A new integrated potable reuse process for a small remote community in Antarctica

Abstract

To meet water reuse and discharge requirements in Davis Station, Antarctica, an advanced water treatment plant (AWTP) had been designed and tested for nine months. The key design factors for operating in small communities in remote areas included low maintenance requirement (low chemical inventory, minimal onsite labour), high LRVs for pathogens, robust operation, and high automation. Based on these requirements, the seven-barrier AWTP included ozonation, ceramic microfiltration, biological activated carbon, reverse osmosis, ultraviolet radiation, calcite filtration and chlorination. The nine month test demonstrated that the plant was able to provide minimum LRVs of 12.5 for virus and bacteria, and 10 for protozoa. The overall estimated chemical consumption was lower than equivalent continuous operations elsewhere due to a reduced number of Clean in Place (CIP) cycles as compared to industry. This was achieved by optimised integration of the barriers.Furthermore, there was no functional failure of major barriers and the automated online pressure decay test (PDT) validations for MF and RO were successful. Although some minor improvements, such as a reduced frequency of RO pre-filter cartridge replacement, are still needed, the new integrated plant has fulfilled the requirements of high pathogen LRVs, remote online control and validation, and relatively low chemical consumption. Keywords: Water treatment; water reuse; potable reuse; advanced water treatment plant * The LRVs are credited based on health regulator guidelines e.g. the USEPA Long Term 2 Enhanced Surface Water Treatment Rule, Guidelines for validating treatment processes for pathogen reduction,

Small Scale Direct Potable Reuse (DPR) Project for a Remote Area

“…The PDT rates of the two ceramic membranes were all below the 1.4 kPa/min limit for the entire test period, apart from when there were leaking valves [11]. The PDT data always met the required CCP limit, confirming the reliability of the ceramic MF membranes for attaining this CCP.…”

“…It was found that the depletion of the ozone was directly related to the turbidity rather than the ammonia concentration [11].…”

“…It was found that the depletion of the ozone was directly related to the turbidity rather than the ammonia concentration [11]. The Davis Station MBR should produce a reliable, low turbidity feedwater that will enable an ozone residual to be maintained, and subsequently allow the use of CT values set by the US EPA Long-Term 2 Enhanced surface water treatment rule to define the LRV value.…”

“…The ozone transferred to the feed water was in the range of 60% to 80%, and did not show a clear relationship to the pressure in the contact tank. However, maintaining the dosed ozone >11.7 mg/L was sufficient to ensure >2 LRV for bacteria and virus [11]. …”

“…Fouling of the RO membrane also occurred and a CIP was required after a period of 4-5 months, indicating a need for 2-3 CIPs each year [11]. A fouled RO membrane was also subjected to autopsy.…”