Even as cities like Brisbane, Australia, are inundated with flooding, they must plan for the bigger picture that includes recent years of drought and an uncertain future. To address these and other issues in the future, communities throughout the world are increasingly turning to holistic water reviews, conservation and previously untapped supply options. Water reuse is an effective supply option that is not adversely affected by climate, geographic location or water supply situation, so it is an increasingly important component of water supply strategy. Public education and acceptance are key to the success of reuse, and it is essential for everyone to understand the many issues and misconceptions surrounding reuse before it can more fully occupy its rightful place in the integrated water supply management portfolio.
Terminology and End Use
Confusion about reclamation (high level treatment of wastewater for reuse) and reuse largely stems from unclear terminology and misunderstanding about the different levels of treatment needed for different reuse purposes. The most frequently used categories of reuse are non-potable and indirect potable. While non-potable reuse is accepted, indirect potable reuse (IPR) can cause significant angst in a community ? when it is publically identified.
The reality is that IPR can be planned or unplanned. Planned IPR is the dedicated discharge to a reservoir or an aquifer that serves as the drinking water supply for a community. Unplanned IPR is the discharge to a river such as the Thames, Mississippi or Ohio rivers, which serve simultaneous roles as discharge receivers from wastewater plants and water supply sources for drinking water plants. Throughout the world, a significant amount of our drinking water supplies are a function of IPR. The third category, direct potable reuse, is the most contentious reuse option. Although piloted and reviewed in many communities, it has only one known installation: Windhoek, Namibia. ?
The critical factor for determining whether planned water reuse is appropriate is the end use of the reclaimed water. This in turn determines water quality requirements, methods of conveying water to the customer, and required level of treatment. Non-potable reuse encompasses various types of irrigation, industrial reuse, recharge of non-potable water aquifers and other methods of reusing reclaimed water with no connection to drinking water supplies. ?
Planned indirect potable reuse ? the discharge of high-quality reclaimed water into a surface water or groundwater source that is used as a drinking water supply ? is increasing. Depending on the ultimate reuse method and reuse location, it can require a higher level of treatment, including advanced treatment processes to address salinity, microconstituents and nutrients. For example, potential discharge from the Bundamba Advanced Water Treatment Plant (AWTP) in Brisbane, Australia, to a reservoir that serves as a potable water supply drove the need for salinity, nutrient and microconstituent removal using high-end technologies. At the Black & Veatch-designed Butler Drive Water Reclamation Facility in Peoria, Ariz., wastewater is treated using MBR and UV prior to percolation ponds to reclaim the water as a renewable water supply through aquifer recharge. By recharging the aquifer, the city earns water credits, which means that Peoria can extract the equivalent amount of water from the aquifer to meet future water needs. With indirect potable reuse, groundwater and reservoir systems create a natural environmental buffer.
Dual Distribution
The distribution and storage of the reclaimed water is becoming increasingly important. Issues related to degradation of the highly treated reclaimed water from advanced water treatment plants must be addressed through modifications in distribution system design and storage. Dual distribution systems and specially designed storage facilities to reduce degradation impacts are becoming increasingly popular. Distribution of reclaimed water can also be achieved through new concepts that utilize smaller pipelines for potable water and conventionally designed (relatively large-diameter) distribution systems for delivery of reclaimed water.
Alternative Water Supplies for Reuse
Increasing attention is being paid to alternative supplies for use as reclaimed water. The harvesting of stormwater, followed by treatment and distribution as reclaimed water, is becoming increasingly important, but in most states this water must be treated to the same stringent standards as reclaimed wastewater. Graywater, generally defined as all wastewater generated in a household except toilet wastes, is finding many advocates for its use at individual homes for irrigation purposes and sometimes for toilet flushing if properly treated. Public health officials in some jurisdictions are less enthusiastic about its use because it does not generally receive any treatment. Issues surrounding ultimate responsibility to prevent plumbing cross-connections have also troubled many communities considering the use of graywater in public buildings as well as individual homes.
Issues Identified by Water Industry Leaders
Representatives of leading agencies around the world came together to discuss common themes and specific regional differences in reuse practices in a series of six roundtable events hosted by Black & Veatch during major conferences from October 2009 through June 2010.
