Free Oil

• Droplet size 10 microns and larger
• Will separate in a 6″ high beaker in 90 seconds
• Requires gravity separation such as API type

Dispersed

• Droplet size 149 microns to 20 microns
• Will separate in a 6″ high beaker in 80 minutes
• Requires gravity coalescing such as the OCS separator

Mechanically Emulsified Oil

• Droplet less than 20 microns in size
• Will not separate in a 6″ high beaker in 80 minutes
• Requires chemical treatment and coalescing or chemical treatment and Dissolved Air Floatation or Ultra Filtration

Chemically Emulsified Oil

• Droplet less than 20 microns in size with surfactants or emulsifiers present
• Will not separate in a 6″ high beaker in 80 minutes
• Requires chemical treatment and coalescing or chemical treatment and DAF or UF, the surfactants will pass through with the permeate

Soluble Oil

• No discernible droplet size and the ions are crossed linked in the water
• Will not separate in a 6″ high beaker in 80 minutes
• Requires chemical treatment and coalescing or chemical treatment and DAF or UF, (with solublizers staying with the permeate)

Introduction

Environmental awareness is presently manifesting itself in tightening environmental legislation throughout the world.

Many industries discharge liquid waste contaminated with hydrocarbon or oil-like pollutants. Sources of such waste include petroleum and petrochemicals refining and processing, tramp oils from machine tool coolants, utility operations, sanitary sewage, bilge and ballast water, contaminated surface runoff.

Oil discharges into the environment typically have deleterious effects. Oily waste discharge creates potential safety hazards and consumes dissolved oxygen necessary to aquatic life.

Toxic effects of oil fall into two categories (Laws, 1981):

1. Effects due to smothering or coating of animals or plants with oil. Coating effects are most noticeable when large amounts of free oil are present as in an oil spill. Coating effects are not usually found when only parts per million (ppm) are present, as is the case of an industrial plant effluent.

2. Disruption of animal’s or plant’s metabolism due to the ingestion of oil and incorporation of oil into the organism’s fatty tissues. Generally, toxic compounds are not water-soluble but are oil soluble, thus tending to accumulate in body fat and damaging animals or human beings.

This paper introduces the oil-in-water separation theory and the basic criteria for selection and design of a separation system, presenting an up-to-date overview of technologies currently available and of their capabilities in terms of achievable discharge levels.

2. Background

Oil can exist in water in several forms:

• Free Oil is composed by oil droplets with a diameter exceeding about 30 microns. It rises quickly to the water surface when given a sufficient quiescent settling period.
• Mechanical dispersions are distributions of fine oil droplets ranging in size from less than 1 micron to 30 microns and having stability due to electrical charges and other forces, but not due to the presence of surface active materials.
• Chemical emulsions are distributions of oil droplets similar to mechanical dispersions, but which have additional stability due to chemical interactions typically caused by surface active agents present at the oil/water interface.
• Dissolved oil is dissolved in a chemical sense; the removal by normal physical means is impossible.
• Oil that adheres to the surface of particulate materials is referred to as oil-wet solids.

The degree of an oil/water separation problem depends on the oil droplet size distribution. Separation problems also involve chemicals other than oil, which have an effect on the treatment required.

The degree of the dispersion/emulsion of the oil is difficult to assess, but steps can be taken to discourage its formation by:

1. Preventing from using detergents, which may cause stable chemical emulsions.

2. Ensuring an adequate size piping to avoid the possibility of turbulence and formation of fine droplet dispersions.

3. Avoiding devices such as pumps, especially centrifugal ones, valves, especially globe ones, and other restrictions in flow, such as elbows, tees, etc., or simply unduly small line sizes, which may create shear stresses and enhance the formation of mechanical dispersions. As a matter of fact, where an oil and water mixture has to be presented to the separation equipment, it is of the utmost importance to select a pump which imparts the lowest amount of energy to the mixture, as any excess energy thus created has to be removed by the equipment. For this reason, the use of high speed centrifugal pumps, although relatively cheap and small, should be avoided and pumps of low shear characteristics, such as peristaltic or progressive cavity, used.

