Evaluation of Sewage Sludge Incinerator Ash Beneficial Use Alternatives

Client: Delaware County Regional Water Control Authority (DELCORA)

Project: Evaluation of Sewage Sludge Incinerator Ash Beneficial Use Alternatives

Project Type: Biosolids, Residuals, and Hauled-In Waste Market Studies

Industry: Utilities

Location: Delaware County, Pennsylvania

DELCORA generates 17 tons per day of dry ash from two multiple hearth incinerators. This ash is currently bagged in a custom truck liner before being disposed of in a landfill, at a significant cost to the utility.

Our team engaged with DELCORA to identify potential alternatives for ash management that both achieved cost savings and beneficial use. The project included reviewing historical ash analytical data, conducting a regulatory assessment in Pennsylvania, New Jersey, and New York, and identifying potential beneficial use outlets for SSI Ash. Opportunities explored included soil blending, use as a cement and concrete additive, P extraction, and incorporation into decorative pavers and pervious pavement. Additionally, a follow up study was performed to assess the odor reduction potential of SSI ash when combined with Class B biosolids.

The odor evaluation identified the intensity and hedonic tone of the Class B lime stabilized biosolids improved as ash addition increase – with the best score at 20% ash addition. The market analysis identified opportunities from multiple markets including a Class B biosolids generator, asphalt production, and as a compost additive. DELCORA’s SSI ash slightly exceeds existing general permit metal limits, limiting this option without reopening the General Permit. DELCORA elected to maintain the existing management option, but knows these options are available as future opportunities.