Abstract

The delivery of treatment and supply solutions for the management of water infrastructure for small and remote communities presents unique challenges. The identification of water quality hazards, the management of risks and conducting plant performance validation and verification activities can all be problematic. The ‘Demonstration of Robust Water Recycling’ (Robust Recycling) Project was funded by the Australian Water Recycling Centre of Excellence (AWRCoE) and the Australian Antarctic Division (AAD) as a means of developing strategies for the provision of small scale water treatment schemes from non-traditional water sources. Using the example of the AAD's Davis Station, this project featured an alternative approach to the establishment of a risk management framework for water recycling. This approach may be applicable to both drinking and recycled water schemes in other small and remote communities.

INTRODUCTION

In Australia over the past decade, the adoption of a ‘whole-of-water-cycle’ management approach to water security has seen the widespread implementation of a range of alternative water supply schemes. However, applying this same approach to small and remote communities greatly magnifies the obstacles and challenges to providing these types of services. Human occupation in remote areas faces the same water security and disposal problems as for more central urban communities. However, many of the contributing factors are greatly magnified.

This has been the experience of the Australian Antarctic Division (AAD) and their project partners Victoria University, the University of Melbourne, Veolia, TasWater, Coliban Water and AECOM Australia. The project team worked in conjunction with the Australian Water Recycling Centre of Excellence (AWRCoE) to develop technologies and management strategies to improve the treatment of station wastewater at Davis Station, in Antarctica (Figure 1). The project was called ‘Demonstration of Robust Water Recycling’ (Robust Recycling project).

Figure 1

Davis Station, Antarctica. The location of the AWTP and recycled water scheme for which this water quality risk management strategy was developed (AWRCoE/AAD-funded Robust Recycling Project). Courtesy of Australian Antarctic Division.

Figure 1

Davis Station, Antarctica. The location of the AWTP and recycled water scheme for which this water quality risk management strategy was developed (AWRCoE/AAD-funded Robust Recycling Project). Courtesy of Australian Antarctic Division.

The development of an AWTP for Antarctica

Davis Station, Antarctica, established in January 1957, has discharged wastewater from its sewage outfall for more than 50 years. Scientific studies conducted by the AAD Human Impacts Science Program have demonstrated direct ecological impacts from this discharge on the marine environment. As part of its commitment towards minimising impacts on the Antarctic environment, the AAD is installing a new state-of-the-art wastewater and advanced water treatment facilities (Figure 2) at Davis Station, Antarctica. The Advanced Water Treatment Plant (AWTP) is to be housed in a temperature controlled building operating a 19 °C to ensure optimal operating conditions for process control, and to protect it from the harsh weather conditions experienced in the Antarctic. The AWTP will be capable of producing high quality treated water with the objectives of significantly reducing the quantity and environmental impact of ocean discharges and providing a source of reuse water for station activities. The treatment facilities and associated reuse applications will also provide a demonstration of water recycling and reuse capabilities for small scale and remote applications, such that it might find application at other locations.

Figure 2

Process flow diagram for the Davis AWTP.

Figure 2

Process flow diagram for the Davis AWTP.

Due to the remoteness of the location, and the logistical difficulties of providing suitable staff and equipment, essential requirements for the advanced water treatment plant (AWTP) include the following:

  • A high level of automation and the capacity for the plant to be monitored and controlled remotely, with minimal onsite operator intervention.

  • Extra-high credible log reduction values (LRVs) for pathogen removal (Barker et al. 2013).

  • Minimal manual maintenance and chemical dosing requirements.

  • A reliable functional Recycled Water Quality Risk Management Plan (RWQRMP).

The project team, comprising representatives from the AAD, academia and industry, came together in mid-2012. They were tasked with the design, build, commissioning and operation of the Davis AWTP. Initial scoping, HAZOP, detailed design and construction occurred over a two-year period from 2012 to 2014. The plant was then relocated to TasWater's Self's Point Wastewater treatment plant (SPWWTP) in Hobart, Tasmania. Process optimisation and validation studies were carried out at Self's Point for around 12 months using a secondary treated wastewater effluent as a feedwater source. The final objective will be installation, commissioning and implementation of the AWTP at Davis Station in 2017–2018.