Ideal inlet conditions for an oil-water separator are:

1. Gravity flow (not pumped) in the inlet piping.
2. Inlet piping sized for minimum pressure drop.
3. Inlet piping straight for at least ten pipe diameters upstream of the separator (directly into nozzle).
4. Inlet piping containing a minimum of elbows, tees, valves, and other fittings.
5. Inlet piping should be as smooth as possible to avoid turbulence caused by pipe roughness. Smooth PVC is preferable to rough concrete. Nevertheless it must be pointed out that a slight amount of turbulence (i.e. at Reynolds numbers close to translation) is likely to increase the probability to coalescence with other oil droplets.

The importance of viscosity

From Stokes’ Law, the lower the water viscosity, the faster the oil rises in water.

Increasing the temperature will significantly reduce water viscosity. For example, oil droplets in water at 4 degrees C (40 degrees F) will rise at only half the rate as if they were at 32 degrees C (90 degrees F), if other parameters remain the same.

The importance of specific gravity and oil droplets diameter

From Stokes’ Law, the greater the difference in specific gravity between oil and water, the faster the oil droplet rise in water. For example, a fuel oil that has a specific gravity of 0.8 will rise twice as fast as oil with a specific gravity of 0.9.

The importance of both oil droplet diameter and specific gravity is pointed out in the following table where it may be seen the travel time for a 10 cm (4 in.) vertical distance for various values of the two parameters. Time is expressed in hr.min.sec.

Determination of specific gravity, viscosity and oil droplet size

Water viscosities as well as specific gravities of water and oil are readily obtained from literature data. It must be pointed out that, in the design phase of separation devices, a wide variety of temperatures (and therefore of viscosities and specific gravities) have to be considered to take into account summer and winter conditions as well as possible process upsets.

Oil droplet size is much more difficult to be determined. The most common way to measure it is by particle size counters such as laser light scattering analyzers.

This treatment sequence requires a reaction tank and a pH adjustment tank. The salts and polymers that break the emulsions are added to the tank by means of metering pumps and mixed with mechanical mixers, or injected in line prior to the tank and the pump, using the pump as the mixer. Metals can be removed in the second tank. The final polishing step again consists of a tank filled with organoclay. Activated carbon use is optional.

Either of these systems depends on a final polishing step with organoclay to allow zero discharge and recycling of the wastewater. Wastewater treatment costs range around $0.5-0.10/gallon, which is considerably cheaper than hauling it away, particularly if the wastewater is hauled over long distances. There are no liabilities such as those involved with hauling wastewater and the potential of spills due to accidents. Zero discharge and recycling implies near zero dealings with local water authorities.

Techniques For Splitting Oily Emulsions

The design of oil/water separators is based on Stoke’s Law, the lighter oil droplets impact on the slant ribs of the media, coagulate, and rise to the surface. The principle of air flotation is that oil droplets will adhere to air and gas bubbles and rise to the surface of the tank. Chemically emulsified oil can be removed by heating the water from 150-220 degrees F, which can become expensive. Evaporators remove the water and leave the oil behind. This is expensive and results in difficult clean ups of the elements of the evaporator. The addition of salts, polymers, bentonite powders and pH adjustment are the most difficult, but also most successful method of breaking emulsions and removing the oil.

When chemical treatment is applied, prior bench testing is required. The first step is addition of an inorganic salt, such as magnesium or aluminum sulfate, which may be sufficient to break emulsions, or de-emulsify the oil, if sodium soaps are the emulsifier. If that is not successful, a cationic coagulant may be added. The purpose is to neutralize the charges on the oil droplet caused by the emulsifier, ie. drive the zeta potential towards zero. If this step is not successful, the pH may have to be adjusted downward to 3.5 with sulfuric acid, which results in the break up of the surfactant. Coagulants and flocculants may then be added to remove the oil. This step is followed by passing the water through a bed of organoclay to remove the last traces of oil (polymers are not economical below 30 ppm), adjustment of the pH to 5 or higher, and a pass through an activated carbon bed. Now the water can be reused.

Breaking emulsions and getting the right pH will increase performance. pH can be used to increase capacity. When the absorbate is neutral (no ionic charge) it will fit into the long hydrocarbon chains in the Quat and the micro pores in carbon. The closer you get the absorbate to its saturation concentration the better it will adsorb. For example, benzoic acid is soluble at 1-2 grams ,but benzoate ionic form is 50 grams soluble per liter of water.

