Grantee Research Project Results
Final Report: Ecological Treatment of Blackwater for Onsite Non-potable Reuse
EPA Contract Number: 68HERC23C0010Title: Ecological Treatment of Blackwater for Onsite Non-potable Reuse
Investigators: Sund, Nicholas
Small Business: LeapFrog Design
EPA Contact: Richards, April
Phase: I
Project Period: December 12, 2022 through June 11, 2023
Project Amount: $99,990
RFA: Small Business Innovation Research (SBIR) Phase I (2023) RFA Text | Recipients Lists
Research Category: SBIR - Air and Climate , SBIR - Water , SBIR - Homeland Security , SBIR - Sustainability
Description:
Across the country, growing demand for high-quality water is met with long-term challenges due to drought, changing weather patterns, sea level rise, and water pollution. Current trends of increased water use have led to extreme water scarcity across most of the western United States. This rise in demand for water along with its increasing scarcity is causing unsustainable pressure on remaining fresh water resources. Furthermore, failure of existing wastewater infrastructure, specifically, decentralized wastewater treatment, is at unsanitary and unsafe levels.
Failed septic systems are one of the most significant contributors of nutrient pollution in our waterways. Approximately 24% of households in the United States (roughly 60 million) currently depend on septic systems and one-third of all new homes are being built with septic. These homes are typically in rural areas, barrier islands, or other areas difficult for centralized water systems to operate. Unfortunately, failure rates of conventional septic systems in some states are as high as 50%. In coastal areas and regions prone to precipitation and flooding, failing septic systems contaminate groundwater and local waterways with dangerous pathogens.
Currently, untreated and undertreated wastewater from failed septic systems and cesspools leaches into surface and groundwater, creating a toxic missed opportunity. Instead, we can elegantly transform this wasteful byproduct into clean water fit for reuse. Wastewater can be captured and treated onsite for non-potable reuse, reducing water pollution and extending the water supply at the same time.
LeapFrog Design has developed nature-based treatment technology for non-potable greywater reuse and is now expanding the applications of this technology to septic treatment and reuse. Using wetland ecology, our biological system utilizes a series of plant-microbe relationships for water reuse and treatment. LeapFrog Design’s modular ecological treatment system is an ideal innovation for decentralized wastewater treatment technology. Firstly, our system is an attractive landscape feature that utilizes wetland ecology to reduce filter strain and avoids expensive mechanical energy needs. Biological treatment processes have a low energy footprint, and the system requires only minimal power for intermittent pumping. Secondly, we utilize remote monitoring in the form of embedded sensors and automated controls to analyze treatment efficiency data. Remote monitoring and the modular above-ground position of our system reduce maintenance costs that would otherwise be highly variable in conventional septic markets. Therefore, our modular ecological treatment system has the ability to provide alternative, sustainable decentralized wastewater treatment for intentional non-potable reuse. Our system has the potential to increase water efficiency within single-family homes and help communities lacking basic, reliable water and sanitation infrastructure.
This Phase I award had three main objectives:
Objective 1. Meet relevant standards for treatment and reuse
Objective 2: Easily integrate with existing residential septic systems and landscapes
Objective 3: Reduce the cost of septic system monitoring and maintenance
Summary/Accomplishments (Outputs/Outcomes):
Throughout the 6-month Phase I award a fully functioning treatment system was installed with all auxiliary systems enabling its operation at a residential scale. Our primary technical challenge was adapting our ecological treatment process for septic effluent. We began by testing individual system components and processes in isolated benchtop experiments to ensure that they are capable of providing necessary functionality given typical septic influent characteristics and operating conditions. We used real-world blackwater collected from the local municipal wastewater treatment plant. All system mechanical, electrical, and plumbing systems were able to function as designed.
We then integrated these components and processes into a full-scale treatment system sized for a typical household. which will be tested in both lab and field conditions. Testing involved a realistic daily loading schedule to simulate typical household wastewater flows. Following thorough lab testing, we will conduct field testing by deploying the treatment system in an outdoor environment and integrating it with an existing septic system at a local residence. This allowed us to test all of the system components, pumps, valves, etc. under realistic outdoor conditions including changing weather and temperature fluctuations. This process also allowed us to test and optimize the assembly and installation process, to minimize the overall installation time. Additionally, our existing remote monitoring and control system, which was developed for the greywater system, was adapted for septic treatment. It included additional controls for UV disinfection and a septic tank transfer pump.
Throughout the Phase I award, we also developed several additional technology enhancements that enabled the adaptation of our nature-based treatment system for septic effluent. Ultraviolet disinfection was integrated into the system to ensure complete E. coli and coliform removal. Our proprietary hydroponic growing media was supplemented with granular activated carbon to enhance denitrification. We prototyped a passive recirculation and flow-splitting valve designed to maintain a constant recirculation rate and influent loading rate independent of upstream fluctuations. The end result was a fully functioning “production prototype” that has been tested under field conditions and is now further pilot-scale testing and manufacturing.
Conclusions:
The Phase I award allowed us to meet our objectives. Demonstrate that our nature-based treatment solution can provide effective treatment and nitrogen removal of domestic blackwater.
We were also able to easily integrate the treatment system with an existing residential septic system and greatly reduce the installation time. All treatment components were able to be located above ground which means the system did not require any excavation or heavy equipment. Only minimal modifications were made to the existing septic tank lid. Two people were able to complete the installation in a few hours.
Our preliminary results from Phase I show that the treated water quality is close to reuse standards in several key parameters. First, the higher loading rate of Total Suspended Solids (TSS) in septic effluent showcased the effectiveness of our proprietary container design which utilizes integrated baffles to enhance pretreatment.
Second, nitrogen removal can meet required targets as long as enough planter modules are used. Additional time is needed to optimize the recirculation ratio and hydraulic loading rate to achieve maximal nitrogen removal and minimize the overall system footprint. Additionally, we will need to run the treatment system over a longer period to estimate the water collection potential of the technology as a yearly average. We propose to validate both of these objectives during Phase II of the award.
In addition to the technical R&D completed in this project, we also participated in the EPA-sponsored I-Corps program to validate our product features and accelerate our commercialization efforts. Through this program, we validated that our above-ground system is favorable compared to below-ground systems because it does not require extensive excavation. This design makes integration with existing septic systems easier. We also learned that pump maintenance is a significant O&M cost for septic system technicians and service providers and that our remote monitoring system could improve problem detection and proactive maintenance.
Based on these findings, the team made significant commercialization progress in the advanced septic treatment market. One of our main findings is that, although the septic reuse market and regulatory landscape need more time to mature, the market for non-reuse applications of treated blackwater is vast and solutions are permittable today. We have found several customers in the septic upgrade as well as the tiny home market that need more affordable and scalable blackwater treatment solutions. Many are interested in using our system in combination with urine-diverting toilets to separate feces and other solids from the wastewater stream. This combination of technology can improve the overall wastewater treatment process and may in fact be more suitable for providing fit-for-purpose water for reuse applications. We propose further investigation of feces-separated blackwater treatment and reuse in a subsequent Phase II award.
SBIR Phase II:
Ecological Treatment of Blackwater for Onsite Non-potable ReuseThe perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Conclusions drawn by the principal investigators have not been reviewed by the Agency.