Challenges for risk management

This project required the development of a RWQRMP that was consistent with the requirements of the Australian Guidelines for Water Recycling (AGWR) and the Australian Drinking Water Guidelines (ADWG). This presented several challenges as the ability to carry out the risk assessment process and the process validation activities using methods traditionally applied was compromised due to the remote location of Davis Station. For example, carrying out the water supply system analysis – hazard identification and risk assessment – could not be supported by a comprehensive array of historical water quality data as it did not exist. The ability to perform in situ process validation/verification activities was impractical and lacked the technical support to be effectively carried out. Both of these aspects have traditionally been crucial in the development of a reliable and functional RWQRMP. Therefore, to address these challenges, the project team applied an innovative approach to the development of the RWQRMP. Emphasis was placed upon the development of a RWQRMP with a strong policy commitment, with supporting management processes and procedures (both administrative and operational). The aim of this was to ensure that the performance capability of both the onsite management practices, as well as the infrastructure, were able to meet the desired treated water quality standards.

This project has provided an opportunity to demonstrate the strength of policy and governance in the development, delivery and operation of these types of services. This is an approach that may be suitable for small and remote communities, where logistical obstacles exist to gaining large volumes of water quality data and ready access to technical equipment and expertise (Gray et al. 2015a, 2015b; Northcott et al. 2015a, 2015b; Scales et al. 2015a).

MATERIAL AND METHODS

Risk management framework and RWQRMP development

The formal risk management framework used to develop the RWQRMP followed relevant Australian national guidelines, which form the basis of the water-related regulation used by Australian states and territories:

The aspects of the RWQRMP that were specifically developed by the project team during this phase of the project are detailed below.

Water supply system risk assessment (Element 2 of AGWR Phase 1)

The project team applied the Hazard Identification and Critical Control (HACCP) principles to the water supply system analysis and risk assessment process. A specialist team was assembled to conduct a water supply system analysis. This included key AAD employees, and academic and industry partners with a broad range of relevant scientific, technical and operational knowledge, experience and expertise.

The identification of the hazards likely to exist in the source water, or that could occur, or be present, at each of the system process steps, was based upon the following information:

  • A quantitative microbial risk assessment (QMRA) to determine the pathogen reduction requirements for possible potable reuse at Davis Station (Barker et al. 2013).

  • Water quality data from samples collected from a number of locations within the Davis Station wastewater system during the summer expedition of 2013/2014.

  • First hand working station knowledge provided by the AAD personnel attending the workshop.

  • Manifests of compounds taken to Antarctic stations by AAD.

  • Expert opinion and knowledge provided by the scientific and technical workshop attendees experienced in the fields of water treatment and water quality.

Due to the absence of a large water quality data set to support the HACCP process, the project team trialled a different approach to the HACCP process; one that has relied upon the first hand operational knowledge of AAD personnel. The physical isolation and compactness of the Davis Station system was unique. This made the source water inputs well known to AAD personnel, as all the products that are present at the station are recorded and shipped there by the AAD. This allowed the project team to identify the potential water quality hazards likely to enter the wastewater stream and be present in the AWTP feedwater. Based upon this, the risks posed by each of these hazards and the capability of the AWTP to manage/control these risks were assessed.

Risk evaluation used the AGWR Phase 1 qualitative measures for likelihood and consequence were used to provide risk estimates. The uncertainty associated with the risk estimates was considered by the project team to identify knowledge gaps and areas for further research.

Preventative measures for recycled water systems (Element 3 of AGWR Phase 1)

Based upon the risk assessment information critical control points (CPPs) for the system were identified as per the required criteria set out by the AGWR Phase 1. Any process or activity within the system that did not specifically meet the criteria for a CCP, but were still considered an important operational/process step to ensuring the quality of the final product, were termed quality control points (QCPs). The critical limits and target criteria for each CPP were developed and tested during process validation and verification period at SPWWTP.

