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STEADIGRO™, Catalyst for a Paradigm Shift Toward Recognition of the Value of Quality Biosolids Products - A Case Study of the Evolution of the Derry Township Municipal Authority's Solids Handling Program

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The generation of biogas and its use as a fuel source for thermal drying of biosolids is being considered by numerous agencies. Derry Township Municipal Authority (DTMA) has successfully developed a solids management approach that includes anaerobic digestion, septage and grease trap acceptance and pretreatment, biogas production, centrifuge dewatering, and thermal drying utilizing the digester biogas produced for drying. This approach has allowed DTMA to accomplish the production of an Exceptional Quality (EQ) product suitable for sale and public distribution and one that can be eventually be moved to higher value fertilizer markets.

For decades, DTMA produced a consistent and stable Class B product that was land applied as a liquid and/or dewatered cake to local farmland as part of their self-managed program. The program was very cost effective, but farmers were only moderately interested in accommodating biosolids applications. Stricter requirements to comply with erosion control and no-till land requirements, dependency on good weather, increased biosolids production (from increased flows, lower effluent requirements, and hauled in waste and grease program) and loss of some farmland created increasing difficulties with storage capacity and the land application program at the plant. Increasingly, DTMA was required to utilize outside contractor hauling and/or landfill disposal, significantly increasing the cost of the DTMA land application and reuse program.

A biogas utilization study conducted in early 2004 concluded that the best use for the biogas was as a fuel to drive the thermal drying of the Class B biosolids cake. This conclusion also coincided with the DTMA biosolids program goal to better manage biosolids with the intent of moving to an EQ product (established as part of the goal setting element in the National Biosolids Partnership's Environmental Management System program). Utilizing the biogas to achieve EQ biosolids brought all the goals together and made the approach very desirable to the DTMA staff and Board.

Once DTMA began producing a consistent, thermally dried product, the biosolids were characterized and evaluated for potential entry in existing local markets as part of a marketing study conducted by Material Matters. Those markets included primarily fertilizer markets such as agricultural, nursery, turf, and golf courses. User information sheets, fact sheets, and product descriptive materials were developed for the initial market survey. Also, pricing information was developed and graphs were created showing the price of nitrogen fertilizer on $/lb basis for use in market survey.

In order to complete the fertilizer registration process required in Pennsylvania, DTMA was required to have a product name. After what can only be described as an interesting brainstorming session (with a public relations firm) to develop a suitable product name, several candidates were selected (and many “unsuitable” names were shelved). Because the dried EQ, granular product improves and enhances soil structure, and supports consistent, uniform plant growth, the name CLEARWATER STEADIGRO™ was selected and a logo was created. A product name and identity was also needed to assist in breaking into the desired markets. This paper will describe the progression of the biosolids management program from a waste mentality and concern for “getting rid of” solids, to one of product focus and placement in existing markets. It will also describe the surveys, demonstrations, and field trials that took place. In addition, the program costs, and actual and projected product revenues generated from sale of the biosolids will be summarized. Future plans include consideration of product enhancements such as screening for size and fortifying to meet specific product requirements will also be discussed.

Keywords: Exceptional Quality (EQ) biosolids; crop yield; diammonium phosphate (DAP); fertilizer; grain size; plant available nitrogen (PAN); thermal drying

Document Type: Research Article


Publication date: 2010-01-01

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