Figure A in Technical Bulletin #46 shows the schematic diagram for an aluminum can manufacturers wastewater treatment system. Their treatment added surfactants to wash oil off aluminum sheets. They used hydrofluoric acid to separate the oil from the surfactant.

Figure B shows how Biomin improved the process. Since the aluminum can manufacturer adds acid for etching the cans, adding more acid was not necessary… Biomin simply added a vessel of Organoclay followed by a vessel of activated carbon. The Organoclay removed the surfactant and oil and activated carbon functioned as a polisher, removes traces 1 PPM or less dissolved oil.

Surfactants used for this application should be non-ionic, like Union Carbide’s Triton 150 which provides pH 3-5 maximun breakage of the oil-surfactant binding. Organoclay has high capacity for oils and surfactant and activated carbon removes the traces. Anionic and cationic surfactants interfere with oil removal capacity. Laboratory studies with “Column Test Methods” have demonstrated these oil capacity changes.

A Biomin Column Treatment Tutorial is provided to show you how Biomin column data can be used to design a treatment system for a wastewater stream.

Biomin Organoclay Courses

George Alther, president of Biomin, provides practical courses on “Principles and Practices of Organoclay.” Courses are also provided in conjunction with the International Activated Carbon Conference in Los Angeles CA on April 27-28, 2010 and Pittsburgh PA October 5-6, 2010.

View Technical Bulletin #46 here

During the course entitled “Organoclay Principles and Practices”, Mr. Alther will provide the tools to successfully use organoclays including what they are made of, how they work, their chemistry and how to select the best organoclay for specific applications. Different applications of organoclays will be discussed including non-ionic procedures used to remove oil and sheen from water and polar procedures to remove humic acids, THM’s and chelates from water. Waste water cleanup success in an economically acceptable manner depends on an understanding of pre-polishers and post polishers. Organoclays are also used as post polishers for oil/water separators, DAF units and oil skimmers.

Recycling of wastewater is becoming more prevalent in water starved areas, especially in developing countries and organoclays can help achieve what those above mentioned units cannot by themselves. Biomin International has patent methodologies for organoclay technology. “It is always an exciting experience to participate in international conferences regarding global waste water treatment as there are many advancements being made globally and this is an opportunity to meet friends and attendees and promote our product line”, said Alther. “In actuality, the global end user is the beneficiary of using my Organoclay for water decontamination and soil stabilization in the future”. George is an internationally recognized expert on organically modified clays and their use in environmental applications and has participated in many international conferences during his career.

Biomin International is currently developing international contacts for synergistic markets associated with its patented Oilsorb technologies and has successfully signed distribution agreements with Nigeria, Qatar and India. Joseph P. Cool, International Business Development/Export Director said “We are currently working with both domestic and international companies for development and implementation of Oilsorb methodologies and synergistic technologies for worldwide utilization including specific SE Michigan applications. International conferences such as these provide forums for identifying potential Partners for follow up discussions in the development of global business opportunities for successful water treatment globally using the Oilsorb technology”.

About Biomin, Inc. (www.biomininc.com)

Biomin International, Inc. manufactures state-of-the-art water filtration media and flocculants for removal of oil, grease, and other organics (i.e. PCBs, PNAH, PCP, and color/tannin) from water.  Biomin’s products include OilSorb^TM, ColorSorb^TM, Clayfloc^TM, EC-300, and EC-400.  Biomin filtration products are used throughout the world and have been approved for use by the U.S. Army Corps of Engineers, U.S. Environmental Protection Agency, U.S. Department of Defense, U.S. Department of Energy, the Iowa Department of Transportation, and other federal and state environmental protection departments. Its products have documented case study results that indicate cost savings up to 50% while bringing customer facilities into compliance with governmental discharge requirements.

Biomin International, Inc., an Oak Park, MI-based oil and water separation/filtration company participated in the first meeting of the Macomb Manufacturers Survival Group at the invitation of Express Employment Professionals. The meeting was held at the Express Employment Professionals office located on Morley Road, Clinton Township on 9 July 2009.