Process validation & verification (Element 9 of AWGR Phase 1)

TasWater provided an Australian mainland site at SPWWTP, New Town, Hobart, as a demonstration operation site to commission and perform the process validation and verification activities. The SPWWTP was considered by the project team as a suitable mainland site with a wastewater stream comparable to Davis Station; that being predominately domestic in composition, with the characteristics of effluent that has received secondary treatment prior to feeding the advanced water treatment plant.

Robustness criteria and analysis

The reliability and robustness of the AWTP was assessed against a set of pre-formed criteria (Table 1). The conclusions from the work are based on demonstrated results from the trial and an analysis of likely differences between the trial case and when the plant is located at Davis Station. In addition, further challenge testing was conducted for bromide and iodide treatment.

Table 1

Robustness criteria for the AWTP

CriteriaCommentOutcome
Remote operation The plant should be able to be started and stopped, as well as be operated and monitored, from a remote location. The AWTP is judged to meet the criterion to be able to be operated remotely. 
Auto start/stop The AWTP should be able to operate on a batch basis, such that it starts and stops automatically, in order to satisfy the treatment of the variable wastewater flows from the secondary treatment plant. The plant is judged to meet the criterion to be able to start and stop automatically and operate in batch mode to cater for seasonal variations in feed volumes. 
Unskilled local operation Local operation of the AWTP should be possible, using personnel with a good operational knowledge of the AWTP, but having qualifications in the plumbing and electrical trades and not expertise in water treatment. In the first 12 months' operation, the plant did not meet the criterion that it could be operated for an extended period whereby intervention from highly skilled personnel would not be required. It was recommended that the plant be operated for a further trial period to reduce fault types that would require skilled intervention. 
Low risk of non-conforming water Product water from the AWTP should have an extremely low risk of non-conformity with the AGWR and wastes from the plant should show an extremely low risk of being harmful to the marine environment. The water quality of the product and discharge streams of the plant met the requirements for potable water, as laid out in the AGWR, and the discharge is safe for the marine environment. 
Low chemical/energy use The AWTP should be able to operate with a reduced chemical inventory and at an energy cost that is comparable to, or better than, other sources of potable quality water (i.e. desalinated water). The energy use should be significantly better than current AAD operations. The AWTP was judged to be of low chemical inventory. The energy use of the plant was judged to be significantly less than current AAD operations for the production of potable water. 
Long plant lifetime The AWTP should be designed to operate for 20+ years, using piping and componentry that is able to withstand the rigours of transport and saline, chemical and marine environments. A number of the fixtures in the AWTP were considered not to meet the criterion that the plant should be able to operate for 20+ years. It is recommended that components not meeting this criterion be replaced with materials of higher specification or with a more appropriate material. 
CriteriaCommentOutcome
Remote operation The plant should be able to be started and stopped, as well as be operated and monitored, from a remote location. The AWTP is judged to meet the criterion to be able to be operated remotely. 
Auto start/stop The AWTP should be able to operate on a batch basis, such that it starts and stops automatically, in order to satisfy the treatment of the variable wastewater flows from the secondary treatment plant. The plant is judged to meet the criterion to be able to start and stop automatically and operate in batch mode to cater for seasonal variations in feed volumes. 
Unskilled local operation Local operation of the AWTP should be possible, using personnel with a good operational knowledge of the AWTP, but having qualifications in the plumbing and electrical trades and not expertise in water treatment. In the first 12 months' operation, the plant did not meet the criterion that it could be operated for an extended period whereby intervention from highly skilled personnel would not be required. It was recommended that the plant be operated for a further trial period to reduce fault types that would require skilled intervention. 
Low risk of non-conforming water Product water from the AWTP should have an extremely low risk of non-conformity with the AGWR and wastes from the plant should show an extremely low risk of being harmful to the marine environment. The water quality of the product and discharge streams of the plant met the requirements for potable water, as laid out in the AGWR, and the discharge is safe for the marine environment. 
Low chemical/energy use The AWTP should be able to operate with a reduced chemical inventory and at an energy cost that is comparable to, or better than, other sources of potable quality water (i.e. desalinated water). The energy use should be significantly better than current AAD operations. The AWTP was judged to be of low chemical inventory. The energy use of the plant was judged to be significantly less than current AAD operations for the production of potable water. 
Long plant lifetime The AWTP should be designed to operate for 20+ years, using piping and componentry that is able to withstand the rigours of transport and saline, chemical and marine environments. A number of the fixtures in the AWTP were considered not to meet the criterion that the plant should be able to operate for 20+ years. It is recommended that components not meeting this criterion be replaced with materials of higher specification or with a more appropriate material. 

