The Gear Box: New Septic Tech Aimed at Cleaning Up Cape Cod

Cape Cod has long dealt with water quality problems. This is due to the high water table, but it is also a natural consequence of life in coastal locations. Experts have also determined that The Cape’s water quality woes stem mostly from existing septic systems.

The traditional Title 5 systems that are common in Cape Cod, and across the nation, do remove contaminants and pathogens that can be harmful to human health. But they have their limits and were not designed to handle the high volumes of nutrients, most especially nitrogen, by which they were being overwhelmed.

It is for this reason that innovative thinkers, like the people behind the Shubael Pond Project, have come up with some novel, new septic designs that look like they have the potential to solve the problem. These “alternative” designs are optimized to reduce the amount of nitrogen found in household wastewater. These systems were approved by the Massachusetts Dept. of Environmental Protection (MADEP) despite the fact that they had yet to deliver the level of nitrogen reduction a water treatment plant delivers. Even so, the people behind the project decided to move forward, certain that they will reduce excess nutrient levels if not mitigate them completely.

The people at Shubael Pond Project and MADEP say that even if these new systems are not a complete solution to Cape Cod’s water quality problem, they can still be part of a broader solution. By constructing a group of 40 systems in a test neighborhood, the team believes they can demonstrate that groups of these systems can accomplish what single or isolated systems could not. They choose a neighborhood adjacent to Shubael Pond where groundwater conditions are just right for monitoring the effect these systems will have in practice.

The pond was also closed in 2019 due to cyanobacteria. This makes the location an even better test location since the results are easier to measure with certainty. In 2021, the project managers decided to install a total of 15 systems in the test area.

Elegance in Design

While the concept was more than two years old by the time teams started installing it, it remains the most promising design of its kind so far. The systems have come to be known as NitROE systems, and they are exceedingly simple.

The project installed 6 units in August of 2021 in an area with 350 homes. The system was developed by a company known as KleanTu. It consists of a 2,000-gallon tank that relies entirely on gravity with the exception of a small electric air pump. The units consist of a limestone aeration chamber and a chamber that contains wood chips. The limestone aeration chamber turns ammonia into nitrate and the wood chips section changes nitrate into nitrogen gas.

The early experimental systems also included sampling ports on the outside of the unit close to the ground. According to data gathered on the progress of the experiment, traditional Title 5 units can only mitigate between 20 and 30% of the nitrogen found in household wastewater. The NitROE units, conversely, are able to eliminate between 80 and 90% of excess nutrients.

Working out the Bugs

The units have an expected useful life of 20 to 25 years. At the end of that period, it is presumed that the units will need to be dismantled and completely replaced. However, the designers will focus on making them repeatably serviceable with future iterations. For the time being, the goal is to test the units and remove them at the end of their operational life.

The KleanTu company has high hopes for this technology and in 2022, they have been able to get the efficiency of the system up to a consistent 90%, a marked improvement. At just five years old, the concept is still quite new with plenty of room for improvement.

KleanTu is looking to make improvements to the performance of the units during winter temperatures. They say they have also enabled the systems to include phosphorous treatment for disinfection of the unit when needed.

At present, the biggest concerns are about long-term commercial viability, since the units need to be dismantled at the end of their functional life. But removable and replaceable tanks are likely to be the way these issues are solved.


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