In a testament to the power of innovative technology and strategic planning, the City of Chattanooga, Tennessee, has achieved a remarkable transformation in its water and wastewater treatment infrastructure. By partnering with Jacobs Engineering Group, the municipality has successfully identified and implemented solutions that have resulted in a staggering $8.6 million in annual savings and revenue.
The catalyst for this transformation was an energy audit conducted by Jacobs in 2022 at the Moccasin Bend Water Treatment Facility. This audit revealed a number of inefficiencies and outdated technologies that were contributing to high operating costs and environmental concerns.
MABR vs. HPO: A Technological Advance
One of the most significant issues identified was the facility’s reliance on a high-purity oxygen (HPO) process for sludge treatment. This outdated method was both energy-intensive and inefficient. Jacobs recommended replacing it with a membrane aerated biofilm reactor (MABR), a more advanced technology that offers superior performance and lower energy consumption.
Unlike HPO, which requires the continuous introduction of oxygen gas into the wastewater, MABR utilizes a membrane to facilitate the transfer of oxygen from the air to the wastewater. This passive oxygen transfer process is more efficient and energy-saving than the active aeration employed in HPO. Additionally, the biofilm that forms on the membrane surface in MABR provides a highly effective environment for microbial activity, leading to improved sludge degradation and nutrient removal. This enhanced biological performance, coupled with the reduced energy consumption, makes MABR a more sustainable and cost-effective option for sludge treatment compared to HPO.
Optimizing Efficiency
In addition to the MABR, Jacobs suggested several other improvements, including converting the solids train from lime stabilization to thermal hydrolysis (THP) and mesophilic anaerobic digestion (MAD), and incorporating fine bubble aeration to further reduce energy costs.
The proposed improvements to the solids train and aeration system would also contribute to increased energy efficiency. THP involves subjecting the sludge to high temperatures and pressures, which breaks down organic matter and improves its biodegradability. This pre-treatment step enhances the efficiency of subsequent anaerobic digestion, leading to increased biogas production. The biogas can then be used to generate electricity or heat, reducing the facility’s reliance on external energy sources.
Fine bubble aeration, which involves the introduction of small air bubbles into the wastewater, promotes more efficient oxygen transfer and reduces the amount of energy required for aeration. By optimizing the solids treatment process and implementing energy-efficient aeration techniques, the facility could achieve significant reductions in overall energy consumption.
How the Project Will Pay for Itself
The proposed changes came with a significant price tag of $136 million. However, Jacobs’ analysis demonstrated that the long-term benefits would far outweigh the initial investment. The optimized operation at Moccasin Bend was estimated to generate savings in several areas, including biosolids reduction, increased biogas production, reduced hypochlorite demand, energy savings, and reduced cake hauling costs. Moreover, the facility was expected to generate additional revenue through the sale of biogas. Jacobs estimated that the savings and revenue from the changes would cover the costs of the investment in approximately 15 years.
Key Takeaways
The successful transformation of Chattanooga’s water treatment infrastructure demonstrates the transformative power of innovative technology and strategic planning. By embracing a holistic approach and investing in advanced solutions, municipalities can achieve significant improvements in efficiency, cost-effectiveness, environmental sustainability, and community well-being. The lessons learned from Chattanooga’s experience can serve as a valuable guide for other communities seeking to modernize their water treatment facilities and create a more sustainable future. Here are the key takeaways for other municipalities looking to cut costs and invest in sustainability:
- The power of technology: Advanced technologies like MABR can offer substantial improvements in efficiency and cost-effectiveness.
- Holistic approach: Addressing multiple areas of the water treatment process can yield even greater benefits.
- Long-term investment: While the initial investment may be significant, the long-term savings and revenue can justify the cost.
- Environmental benefits: Improved water treatment practices can also contribute to environmental sustainability.
- Community impact: These improvements can have a positive impact on the community by ensuring access to clean water and reducing environmental pollution.
- Industry leadership: By adopting innovative solutions, Chattanooga has positioned itself as a leader in water treatment and sustainability.
- Economic benefits: The project has created jobs and stimulated local economic growth.
- Resilience and adaptability: The project demonstrates the importance of adaptability in the face of changing environmental conditions and regulatory requirements.
- Public-private partnerships: Successful water treatment projects often involve collaboration between public and private sectors.
- Data-driven decision-making: The use of data and analytics can help identify inefficiencies and optimize operations.
- Continuous improvement: Successful water treatment facilities are committed to ongoing improvement and innovation.
The success of Chattanooga’s water treatment project highlights the importance of a holistic approach to infrastructure management. By addressing these multiple areas of the treatment process, municipalities can maximize the benefits of their investments and achieve significant cost savings and environmental improvements. This case study serves as a valuable example for other communities seeking to improve their water treatment facilities and promote sustainability.
SOURCES: Water, Water Technology Online
