Barriers to the adoption of sewage mining include public perceptions of the quality of the recycled water, a fragmented and inconsistent regulatory framework, and a lack of robust and transparent economic evaluations of infrastructure investment opportunities. The article focused on recycled water and the drivers and barriers to the development of one of its elements, the sewage mining industry, in Australia. Conclusions are provided in Section 7, which outlines a strategy to enable the growth of a sewage mining industry.
Failure to develop recycling resources such as sewage mining leaves communities vulnerable to the constant vagaries of the environment and the maintenance of short-term 'patch'.
Introduction
The funding of large-scale infrastructure in the water industry through government grants has led to claims that it restricts private sector investment and hinders competition (Young 2007). The potential of PPP involvement in the recycled water industry has increased with changes in policy and with technological advances. In the field of wastewater management, urban wastewater treatment plants have traditionally been centralized due to health and reliability concerns and the small capacity of alternative systems.
However, improved technology offers scope for small-scale development and private sector involvement (Tjandraatmadja, Burn et al. 2005). in the provision of water infrastructure and water supply.
Research Questions
Sewer Mining
Sewer mining drivers
Sewage mining can and does provide a significant number of benefits for local communities, businesses and organisations. In other words, the treatment can be tailored to specific user requirements, there is no longer a need for a one size fits all product. The PPPs can take a variety of forms, such as design and construct, build own and operate and long-term contractual arrangements.
Sewer mining barriers
- Public perceptions
- Regulatory framework
- Financial evaluations
- Product quality
One of the key areas identified by the Productivity Commission (Productivity Commission 2008) was the need for further research into the costs and benefits of using prices to indicate water scarcity and resource allocation. Consumer perceptions of prices and costs in the water sector need to be addressed to some extent through consultation and education programmes. Given that the public has little knowledge of the true costs of the water sector (Hurlimann, McKay et al. 2005), it is important to engage widely with the community on both pricing and health issues.
The regulatory and legislative framework has failed to keep pace with the pace of technological change in the recycling industry and sewage mining in particular. Water is not necessarily a natural monopoly, "One of the main insights of the privatization program in Britain was that network services such as gas, electricity and water contain elements of natural monopoly but also potentially competitive sectors." (Robinson 2004). Queensland has already promoted the idea of a more streamlined approach to the water industry by simplifying and increasing certainty in the regulatory process and improving the timeliness of regulator decision-making (Queensland Government 2007).
One of the key elements in any decision to undertake a PPP is their financial evaluation process. Real options theory builds on the Black and Scholes option pricing models developed in the early 1970s. The value of real options is that they can provide a framework for qualitative consideration of alternatives where flexibility is required in the face of uncertainty (Howell, Stark et al. 2001).
Externality pricing (i.e. non-market costs or benefits) is an important element in cost-benefit analysis (CBA). In some cases, depending on the reuse application, treatment may not be a financially feasible option in the traditional sense.
Planning and Implementing a System
Examples of sewer mining operations
- Sydney Olympic Park
- Beverley Park Golf Club
- Riverside Rocks Park
- Ecovillage at Currumbin
- Kings Domain gardens
- Southwell Park
There is potential to use sewage mining in many applications, including for example in over 200 golf clubs in Sydney that are located directly over sewer lines and that use up to 4 ML of potable water per day to irrigate their greens (Farmhand Foundation 2004). Sewage mining is part of the Sydney Olympic Park Authority Water Reclamation and Management Scheme (WRAMS) at Homebush Bay in Sydney, where reclaimed water replaces 50% of the potable water that would otherwise be used in the Sydney Olympic Park and Newington Estate (Sydney Water 2006) ) . About 40% of the recycled water is used for toilet flushing and 60% for irrigation and operational washdown activities (Sydney Olympic Park 2006).
Waste water is collected through a low infiltration sewage system that is treated to class A+. highest standard) and is recycled for on-site irrigation, household toilet flushing and external household use (Tanner 2007). In 2002, Melbourne Water trialled a sewage mining system at Kings Domain Gardens, later at Albert Park Lake and now transferred to Werribee, showing that membrane technologies could produce Class A reclaimed water from Melbourne sewage. The unit, housed in a 12m shipping container, had no major environmental impact and was suitable for exploiting the potential of on-site water reclamation to irrigate parks in Melbourne (Radcliffe, 2004) or to top up Albert Park Lake, delivering 30,000 litres. high quality water. recycled water every day.
The Southwell Park sewage mining project in the Australian Capital Territory is designed to recycle up to 600kl per day. Sydney Water has pursued localized water recycling schemes involving sewage mining, but uptake rates appear to be low. In February 2008, Sydney Water highlighted just two examples of sewage mining initiatives in greater Sydney.
However, Sydney Water noted that more sewer mining initiatives were on the way and that the NSW Government's Metropolitan Water Plan 2006 encourages innovative private solutions to water supply, particularly through recycling. Sydney Water was also able to point to larger-scale recycling programs involving sewage treatment plants.