RESULTS AND DISCUSSION

Risk assessment outcomes

The outcomes of the risk assessment demonstrated that the highest ranking risk was the health risk posed by pathogenic microorganisms in the source water. This was followed by a range of chemical compounds derived from products used to conduct station activities, for example:

  • volatile organic carbons;

  • pharmaceutical products/metabolites;

  • Chemicals of Concern (CoCs) (considered broadly at this stage of the project as carcinogens, endocrine disruptors and hormones);

  • heavy metals; and

  • hydrocarbon compounds.

Hazardous events identified included a gastroenteritis outbreak (affecting at least one third of the station population), chemical leaks and spills, bulk disposal of organic waste products and equipment/process malfunction or failure.

Overall, the outcome of the risk assessment indicated that the AWTP treatment barriers should adequately control the health risk associated with the presence of any pathogenic microorganisms under normal station operations. This outcome was supported by the QMRA (Barker et al. 2013). The risk assessment also indicated that the AWTP treatment barriers should also adequately control any health risk derived from the physical, chemical and radiological hazards. However, varying degrees of uncertainty are associated with some of the risk determinations. The greatest area of uncertainty identified was associated with the risk posed by chemical compounds and in particular CoCs. To address this uncertainty the project team developed a process to determine the removal of CoCs through the Davis Station AWTP (Scales et al. 2015a). This work provided evidence to support CoCs risk assessment outcomes (by reducing uncertainty) and establish barrier performance criteria for CCP development applicable to CoC removal.

The risk assessment identified the key points within the system at which control can be applied to reduce water quality risks. These points were drafted into one QCP plan and six CCP plans. These plans form a critical element of the RWQRMP. These were trialled during the proxy site demonstration operation at the SPWWTP.

Process validation and verification

A key output for the project specified by the AWRCoE was to ‘develop robust recycling designs and concepts for plant operations’ for small and remote communities. An essential element to ensuring the delivery of a robust system is plant performance validation and verification. This stage of the project required resources that were impractical for Davis Station; for example, access to specialist technical expertise, maintenance support, equipment and analytical facilities. The use of the proxy site at the TasWater SPWWTP, as a demonstration operation, has allowed the performance validation and verification stages to occur at a mainland location, with full access to the resources required.

This has provided the project team with an operational setting to test the application of the RWQRMP. The research required to reduce risk uncertainty can be conducted using the full scale plant and simulating high risk water quality hazards. The impact of chemical constituents/metabolites and hazardous events can be assessed, and the reuse implications determined.

The proxy site trials demonstrated that treated water quality met ADWG guideline values. The five barriers for pathogen control provide reliable protection, as did the batch-based processing mode employed in the system, where all CCPs are confirmed before a batch of water is sent for storage. On-line CCPs can be measured for all barriers, assuming an ozone residual can be achieved for the first barrier. Micro-contaminants are effectively removed by ozonation and BAC filtration, with higher quality achieved after reverse osmosis.

These validation results suggest that the demonstration plant is technically able to achieve the desired water qualities. Further operation and water quality testing has continued beyond the conclusion of the Robust Recycling project, to confirm the reliability of the AWTP for producing suitable quality water.

