Wastewater is not typically considered an engaging topic of conversation, much less a potential asset to green building.   Yet, green builders are recognizing that water, along with energy and materials, is the essential ingredient for locally reintegrating natural and human ecosystems.  New onsite ecological wastewater treatment and reuse technologies now offer green builders the opportunity to go further in changing the face of communities by including beautiful, functional “ecosystems as infrastructure” directly in the design of the built environment.

Whether for new buildings or revitalizing existing structures and communities, decentralized wastewater reuse can create vitally important environmental and economic value to the larger community.   With advanced ecological technologies, it is possible to go well beyond conventional graywater recycling.  Advanced ecological treatment systems take high-strength (blackwater) wastewater, utilize the nutrients, and clean it to tertiary standards suitable for onsite reuse.

Incorporating such systems into green building designs offers environmental value even in many situations where a sewer grid is accessible.  The looming water shortages, combined with water infrastructure that is overtaxed, aging, and expensive to maintain, are bringing many municipalities to the edge of crisis.  New water treatment concepts and technologies for green building can help municipalities address those problems through ecological solutions, as well as offering environmentally sound approaches for sites with no access to municipal treatment.

Today’s System is Unsustainable
Many municipal officials, scientists, engineers, and green building leaders are now aware that continuing the centralized approach to water infrastructure isn’t sustainable economically or ecologically.  We can’t afford to maintain and expand this system to continue to deliver the quality, quantity and consistency of water we currently consume, much less meet the demands of the future.

The centralized approach has been the standard for centuries and provided substantial advances in public health and urban quality of life. This approach, with some exceptions, is focused on large-scale, municipal systems, treating all water to drinking standards regardless of intended use and using water once before sending it downstream.  The centralized approach uses technology to replace nature and natural processes, often generating additional pollution in the form of large quantities of sludge and impacts on receiving water bodies.

Many centralized systems still function well, and with proper maintenance will continue to do so for decades into the future.  However, the future belongs to technologies that enhance nature; that are less intensive in capital, energy, and chemicals.  Strategic integration of the new ecological technologies with the existing systems can create a resilient, flexible, and evolving system that can better match future needs.

The change is needed now.  The 2009 American Society of Engineers “Infrastructure Report Card”, which graded U.S. public works, gave wastewater infrastructure a D minus; and the Environmental Protection Agency estimates a funding gap of over $500 billion between expected expenditures and needs to update or replace existing systems and to build new ones to meet increasing demand.  At the same time, fresh water resources are being stressed as demand outpaces replenishment.

Wastewater reuse as a strategy makes environmental and economic sense, in part because not all of our needs are for drinkable water.  The American Water Works Association documents that average daily water use per capita in the United States goes predominantly (more than 70%) towards uses that do not require drinkable water (such as irrigation, toilets, cooling, and industrial process water).   Reusing treated wastewater can go a long way toward meeting these non-potable needs and significantly reduce the demand for fresh water.  Reuse is green in itself, but centralized reuse systems have large costs in infrastructure and energy.  Reliable, effective decentralized ecological treatment systems can be employed that do not require moving water long distances and by the use of a natural process further add truly green value.

A New, Local Water Model
Explicitly beginning to create a decentralized model that employs emerging and ecological engineering advances allows for extensive local water treatment and reuse – and creates opportunities for the green building community.  Advanced ecological wastewater treatment technology allows systems to be closely integrated into individual buildings, campuses, and communities.  Not only can water treatment and reuse become beautiful design elements in a project, these systems can offer net benefits to clients, gain substantial LEED credit, and can be a key part of a net zero design strategy.

Incorporating wastewater reuse into specific projects contributes to the adaptation of a model for our regional water and wastewater infrastructure that is analogous to the structure of ecosystems.  Natural ecosystems are decentralized and composed of large numbers of diverse, fractal components that use and reuse water, energy, and materials locally. The streams and rivers in a region display a decentralized structure of repeating patterns at different scales, and nutrients are utilized and recycled all along the way.

Decentralized treatment systems have been under development for some time, but now the most advanced systems integrate 21^st Century ecological engineering, biomimicry, and networked information technology.  For example, Nature’s most productive ecosystems – the tidal estuary - has been replicated and enhanced to create a blackwater treatment and reuse system with reliable, predictable performance in a compact, contained package.