The meeting was attended by several local SE Michigan companies with the goal of introducing local manufacturing companies for exploration and development of global opportunities. The group of attendees included Representatives of Biomin International, Express Employment Professionals, PAT Engineering Enterprises, Target Equipment Leasing, Drake Enterprises and Bermar Associates. The meeting consisted of company introductions and a presentation entitled “Going Global: The Survival of Local Manufacturing in Macomb County – An Overview of Strategies”. Joseph P. Cool, International Business Development/Export Director of Biomin International gave the presentation which included interaction with the audience.

JoAnn Wiegand, Owner/General Manager of Express Employment Professionals is very knowledgeable regarding the changes in the manufacturing industry in Macomb County and initiated the invitation to Cool as Speaker based on his extensive experience globally. Wiegand said of the event “This was a great start. Thanks to Cools’ presentation, I now see limitless possibilities for Macomb Manufacturers to increase market share”. One of the goals of this first meeting was to develop local connections in several manufacturing sectors for further connections globally.

George Alther, President/Founder of Biomin International said “Based on future orders of the Biomin product line globally, additional personnel will be required for our Oak Park manufacturing facility which is our synergy with Express Employment Professionals to provide personnel”. Biomin International and PAT Engineering have recently signed an exclusive agreement for distribution of Biomin’s global waste water treatment solutions for Qatar and India initially based on a recent factory visit by PAT Engineering Representatives from Qatar.

Biomin International is very interested in developing local and international contacts for synergistic markets in SE Michigan dedicated to global waste water treatment processes. Cool said “I strongly believe there are many synergistic connections in local SE Michigan manufacturing market sectors and subsequent conversations and discussions will provide a very good platform for future global development of not only Biomin International but also local manufacturing companies”.

About Biomin, Inc. (www.biomininc.com)

Biomin International, Inc. manufactures state-of-the-art water filtration media and flocculants for removal of oil, grease, and other organics (i.e. PCBs, PNAH, PCP, and color/tannin) from water.  Biomin’s products include OilSorb™, ColorSorb™, Clayfloc™, EC-300, and EC-400.  Biomin filtration products are used throughout the world and have been approved for use by the U.S. Army Corps of Engineers, U.S. Environmental Protection Agency, U.S. Department of Defense, U.S. Department of Energy, the Iowa Department of Transportation, and other federal and state environmental protection departments. Its products have documented case study results that indicate cost savings up to 50% while bringing customer facilities into compliance with governmental discharge requirements.

About Express Employment Professionals  (www.expresspros.com/clintontownshipmi)

JoAnn Wiegand has been providing staffing solution since 1994 for business in Sterling Heights and Clinton Township as an Express Employment Professionals franchisee/owner. The business has evolved from providing temporary employees with clerical or light industrial experience. Today the full service office provides a broad range of human resource assistance to local businesses including payroll processing, professional searches, skilled trade placements, skills testing, training programs, writing handbooks and safety audits.

Improves the Uniformity and Performance of Organoclay to Preferentially Adsorb and Sequester a Wide Range of Hydrocarbon and Petroleum based Contaminants in a Remediation Setting

AquaBlok, Ltd., a manufacturer of innovative clay-based composite materials, in cooperation with Biomin, Inc. is pleased to offer a new way to deliver Biomin’s proven
organoclay product in a way that is low cost and provides for ease of delivery and improved performance.

AquaBlok® + ORGANOCLAY provides the following primary benefits, compared to the use of conventional powdered or pelletized organoclay products:

1. More efficient use of organoclay through use of a thin coating on a substrate/core
2. Greater product effectiveness through higher organoclay surface area
3. Improved delivery to sediments through a standing water column
4. Lower cost per pound for a target volume
5. Ease of handling and placement

View the rest of this bulletin as a PDF

During the day-long conference, three session tracks were provided for Participants to attend in which local expert engineers and scientists provided information for interactive discussions regarding solutions to the State’s most pressing water issues.

“We have to protect our resources. That is why we were able to bring together an impressive group of individuals to share their knowledge and start a dialogue on how we can engineer a solution. This successful event was the starting point of an important journey.” Brenda Moragne, Director of Conferences, the Engineering Society of Detroit.

For the full story, view the PDF.

