ORGGANOCLAYS CAN CUT THE COST OF CLEANUP OF PRODUCED WATER, WASTEWATER AND GROUNDWATER BY 50%

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1 ORGGANOCLAYS CAN CUT THE COST OF CLEANUP OF PRODUCED WATER, WASTEWATER AND GROUNDWATER BY 50% George Alther President Biomin, Inc. P. O. Box Ferndale, Michigan and Tommy Wilkerson Flo-Clean LLC Lafayette, LA ABSTRACT Organically modified clays (organoclays) are well known to the oil well drilling industry where they are used as viscosifiers of the drilling mud and to prevent fluid loss. What is less known is that they have been used for some 20 years for the cleanup of water, and lately, as components of permeable barriers and for sediment stabilization. Their primary function is to remove organic compounds of low solubility from water, particularly oil, creosote, PNAH's and PCB. It is well understood that activated carbon is susceptible to blocking of its pores by large organic hydrocarbons of low solubility such as the ones mentioned above. Organoclays remove oil from water at seven times the rate, as does activated carbon. Similar removal capacity advantages occur with other compounds such as PNAH, PCB, chlorinated phenols and others. The best system for the removal of fuels and BTEX's from water is the organoclay/carbon system, because the organoclay will preferentially remove toluene and xylene leaving the GAC free to remove benzene, thus preventing the "roll off" phenomena. Lastly, the organoclays also remove small amounts of heavy metals from water. This paper will discuss organoclays, what they are, how they work, and present laboratory data and case histories. INTRODUCTION When bentonite or other clays and zeolites are modified with quaternary amines they become organophilic. Such modified bentonites are used to remove mechanically emulsified oil and grease and other sparingly soluble organics. If the organoclay is granulated, it is placed into a liquid phase carbon filter vessel to remove FOG's and chlorinated hydrocarbons. In this application the clay is mixed with anthracite to prevent the early plugging of the filter by oil or grease droplets. In batch systems a powdered organoclay is employed. Organoclay removes mechanically emulsified oil 500% to 700% more effectively than activated carbon alone. Oil and grease and other large sparingly soluble chlorinated hydrocarbons and NOM's (Natural Organic Matter) and PNA's (Polynuclear Aromatics) blind the pores of activated carbon (and ion exchange resins and membranes) reducing its effectiveness significantly. It is, therefore, economically advantageous for the end user to pre-polish the water before it enters carbon vessels. Operating costs can often be reduced by 50% or more.

2 NATURE OF ORGANOCLAYS Organoclays consist of bentonite modified with quaternary amines. The major constituent of bentonite is the clay mineral montmorillonite which has an ion exchange capacity between mg/gram. The nitrogen end of the quaternary amine is exchanged on the clay surface, rendering the clay organophilic. This means that swelling in water is minimized but swelling and gelling in organic fluids such as diesel fuel, gasoline, and others is greatly enhanced. This ability has resulted in the use of organoclay powders as thickeners in paints, greases, lubricants, etc. When organoclay is placed into water, the amine chains will stand up and extend into the water. As mechanically emulsified oil, fats, greases, and lubricants pass by these chains, they partition into the organics holding the organics by coulombic forces (Electrostatic, Van der Waal). This activity takes place at the surface of the clay platelets, in contrast to activated carbon, where adsorption takes place inside the pores. When an oil droplet or some other large organic molecule is passed through an activated carbon column, the droplet will either fill the pore or sit on top of it, blinding the carbon and preventing removal of such items as VOC's, which is the reason for using carbon in the first place. The blinding of the carbon results in frequent change outs, making recycling of the water uneconomical. The end user may simply choose to have the water hauled away by tanker truck. An example of a tank car wash operation looks as follows: A company spends $2,000 a month on water at an average cost of $2.00 per 1,000 gallon. It uses about one million gallons per month. This water is probably hazardous, so the company pays another $0.12/gal for hauling charges amounting to $120,000 per month. The total cost is now $122,000 a month. The reason the company would not run the water through carbon columns is because there are some 10 ppm of oil in the water. Now if they first pass the water through an organoclay column, at a flow rate of 25 gpm, 24 hrs a day, 7 days a week, it would only require 2000 lbs. of organoclay per year in a vessel 4 feet in diameter with a 3 foot 6 inch bed depth. The total capital cost would be about $ , and if they decided to add one or two activated carbon vessels, the capital outlay would only be approximately $15, Considering that most of the effluent water can be recycled, eliminating hauling altogether, it is obvious how quickly such a system would pay for itself. The organoclay/anthracite system blends organoclay with anthracite to prevent early clogging of the pores, and when blended, they remove 50-60% of their weight in oil. Common applications for water treatment with organoclay are: Ground water remediation, wood treatment (creosote), boiler feed water, storm water runoff, heavy equipment and vehicle cleaning, industrial waste water, and any water that contains oil and grease. Organoclay is used as a post polisher to oil/water separators and as a pre-polisher for activated carbon, as well as ion exchange resins, membranes, ultra filtration systems, and air strippers to prevent fouling. Powdered organoclays are used with rotary vacuum filters and in batch treatment systems to remove traces of oil, other organics and heavy metals. This article presents research data and case histories from different situations. CASE HISTORIES FOR STANDARD FLOW-THROUGH APPLICATIONS A. Ground water in an Army Corp. of Engineers site in Alaska was contaminated with diesel fuel. Three vessels filled with activated carbon were set up and ground water was passed through. The carbon lasted for two days when breakthrough occurred. The carbon was replaced and three vessels with organoclay/anthracite were placed in front of the carbon. After three months of pumping, the site was clean and neither the organoclay nor the carbon were spent.

