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New wastewater technology could help clean up lakes

Jim Lockrem of SJE-Rhombus fills a beaker of clean wastewater and shows it to Mary Ann Bond and Denise Oakes of the MPCA at the Lake Melissa Ceramic MBR Cluster System. (Brian Basham/DL Newspapers)1 / 3
The Ravenswood Beach wastewater treatment facility takes up only about 200 square feet, a much smaller space than would be required using older technologies. (Brian Basham/DL Newspapers)2 / 3
Wastewater before going through the ceramic cleaning process and the same water after. (Brian Basham/DL Newspapers)3 / 3

It's the most exciting news since you first learned to use the big toilet by yourself --  SJE-Rhombus has a new treatment system that could be the next great thing for the health of Minnesota lakes.

The compact system takes toilet water and turns it into water nearly clean enough to drink.

"This is state-of-the art -- this is one of the cleanest small systems in the United States," said Jim Lockrem, technical director of SJ Rhombus' environmental group.

It is the first flat sheet ceramic MBR treatment plant in the United States.

"Worldwide, it's the highest level of treatment available at this time," added Mike Metelak, marketing director for the environmental group.

Both men have been deeply involved in developing the new system, as has Dave Long, in charge of new product development for the company's environmental group.

They have high hopes for the success of the system.

"We expect this to be a (growth) catalyst," said Metelak.

The system weds SJE-Rhombus' expertise in electronic controls with cutting-edge German technology in the form of ceramic filters.

"We have the exclusive rights to market this technology throughout North America," Metelak said. The membrane appears solid, but actually provides microfiltration down to .2 microns (about 1,000 times smaller than a human hair).

With 500,000 individual septic systems and 1,000 cluster systems in Minnesota, and growing concern about pharmaceuticals and endocrine disruptors finding their way from human waste into surface water, the new technology could help clean up the state.

The system already serves the 36 homes on Lake Melissa's Ravenswood Beach, which has been a test site of sorts for the new technology.

Ravenswood Beach has long had a group septic system, but one of two small drain fields was failing after 30-some years of operation.

It seemed like a good place to test SJE's new Ceramic Membrane BioReactor, and the system was installed between the existing two-part collection tank that receives sewage from all the homes, and the drain fields, which were used as final treatment for the brown water.

The new process uses old technology -- adding air to wastewater to create a biological system -- to eat the sewage.

But it does so in a much smaller space -- about 200 square feet compared to about 4,000 square feet needed to handle 10,000 gallons a day under the old technology, Lockrem said.

"Adding air is old technology, but it requires a big footprint and you do not get the same level of treatment," Metelak said. "The membrane allows for a small footprint."

The brown water that is left over used to go into the drain fields. Now it runs through the ceramic filter and comes out sparkling clean.

It is still pumped into the drain fields, but for disposal, not final treatment. The water is so clean it actually fixed the failed drain field, which no longer has problems with surface ponding.

"That won't happen in all cases, but it did in this one," Lockrem said.

The processed water could easily be used for lawn watering or flushing toilets, and is clean enough to be discharged into wetlands.

"It's a water resource now," Metelak said. "It's almost a waste to just put it in the ground."

The new technology has implications for water-scarce parts of the world, in that, with minimal treatment, it would essentially allow water to be continually reused.

The ceramic filters are self-cleaning -- they are periodically backwashed with the clean, treated water --  and the system has automated controls that can be monitored and controlled from the internet.

Conventional activated sludge treatment plants are "typically very operator-intense," Lockrem said. "They have to make sure the biology maintains the proper settling characteristics. But with the ceramic membranes you do not need to worry about the settling characteristics, because you cannot pass solids through."

The Ravenswood Beach septic system handles anywhere from 900 gallons per day in the wintertime to 9,000 gallons per day during peak summer weekends.

SJE's Ceramic Membrane BioReactor system is

very expandable, Metelak said. "That's one of the beauties of membranes. We're targeting municipalities (that process) up to a 1 million gallon flow per day."

The filters will last about 20 years before replacement, about three or four times longer than conventional filters.

The new process could be a solution for expanding smaller cities like Detroit Lakes. Instead of running all sewage through a central plant, outlying areas could be served by smaller systems.

The Ravenswood Beach project is a collaborative effort involving the Ravenswood Beach Improvement Corp., SJE-Rhombus, and the University of Minnesota Water Resources Center.

"Ravenswood beach 30 years ago was very innovative in setting this (collective septic system) up," said Lockrem. "This just carries on the tradition they started 30 years ago with wastewater treatment."