Robustness criteria and analysis

A trial period of investigation (August 2014 to June 2015) was undertaken where the objective was to demonstrate that the AWTP can meet the robustness criteria designated by the AAD. These criteria are outlined in Table 1. The main outcomes, up to July 2015, are also outlined in Table 1 (Scales et al. 2015b).

Policy-based risk management framework

A Davis Station RWQRMP was developed for the AWTP. The purpose of the RWQRMP is to ensure the AWTP plant produces water that is fit for purpose. That purpose is to meet the environmental requirements for the outfall for Davis Station wastewater treatment process and to potentially provide options for alternative recycled water end-uses. The structure and content of the RWQRMP has been prepared in accordance with the AGWR, phases 1 and 2 (NRMMC EPHC NHMRC 2006, 2008).

However, to develop an operational RWQRMP, assurance is needed that the identified risks will be adequately controlled and managed. This requires the risk uncertainty to be reduced. This was particularly the case for chemical risks. In the absence of, or the inability to conduct, a detailed water quality assessment, one approach is to focus effort upon the establishment of a strong recycled water policy commitment, along with the development of detailed management processes and procedures designed to ensure treatment performance capabilities. Importantly, the policy and management strategies are strongly focused on source water input control, such as:

  • approved chemical/products inventory and chemical change management processes;

  • chemical management procedures, i.e. onsite storage, handling and usage, spill response and containment;

  • the implementation of onsite waste management procedures; and

  • products for return to Australia procedures (or generically off-site disposal procedures).

The risk management strategies outlined above are supported by the Risk Assessment of the Removal of CoCs in the Davis Station Advanced Water Treatment Plant study undertaken by the project team (Scales et al. 2015a). The study states that the need for source water control is heightened in a small community due to the impact upon operations that a toxic spill may have and the reduced number of process barriers (the multi-barrier approach) applicable to CoCs removal. Out of the AWTP seven process barriers, the study found that two could be designated as CCPs (Scales et al. 2015a). These are the RO and ozone barriers. These were determined using the operational data from the SPWWTP trials (Gray et al. 2015a). The outcome of this study provided the project team with a viable method to assess the risk associated with chemical use at the station. A series of LRVs were developed for CoC compounds and provided the ability to better understand the risks associated with some of the high risk hazardous events identified, i.e. chemical spills or disposal of products to the wastestream versus return to Australia practices, as well as general chemical use at the station, i.e. pharmaceuticals, personal care products. This replaced the conventional method of understanding chemical risk through undertaking a comprehensive water quality sampling and analysis program.

The risk management process applied to the Davis Station AWTP is a clear demonstration that a functional RWQRMP can be developed without relying upon water quality data collection or onsite process validation/verification. Much of the approach taken by the project team for the Davis AWTP is applicable to any small remote community, where source water inputs are known and can be reasonably controlled.

CONCLUSIONS

Arising from this project were four key aspects in the risk management approach: adoption of a strong, policy-based, risk management framework, water supply system risk assessment, process validation and verification, and robustness criteria and analysis.

This project has demonstrated that it is possible to develop a risk management framework in the absence of large water quality and process data sets. In this case, the approach is the establishment of a strong safe water quality policy commitment. Importantly, the policy and management strategies are strongly focused on source water input control.

In contrast to a water quality system assessment conducted by a large urban or regional water utility, the physical isolation and compactness of remote supply systems make them unique. AAD personnel, with first hand operational knowledge, provided the key information source required to construct a ‘catchment-to-tap’ hazard and risk profile.

An essential element to ensuring the delivery of a robust system is plant performance validation and verification. One approach is the use of a proxy site and/or demonstration operation. This enables the performance validation and verification stages to occur at a location which has full access to the resources required, and then for the validated and/or verified processes to be installed at the remote site.

Finally, the plant robustness criteria were developed based upon interviews/consultation with local operations staff, supervisors, engineers and managers. This allowed for customisation of the Robustness Assessment to address the specific needs of the operation.

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