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Cesco Solutions, Inc. Recommends —
Choosing a Detergent for Refinery Use

Remember when cleaning oil and carbon deposits at a refinery was a low priority? Cleanup was sporadic and typically utilized products that were caustic or contained chlorinated solvents. We cleaned only when necessary and gave little thought to the personal and environmental risks associated with the products used. Over time, we have recognized the importance of good housekeeping and products that are safe and have a minimal impact on wastewater treatment systems and the environment. Here are key criteria when determining an acceptable product for cleaning within a refinery:

Cost — What is the true cost of the product to clean a measurable area (effectiveness)?
Impact — How does the product and contaminants it carries impact the wastewater system and discharge limits?
Safety — What are the exposure and other risks associated with the product?
Environment — How does this product impact the environment?
Regulatory compliance — Does this product meet local, state and federal regulations?

Cost is a primary consideration when choosing a detergent product. Unfortunately, the price per gallon rarely reflects the true cost of cleaning. This needs to be determined by calculating the cost to clean a measurable area. By reviewing how much a detergent can be diluted and still provide performance, true cost is determined. This is almost never done and can save tens of thousands in detergent costs annually by using simple laboratory tests. Depending on the application, the Immersion Tar, Large Coupon Immersion or foam Cell Test (available by request) can be used to determine which detergent performs best on cost. All three tests utilize typical oil/carbon deposits, measurable surface area, temperature and dilution to pick a winner.

The impact the product and contaminants have on wastewater systems and discharge limits is another area that can be hard to quantify. Toxicity, oil/water separation and foaming characteristics should all be considered as part of the selection process. Toxicity information should be available on every detergent MSDS that is reviewed. Products that have a LC50 toxicity of less than 100 mg/L (Fathead Minnow) should not be used within the refinery for cleaning. Anything above the LC50 100 mg/L provides a greater margin of safety for the wastewater system and allows for adequate detergent usage during heavy cleanup periods (turnarounds).

Oil/water separation is critical when using detergents for cleanup in a refinery. During turnarounds, detergents are used in high quantities and can cause heavy emulsified hydrocarbon loading in the wastewater system. Using the High Shear Phase Separation Test (available upon request), it can be determined if a detergent will provide adequate oil/water separation. This test measures oil/water separation, oil and grease numbers of the effluent and Chemical Oxygen Demand (COD). Any rag layer is usually treated with calcium chloride to determine ease of treatment. A Low Shear Phase Separation Test is available to evaluate detergents where light mixing and gravity are used during the cleanup process.

Foaming can cause cosmetic and operational problems to wastewater systems by reducing throughput and causing level control mechanisms interference that may initiate overflow of aeration basins and activated sludge. Foaming problems can also produce community concerns. By using low to moderate foaming products, the negative impact of detergents on the wastewater system can be controlled. Using the Foam Cell Test, detergents can be evaluated to determine foaming characteristics and impact on wastewater.

Personal and environmental safety should be a primary consideration when selecting a detergent. The MSDS (Material Safety Data Sheet) is your best source of information. Look to work with supplier MSDS that provide complete information and accurately reflect the true risks of the product. At a glance, the HMIS (Hazardous Materials Identification System) can be used to determine product safety. Ratings are used on a scale of 0-4 to rate Health, Flammability and Reactivity. A letter system is used to provide suggested PPE (Personal Protection Equipment). Upon accessing the HMlS rating, other criteria such as pH, Flash Point, LC 50 (Fathead Minnow), VOC (Volatile Organic Compounds), Hazardous Materials and SARA reportables should be reviewed carefully. Each refinery should have guidelines as to what limits are required on the above criteria. Below are some suggested limits on each.

HMIS: Health 0-2, Flammability 0-1, Reactivity 0-1, PPE — chemical goggles, rubber gloves, safety boots, apron.
pH: l0
Flash Point: Not less than 212 F.
LC 50:100 mg/L (Fathead Minnow)
VOC: 5% or less
Hazardous materials: No caustics, acids, oxidizers, known carcinogens or toxic substances.
SARA reportables: None

The topic of environmental impact is controversial and difficult to assess. The ingredients used in the manufacturing of a detergent must be considered based upon the capacity of treatment at wastewater. Even a refinery with good secondary treatment should use highly biodegradable ingredients and avoid synthetic surfactants, phosphates and carbon-based solvents. There is supporting evidence that even at low levels, these materials can have a negative impact on the environment.

For instance, it is believed that nonylphenols are bad actors in regards to impacting fish populations. Europe has already changed to ethoxylated alcohol chemistries to address this issue, as well as questionable biodegradability. In Europe and the United Sates, certain regulatory agencies have viewed phosphates as contributing to algae bloom and poor water quality. As a result, other conditioners such as EDTA have replaced phosphates in detergent formulations. The actual biodegradability of a detergent product is hard to evaluate without using expensive and time-consuming tests. Therefore, continuing to focus on the ingredients of the product is probably the best method of addressing the biodegradability issue. Below are suggested substitutions that would be beneficial:

• Ethoxylated alcohol’s instead of nonylphenols
• Biodegradable organic solvents
• EDTA instead of phosphates

Regulatory compliance is problematic in that there are multiple authorities at the Federal, State and local levels, all of which have different laws and limitations. Air and water quality is of primary consideration when determining discharge limits and reporting requirements. Many of the limits identified under personal and environmental safety will have a positive regulatory impact. There is typically a cost for plant effluent if secondary treatment is provided by an off-site source. Regulatory entities have continued to reduce emission standards and increase reporting requirements. Fines and charges are being developed to penalize regulatory offenders and pay for governmental programs. The net result will be increased costs of refining as new equipment and personnel are added to meet these new standards.

Refinery detergent selection can play an active roll in reducing new operating and regulatory costs. By testing and rating products based on cost, wastewater impact, safety and the environment, a refinery becomes proactive rather than reactive. Operating costs are lowered using more effective products and detergent selection becomes part of the solution for meeting discharge limits and regulatory guidelines. By using a proper detergent selection process that considers all factors, refineries will be financially rewarded and enhance environmental standing within their community.

   
   
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