Organoclays are a cost-effective, easy-to-use method for removing oil from water in a variety of applications

by George R. Alther

Because stormwater runoff from parking lots, paved streets, and asphalt-covered roofs often is contaminated with oil; benzene, toluene, ethlybenzene, and xylene (BTEX); and fuels that have leaked from vehicles or leached from asphalt, it is unacceptable for discharge into the sewerage system. Some states now limit the concentration of oil that can be discharged into surface waters to 10 mg/L.

Industries and municipalities, therefore, are installing systems that can remove these contaminants from stormwater. Typical systems include oil-water separators and ultrafiltration systems — both of which have limitations. Oil-water separators cannot reduce the oil level to less than about 15 Mg/L and do not remove BTEX; ultrafiltration units’ membranes quickly become fouled by oils. Using organically modified clays (organoclays) to remove oil from stormwater is a less common, but more effective method that typically removes oil to concentrations less than 3 mg/L.

Organoclays have been modified with quaternary amines to remove oils and other non-polar compounds with low water solubility from water by means of a partitioning mechanism. Typically, the clays are used in a granular form, blended with anthracite, and placed into activated-carbon adsorber columns through which stormwater flows are directed. A treatment combination in which activated carbon follows the organoclay typically is most effective. Organoclay removes seven times more oil than activated carbon (an oil content equivalent to 50% of its weight). Therefore, in this treatment combination the organoclay removes the oils and the carbon removes the BTEX.

Description of Organoclay

Organoclays are manufactured by modifying bentonite – chemically altered volcanic ash that consists primarily of the clay mineral montmorillonite – with quaternary amines, a type of surfactant that contains a nitrogen ion. The nitrogen end of the quaternary amine (the hydrophilic end) is positively charged and ion exchanges onto the clay platelet for sodium or calcium. The bentonite has a charge of 70 to 90 milliequivalent per gram (meq/g). After it is treated with the quaternary amine, approximately 30 to 40 meq/g remain, which gives the organoclay the capability to remove small amounts of common heavy metals, including lead, copper, cadmium, and nickel.

Organoclay can be used in granular form in carbon vessels or as powder in batch-treatment systems. As the organoclay is introduced into water, the quaternary amine is activated and extends perpendicularly off the clay platelets into the water. A chlorine or bromine ion is attached loosely to the carbon chain.

The positively charged sodium ions replaced by nitrogen bond with this chlorine ion, causing the sodium salt to wash away, leaving behind a neutral surfactant – the organoclay.

The hydrophilic end of the amine dissolves into the oil, removing it from water. Because the partition reaction takes place outside the clay particle, in contrast to adsorption of oil inside activated carbon pores, the organoclay does not foul quickly like activated carbon does. The anthracite that is blended with the granular organoclay also has oil removal capabilities, and has about the same bulk density [56 lb/ft3 (897 kg/m3)] as the organoclay to prevent the interstitial pores from filling with oil immediately.

Organoclays also are effective in removing chlorinated phenols and other hydrophobic, chlorinated compounds that are sparingly soluble, including polynuclear aromatic hydrocarbons and polychlorinated biphenyls. When combined with activated carbon, organoclays remove BTEX much more economically, because the organoclay removes low-solubility compounds, including xylene and toluene, while the carbon removes benzene. Figure 2 (p. 33) compares the costs of using activated carbon, alone, to remove oil from water versus using organoclay-anthracite to remove oil. Organoclay reduces operating costs by approximately 50%.

Application Options

One of the most common uses of organoclays is for stormwater cleanup. Various application methods are available, depending on the facility setup and the volume and chemistry of the stormwater being treated.

When local authorities required a facility in New York state to capture stormwater runoff from its parking lot and treat the water before discharging it into the city sewer, the facility constructed a collection and storage pond, and used organoclay to treat stormwater effectively.

At the lowest point of the pond, a trench was dug and 10-ft-long x 6-in.-wide (3-m-long x 150-mm-wide) slotted polyvinyl chloride pipes were placed inside, vertically, in a zigzag manner that caused each pipe to overlap the next one. The pipes were surrounded with soil to keep them in place and then filled with a granular organoclay-anthracite blend (30% and 70%, respectively). When stormwater fills the pond, it passes through the pipes at a rate of approximately 10 gal/min (38 L/min), and the organoclay in the pipes removes oil and gasoline from the stormwater. The water flows through the organoclay-anthracite barrier directly into the sewer system.

