AC25 Maximizing Biosolids Value: Post-Upgrade Optimization and Market Development

CWEA Members: $35.00
Non-Members $45.00

This presentation explores the optimization of new solids handling facilities and the creation of marketable biosolids products, drawing insights from two major utilities: Hampton Roads Sanitation District (HRSD) and JEA.

HRSD’s Atlantic Treatment Plant (ATP) transitioned from Class B to Class A biosolids production by commissioning a Cambi thermal hydrolysis process (THP) skid in mid-2020. This transition resulted in increased solids capacity and improved final dewatering performance. The presentation will delve into the startup and optimization process, highlighting lessons learned and how these upgrades have prepared HRSD to adapt to future regulatory changes.

Initial startup required ATP to disinfect digesters and all associated piping. The first digester was filled with heated disinfected non-potable water and seed from DC Water’s digesters. The approach to ramping up thermally hydrolyzed sludge feed started at 50% of DC Water’s loading rate and increased over several weeks.
Using existing dewatering centrifuges, the final dewatering cake solids improved from 14-16% total solids (TS) to 30% TS after THP implementation and optimization. Curing pilots using the 30% cake and a windrow turner determined the most efficient method for producing a low-odor, aerobically cured product. Lessons from 2023 pilot studies have been applied to full-scale curing operations initiated in early 2024.

JEA, one of Florida’s largest utilities, has proactively planned for the future of their biosolids program. In 2017, JEA’s master plan recommended decommissioning the old thermal drying system and outsourcing Class B dewatered cake processing to a third-party. However, this dependence led to uncertainties in costs and regulatory compliance.

In 2020, JEA revised their strategy, recommending a new regional biosolids handling facility at the Buckman Water Reclamation Facility (BWRF). This facility, designed to handle solids from all 12 JEA-owned water reclamation facilities, includes advanced thickening and dewatering equipment, two large thermal drum drying systems, and infrastructure for high-quality pellet production. These upgrades provide JEA with the flexibility to pivot as regulatory drivers change and new market opportunities arise.

The presentation will discuss innovative strategies employed by JEA, including a pilot of an in-line high-shear dynamic mixer to re-wet dewatered cake solids, reducing transportation costs and capital expenses.
Learning Objectives:
Describe the startup and optimization process of thermal hydrolysis and its impact on biosolids capacity and quality.
Explain approaches to evaluating and upgrading biosolids handling facilities, focusing on infrastructure, process reliability, and market development.
Identify key lessons learned in the production and market development for biosolids products.