In just the past decade, such modular water treatment systems have been commercialized with reduced energy consumption, small system footprint, and high-quality, tertiary treatment performance.  Tidal wetlands are among the most productive ecosystems in nature.  By adapting these ecological treatment processes to human wastewater, Tidal Wetland treatment systems reduce the footprint of early wetland designs by 80%, yet require less than 25% of the energy of typical mechanical treatment systems (e.g. activated sludge or membrane bioreactors). Tidal wetland systems can be readily incorporated into urban and suburban sites due to the compact footprint. Because they are also beautiful in addition to being functional they have been integrated into site design or even into building architecture as interior features in lobbies or atria.

Other technologies are available to combine individual decentralized systems into regional networks for practical treatment application at the urban scale.  These technologies include alternative disinfection approaches, advanced membrane systems, and inexpensive automated, networked operations and monitoring technologies that have reduced the cost of operations and maintenance.

Example Applications
As in many other technological infrastructure systems (e.g. energy and telecommunications), the momentum is already shifting to decentralized, small-scale approaches.  Green builders in many parts of the country are making wastewater reuse a central part of their green strategy.   Systems are in place or under construction in such diverse applications as office buildings, housing developments, military bases, resorts, schools and universities, and food processing operations.  Some examples include:

• The Port of Portland opened a new headquarters and adjacent parking structure in May 2010 for 550 Port staff members at the Portland Airport. Named by Forbes as one of the 10 greenest buildings in the world, all wastewater from the building is collected and treated by an engineered tidal wetland treatment system in the main lobby of the building. Treated water is reused for toilet flushing and cooling towers, helping to reduce water use by over 70 percent.
• Guilford County Schools near Greensboro NC saved over $4 million dollars in capital costs by opting for a decentralized approach to wastewater reuse.  All wastewater from a middle school and a high school is treated by an on-site tidal treatment system.  The system is located between the two buildings and provides aesthetic and educational benefits in addition to supplying irrigation water for the school’s athletic fields.
• The San Francisco Public Utilities Commission new 13-story, 277,500 square foot administration offices is under construction, designed with cutting edge, green building technology.  The urban building will generate its own energy through integrated solar panels and wind turbines, and treat and recycle all wastewater for reuse with an onsite ecological treatment system. The system will be integrated into the lobby and outside landscaping, taking all grey and black water from the building and treating the water through advanced ecological engineering processes.

Green Builders – Integral to the Transition
The green building community is making substantial strides toward reducing the costs, energy consumption, resource requirements, and climate footprint of the built environment.  Implementing decentralized, ecological wastewater systems furthers all those goals and enhances the impact of green design on the larger community.  The green building community can employ these systems to help develop a more ecological water cycle by:

• Looking for specific project opportunities to profitably apply advanced onsite or community-scale treatment units
• Working with experienced ecological engineers to design projects to a high set of performance standards based on sound technical principles to protect public health and meet green building performance objectives.
• Demonstrating value added to clients – the water/energy/money equation can make a compelling case for decentralization
• Building collaboration with municipalities and generating local choices, experimentation, demonstration, and communication/education programs based on the experience

Members of the green building community have become leading 21^st Century visionaries – seeing alternatives for sustainable design and bringing them to life, creating the future in the process. We know that there is no desirable, sustainable future without adequate, high-quality water flowing through human society and through the ecosystems that support it.  Green builders have the opportunity to lead the evolution of our water infrastructure to provide a sustainable ecological basis for truly green buildings and communities.

About the Author
Mr. Kirksey has over 30 years of experience in environmental engineering, technology, and management with an emphasis in sustainable water and energy infrastructure.  He leads operations for Worrell Water Technologies, a company offering a diversified suite of water and wastewater treatment technologies and services.  A special focus at Worrell Water is advanced ecological wastewater treatment applied to integrate natural and human ecosystems.

Mr. Kirksey’s prior experience includes senior management roles in the private sector, non-profit organizations, and government.  Specific roles included Vice President and Senior Fellow with the American Society of Civil Engineers Research Foundation; Senior Policy Analyst in the Florida Governor’s Office; and domestic and international consulting with Battelle, Price Waterhouse, and SAIC. His background includes international work experience in over a dozen countries in Asia, Europe, and Africa.

Mr. Kirksey has an M.S. in Environmental Systems Design from Southern Illinois University; and a B.S. in Civil Engineering from Tennessee Technological University.  He is a Registered Professional Engineer in the State of Florida.