For several decades, lobe and multistage blowers were the tried-and-true blower technologies for wastewater treatment plants. Over the past 15...
Turning wastewater treatment plants into recovery centers for valuable resources
Many years have passed since “wastewater” became a more acceptable term than “sewage,” even as any mention of the word “sludge” was avoided whenever possible. It is now time for another terminology transition for this oft overlooked resource pool, to a nomenclature that underscores its economic benefits for both public and private sector investors.
Unfortunately, from a business standpoint, the current conversation about wastewater focuses more on the elimination of undesirable elements than the vast opportunity to recover valuable resources such as water, energy and other essential nutrients. Especially in countries that use a disproportionate share of water and energy, the continuous recycling of these resources will better serve current and future generations than delving deeper into dwindling supplies.
With that in mind, wastewater treatment plants are poised to become resource recovery centers, generating valuable products and operational savings in conjunction with the treatment of used water wherever there is a business model to support it.
Population growth and migration, finite water resources, energy restrictions, limited long-term nutrient supplies, climate change and stressed finances are forces that already commonly drive communities to consider resource recovery. Specific objectives and circumstances, however, differ across communities and regions. Smart utilities and private investors can seize the opportunity to generate meaningful returns and simultaneously earn recognition for green practices by implementing business strategies that balance resource supply and demand with competing needs and local realities.
Let’s take a look at three particularly important examples of how recovery strategies translate into both conserved resources—natural
and economic—as well as significant capital growth opportunities.
From Singapore to Scottsdale, Ariz., water recovery for industrial or other water reuse applications is gaining popularity as demand outstrips supply and public acceptance grows. Water is already continuously reused because the water drawn from local rivers has been used by industries, households and others, treated, and discharged upriver of water supply intakes. Technology solutions now enable us to speed up nature’s processes for cleaning water, but it is necessary to educate the public about the true value of water and the need to move past the “yuck factor,” especially where water scarcity is an issue.
It is equally important to match the level of treatment to the specific reuse purpose to ensure that cost factors are aligned. For example, purification of water designated for industrial uses such as boiler cooling to levels compliant with federal drinking water standards can create a poor value proposition. By contrast, use of advanced treatment (membrane bioreactor) technology at the Butler Drive Water Reclamation Facility in Peoria, Ariz., to produce high-quality effluent for aquifer recharge creates a water resource that makes sense both environmentally and economically.
A concerted effort to reduce greenhouse gases and control escalating energy costs has sparked growing interest in gas recovery and power generation at treatment facilities. Energy represents between 25% and 60% of a wastewater utility’s operating costs; therefore, savings achieved through reduced energy consumption can have significant financial benefits.
In many areas, biogas generated during treatment is used, especially at large facilities, to power system equipment and maximize energy efficiency. Energy recovered from within the system also can be used to heat city buildings or generate electricity to sell to local power grids.
In the U.K., for example, the Cotton Valley Wastewater Treatment Plant applies advanced technologies to yield more biogas from organic matter, creating enough electricity to run the plant.
In the U.S., many large wastewater treatment facilities are likewise moving toward energy neutrality, seeking to recover or generate as much energy as they consume. California’s East Bay Municipal Utility District wastewater utility has become the first in the country to generate more power than it uses, thanks to a new jet-engine-sized turbine and an import of chicken blood, food scraps and cheese production waste. The $32-million power plant expansion is a model for the industry because it helps eliminate problematic waste streams, reduces greenhouse gases and is a good deal for ratepayers.
As a result, investment in energy-efficient technologies in tandem with energy generation/recovery technologies pays dividends environmentally and economically through a reduction in energy needs and replenishment of energy supplies.
Phosphorus is a limited natural resource that all animals and plants need to live, yet only a few countries—including Morocco, the U.S. and China—have substantial supplies of this essential element. Although the prediction of reserve depletion in 100 to 200 years is too far away to get the crisis planning engines humming, environmental leaders have begun the dialogue and manufacturers are investing in technologies to recover phosphorus. For investors, it is a safe long-term investment in a commodity that will still be in great demand as its scarcity increases.
The economic benefits already are quite tangible. At the Clean Water Services Durham Advanced Wastewater Treatment Facility in Tigard, Ore., for example, 100% of the wastewater stream is being treated with Ostara’s nutrient recovery technology, removing 90% of the phosphorus in the wastewater’s liquid stream and producing 500 tons of Crystal Green fertilizer annually. Opened in 2009, this first-of-its-kind, full-scale commercial nutrient recovery facility is expected to pay for itself within five years through a combination of fertilizer sales, accelerated compliance with more rigorous resource standards and savings in energy and maintenance costs.
In Lawrence, Kan., the first U.S. pilot test of Asahi’s phosphorus absorption media showed promising results by reducing phosphorus in the effluent to ultra-low levels while recovering phosphorus for use as a high-grade fertilizer.
Increasing phosphorus reserves also conforms to heightened federal and state nutrient discharge limits that protect receiving water bodies. Repurposing the very phosphorus that may have otherwise stimulated algal growth in coastal areas and large lakes to instead fertilize food crops represents measurable profit potential for private enterprises while helping offset costs for public entities.
Of course, the economic benefits and private investment potential of any resource recovery operation requires sound business planning and sufficient outlets to make use of the recovered product. There is no reason to add advanced treatment processes to an existing facility to produce high-quality reuse water if that product is unacceptable to the local end-users for any reason. Nor does it make dollars or sense to turn biosolids into market-grade fertilizer if there is no local demand. That said, the demand for post-treatment products is, on the whole, strong—and is expected to increase.
Kentucky Case Study
The Louisville and Jefferson County (Ky.) Metropolitan Sewer District produces and distributes highly treated biosolids fertilizer to local hardware stores. Louisville Green, produced at the Morris Forman Water Quality Treatment Center, primarily is sold for agricultural use in the state. The district uses recycled methane gas from its wastewater treatment operations as the primary fuel for the dryers that ready the product for market.
Economic, social and environmental bottom lines have long converged on recycling as the right thing to do. A paradigm shift that allows wastewater treatment plant owners to capitalize on resource recovery requires vision, business model evaluation and funding. The path ahead is difficult as municipal plant owners and their communities will have to embrace the potential of private investment; but organizations, governments and private investors around the world are increasingly realizing that, as a bottom-line proposition, a wastewater treatment plant by another name can smell ever so sweet.