3 B. A foundry in Illinois had set up a water treatment system consisting of various settling and coagulation tanks, an oil/water separator, and a sand filter followed by an activated carbon vessel. The purpose was to remove solids, oil and grease, phenolics and some heavy metals, primarily lead. When the foundry used more than 1,500 gpd of water, an event which happened frequently, they would be out of compliance with regulations which resulted in fines. To remedy the situation the sand in the sand filter was replaced with organoclay/anthracite. In spite of varying flows, the foundry has been in compliance ever since. C. Chlorinated hydrocarbons and PCB needed to be removed from sediments of a river in western New York as part of an NYSDEC consent order. The plan was to dewater the dredged sediment and clean up the effluent water. The contractor set up two multi media sand filters, each including pea gravel to cover the laterals, grade 68 sand, plus organoclay/anthracite. This was followed by two vessels filled with activated carbon. The organoclay/anthracite removed the oils and other hydrocarbons while the carbon removed the remaining PCB. The effluent quality fulfilled all NPDES requirements and the project was a complete success at a much lower cost than if activated carbon had been used exclusively. ORGANOCLAYS REMOVE SPARINGLY SOLUBLE CHLORINATED HYDROCARBONS A comparison between organoclay powder and activated carbon powder in the efficiency of removing phenolic compounds is shown in Table 1. Another case of ground water at a RCRA site in New Jersey showed similar results is shown in Table 2. The primary purpose of the organoclay/anthracite was to remove oil and protect the carbon. In some cases the organoclay removed all the toluene. This data indicates that pretreatment with organoclay helped the activated carbon considerably in removing chlorinated hydrocarbons. If there were benzene in the water the carbon would be extremely efficient in removing all of it due to the pretreatment with the organoclay. Laboratory data is shown in Table 3. The next case, in Table 4, shows the data from sump sludge water that was passed through an organoclay/anthracite bed. CASE HISTORIES SHOWING PESTICIDE AND PNAH REMOVAL A. A lab trial showed powdered organoclay to be very efficient in the removal of pesticides such as: Alachlor; Diazinon; Metolachlor; 2,4-D; Trifuralin; 2,4,5-T' and others from water. Note, these are chlorinated hydrocarbons. B. A ground water was contaminated with 100 ppm of fuel oil, of which 10 ppm were BTX's, while the other 90 ppm consisted of polynuclear aromatic hydrocarbons such as anthrazine, naphtalene, paraffins, and waxes. Originally two activated carbon vessels were used for pump and treat clean-up. The carbon had to be changed every two weeks. Additionally, after exiting the carbon vessels, the water still had a sheen of oily material, probably paraffin and waxes, which the carbon did not remove at all. Then a vessel filled with organoclay/anthracite was placed in front of the carbon. Now the GAC is changed every four to six months while the TOC analysis shows non-detect.

