Landfill Wastewater Sludge Reduction Project

Sustainability Spotlight for Wastewater Landfill Sludge Reduction Project

Project Summary:

Bond Water Technologies was approached by a large national food processing plant to help manage their wastewater sludge reduction plan. The plant estimates a daily sludge haul of 3,000 gallons (3% solids) from its wastewater treatment process, incurring $500K in sludge hauling costs alone in 2023. The project aims to reduce daily sludge hauls, landfill additions, and associated carbon emissions from trucking transportation.

Project Implementation Steps:

1. Evaluation of Current Process and Investigation:

• • Assessed the existing process, which includes an EQ tank (250K) feeding centrifuges before chemical treatment to remove solids, with an average 35% solids rendered into feed for livestock.
  • Initiated an investigation into the possibility of sending sludge generated from the treatment process to the centrifuges for removal via rendering, aiming to eliminate landfill disposal and reduce transportation mileage.

2. Evaluation of Chemical Treatments:

• • Identified GRAS approved chemistries for coagulant and polymer treatment to enable rendering of treated sludge. 

3. Development of Chemical Feed System:

• • Created an automatic chemical feed system to adjust with varying strengths of incoming wastewater streams, preventing under and overfeeding of chemistry.
  • Utilized a TSS monitoring feed system to base feed all chemistry at the lowest end of the feed range, automatically adjusting as incoming TSS increased.

4. Installation of Sludge Recirculation Pump:

• • Installed a sludge recirculation pump and feed pump to mix the sludge tank and provide a consistent percent solids feed to the centrifuges.

5. Automatic Adjustment of Polymer Feed:

• • Addressed variations in percent solids from the sludge tank due to decanting by automatically adjusting polymer feed for thickening.
  • Added an additional TSS probe to the centrate tank of the centrifuges connected with the variable-speed polymer feed system to automatically adjust polymer feed to varying conditions and target a solids capture rate.

Project Outcomes:

• The facility earned “The Most Improved Industrial Pre-Treatment Award”.
• Successfully implemented feeding sludge to the centrifuges, resulting in significant achievements:
  • Reduced sludge hauls from daily to monthly, with an estimated monthly landfill reduction of 87,000 gallons.
  • Projected monthly mileage reduction in trucking transportation of 3,000 miles, leading to an associated CO2 reduction of 5,610 pounds per month.

References:

• Greenhouse Gas Emissions from a Typical Passenger Vehicle: Questions and Answers – Fact Sheet (EPA-420-F-23-014, June 2023)