Innovative Wastewater Techniques
The Moorhead Environmental Complex uses innovative wastewater techniques including composting toilets and a constructed wetland wastewater treatment system.
Why would you want a composting toilet?
Our campus has a stream running through it. The Center’s scientists have been studying White Clay Creek for more than 40 years, and as our science has grown, so have our buildings and our staff. When you have more people, you have more . . . well, you know.
We seek to utilize and treat water in a way that more closely mimics nature — leaving a smaller overall environmental footprint, better protecting the White Clay Creek. Composting toilets and a water reuse system for flush toilets will reduce water use by more than 40% over conventional systems.
How does it work?
Other than the obvious ingredient, composting “humanure” requires good drainage, a constant flow of air, a high-carbon bulking material like bark mulch or sawdust, and time. Adding redworms can help reduce maintenance and speed up the process.
What will we do with the finished compost?
If the process works as planned, more than 90% of the input material will be converted to water and carbon dioxide, leaving us with a small amount of dry material similar to topsoil. It can be removed as necessary by a licensed handler.
Wetland Wastewater Treatment
A “constructed” wetland? Can this really work?
We know that natural wetlands are excellent filters, removing pollutants and nutrients as water flows through them toward lakes, rivers, and oceans. Scientists and engineers have sought to replicate many of these natural processes in engineered wetlands.
As of 2004, there were more than 1,000 constructed wetlands in operation in the U.S. and more than 5,000 operating in Europe. When planned, constructed, and maintained properly they have many benefits, including water reuse, and wildlife habitat.
A newly planted constructed wetland (top) and the same site two years later.
How efficient are these systems at removing heavy metals?
In an EPA study conducted in 2003 on a four-year-old wetland treatment system with 48 hour retention time, the following removal rates were achieved:
- Copper and mercury: greater than 80% removal
- Lead: 83% removal
- Zinc: 60% removal
- Nickel: generally unaffected
What about nutrient removal?
The same study showed that nitrates were removed completely from the water column as soon as it entered the wetland system, and that the anaerobic conditions of the wetland reduced manganese and iron to soluble forms and increased dissolved organic carbon, which is a food source for microorganisms.
How do you maintain a wetland treatment system?
Maintenance is minimal, and consists of making sure that the vegetation is growing well and that water is flowing freely through the system.
Don’t try this at home!
Unlike many of the “green” concepts and materials incorporated our building, a wetland wastewater treatment system requires many layers of certification from design to implementation, including the services of a professional engineer and certified installer.