Abstract
An Advanced Water Treatment Plant (AWTP) for potable water recycling in Davis Station Antarctica was trialed using secondary effluent at Selfs Point in Hobart, Tasmania, for nine months. The trials demonstrated the reliability of performance of a seven barrier treatment process consisting of ozonation, ceramic microfiltration (MF), biologically activated carbon, reverse osmosis, ultra-violet disinfection, calcite contactor and chlorination. The seven treatment barriers were required to meet the high log removal values (LRV) required for pathogens in small systems during disease outbreak, and on-line verification of process performance was required for operation with infrequent operator attention. On-line verification of pathogen LRVs, a low turbidity filtrate of approximately 0.1 NTU (Nephelometric Turbidity Unit), no long-term fouling and no requirement for clean-in-place (CIP) was achieved with the ceramic MF. A pressure decay test was also reliably implemented on the reverse osmosis system to achieve a 2 LRV for protozoa, and this barrier required only 2–3 CIP treatments each year. The ozonation process achieved 2 LRV for bacteria and virus with no requirement for an ozone residual, provided the ozone dose was >11.7 mg/L. Extensive screening using multi-residue gas chromatography–mass spectrometry (GC–MS) and liquid chromatography–mass spectrometry (LC–MS) database methods that can screen for more than 1200 chemicals found that few chemicals pass through the barriers to the final product and rejected (discharge) water streams. The AWTP plant required 1.93 kWh/m3 when operated in the mode required for Davis Station and was predicted to require 1.27 kWh/m3 if scaled up to 10 ML/day. The AWTP will be shipped to Davis Station for further trials before possible implementation for water recycling. The process may have application in other small remote communities.
Highlights
Davis Station, Antarctica, is operated by the Australian Antarctic Division (AAD) for the purposes of undertaking environmental research
The demonstration plant was operated for nine months and was able to reliably produce product water suitable for drinking and a brine of low environmental impact
Membrane processes were integral to achievement of this outcome, with the ceramic MF producing low turbidity filtrate of approximately 0.1 NTU, on-line verification of membrane pathogen integrity via pressure decay tests (PDT) and required no CIP over the 9 months of the trial
Summary
Davis Station, Antarctica, is operated by the Australian Antarctic Division (AAD) for the purposes of undertaking environmental research. The AAD is committed to minimizing the impact of their presence on this pristine environment and a desire to minimize the effect of their wastewater discharge on the Antarctic receiving waters offered the opportunity to consider a direct potable reuse (DPR). An environmental impact assessment of wastewater discharges to the receiving environment conducted by the AAD identified the need for tertiary treatment of sewage. Given the high quality of tertiary treated wastewater, only incremental additional treatment would be required for potable recycling that would enable greater water availability at Davis Station and reduced energy consumption for producing drinking water compared to the current treatment of a cold, hypersaline source water. Operating a potable water recycling plant in Antarctica is challenging, as the treatment process must consistently treat water to the quality required for drinking.
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