Costs and pricing
These were the Homebush Bay Water Reclamation and Water Management Scheme and the Sydney Olympic Park Authority's Kogarah Council initiatives (see above). These include the proposed Hoxton Park project where recycled water will be provided to residents and businesses, as well as a recycled water supply to the BluesScope industrial plant in Wollongong (Sydney Water 2008). This cost was compared to the option of reusing wastewater from a central treatment plant, which would cost between $650/ML and.
However, the capital costs of this system would be greater at $6 million to $6.5 million compared to $2.4 million at the Southwell facility in the ACT. The submerged membrane bioreactor wastewater treatment process combines an aerobic biological treatment process with a submerged membrane system. Technological advances combine with the added advantage of a small footprint, making this a sought-after technology.
This system is a biological purification process in which a mixture of sewage and activated sludge is shaken and aerated. The combination with organisms creates a biological flake that reduces the organic content of the sewage water. Given the highly regulated nature of Australia's water industry, the variability in pricing regimes and the public perception that recycled water should be discounted against drinking water, it is not surprising that the supply of recycled water is rarely economically viable and rarely fully cost-recovery ( Hurlimann). , McKay, & Geursen, 2005).
The table below illustrates the variation in the price of drinking water in Australia, where water prices contain 2 elements, a fixed access charge and a volume charge. The cost to connect and use the infrastructure ranged from $34 to $173 for water connection with usage charges varying widely, while fees for sewer connections range from $89 to $410, with most authorities choosing not to charge usage charges.
Regulatory and Policy Framework
Roles and Responsibilities
This table identifies the key actors in the recycling process and the policy issues they face.
Towards an Improved Policy / Regulatory Framework
Limitations of the Study
Future Research
Conclusion
Urban developers and local governments working together: reusing water safely and appropriately IPWEA NSW Division Annual Conference. 34;Sustainable water management:: some technological and social dimensions of water recycling." Sustainable Developments International Retrieved from. Judd, The MBR book (2006) Principles and applications of membrane bioreactors in water and wastewater treatment, Elsevier, Oxford.
Risk assessment and health effects studies of indirect potable reuse schemes, Center for Water and Waste Technology, University of New South Wales. Independent Inquiry into the Financial Sustainability of NSW Local Government (LGI), NSW Local Government and Shires Associations (LGSA), May 2006. Securing Australia's urban water supply: Research notes for selected case studies, research notes prepared for the Department of the Prime Minister and Cabinet.
Third Party Access in Water and Sewage Infrastructure: Implications for Australia., Research paper prepared for the Australian Government Department of Agriculture, Fisheries and Forestry. In– Water Recycling Australia 2nd National Conference, Brisbane, 1-2 September 2003 CD-ROM, Australian Water Association: Sydney. SCEFPA (House of Representatives Standing Committee on Economics, Finance and Public Administration) 2003, Rates and Taxes: A Fair Share for Local Government.
34;Urban systems review-Reviewing concepts in urban wastewater collection and treatment to ensure infrastructure sustainability." Water Science and Technology: Water Supply. Workman G, Herbert R, Tink G 2003, Review of Reform of Plumbing Legislation Required for Urban Water Recycling, 2nd National Conference, Water Recycling Australia, Conference Abstracts 1-3 September 2003.
Glossary
Although turbidity (to some extent an aesthetic aspect) and pH are mentioned, the proposed parameters are mainly expressed in terms of thermotolerant coliforms (also known as faecal coliforms). Coliform values are given in Standards 9-2 for thermotolerant coliforms for various recycled water applications (Ratcliffe, 2004). There are basically three sewage treatment processes, physical, chemical and biological.
Each of the processes has a number of steps that require a specific technology, leading to a grade of water quality which in turn leads to the next step for higher quality water. To further explore the broad groups of technologies available for water treatment, representative technology types are described. These technologies listed below provide an overview of the most common and applicable treatment systems available and include;.
Activated sludge is a suspension of microorganisms in water that are activated by air providing oxygen, so the activated sludge process is an aerobic process of suspended growth. Fixed growth treatment systems are used primarily to remove dissolved and colloidal organic matter from water. The wastewater flows between and through the non-woven lightweight textile material in the RTF and through the sand layer in the RSF.
As the stream percolates through the wetland, biological oxygen demand (BOD) and total suspended solids (TSS) are reduced primarily by biological decomposition. There are four classes: microfiltration has the largest pore size, decreasing to ultrafiltration, nanofiltration and reverse osmosis. As pressurized water is passed through a membrane, it 'squeezes' through the structure and the membrane captures larger contaminants.
There are two basic configurations for an MBR: an integrated submerged bioreactor that immerses the membrane inside the activated sludge reactor and a bioreactor with an external membrane unit.
