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 Michigan.  The plant consists of  Bar Screen  Microscreens  3 Aerated Lagoons  2 Clarifiers run in series  FeCl 2 and Polymer fed  UV Disinfection

The City of Clare WWTP  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 issue.  The NPDES permit limit for Ammonia Nitrogen is 11.0 mg/L from May 1 st 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 Solutions Examined  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

Solution Selected  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  The fixed media chosen was the ENTEX Technologies, Inc. Webitat modules.  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.

The Pilot Plant

The Process  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 Modules

Installation

Aeration System

Piping and Control Valves

Piping continued

Lagoon Mixing  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.

Operation  Units have controlled air flow  Control valves open once a week to full to scour the media

And now for the Important Stuff  Well how’s it working?  Installed December 2011

Ammonia Final Effluent 2012 20 25 10 15 0 5 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 Series1

Ammonia Final Effluent 2013 10 14 16 18 12 0 4 6 8 2 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 Series1

Ammonia Nitrogen 2014 20 25 30 10 15 0 5 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 Series1

2014  Finally a cold winter to really test the system out.  How will it perform? – stay tuned!!!

Questions