Biosolids Composting

“Biosolids” is the public relations name that was given to sewage sludge back in the early 1990’s.  In most industrialized nations, commercial and domestic waste water is collected and treated to remove substances that would otherwise be harmful to human health and the environment. This is also true for homes on septic systems because the solids that are pumped from the septic tank also need to be processed.  The residual semi-solid material from the waste water treatment process is now referred to as Biosolids.

Biosolids are generally dewatered at the treatment plant to a point where they contain 15% to 25% solid matter (i.e., 75% to 85% water).  They tend to be nutrient rich and as such, they are compostable.  Wet substrates such as Biosolids require a considerable amount of bulking material to meet the moisture and porosity requirement of an initial compost mix.  Bulking agents typically consist of relatively dry ground up land clearing debris (“hog fuel”) and shredded urban wood waste (lumber scraps and pallets).

When Biosolids are produced they are generally considered a “Class B” by-product, meaning that they still contain sufficient pathogens to cause harm to individuals who inadvertently consume them.  Class B Biosolids can be safely land applied for forage crops (i.e., crops for non-human consumption).

By meeting certain temperature requirements (131oF for a minimum of 3-days) Class A Biosolids compost can be produced and distributed for unrestricted use in gardens, non-food crops and roadside erosion control projects. 

Biosolids compost can be produced through the aerated static pile (ASP) method, as illustrated by several projects completed by O2Compost over the last 15 years.  Many of these projects started with a “Biosolids Disposal Problem” and now cannot produce enough biosolids compost to meet the local demand. 

Project Experience - Biosolid Composting

Fort Lewis

Snohomish, Washington
O2Compost is currently conducting a pilot demonstration project in support of the U.S. Army’s goal of zero discharge from military bases. The objective of this project is to evaluate the compostability of a wide range of waste materials, including biosolids, municipal green waste and food waste materials, as well as horse manure and petroleum contaminated soils.

City of Grants Pass

Grants Pass, Oregon
O2Compost served as compost sub‐consultant to Parametrix, Inc. for the design, construction and start‐up of the Jo‐Gro Biosolids Compost Facility (2000‐2002). This project included site selection at the Merlin Landfill, facility sizing analyses, conceptual design, permitting, and assistance through construction and facility start‐up. Follow‐up services included personnel training and third party review.

City of Port Angeles

Port Angeles, Washington
O2Compost served as compost sub‐consultant to Parametrix, Inc. for the re‐design of an existing biosolids compost facility located at the Port Angeles Landfill (2001‐2003). This project included a thorough waste stream analysis for 5, 10 and 30‐year time horizons. It also included technical assistance in designing a below‐grade aeration system, equipment selection, construction review meetings, and personnel training.

City of Everett

Everett, Washington
While under previous employment with E&A Environmental Consultants, Peter Moon provided technical assistance in conducting a pilot test project for the City of Everett (1991‐1992). This project included design and construction of 18 test piles to evaluate various combinations of feedstock materials, representing both spring and fall conditions. It further included thorough monitoring of the piles for temperature, oxygen demand, carbon dioxide production, and potential for odor emissions.

EKO Biosolids Compost

Maui, Hawaii
In 2010, O2Compost served as a sub‐consultant to Gershman, Brickner & Bratton, Inc. (GBB) to conduct a telephone survey and benchmark review of the EKO Biosolids Composting Operations in Maui, Hawaii. As part of a contract renewal process, the objective of this project was to compare EKO’s Aerated Static Pile (ASP) composting methodology with other privately operated biosolids compost facilities located throughout the United States.

View some of our completed Biosolid composting projects:   Clearwater Technologies or our other projects

Contact Us to find out if Biosolids composting is a viable solution for your municipality.