Optimization Strategies To Streamline Community Wastewater Utility Operations
By Dennis F. Hallahan and Ashley Donnelly
The availability of robust, stable treatment systems with simple treatment processes and O&M is key to serving growing community wastewater treatment demand.
Wastewater utilities confront a myriad of challenges, from aging infrastructure to evolving regulatory standards and the emergence of new contaminants. This demands a delicate balance of managing treatment processes and infrastructure with constrained resources and time. The difficulty lies in efficiently addressing these issues while meeting growing community demands. Decentralized wastewater treatment is an often-overlooked answer, allowing for a customized solution based on the specific needs of the community. Decentralized wastewater treatment systems can sustain the environment and smart community growth while protecting public health. Engineers, municipal health officials, and regulators need innovative wastewater treatment solutions. The latest evolution of decentralized systems can efficiently handle residential and commercial daily flows and can be a cost-effective alternative to the large, centralized wastewater treatment plants of the past. In fact, some decentralized community systems are collecting and treating more than one million gallons of wastewater per day.
Benefits Of Decentralized Systems
From reduced infrastructure costs to managed aquifer recharge (MAR), decentralized systems offer a resilient and reliable approach to wastewater treatment, minimizing potential environmental impacts while offering flexibility and scalability. Allowing for incremental expansions based on population growth and changing wastewater characteristics, decentralized systems not only offer numerous environmental benefits, but also economic benefits as well offering opportunities for service providers, inspectors, installers, and designers, as noted by the U.S. EPA. These benefits make it an attractive option for addressing wastewater treatment challenges in various contexts.
Decentralized onsite wastewater systems are tried and true; they are the workhorses that protect public health. These systems serve us well, with 25% of the population and 30% of new construction in the U.S. utilizing this technology. Effluent is treated onsite, keeping water local to its original source, all while recharging local water supply aquifers. Where individual onsite septic systems are the norm, town officials have a host of traditional and advanced decentralized treatment system possibilities to protect local waterways and water supplies, upgrade outdated systems to reduce nitrogen loading, and improve overall wastewater management for the community. Because of the advances in collection, treatment, and dispersal, system technology and configurations previously only available for large-scale decentralized systems are now available for small-scale systems as well. The recent class of Alternative Onsite Wastewater Treatment Systems (AOWTS) offers high-level treatment strategies and system designs that address nitrogen reduction, watershed protection, and sensitive environments that are particularly critical for coastal communities and those where discharge to surface waters may be limited.
Advanced Wastewater Treatment Solves Greater Issues
Advanced treatment technologies for small-scale residential and commercial systems are now available that can treat wastewater to levels previously only achievable by large-scale wastewater treatment plants.
Well-known technologies include combined treatment and dispersal, extended aeration, and fixed-film systems. These treatment processes utilize naturally occurring microbial communities, which consume the organics and reduce the strength of the waste. Passive advanced treatment technologies, such as combined treatment and dispersal, remove up to 99% of wastewater impurities (BOD/ TSS) without using any electricity or replacement media. Highly purified wastewater is then released to the soil, recharging the groundwater and preventing soil and groundwater contamination.
Active advanced treatment systems provide high-quality effluent and are effective in reducing BOD, TSS, nitrogen, and other constituents. Depending on the technology, the treated water can be captured for reuse for non-potable purposes such as irrigation or industrial processes. This reduces freshwater demand and offers this highly treated wastewater a second use prior to returning it to the groundwater. Reuse may require additional levels of treatment, such as disinfection.
Passive and active advanced treatment technologies present unique benefits, offering system designers the ability to provide site-specific solutions that tailor the system design to address the specific needs of the area. Passive treatment systems allow a system designer to offer a highly treated effluent solution in remote or off-grid areas where centralized systems may not be available or are too costly for connection.
Here, one of the drainfields for the community of Rowan, Iowa, is being installed under the local ballfield.
Environmentally Sensitive Areas
In areas with strict environmental regulations or sensitive waterbodies, advanced wastewater treatment may be necessary to meet the required discharge standards. Installing advanced treatment systems can ensure compliance with applicable regulations. Enhanced nutrient removal is required to achieve these discharge standards to protect waterbodies or when a National Pollutant Discharge Elimination System (NPDES) permit is required. Advanced treatment technologies can remove a high percentage of nutrients including nitrogen and phosphorus from wastewater, which is key in sensitive environments. Additional treatment options, such as disinfection with UV light or chlorine, can effectively reduce or inactivate bacteria, viruses, and other microorganisms. This reduces the potential for waterborne diseases, thereby protecting public health.
A lakeside community in New Hampshire installs a passive combined treatment and dispersal system to treat 50,000 GPD with nitrogen reduction.
Long-Term Sustainability And O&M
Advanced wastewater treatment systems often incorporate features that provide ease of maintenance. Remote monitoring and sensors have been introduced for effective management. All treatment systems, passive or active, require some level of operations and maintenance. These O&M frameworks are one of the most critical parts of the wastewater management infrastructure, providing reliability and confidence in their operations.
Conclusion
Utilities have successfully identified less-capital-intensive decentralized solutions designed with O&M in mind to extend the life and expand the capacity of existing utility systems. These utilities have successfully installed robust treatment systems to replace or rehabilitate outdated systems. This increases the opportunity to protect natural resources and public health at a cost that communities can afford while generating opportunities for local employment. Engineers embracing these new options find them easily adaptable to various site conditions. Such decentralized systems provide long-term treatment solutions designed with O&M in mind.
About The Authors
As technical training and sales development manager at Infiltrator Water Technologies (IWT), Ashley Donnelly manages the inside sales team and is responsible for maintaining and building customer relationships including assisting engineers, contractors, and regulators with technical and design information, training, installation, and O&M. In 2020, she launched IWT’s webinar program, which is currently accredited in over 12 states and has trained over 2,000 attendees on various contemporary industry topics. She serves on several industry committees, including TOWA, NOWRA Emerging Professionals, and NEWEA Small Communities Committee.
Dennis F. Hallahan, PE, is the technical director of Infiltrator Water Technologies. Hallahan has over 30 years of experience with the design and construction of decentralized wastewater treatment systems. He has written numerous articles for onsite industry magazines and regularly gives presentations nationally on the science and fundamentals of onsite wastewater treatment systems. Hallahan also serves on various national industry association wastewater committees.