4 HEAVY METALS REMOVAL BY ORGANOCLAY A. Anions Two grams of organoclay when treated with a specific amine will remove 17 ppm of arsenite from water spiked with 20 ppm of arsenite. Similar results are also achieved with selenium or hexavalent chrome. To achieve such results, specific quaternary amines must be used. However, some reduction of all of these anions is achieved when using standard quaternary amines. These results propose that partition is not the only mechanism that operates in the removal of organic compounds. Anion exchange with the chlorine end of the quaternary amine, identical to the mechanism that operates with anion exchange resins is the second removal mechanism. This theory is supported by the high removal capacity of organoclay for chlorinated hydrocarbons. Anion exchange resins use quaternary amines with exchangeable chlorine and hydroxyl ions for removal of hexavalent chrome and arsenite. B. Cations Table 5 shows removal of heavy metals by organoclay/anthracite from the same sump sludge water as Table 4. Two mechanisms again seem to be responsible for the removal of heavy metal cations by organoclay/anthracite. Bentonite, after it is modified with quaternary amines, still retains some 40% of its original cation exchange capacity, or mg/gram, allowing it to act as a cation exchange resin. There is also some evidence that the iron in the water, at a certain ph, precipitates onto the anthracite with other metals co-precipitating. A word of caution is appropriate: We do not recommend the design of a system for metals removal alone. Only 30% of the clay/anthracite mix is organoclay, thus under standard flow conditions adsorption capacity is limited. The organoclay eventually becomes coated with oil resulting in loss of its exchange capacity. This ability of the organoclay to remove metals is, however, an added benefit for the clay/carbon system. When combined with other media, the following scenario occurred in one case: Tumble water from a plating operation contained oil and some 2 ppm of zinc. (Discharge permits require less than 1 ppm of zinc.) Two 55 gallon drums with internals were set up preceded by an oil/water separator. The first drum was filled with organoclay/anthracite and was used as a post-polisher after the oil/water separator. The second drum was filled with natural zeolite which removed the zinc. The organoclay prevented the oil from plugging the pores of the zeolite. The plating fabricator is now in compliance with regulations and the media only needs to be changed every six months. In another finding, a foundry detected organically bound lead in its rinse water. A three-step procedure was instituted: first an organoclay/anthracite vessel was used, followed by activated carbon, and finally followed by a vessel with an anion exchange resin. It operated successfully and placed the foundry into compliance with discharge permits. It has also been found that organoclay/anthracite is excellent in removing colloidally bound metals such as nickel and cadmium. The mechanism here is believed to involve the zeta potential of the clay resulting in adsorption rather than an exchange mechanism. The anthracite may also be involved in this phenomenon. Furthermore, even bioremediation can benefit from pretreatment with organoclays. One situation involved a ground water containing oils. An oil/water separator was installed including a mechanism which added an emulsion breaking polymer. This was followed by a tank into which bacteria were added to remove the remaining oil and was followed by an air stripper and an activated carbon tank. Given the

5 relatively high flow rate, the bacteria hitched a ride on top of the oil droplets passing through the entire system and coating the media in the air stripper, rather than digesting the oil. Placing a tank filled with organoclay in front of the air stripper would have eliminated this problem. The bacteria could have eaten the oil that was collected on the organoclay (hopefully they would eat only the oil, leaving the quaternary amine in place) providing some regeneration. MORE CASE HISTORIES 1. An organoclay wastewater treatment system was used at several natural gas compressor stations. Oil leakage and spills, when servicing compressors together with maintenance wash down water, are being satisfactorily treated with oil removal systems that consist of a wastewater holding tank with an oil drain off valve, a coalescing oil/water separator fitted with an oil skimming weir, an effluent holding tank, and two tertiary polishing filters. The first filter is bedded with organoclay/anthracite media which has a very high affinity for sorption on oil and grease and other sparingly water soluble contaminants. The effluent from the first filter then flows through a GAC (granulated activated carbon) filter to remove more soluble "light ends" before being discharged. Routine system maintenance is minimal and the filter medias have provided excellent bed life. The media lasts longer than one year. Effluent quality is low to non-detect allowing re-circulation of the water if desired. 2. A refinery in Canada discharged boiler feed water through a lime softener and desired to recycle the water. The water contained 8 ppm of total organic carbon, of which lube oil was 3 ppm, with spikes of 9 ppm. The remainders where chelating agents and amines used for scale prevention. Several ppm of iron were also present. The water runs at 30 psi and a temperature of 170 degrees F. A vessel with 10,000 lb organoclay was installed. Since this is boiler feed water, extensive backwashing was required to remove any suspended clay fines that add silica to the water, and to remove salts such as sodium chloride, which is commonly associated with bentonite. The silica content stabilized at 5 ppm, which was acceptable, and the conductivity also decreased to acceptable levels. After the system was brought on line, the oil content of the water was less than 0.5 ppm. The iron content was much lower but not measured. The system has lasted for over a year with no change out. The organoclay not only removes the oil, which means the water does not have to be reheated very much, perhaps by 20 degrees F, but also the iron. The iron precipitates onto the anthrazite at a ph of 7.8. This results in co-precipitation of other heavy metal cations which is a nice side benefit. PRODUCED WATER CASE STUDY An oil field produced water at a site in central Michigan containing 500 ppm of residual oil. Problem: Dispose daily of 3,500 bpd water containing 500 ppm oil into a water injection well. Injection rates where reduced constantly because oil in the water plugged the pores in the down hole formation.

