Application – Dissolved Air Flotation (DAF) Retrofit
Objective:
To improve the performance of an existing wastewater Dissolved Air Flotation system at a gourmet and specialty meat processing plant. Specifically to:
- Reduce WWTP (Waste Water Treatment Plant) downtime due to equipment fouling;
- To lower municipal surcharges related to high BOD (Biological Oxygen Demand), TSS (Total Suspended Solids), and FOG (Fat, Oil and Grease) for discharge to sewer;
- To reduce transportation and tipping charges for waste sludge;
- To reduce chemical usage.
Background:
This particular processing plant purchased a DAF several years ago to process their waste water stream. Unfortunately, since the original installation, the plant has been unable to consistently meet the discharge limits set by the municipality at design flow rates of 450 LPM. The original DAF system comprised of two 7.5 HP electric driven centrifugal pumps, a 24” x 72” saturator vessel filled with plastic media, a 120 gallon – 10 HP compressor for air injection, a 6’ long x 6” diameter horizontal diffuser with twenty each 3/32” diameter nozzles to introduce aerated water into the flocculated inlet stream, and finally a 6’ x 6’ x 11’ long flotation cell.
As with most meat processing facilities, the waste stream is rich in fats, oils and grease, and suspended solids, along with high BOD. In this case, the waste stream varied continually depending on the products being processed on the production line. Because of the constantly changing waste streams and inefficient flotation achieved in the DAF cell, the system quickly became overloaded resulting in “short circuiting” of untreated water into the clarified and recycled water. This resulted in FOG and oil wetted solids build-up in the saturator media. Once the saturator media plugged, the FOG and oil wetted solids carried over to the diffuser plugging the nozzles and disrupting the aerated recycled water flow. When this occurred, the WWTP would need to be shut down for nearly one day to drain the mostly untreated water from the DAF cell. In addition it was necessary to drain and open up the saturator and clean the contaminated media, along with clearing the plugged diffuser nozzles.
The need to perform this maintenance was occurring every two days and was resulting in untreated water being discharged to the sewer. It was this increased frustration with the WWTP operation, having to hire a tank truck to pump out the sludge vessel every two days, and high chemical costs which led the plant’s Waste Water Engineer to search for alternate treatment methods.
The Solution:
Muddy River Technologies Inc. was approached to run trials with a pilot Micro-Air Separation System (MASS) to determine the best course of action with emphasis put on dewatering sludge. The pilot unit was brought to the plant site and setup to treat a side stream of the plant waste water. The same chemicals were used in the pilot as used in the WWTP. The pilot operation drastically improved effluent water and sludge quality.
After completion of the pilot testing, Muddy River Technologies determined that the solution was not to focus on dewatering of the sludge, which was just a symptom, but to address the cause of the problem, which was the existing air flotation system.
Based on laboratory results of the pilot testing, work began to retrofit the existing DAF with a Muddy River MASS using our proprietary Micro Bubble Generator (MBG).
After removing all unnecessary equipment; pumps, saturator, compressor, diffuser pipe and nozzles, Muddy River’s MASS was installed. The sludge outlet was redesigned to handle the thicker, dryer sludge and a single outlet diffuser was installed to eliminate the possibility of plugging.
About Muddy River:
Muddy River Technologies Inc. is a leading manufacturer and distributor of advanced separation technologies for a wide range of industries. Our staff has an extensive amount of experience within such fields as Petro-Chemical, Food and Fish Processing, Manufacturing, Agriculture and Light industry, as well as the use of Ozone in disinfecting effluent streams. Our facilities include a well equipped laboratory for bench trials and pilot units for on-site testing. Please contact us for additional information or visit our website.
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