Four key recommendations emerged from discussion points common to the various venues, leading to the conclusion that water utility and other industry leaders should:
- Work together to overcome existing public misconceptions through clear, consistent and continuous communications about water reuse and its place within an integrated water portfolio; ?
- Emphasize the value of recycled water as a sustainable resource that will help meet future demands on the water supply; ?
- Take a more integrated and open-minded approach to portfolio management as they develop water resources for their customers; and
- Call for more streamlined regulations and clearer guidelines around standards in order to improve industry knowledge of the impact of water reuse.
The following comments by the many agency representatives highlight the major issues identified in the reuse roundtables. ?
We made a decision very early on that we were going to tell it like it is. We felt that if we didn?t get buy-in early, we weren?t going to be able to make the investment we needed to make reuse work.
Sometimes we have to go back to consumers with new data and say, ?But now we know more.?
There needs to be a greater focus on educating people about how much water they consume. Consumers often believe that accessing water is their human right because it falls from the sky, but they fail to consider the treatment process that water goes through to make it suitable to drink or the cost of transporting water to their taps.
We need to institute strong programs of public education in the schools that educate about water reuse. These programs should carry the messages up from children to parents.
When you compare and contrast reuse with other alternatives, you find that there are tradeoffs, so we need to make the public aware of their options.
You don?t want to make decisions in crises; however, a crisis can highlight a problem that enables you to come to a solution you might not have had otherwise.
?Reused water? may have a negative connotation in some places; renaming this resource ?refreshed? water or
?renewed? water, for example, could encourage public acceptance.
Utility leaders should work with local communities to determine where and when consumers would be willing to accept reused water. This consultative approach will help overcome any yuck factor that arises when people consider reused water only as a potable water source.
People think, ?If dams are 80 percent full now, why should we go ahead and move to reuse?? But the time for the debate to begin is now, even if it is raining.
We need to think laterally about integrating reuse into existing systems and avoid viewing water portfolio options as mutually exclusive. It shouldn?t be desalination versus reuse ? but desalination and reuse. ?? ?
Significant barriers for reuse arise when various departments within the same government body have competing missions and objectives and when separately governed, special-purpose entities focus on only one aspect of water. Combining drinking water and wastewater management within a single agency creates an advantage for overcoming barriers to reuse.
Regulations regarding acceptable levels of particular compounds and microconstituents should be established at a local level; what works in one country may not work in another, and we need to decide what level of zero is acceptable and what level is affordable in tough economic times. The water industry needs to build a bank of credible, robust data points to demonstrate that reused water is safe and acceptable for public use.
The costs to produce highly treated reused water are often higher than traditional alternatives, so there is a disconnect among price cost, and value. Reused water is often priced to promote its use, but it needs to be priced realistically to be taken seriously as a sustainable water source for the future. Industry guidelines must therefore consider the cost to treat it to appropriate standards and the alternatives.
Conclusion
Reuse terminology is confusing, and even the preferred way to refer to the planned reuse of reclaimed water varies by region. Whether it?s called water reuse, reclaimed water, recycled water or refreshed water, it?s a sensitive subject that requires proactive and clear public communication as well as a more unified approach by agencies and organizations responsible for water management. End-use purpose is the most important factor in determining whether planned water reclamation and reuse is appropriate and then in determining water quality requirements, distribution methods and required level of treatment.
The recent flooding in Brisbane doesn?t negate the importance of a successful recycled water project with local ties, especially considering that flooding can compromise current water supplies. The Bundamba AWTP is one of three advanced treatment plants constructed as part of the Western Corridor Recycled Water Project to assist WaterSecure in providing climate-resilient water sources for South East Queensland. The purified water is available for use by power stations, industry and Wivenhoe dam as necessary to supplement the region?s drinking water supplies.
WaterSecure has used water from the AWTPs in the flood recovery effort for cleaning and washdown purposes ? as well as for continued supply to power stations. The authority has also ramped up its desalination plant due to quality issues with surface water in times of flood. These actions demonstrate the value of climate-resilient water supply sources whether it rains too much or too little.? ?
Cindy Wallis-Lage is executive managing director of technical solutions in the Kansas City, Mo., office, of Black & Veatch (Overland Park, Kan.) and Alan Rimer, Ph.D., is the company?s director of water reuse based in Cary, N.C.