The system also could have been constructed by filling the entire trench with an organoclay-anthracite blend. However, installing the piping system saved the facility money in the long run, because less material is needed to fill the slotted pipes than to fill the entire trench. The piping system also simplifies maintenance. Removing the pipes from the trench, replacing the organoclay, and returning the pipes to the trench is easier than emptying the entire trench.

While the trench configuration is ideal for cleaning stormwater that is collected in a pond; other application methods are available for facilities that encounter large volumes of stormwater runoff and want to reuse treated stormwater – as boiler feed water, for example.

Photo 1 (p. 31) shows two adsorption vessels, the first one filled with organoclay-anthracite, the second one filled with activated carbon. The vessels are preceded by bag filters and an oil-water separator. Setups like this one are particularly effective for utility companies and other large processing facilities that have serious problems with stormwater runoff, particularly in states like Florida and Texas, which experience frequent heavy rainfall.

Another way to apply the technology is to install a trailer-mounted system equipped with an adsorber vessel filled with organoclay-anthracite, followed by a system filled with activated carbon. An oil-water separator could be added by constructing a larger trailer. Cities use configurations like this as mobile treatment systems that can be driven from one city-owned parking lot to the next to clean up stormwater.

Case Histories

The case histories below illustrate how organoclay-anthracite has been used to remove oil and grease from water efficiently, and to protect activated carbon from fouling.

Hill Air Force Base (Ogden, Utah). Stormwater runoff and wastewater from paint stripping, degreasing, electroplating, and other airplane cleaning operations contained oil, grease, trichloroethylene, tetrachloroethane, chloroform, methylene chloride, and heavy metals including lead, cadmium, nickel, and zinc. The combined wastewater stream was collected in a sump system, treated in a secondary clarifier and a dissolved air flotation unit, and then treated in three organoclay vessels, followed by four carbon vessels. This system operated for more than 3 years without requiring a changeout of the organoclay or activated carbon media.

Alaska industrial site. When groundwater contaminated with diesel fuel was treated with three activated carbon filters, breakthrough occurred within 2 days. Placing three filters filled with organoclay in front of the carbon solved this problem. The cleanup project was completed in 3 months; neither the organoclay nor the carbon beds were exhausted at that point.

Florida power plant. A Florida utility installed a stormwater treatment system consisting of several 50-gal/min (189-L/min) adsorption vessels filled with 1600 lb (726 kg) of organoclay. Stormwater is routed through the vessels and given a 5-minute retention time. When it rains, water entering the system exhibits sheen and contains about 10 mg/L of oil. The organoclay removes 60% of its weight in oil, is performing as expected, and requires minimum maintenance. Since installing the system, the facility’s runoff has met all local discharge specifications.

Arkansas residential community. When a 10 000-gal (37.9-m3) underground storage tank leaked diesel fuel into the aquifer surrounding a small community, the contaminated water plume threatened to infiltrate a municipal water supply well located several hundred feet down-gradient from the tank. A contractor drilled four interceptor wells to withdraw the contaminated water before it reached the municipal well. The total extraction rate was 50 gal/min (189 L/min), and average oil and grease concentrations were 35 mg /L. The extracted groundwater was passed through an oil-water separator and then a column of organoclay adsorption media, and the treated effluent was re-injected into the aquifer upgradient of the tank. The final treated effluent recorded oil and grease concentrations of less than 1 mg/L. No hydrocarbons ever were detected in the municipal drinking water well.

California refinery. A California refinery installed a temporary system to treat stormwater runoff to meet local regulations requiring that no more than 10 mg/L of oil be discharged into the sewer system. The existing system included equalization tanks, bag filters, and a flocculant-addition tank. A huge 2,000-gal/min (7600-L/min) adsorber was installed that contained 72,000 lb (32,000 kg) of organoclay. As soon as the system went on-line, the facility became compliant with the regulations – the oil content in the treated water dropped to less than 5 mg/L.

As the above examples show, whether it is used in combination with activated carbon or, by itself, organoclay is an effective filtration media to remove small amounts – 200 mg/L or less – of oil and grease from water. The system has proven itself reliable and cost-effective in municipal and industrial applications throughout the United States, and is an ideal stormwater treatment solution.