Water Scarcity and the Potential Role of Distributed Wastewater Management: Large Firm Client Perspective
Abstract:If there is a unique perspective provided by 33 years of experience in a large consulting, engineering, construction, and operations firm, it results from working with hundreds of municipal government and utility clients, both large and small, who are responsible for providing infrastructure, protecting the environment, and delivering reliable services in the areas of water, wastewater, and stormwater management. Most of those clients are faced with the challenges of increasing water demands and the declining reliability of traditional sources of high-quality surface water and groundwater supplies. In that context, distributed approaches to wastewater treatment, as part of integrated water management systems, will inevitably play a more significant role in addressing immediate and future water supply shortages.
Why such confidence? A number of factors are driving the convergence of what have been largely separate utility functions of drinking water, wastewater, and stormwater management. The drivers are both positive and negative. On the negative side, water scarcity is an increasingly difficult challenge given growing urban populations in watershort regions of the world, environmental concerns associated with the watershed impacts of withdrawing and exporting water long distances to meet those needs, and the energy consumed in making that happen. The increased hydrological uncertainty and more extreme weather conditions resulting from climate change compound the challenge.
At the same time, there is reason for optimism. We are seeing technology breakthroughs in water treatment processes using membranes that allow us tremendous flexibility in the management of water quality – making virtually every available water source, including wastewater, brackish groundwater, and sea water, a potential new water supply. Also, we have been increasingly successful in developing watershed-based planning approaches that incorporate low-impact development practices, reduce the amount of run-off from the built environment, and create small-scale water supply opportunities within communities at the local level. Finally, a conservation and efficiency ethic is informing decision-making in most communities, demanding that we avoid waste and recycle where possible.
Together, these forces are driving us away from exclusive reliance on single-purpose, large-scale, centralized systems that import water from long distances and export wastewater and stormwater to remote receiving waters – so-called fast-conveyance, large-pipe approaches. Instead, we are developing smaller-scale, closed-loop, integrated systems that attempt to recreate the water-cycle in more localized settings, restoring and protecting urban watersheds while meeting reduced per capita municipal and industrial water demands.
We are becoming more holistic in our approach to water management, breaking down the infrastructure and institutional barriers between water, wastewater, and stormwater utility functions. When those barriers come down, wastewater almost always emerges as a potential new source of water supply. Furthermore, at higher levels of water recycling, it becomes desirable to treat and reuse wastewater as close as practical to the locations where it is generated and needed, pushing us all in the direction of more distributed wastewater systems.
With both the motive (addressing water scarcity) and the means (new technologies and approaches) established, the direction of change seems certain to favor increasingly distributed wastewater systems. What is less easy to predict is the pace of change. Will the new technologies be used to promote fundamentally new approaches, or only be employed to extend the life and capacity of traditional infrastructure systems?
The public policy discussion regarding the relationship between water and wastewater infrastructure, particularly as it relates to public health issues, will greatly influence the speed of adoption of new approaches to integrated water management. As much as any other issue, establishing broad consensus around the appropriate role and application of recycled water for non-potable, in-direct potable, and/or direct potable reuse within communities will affect the pace of wide acceptance of more distributed systems. In cases where water planners have adopted recycled water as an essential source of future supply, the evolution of more distributed wastewater management systems becomes a natural progression of the process.
What impedes progress in this direction is largely the institutional segregation of decision-making into the traditional silos of water, wastewater, and stormwater management. Those divisions exist within government, utilities, academia, and large consulting firms. Just as importantly, they have provided the organizing framework for the regulatory process, which can limit the pace of change as well.
In this setting, large engineering firms have an important role to play as an enabler of these innovations and advances. Many policy and decision makers within the public utility and regulatory sectors rely on the advice that the consulting engineering industry provides regarding safe and appropriate engineering solutions to urban infrastructure needs. We need to be sure that we do not inadvertently create barriers to positive change.
At the same time, we cannot compromise our public health and safety responsibilities. The changes we make to our systems and approaches need to offer communities the same level of reliability that we sought in more traditional approaches. We should also be highlighting the health and safety consequences of inadequate supplies as the traditional systems, in many areas, are becoming less reliable in their ability to meet increasing water demands.
What can we do as an industry to advance the pace of change? Further research, development, and innovative demonstration projects focused on the following areas would help:
further advances in the technology of water treatment that provide flexible water quality improvements where needed;
institutional reforms in places where water management responsibilities are divided among semi-independent water, wastewater, and stormwater agencies;
advanced systems modeling that improves understanding of the complex interrelationships that exist within urban environments;
improved data collection and performance monitoring to confirm that integrated systems are achieving design standards and functioning safely;
increased emphasis on both the energy demand and generation opportunities of water infrastructure;
continued research into the health-effects and mitigation of persistent microcontaminants in the water supply;
better understanding of the appropriate scale of distributed, closed-loop systems within urban watersheds; and
greater citizen involvement and behavioral change in achieving healthy urban communities and environments.
Finally, it is important that every element of an integrated system be viewed on par with every other element. Often, it is too easy to believe that one technology or approach represents a “silver bullet” solution to all our problems. Integrated management depends on the diversity and risk reduction offered by a broad portfolio coordinated measures. We need better communications, collaboration, and understanding among professionals in all fields to fully realize the opportunities presented by integrated water management approaches. If we can achieve that, the threat of water scarcity will be reduced significantly.
Document Type: Research Article
Publication date: 2008-01-01
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