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from diverse backgrounds with hand-on operation
experience of biological treatment processes.

Our Treatability Lab is one of our many tools used to predict
and troubleshoot problems for multiple industrial waste streams.

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that link our products to regular laboratory testing and technical
assistance together to keep biological treatment systems fully optimized.

NITRA LOC

Refinery Case Study

PROBLEM

A northern California refinery whose products include gasoline, diesel, jet fuel, CARB gasoline, butane, propane, residual oil and asphalt was on the road to slowing down increased production of refined oil products due to the build up of TKN laden wastewater that could not be treated quickly enough by the wastewater treatment plant it discharged to. The California refinery wastewater system consisted of a "Pre-Biox" (Pre-biological treatment) wastewater system with two aeration basins that are then fed into a second activated sludge system. The second wastewater treatment system consists of three parallel aeration basins followed by three final clarifiers. The mixed liquor concentration is kept maintained between 5000 mg/l to 8000 mg/l in the Pre-Biox Aeration Basins by returning sludge from the activated sludge system. The flow to the Pre-Biox is approximately 700 gpm with a TOC loading of 1500 lbs and a TKN concentration greater than 100 mg/l.

The Biox wastewater system received the effluent from the Pre Biox (600 gpm) and an additional 900 gpm from the refineries process waste stream. The TOC loading to the Biox wastewater system is 2500 lbs/day and NH3-N (as a metabolic by-product of heterotrophic TKN degradation) is received from the Pre Biox effluent and refinery process waste stream. The Biox system is continuously fed powdered activated carbon for refractory organics removal purposes and as a prophylactic measure to reduce waste stream toxicity.

The combined waste stream treatment which combines the pre-biox to rough down TKN and NH3N prior to the Biox wastewater system was not able to keep up with recent TKN loading to the wastewater treatment system which resulted in the storage of TKN laden wastewater in pre treatment storage tanks and empty production tanks.

SOLUTION

In January of 2005 River Bend Laboratories, a Division of the Chemtron Corporation based in St. Charles, MO., proposed a new wastewater treatment strategy that would utilize the existing capital structure of the wastewater treatment plant and optimize it by creating hundreds of thousands square feet of surface area within both the Pre-Biox and Biox activated sludge system for the attachment, propagation and retention of nitrifying bacteria at a higher concentration than this wastewater plant has ever experienced. The means for getting this accomplished were detailed in a proposal recommending the retrofit of the existing wastewater system into a Nitrification Enhanced Carrier-Assisted Activated Sludge System.

The Nitrification Enhanced Carrier-Assisted Activated Sludge System proposal detailed the utilization of NITRA LOC, a proprietary nitrification enhancing micro-carrier that when introduced correctly can bring about the creation of a hybrid fixed film/activated sludge wastewater system with significantly increased nitrification capabilities.

The specific wastewater treatment strategy employed involved the incorporation of NITRA LOC with the Pre-Biox mixed liquor and Biox mixed liquor beginning in February 2005.

On day 1 of the wastewater plant retrofit, 8,000 pounds of NITRA LOC was introduced into the Pre-Biox aeration basin, where it became enmeshed in the treatment systems mixed liquor. The 8,000-pound dosage of NITRA LOC was calculated based on the 85,068 pounds of mixed liquor volatile solids found in the wastewater treatment system. The on-going introduction amounts of NITRA LOC would be approximately 400 pounds per day and is a function of the sludge age the wastewater system will be operated at. Modifications of the NITRA LOC feed rate due to an increase in the pounds of NH3-N to be nitrified or due to anticipated or observed waste stream nitrification inhibition will influence the NITRA LOC introduction rate.

RESULTS

The introduction of NITRA LOC into the Pre Biox wastewater treatment system was initiated in early February of 2005. Within two weeks of the retrofit to the NITRIFICATION ENHANCED CARRIER-ASSISTED WASTEWATER TREATMENT SYSTEM there was an increase in the total Kjeldhal nitrogen (TKN) loading (well above 100 mg/l of TKN) to the wastewater treatment system. By the end of March 2005 they were able to feed over 300 mg/l of TKN and maintain effluent ammonia nitrogen below 1.0 mg/l. Since then, the refinery has worked off both the TKN being held in wastewater storage tanks and TKN laden wastewater stored in process product tanks. The retrofit of the refinery wastewater to a Nitrification Enhanced Carrier Assisted Wastewater System will allow for the permanent through put of all waste stream generated TKN and subsequently additional wastewater storage and the usage of empty production tanks will no longer be needed to store wastewater than cannot be treated immediately through the wastewater treatment system.

Case Study Category: 

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