Resource recovery offers wastewater utilities a more sustainable path forward—offering opportunity to generate power for plant operations and additional revenue through sale of renewable energy sources.

By: Todd Williams, CH2M HILL Residuals Resource Recovery Global Technology Leader

Todd Williams will present “Resource Recovery Opportunities at America’s Water Resource Recovery Facilities” during the ‘Growth Markets in Recovery’ strand at the American Water Summit on Nov. 5 at 5 p.m. He will speak on new and emerging opportunities for water market growth over the next several years, summarizing the current market situation in terms of rapidly growing water resource recovery facility opportunities including residuals energy recovery. CH2M HILL’s Water Business Group President Bob Bailey will also speak on a panel regarding the latest developments in the Water-Energy Nexus on Tuesday, Nov. 6.

This summer, the Water Environment Federation and the National Biosolids Partnership released a study regarding resource recovery at Water Resource Recovery Facilities (WRRF) in the United States. More than 5,100 facilities participated in the survey. The majority of facilities treat more than 1 MGD, and about 50% of them currently use anaerobic digestion to process solids.

The study produced some interesting findings that I would like to characterize as “3-3-6”—3 times as many WRRF’s do not have anaerobic digestion as those with; 3 times as many WRRF’s with anaerobic digestion don’t generate power or operate plant equipment with recovered energy as those that do; and 6 times as many WRRF’s don’t import fats, oil, and grease (FOG) or high strength waste to feed digesters as those that do. Given these results, I believe there is significant opportunity for development of energy recovery at WRRF’s in the next 10 years.

The Resource Recovery Model is not complicated. Rather than just accepting and treating wastewater, to recover energy, wastewater treatment plants with anaerobic digestion can accept additional materials beyond wastewater, including:

  • High-strength liquid wastes (HSW)
  • FOG

Using these materials and anaerobic digesters, the facility can produce multiple products, such as:

  • Recycled water
  • Biosolids (which provided carbon and nutrients for agriculture/farm land)
  • Renewable energy (power and heat)

Resource recovery offers numerous benefits to utilities; several facilities that have implemented anaerobic digestion to create biogas are achieving significant value and savings on their bottom line. Gwinnett County, Georgia and Johnson County, Kansas, for example, have both reduced their overall plants electric usage by about 50% through the development of facilities to receive and process FOG and HSW in their existing anaerobic digesters.

The East Bay Municipal Utility District is a prime example of how one utility has incorporated resource recovery into its business model. The utility added a 4.6-megawatt advanced biogas turbine to increase its capacity from 6.5 to 11 megawatts in 2011. On average, the expansion enables the utility to produce enough biogas to generate 6 megawatts of electricity. The plant only requires about 5 megawatts to operate, so by selling its surplus energy (“renewable energy”) back to the grid at a premium price, East Bay MUD has become the first wastewater treatment plant in the U.S. that is a net electricity provider.

Another great example of how one utility is putting resource recovery to work to improve its bottom line is DC Water’s new biosolids management program. DC Water is leading the industry and truly reinventing biosolids technology at the 391 MGD Blue Plains Advanced Wastewater Treatment Plant in Washington DC. This is the largest facility of its kind in the world (American Water Summit attendees will have the opportunity to tour the new facility this week). Developing the first Cambi thermal hydrolysis/digestion/combined heat and power system in the U.S., Blue Plains will reduce biosolids quantities by 50%; cut greenhouse gas emissions dramatically; generate 14 megawatts of clean, renewable power; and greatly improve product quality (Class A). When the facility begins operating next year, it will save millions of dollars annually through its biosolids program alone.

The City of Green Bay, Wisconsin is also implementing a combined anaerobic digestion and incineration facility that in combination will reduce the plant’s overall electrical energy usage by nearly 75%. Other utilities are implementing similar projects to reduce their energy footprint and add power back to the grid. There are so many more opportunities to leverage resource recovery. It’s an exciting field to be in right now as we seek innovative solutions to address energy optimization at water resource recovery facilities.

Todd Williams has spent 33 years working in environmental engineering, with operating and design experience and specific emphasis in residuals and biosolids management. Todd has made numerous presentations and is a contributing author for several articles and books significant to biosolids and residuals management, composting, and odor control including the recently published WEF/WERF/EPA Solids Process Design and Management Manual. Todd is an engineering graduate of Virginia Tech and is the past Chair of the Water Environment Federation’s Residuals and Biosolids Committee. Todd works out of CH2M HILL’s Richmond, Virginia office where he serves as CH2M HILL’s Global Technology Leader for Residuals Resource Recovery and Biosolids Management.