Digester Improvements and Biogas Utilization

City of Lincoln Theresa Street Water Reclamation Facility | Digester Improvements and Biogas Utilization

Digester Improvements and Biogas Utilization

Optimizing the Beneficial Usage of Biogas to Offset Energy Consumption, Reduce Operational Costs and Promote Sustainability Practices

In the past, biogas was considered a nuisance, and either ignored or flared at anaerobic digestion facilities. New technologies and enhanced biogas recovery systems have turned this wasted byproduct into a valuable energy resource. Biogas utilization has emerged as a viable and smart option for generating value from waste byproducts. 

Since 2013, HDR has assisted the City of Lincoln’s Wastewater System with digester improvements and biogas utilization at its two wastewater treatment facilities ─ Theresa Street Wastewater Treatment Facility and Northeast Treatment Facility. 

The existing cogeneration system has been in place and in operation for almost 25 years. Because of its age and condition, substantial capital expenses will be required to keep the system in operation. Furthermore, biogas production has increased beyond the capacity of the existing cogeneration facilities, resulting in the need to regularly waste biogas by flaring. 

Through a collaborative alternatives analysis with the City, our team evaluated the potential viability of other energy utilization management approaches, including: 

  • Replacing the cogeneration system 
  • Providing biogas to University of Nebraska-Lincoln campus boilers 
  • Treating for vehicle fueling 
  • Treating for pipeline injection 

The most viable option was to treat the biogas and inject it into Black Hills Energy’s gas distribution infrastructure. HDR completed design in 2019 for the Biogas Treatment System, which included:

  • Removal of equipment from the existing Generator Building and replacement with two new boilers for digester heating
  • Demolition of existing flare system
  • Construction of new Biogas Treatment System installed within the existing Generator Building
  • Construction of new Utility Gas Analyzer Building
  • Installation of buried HDPE biogas piping from the digesters to the biogas treatment system
  • Installation of a new flare system
  • Installation of buried HDPE pipe from new Biogas Treatment System to the new Gas Analyzer Building
  • Modifications of associated piping systems
  • Electrical modifications necessary for the new equipment

Construction for the Biogas Treatment System began in May 2019, with system startup and performance testing completed in August 2020.

City of Lincoln Theresa Street Water Reclamation Facility | Digester Improvements and Biogas Utilization

Awards

Award of Merit (2021)
Water/Environment Category
Engineering News-Record Midwest