The City of Clare, A Case Study A Case Study of Ammonia Reduction - - PowerPoint PPT Presentation
The City of Clare, A Case Study A Case Study of Ammonia Reduction in a Lagoon Treatment System By John Holland The City of Clare WWTP The Clare WWTP was constructed in 1989. It is one of the few continuous flow through lagoons in
A Case Study of Ammonia Reduction in a Lagoon Treatment System By John Holland
The Clare WWTP was constructed in 1989. It is one of
the few continuous flow through lagoons in Michigan.
The plant consists of
Bar Screen Microscreens 3 Aerated Lagoons 2 Clarifiers run in series FeCl2 and Polymer fed UV Disinfection
The average influent ammonia nitrogen is ranges from
15 to 20 mg/L.
The average BOD ranges from 180 to 250 mg/L. Average flow is 600,000 gallon per day. Detention time is about 30 days in the lagoons. During the winter water temperature can be as low as
slightly above 32F.
The NPDES permit limit for Ammonia Nitrogen is 11.0
mg/L from May 1st to Sept. 30th.
Even with this limit the Clare WWTP could not meet
this limit during the months of May, June and part of July.
In 2008 the MDEQ issued a directive that the issue be
resolved.
The City of Clare and their engineer of record, Goudie,
Fraser and Associates began to look at possible solutions.
Solutions examined
Mechanical Plant Turning part of one of the lagoons into basically an
activated sludge pond.
Air stripping Fixed media
The fixed media option was selected.
Most cost effective Clare WWTP only needed to lower ammonia nitrogen
by about 40% for 3 months of the year.
Could use existing aeration blower as back-up. Did not require extensive modification to the plant. Lagoons were left in operation as units were installed.
The fixed media chosen was the ENTEX Technologies,
A pilot study was performed in early spring to ensure
that the units would work under the conditions present at the Clare WWTP.
The pilot study performed very well under the
conditions.
It was determined that 16 units would be installed. The first 6 would be installed in lagoon #1 to enhance
BOD removal.
There would be no changes to lagoon #2. The final 10 units would be installed in lagoon #3
primary function would be ammonia nitrogen reduction.
The Webitat units did require additional mixing to
ensure proper removal.
The 8 - 30 HP aerators were removed from lagoon #1
and replaced with 6 – 15 HP aerators.
The diffuser system in lagoon #3 was determined to be
sufficient for mixing.
Units have controlled air flow Control valves open once a week to full to scour the
media
Installed December 2011
1/1/2012 1/10/2012 1/19/2012 1/28/2012 2/6/2012 2/15/2012 2/24/2012 3/4/2012 3/13/2012 3/22/2012 3/31/2012 4/9/2012 4/18/2012 4/27/2012 5/6/2012 5/15/2012 5/24/2012 6/2/2012 6/11/2012 6/20/2012 6/29/2012 7/8/2012 7/17/2012 7/26/2012 8/4/2012 8/13/2012 8/22/2012 8/31/2012 9/9/2012 9/18/2012 9/27/2012 10/6/2012 10/15/2012 10/24/2012 11/2/2012 11/11/2012 11/20/2012 11/29/2012 12/8/2012 12/17/2012 12/26/2012 5 10 15 20 25 Series1
1/1/2013 1/10/2013 1/19/2013 1/28/2013 2/6/2013 2/15/2013 2/24/2013 3/5/2013 3/14/2013 3/23/2013 4/1/2013 4/10/2013 4/19/2013 4/28/2013 5/7/2013 5/16/2013 5/25/2013 6/3/2013 6/12/2013 6/21/2013 6/30/2013 7/9/2013 7/18/2013 7/27/2013 8/5/2013 8/14/2013 8/23/2013 9/1/2013 9/10/2013 9/19/2013 9/28/2013 10/7/2013 10/16/2013 10/25/2013 11/3/2013 11/12/2013 11/21/2013 11/30/2013 12/9/2013 12/18/2013 12/27/2013 2 4 6 8 10 12 14 16 18 Series1
1/1/2014 1/10/2014 1/19/2014 1/28/2014 2/6/2014 2/15/2014 2/24/2014 3/5/2014 3/14/2014 3/23/2014 4/1/2014 4/10/2014 4/19/2014 4/28/2014 5/7/2014 5/16/2014 5/25/2014 6/3/2014 6/12/2014 6/21/2014 6/30/2014 7/9/2014 7/18/2014 7/27/2014 8/5/2014 8/14/2014 8/23/2014 9/1/2014 9/10/2014 9/19/2014 9/28/2014 10/7/2014 10/16/2014 10/25/2014 11/3/2014 11/12/2014 11/21/2014 11/30/2014 12/9/2014 12/18/2014 12/27/2014 5 10 15 20 25 30 Series1
Finally a cold winter to really test the system out. How will it perform? – stay tuned!!!