While the term “Water Resource Recovery Facility” may seem like nothing more than a trendy phrase, the name change represents a distinct shift in the role that wastewater utilities can now play.
Wastewater is packed full of resources — nutrients, micronutrients, metals, grit, biopolymers, biosolids, and more — and much of that can be recovered and sold, offering additional income for WWTPs.
The concept of extracting resources from wastewater is not new, as utilizing biosolids and generating energy from digester gas has become increasingly commonplace in the wastewater treatment industry over the past few years. However, many utilities are still unaware of the potential outside market for resource recovery.
A paper on Nutrient Recovery from the Water Environment Research Federation (WERF), summarizes the topic.
“Recently a new category of processes have emerged that extract specific chemical compounds, with market value, from wastewater treatment streams.
These processes include those already commercially available such as struvite harvesting to produce high quality slow-release fertilizer, and those that are not yet commercially available such as biologically-deriving polyhydroxyalkanoates (PHA) from biological nutrient removal activated sludge to produce thermoplastics, and using digester gas to produce methanol or ammonia.”
Biosolids recovery offers a host of opportunities, as biosolids contains essential nutrients such as nitrogen and phosphorus, trace minerals and carbon, and provides significant soil water holding capacity enhancement, according to the WERF report. For farmers, these nutrients can significantly improve crop growth and yields, and reduce the use of chemical fertilizers.
Recent nutrient discharge regulations have resulted in an additional cost burden for many utilities. Recovering these nutrients can offer a solution, according the WERF report.
“Increasing nutrient discharge regulations from wastewater treatment facility discharges has driven a movement to looking into nutrient recovery from wastewater to meet both regulatory drivers and to produce an internal revenue source. Nitrogen and phosphorus are critical components of both our agricultural system and our wastewater treatment regulations, and there is reason to look into recovering these nutrients from wastewater,” writes WERF in their Nutrient Recovery Report.
There is also a significant demand for phosphorus. Readily available phosphorus is being depleted at an unsustainable rate, with current reserves projected to be depleted by 2050. In addition, nearly 90 percent of the world’s estimated phosphorus reserves found in just five countries: Morocco, China, South Africa, Jordan, and the U.S., reports WERF. * Track_01_1100_Nutrient_Recovery
Nitrogen offers a potential recovery opportunity of $9,978 to $74,835 per year for a 10 MGD wastewater treatment facility. Phosphorus offers a potential recovery value of $1,313 to $9,850 per year (figures are based on 2009 prices), according to the WERF report. These prices vary widely, and depend significantly on the natural gas market. While the market rate may be unpredictable, resource recovery should still be considered as it can at least offset costs that WWTFs are increasingly facing as new environmental regulations are implemented.
“Resource recovery is not likely to be a major revenue stream for WWTFs, but rather it may help offset treatment costs to meet current and future environmental goals,” reports WERF. “For example, the revenue generated from struvite recovery may help off-set the cost of meeting nutrient discharge regulations which are being implemented around the world.”