70% Reduction in Biosolids Significantly Reduces Storage Needs

Background

For several years, we have collaborated with a meat processing facility to address their wastewater and permitting needs, including troubleshooting their anaerobic digester, permitting for land application, exploring alternatives for biosolid management, and securing numerous approvals through state regulatory agencies.

The facility had been applying biosolids from the wastewater treatment plant to local farmland throughout the year. Recently, the Wisconsin Department of Natural Resources modified the site’s WPDES permit prohibiting application of biosolids during winter months when the ground is frozen. The facility was required to provide a minimum of 180 days of biosolids storage during cold weather periods. The facility did not have the necessary storage capacity or land area to increase storage capacity and turned to Foth for a solution.

Approach

We conducted a thorough evaluation of alternatives to reduce biosolids volume, including anaerobic digestion and mechanical dewatering and drying. Mechanical dewatering and drying was identified as the best option to achieve the desired results. This cost-effective option also presented an opportunity for a future revenue source as a fertilizer.

Upon approval, our team began designing the new biosolids drying facility featuring moving ring dewatering presses, dehumidification units, solids grinder and granulator, conveyors, and a new building. Additionally, we designed improvements to the WWTP headworks featuring a new building, rotary drum screens, and a grit chamber.

We are overseeing the construction of the facility, with completion slated for summer 2025.

Results

The mechanical dewatering and drying solution is projected to reduce biosolids volume by 70%, allowing the facility to use existing storage capacity. Additionally, the headworks improvements will remove over 85% of biosolids larger than .075 inch, enhancing treatment efficiency.