resulting in the removal of priority chemical constituents in the product water. The feed water quality to the pilot plant was tertiary-treated effluent from a wastewater treatment plant. The unit processes of the AWTP were comprised of an integrated membrane system (ultrafiltration, reverse osmosis) followed by final chlorination generating a water quality that does not present a source of human or environmental health concern. The chemical monitoring program was undertaken over 6 weeks during pilot plant operation and involved the quantitative analysis of pharmaceuticals and personal care products, steroidal hormones, industrial chemicals, pesticides, N-nitrosamines and halomethanes. The first phase consisted of baseline monitoring of target compounds to quantify influent concentrations in feed waters to the plant. This was followed by a period of validation monitoring utilising indicator chemicals and surrogate measures suitable to assess proper process performance at various stages of the AWTP. This effort was supported by challenge testing experiments to further validate removal of a series of indicator chemicals by reverse osmosis. This pilot-scale study demonstrated a simplified analytical approach that can be employed to assure proper operation of advanced water treatment processes and the absence of trace organic chemicals.
In recent years, there has been considerable research effort focusing on the removal o f specific individual contaminants at trace level concentrations instead o f the traditional surrogate, and often ill-defined, water quality indicators. The need for this more precise water quality characterisation has been driven by stricter environmental regulations and legislation, and the increasing need to utilise non-traditional water resources including reclaimed municipal wastewaters. Amongst several advanced technologies used for high quality water treatment, removal o f trace contaminants by nanofiltration membranes has been investigated to a considerable extent. However, it is known that such membrane filtration processes tend not to operate continuously under steady-state conditions. Accordingly, it is surprising that there has been very little published information regarding the impact o f operating conditions on the separation performance, particularly on the removal o f trace contaminants. This study examined the effects o f the operating conditions including feed water chemistry and membrane fouling on the retention o f trace organics by a loose nanofiltration membrane. Emerging trace organics with functional groups having pK a values in the environmental pH range and outside the environmental pH range were selected for investigation. Results reported here indicate that the solution pH and ionic strength can markedly influence the removal o f ionisable trace organic compounds. These observations were explained by electrostatic interactions between the solutes and the membrane surface and by the speciation o f the ionisable compounds. In addition, membrane fouling has also been shown to exert some considerable impact on the retention of trace organics. The underlying mechanisms however remain unclear and are subject to on-going investigation.
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