Biosolids & Residuals

This interactive graphic will guide you through the cutting edge technology that the City of Raleigh is implementing at the Neuse River RRF to more sustainably manage biosolids residuals.

At the F. Wayne Hill WRC, a Fats, Oils, and Grease/High-Strength Waste facility injects waste rich in readily-digestible volatile solids directly into the existing egg-shaped digesters, increasing gas production for the 2.1-MW system.

Our Lifecycle Cost Analysis for two energy recovery alternatives at the James A. Loughlin, Jr., WWTP identified that a full CHP digester gas to energy recovery project would yield $2.40 of present value with each dollar of invested capital.

At the Nansemond Treatment Plant, the addition of sidestream nutrient recovery saves $450,000 annually in reduced chemical usage and sludge disposal.

Recognizing the pressures of increasing urbanization in the Research Triangle Park area and the resultant increased hauling distances – and costs – associated with their residuals management program, Town of Cary now produces a more marketable “Class A – Exceptional Quality” residuals product at the South Cary Water Reclamation Facility.

Beneficial use of digester gas and landfill gas (LFG) generated at the North Durham WWTP project site could result in annual revenue, including offsets for operation of the LFG system, of approximately $184,000 per year without any capital investment.

Lee County Utilities retained Hazen and Sawyer to prepare a Regional Biosolids Management Plan to aid them in developing a long term vision for handling wastewater treatment residuals and producing a Class A residuals product.

High solids dewatering centrifuges produce higher output solids concentrations than competing dewatering technologies and a higher solids throughput per square foot of floor space, reducing the necessary process footprint.

With the promulgation of 40 CFR 503 regulations governing the management and ultimate disposal of wastewater treatment residuals, utilities now often find themselves under pressure to provide upgraded and enhanced residuals treatment and management. Increasingly, state and local government agencies are adopting even more stringent regulations and requirements governing ultimate disposal of residuals generated during the wastewater treatment process. These changes in the federal, state, and local regulatory environment have driven a continued shift to further residuals processing and treatment resulting in a final product which has low pathogen and metals concentrations and does not exhibit significant odors.

To meet these increasingly stringent regulations, Hazen and Sawyer has designed, upgraded and expanded processing facilities for operations ranging in size from 2 mgd to 200mgd, utilizing a wide variety of technologies to produce cost-effective and environmentally-sound biosolids and residuals management programs. Our extensive experience includes research and pilot studies on innovative solids handling techniques, utility and regional master planning, and a wide range of thickening, digestion, dewatering and advanced stabilization technologies.

We maintain top expertise in:

Facility and Regional Planning

  • Integrated planning for on-site residuals management infrastructure that considers impacts of the solids handling unit processes on the liquid treatment train.
  • Utility and regional masterplanning which examines strategic assessments for residuals processing technology in light of geographic and regulatory constraints.

Residuals Processing and Facility Design

  • Evaluation and design of thickening unit process alternatives, including: gravity thickening, rotary drum thickening, gravity belt thickening, and centrifuge thickening.
  • Evaluation of and design of stabilization unit process alternatives, including: aerobic digestion, conventional mesophilic anaerobic digestion, high temperature thermophilic digestion and multi-stage/multi-phase advanced anaerobic digestion.
  • Evaluation and design of dewatering process alternatives, including: belt filter presses, high solids centrifuges, plate and frame filter presses, rotary presses, and screw presses
  • Evaluation and design of advanced stabilization technologies, including: rotary drum thermal drying, alkaline stabilization and pasteurization, composting, and thermal oxidation processes.

Sustainability and Energy Recovery

  • Assistance in development of markets for various types of biosolids, such as: stabilized biosolids for direct land application, distribution and marketing of bulk and bagged composted biosolids, and pelletized heat-dried product for fertilizer amendment.
  • Design of digester gas-fired boiler and chiller plants and co-generation facilities.

Let Hazen and Sawyer’s expertise help you make an asset of the biosolids and residuals from your water and wastewater treatment processes.

For inquiries contact:
Mohammad Abu-Orf