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Exploring the Power of Biogas

While biogas has fueled treatment plant generators and boilers for decades, recent changes in technology may provide additional opportunities for increasing biogas production and optimizing energy production.

South Plant Digester Gas Utilization Study

WTD initiated a study to ensure the agency responds to the changing energy landscape while maintaining a reliable energy supply to support nonstop operations.  This study compares current biogas management systems and energy production facilities at South Plant against alternative approaches to make certain the digester gas produced at the plant is used to its maximum benefit.

View report (6.8 MB)

Co-digestion of Brown Grease

Brown grease from restaurants can accumulate inside sewer pipes and clog them making for inconvenient and expensive sewage backups and repairs. But if properly collected, grease can be a rich source of “food” for methane-producing bacteria in wastewater digesters.  WTD is finalizing a demonstration project proposal for a “Brown Grease Receiving Site” to determine if we can cost-effectively turn this “waste” product into energy.

 View report (5.8 MB)

Maximizing the Benefits of Biosolids

WTD scientists are exploring the feasibility of incorporating the latest technical advancements in nutrient harvesting and odor reduction in biosolids.

West Point Biosolids Odor Study

The Technology Assessment team conducted a biosolids characterization study to determine if it were possible to oxidize sulfur compounds before the biosolids leave the plant.

The study tested whether potassium permanganate (KMnO4), a strong oxidizer known to target sulfur compounds, would reduce biosolids odor if it were added to wastewater solids prior to the centrifuge stage of treatment.

A summary of this study will be posted on this page as soon as it is available.

The Next Wave of Water Treatment

The Technology Assessment Program is committed to identifying the best methods for removing unwanted constituents in wastewater - recent projects concern the removal of estrogens and nitrogen.  Also, in advance of the next era of wastewater infrastructure projects, the program has analyzed and tested a variety of capture and treatment systems to address combined sewer overflows.

Optimizing Estrogen Removal in Municipal Wastewater Treatment

by University of Washington Department of Civil and Environmental Engineering PhD Students Mariko Lust & Ryan Ziels

Natural estrogen (produced in the body) and synthetic estrogen (produced in the laboratory - primarily in the form of birth control pills) can significantly impact the reproductive systems of aquatic animals when it reaches water bodies.  Estrogen compounds can be biodegraded by beneficial bacteria during the wastewater treatment process. However, questions remain as to how to maximize the removal of estrogens found in wastewater during the wastewater treatment process.

By controlling the conditions in different zones of the treatment process, operators can "select" or provide conditions that encourage the growth of certain types of beneficial bacteria.

Researchers want to know which of the three standard treatment processes:

  • aerobic  - oxygen-rich – used to remove BOD
  • anaerobic - no oxygen – combined with aerobic zone to remove BOD & phosphorus
  • anoxic - low oxygen – combined with aerobic zone to remove BOD & nitrogen

is best for a bacterial community capable of biodegrading three commonly detected types of estrogen:

  • Estrone ("E1") – a naturally-produced hormone
  • 17β-estradiol ("E2")  - a naturally-produced hormone
  • 17α-ethinylestradiol ("EE2") – a synthetically-produced hormone

The results will provide greater understanding about which type of bacterial communities are more effective at reducing estrogens from wastewater effluent.

This research will also produce data for use in calibrating process models so treatment plants can better predict which treatment scenarios are best at reducing estrogens or other contaminants of emerging concern.

A summary of this study will be posted on this page as soon as it is available.

For more information about the Technology Assessment Program, contact:

  • Bob Bucher
  • 206-477-9747
  • 201 S. Jackson Street, KSC-NR-0512, Seattle, WA 98104