South Platte Renew seeks out new ways to reduce costs, improve environmental sustainability and increase process performance. We look for new opportunities each day to help us achieve these goals. Below are current projects and innovations taking place.
Projects in Review
The 2019 Master Plan identiﬁes infrastructure improvements and operational enhancements that allow SPR to be both financially and environmentally sustainable. The prioritized implementation plan includes a justiﬁed 20-year capital improvement plan (CIP) that balances capital and operating expenditures to achieve long-term ﬁnancial sustainability. For this plan, longer term planning drivers were also assessed to allocate the physical space needed over the next 20 years. This approach provides a realistic expectation of ﬁnancial resources in the near-term and allows for integrating innovative and reliable processes in the future.
In 2012, SPR initiated the Energy Improvement Program (EIP), which targeted identifying areas where operational improvements or systems innovation could improve overall energy efficiency. One of the areas of focus of the EIP was evaluating the beneficial use of the anaerobic digester gas produced on-site. Historically the facility’s digester gas has been used for digester heating with the remainder (approximately 60 percent of the gas produced) flared in a waste gas burner.
By 2017, the EIP led to the development of the “Biogas Use Applications Report”, a collaborative plan produced in conjunction with Carollo Engineers which identified and compared multiple beneficial use alternatives to solely flaring the biogas. The EIP report recommended utilizing the biogas be refined and injected into a nearby Xcel Energy pipeline for distribution.
Construction of the SPR Biogas Pipeline Injection Project began in September 2018 and was to be complete in October of 2019. The completion of the SPR Biogas Pipeline Injection Project marks the first pipeline injection project implemented at a WRRF in Colorado.
Today, over 95% of SPR’s generated biogas is recaptured as RNG and injected into the natural gas pipeline owned by SPR’s project partner and local natural gas utility, Xcel. This reuse method offsets the equivalent of 7,600 liters (2,000 gallons) of gasoline per day and over 22 million petroleum-fueled passenger vehicle kilometers (13.5 million miles) per year, reducing fossil-fuel-based carbon dioxide emissions by more than 5 million kilograms (5,000 metric tons) per year. Beyond its environmental and community benefits, this pipeline injection system is anticipated to collect a significant return on investment.
Table 1. Regulation 85 Effluent Objectives – 30 Day Average
The table is shown to the left
Included in Regulation No. 85 is a 10-year voluntary incentive program which grants an extended permit compliance timeframe to meet more stringent future nutrient regulatory requirements (Regulation No. 31) to wastewater treatment plants able to achieve voluntary nutrient reductions below the requirements outlined in Regulation No. 85 between 2018 and 2027 (see Table 1). With the existing treatment scheme, SPR is treating to low enough TIN limits and gaining incentive credits for Regulation No. 85 and intends to pursue nitrogen removal incentive credits through the program. Currently, SPR does not have the capacity to treat phosphorus to comply with Regulation No. 85 phosphorus limits or incentive program limits of 1.0 mg/L and 0.7 mg/L, respectively.
After the Master Plan was completed in April 2019, it was determined that chemical phosphorus removal would be the preferential method to decrease effluent phosphorus concentrations at SPR. Chemical phosphorus removal was the selected process alternative due to the fact that SPR can achieve Regulation No. 85 limits with lower capital costs, minimal necessary modifications to the existing infrastructure, and the ability to complement the selected solution to meet Regulation No. 31 in the future. Additional benefits to chemical phosphorus include the potential to increase biogas production from increased solids, mature technology, and adaptability to changing influent conditions.
In addition to the chemical phosphorus removal system design, SPR has included the conversion of the existing chlorine disinfection system to Ultraviolet (UV) disinfection. By converting the disinfection system from chemical disinfection to UV disinfection the facility can drastically decrease chemical usage, have consistent and reliable control over the disinfection process, and effectively meet all discharge permit requirements for disinfection. An additional driver for the conversion to UV disinfection would be abandoning the use of the ammonia bypass flow at the facility needed for chloramination formation. Discontinuing the ammonia bypass, not needed for chloramines with the install of UV, will result in achieving lower TIN limits in the effluent.
SPR has partnered with Laws Whiskey House in Denver, CO to provide carbon-rich stillage as the food source for the pilot project. Laws has shown interest in creating a more sustainable production process which aligns well with initiatives put in place by the Cities of Littleton and Englewood. Through this partnership and with a successful project, SPR may be able to further reduce chemical dependency while reducing the carbon footprints of other local businesses.
Influent Fractionation Study
Our facility has created a Strategic Operating Plan to explore innovative ways to meet strict requirements on certain nutrients before they enter the watershed. Regulations 85 and 31 will force us to improve our processes and enhance our technology. This plan tests biological and chemical treatments on water before it is released into the South Platte River. Our data contributes to development of certain models that will stimulate processes and control nitrogen and phosphorus outputs. Information from the study supplies will help decide the best possible changes moving forward.