Biosolids Technical Bulletin

This bulletin is a "must have" for anyone involved in residuals and biosolids management. Whether you're interested in the latest treatment processes, odor management, beneficial use options, environmental management systems, or public outreach approaches, this publication has the information you need.

But before replacement, the processing capacity and operational requirements for MHI versus FBI incineration should be known. In addition, publicly owned treatment works should be fully aware of the environmental, social, and economic viability — the triple bottom line — of continuing to incinerate solids with renewed MHIs or new FBIs. With an expected increase in regulations applied to incineration, POTWs adopting new FBIs will be in a better position.

Free of Additives

Study achieves biosolids composting without amendments

Use of woody amendments in traditional composting increases materials-handling labor and mechanical costs, as well as the overall facility footprint. However, few instances of engineered biodrying have been applied to unamended biosolids. Such variables as exposure to the elements, ambient air temperature and humidity, pile depth, turning frequency, and available space affect the time to achieve the target solids content, as well as consistent pathogen kill.

Siemens Water Technologies (Warrendale, Pa.) conducted a study to explore whether biodrying of sludge using woody amendment-free composting could be accomplished successfully in its positive-aeration, agitated-bed IPS Composting System located in Bristol, R.I. This unorthodox strategy was expected to be hindered by physical and chemical properties, such as low porosity, low carbon-to-nitrogen ratio, and stickiness. Instead, however, these problems not only were not encountered, the end result achieved “process to further reduce pathogens” and “vector attraction reduction” status.

To the Limit

Biosolids management using a high-solids anaerobic digestion system in Akron, Ohio

The City of Akron, Ohio, has managed biosolids for the last 20 years with in-vessel composting. While the composting facility and marketing of the end product have been a success, they have not come without their share of trials. Odors prevail, and operating costs are increasing at an unprecedented rate as a result of competition for commodities by companies all over the world. In a continuous effort to minimize odors and stabilize costs, the city turned to a high-solids anaerobic digestion process that requires fewer amenities for operation and minimal labor.

The anaerobic digestion process was developed in Germany, where farmers treating their farm manures have been maximizing biogas generation using high-solids feedstocks (whether they are an organic waste or specifically grown for use in the digester) for the last 10 years. In Akron, the anaerobic digestion process is designed to handle up to 4536 dry Mg (5000 dry ton) of municipal solids, which is approximately one-third of the solids being composted.
 
Preliminary results indicate that the city’s sludge would produce biogas amounts of up to 1.2 m³/kg (19.4 ft³/lb) of volatile solids destroyed. This article discusses how close the process has come to meeting this criteria after a year of operation, as well as pathogen and vector attraction reduction requirements for Class A biosolids.

NEWS

U.S. EPA To Propose New Definition of Solid Waste

A change in the definition of nonhazardous solid waste under the Resource Conservation and Recovery Act could make the regulations governing biosolids incinerator air emissions much tougher.

At press time, the U.S. Environmental Protection Agency (EPA) Office of Solid Waste and Emergency Response was scheduled to release by Sept. 15 a proposed definition of nonhazardous solid waste.

EPA issued its advance notice of public rulemaking in the Federal Register on Jan. 2 (74 FR 41). The notice follows a protracted regulatory debate and a court case about whether biosolids incineration facilities should continue to be regulated under Sec. 112 of the Clean Air Act or switch to Sec. 129, which is more stringent.

“We firmly believe that we should be regulated under Sec. 112,” said Bob Dominak, residuals and air emissions manager at the Northeast Ohio Regional Sewer District. Dominak also serves as co-chair of the biosolids management committee for the National Association of Clean Water Agencies (Washington, D.C.) as well as chair of NACWA’s incineration work group.

Biosolids Injection Pilot Moves Forward

Just past the first-year mark, the Terminal Island Renewable Energy (TIRE) project is producing results that are surprising to some in the biosolids industry.

For the 5-year pilot taking place in San Pedro, Calif., anaerobically digested liquid biosolids and wet cake from Los Angeles’ Hyperion Treatment Plant are reslurried to 5% solids and injected into a 1524-m-deep (5000-ft-deep) well with a four-layer concrete barrier. The permitted biosolids undergo various monitoring required by the U.S. Environmental Protection Agency, including fiber-optic temperature sensing in the injection well, microseismic monitoring, additional temperature sensing in the monitoring well, and injection pressure analysis and modeling.

The project’s partners — the City of Los Angeles Bureau of Sanitation and Terralog Technologies USA Inc. (Arcadia, Calif.) — are testing whether Earth’s high temperatures and pressure eventually will convert deslurried wet cake into gas that can be used as a source of renewable energy.