Lakes Article: New
wastewater technology could help clean up lakes
Park Rapids Enterprise
May 25, 2009
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.
system takes toilet water and turns it into water nearly clean enough to drink.
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.
is the first flat sheet ceramic MBR treatment plant in the United States.
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,”
The system weds SJE-Rhombus’ expertise in electronic controls
with cutting-edge German technology in the form of ceramic filters.
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).
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.
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.
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.
won’t happen in all cases, but it did in this one,” Lockrem said.
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
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
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.
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.
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