6 Every three months the operator had to engage a work over rig for three days, and inject hydrochloric acid and xylene-based solvents into the formation to restore permeability at a cost of $7,500 every two months plus down time. Solution: Set up an oil/water separator at well head followed by a three ft. vessel containing 1,200 lb Oilsorb Organoclay. Goal: 5 ppm oil, which was easily achieved. A 100 times reduction. Water injection rates remained constant. Installation costs: $5,900...Includes O/W separator... $2,000 Skimmer... $500 Pump... $400 Filter... $3,000 Organoclay: $1,500 plus freight Replacement of Organoclay: Every three months at a cost of about $2,000 plus disposal fee of spent clay of $40 Cost Savings: $6,000 every three months or $24,000 per year plus down time of three days Change out time is four hours max vs. three days. SUMMARY AND CONCLUSIONS Pretreatment of ground and wastewater with granular organoclay to enhance the life of activated carbon is a useful and established practice. Prevention of fouling of ion exchange resins, membranes, and ultra filtration units is advantageous to the end user. Post treatment after DAF units and oil/water separators to achieve water quality that allows recycling and thus zero discharge is feasible and appropriate in today s environment. The fact that organoclays selectively remove chlorinated hydrocarbons further enhances the efficiency of a carbon pump and treat system. Good results in the removal of oil from antifreeze solutions and acids have also been reported. The organoclay/anthracite's ability to remove heavy metals is a beneficial side effect. Powdered organoclay can be used in batch systems and with rotary drum vacuum extraction systems. Efficient removal of creosote at wood treating operations by means of organoclay pretreatment has benefited such operations. In conclusion, the experiences described in this article suggest that organoclays should be a standard part of most pump and treat systems design.

7 Table 1. Non-ionic organoclays removal capacity of phenolic compounds was determined by batch tests. Concentration:...25 ppm in water Phenol: 78.2% of organoclay weight...solubility: 86 g/l 2,4,6 Trichlorophenol: 98.3% of organoclay weight mg/l 3 Chlorophenol: 89.8% of organoclay weight g/l Pentachlorophenol (PCP):...87% of organoclay weight This means that 100 grams of organoclay can remove 87 grams of PCP, solubility is 80 mg/l. This data shows that the lower the solubility of the phenolic compounds, the higher the efficiency of the organoclay vs. activated carbon. Powdered organoclay removes 76% or more of its weight in oil from water. Table 2. Organoclay/carbon sequence for the treatment of contaminated ground water. The oil content is not known. Organic Compound Solubility (mg/1) at Degrees C Influent (mg/1) Effluent organoclay After carbon 1, 1, 1 Trichloroethane ND ND Trichloroethene ND 1, 1 Dichloroethene ND ND Toluene ND ph Table 3. Indication that pretreatment with organoclay helped the activated carbon considerably in removing chlorinated hydrocarbons. Lab results obtained from a mini-column test (Alther, 2004, 2002). Solubility % by organoclay weight removed Benzene 1800 mg/l 39 Toluene o-xylene insoluble 44 Naphthalene PCB 1260 insoluble 52

8 Table gal of sump sludge water was passed through a vessel filled with 250 lb. of organoclay/anthracite over a period of one hour. Organic Compound Solubility (mg/l) Inflow Conc. (mg/kg) Outflow Conc. (mg/1) Oil and Grease 12 1 COD * 16,084 (mg/1) 202 BOD Phenanthrene ,000 <10 Naphtalene ,000 <10 Fluorene ,000 <10 Pyrene ,000 <10 Benzo(A)Anthrazene ,300 <10 Anthrazene ,000 <10 Indeno(1,2,3,C,D)Pyrene ,000 <10 Table 5. Removal of heavy metal cations by organoclay/anthracite. 300 gallons of sump sludge water were passed through 250 lbs. of organoclay during a period of one hour, or at 6 gpm. Metal Inflow Concentration (mg/kg) Outflow Concentration (mg/kg) Aluminum 1, Barium 3, Cadmium 2.53 ND Chrome Cobalt Copper Iron 3, Lead 1, Manganese Nickel Tin Zinc