R&D on Technology for Treatment of Water-soluble waste lubricant

Transcription

1 2001.M3.1.4 R&D on Technology for Treatment of Water-soluble waste lubricant (Water-soluble waste lubricant Treatment Group) Kazutoshi Shimoda, Toshiaki Tamura, Katuzo Endo, Tetsuichi Fujita, Hiroshi Kodama 1. Contents of Empirical Research For disposal or recycling of water-soluble cutting fluid waste, in general is either consigned to industrial waste companies for a fee or users treat wastewater so that it conforms to the levels stipulated in the Water Pollution Prevention Act, and then discharge it into rivers, etc. The compositions of cutting fluids sold on the market are quite diverse, and large-scale facilities are required for compliance with water quality standards. In Japan, the metal processing industry is distinguished by the fact that there are many corpo entities of relatively small scale, and conventional methods of treating waste lubricant, which require plant campuses and large investments, are problematic. The present research is aimed at development of a means whereby such can be carried out with compact facilities using a method involving membrane. Such a development could be spread widely among regular enterprises, and it could contribute to the reduction of wastes. Depending on their compositions, oily wastes after can undergo thermal recycling as fuel, and this approach can be considered significant also from the standpoint of effective use of petroleum resources. In the present R&D, water-soluble waste lubricant was sepad into water and mineral oil by a membrane processing unit, and the relationships in quality among PH BOD (Bio-chemical Oxygen Demand), COD (Chemical Oxygen Demand) and N-hexane extraction substance (mineral oil substance) were analyzed and investigated. A schematic illustration of this R&D is shown in Figure Water-soluble Waste lubricant Membrane Treatment facility Water standards met? Discharge to river TOC measurement COD measurement BOD measurement Secondary Reuse Figure Schematic Representation of R&D 1

2 2. Empirical Research Results and Analysis Thereof 2.1 Outline of Filter Unit Under the principle of membrane separation, portions of low molecular substances dissolved in water permeate an ultra-filter membrane, and particles of emulsified oil or floating substances are blocked and sepad. Rankings of membrane and of targeted separation substance span a broad range and are not uniform. Separation membrane pore diameters range from 1A to 10 µm. The ultra-filter membrane (UF) blocks the permeation of macromolecular substances on the order of 1,000 to 30,000, but allows permeation of ion molecules and low molecular substances. In reverse osmosis (RO), a membrane module makes use of the principle of dense and lean osmotic pressures. 2.2 Comparison of the Properties of Solution and Permeated Solution Firstly, the water-soluble lubricants (emulsion type - soluble type) of each maker of lubricants were selected at random and subjected to ultra-filter (UF). The relationships between stock and permeated were analyzed and investigated through a comparison of properties. A large number of study for of waste water with UF membranes are being developed, but in reports in general, treated water from water-soluble waste lubricant cannot be discharged as such at present because of the inhibiting action of high molecular substances being dissolved. In recent years, such things as membrane materials that do not require ph adjustment have been developed from diverse standpoints, so a survey was conducted, using polyolefin membrane, to see if permeated water can be kept within water quality standard values with UF membrane alone. As indicated in Table 2.2-1, it was found that in either case the ph value does not change. Sharp differences were noted in TOC, COD and oil. Removal was high, at 90 to 95%, especially in the emulsion type, and it is conjectured that the burden of subsequent processes can be reduced through repeated research on such things as conditions. Respecting the soluble type, however, it was found that because the s of emulsifier, amine and other ingredients that essentially dissolve in water are generally greater than in the emulsion type, the removal s of TOC and COD are low at 50 to 70%, and in any case, secondary by chemical agents, adsorption, RO membrane, etc. must be considered. 2

3 Table Comparison of Properties of and Permeated Solution A company B company C company D company E company type (diluted 20 times) type (diluted 30 times) unit: ppm PH TOC COD PH TOC COD 9.5 9,738 4,380 49, ,998 5,670 14, ,910 1, Removal (%) ,239 4,240 62, ,925 2,740 42, , ,110 Removal (%) ,239 5,680 58, ,817 5,680 58, , Removal (%) ,871 6,000 60, ,175 4,800 8, ,308 1, Removal (%) ,678 4,400 58, ,535 3,440 13, , , Removal (%) Analysis of Metal in Solution and Permeated Solution An analysis was made of metal from the standpoint of burden on the environment and impact on membrane (Table 2.3-1). (a) (b) (c) There is an effect on the removal of heavy metal such as Ba. This means that heavy metals are concentd on the interior side of membrane, and it is suspected that this has an effect on membrane service life and fowling. The metal removal effect is large for Ba, K, Mg and Fe; medium for Ca, and small for Si and Na. It is unusual that K and Na behave differently (both metals are highly hydrophilic). The reasons for this are unclear, although the impact of compounds before can be considered. Table Metal Analysis Results Type A company B company C company D company E company 3 unit: ppm Ba Ca K Mg Si Na Type N company I company K company M company Y company Ba Ca K Mg Si Na Fe

4 2.4 Impact of Dispersed Emulsifier on Membrane Treatment Trial productions were made in order to compare and investigate ingredients included in the emulsion type, soluble type and type with independent ingredients in and model. In the confirmation of ingredients that can be removed by ultra-filter (UF) membrane, the evaluation centered on the impact of dispersing emulsifier on membrane. The prescriptions of model and of independent ingredient aqueous are given in Table Table Model Solution, Independent Ingredient Aqueous Solution (emulsion type 10%, soluble type 5%, type 5% ) type Feed volume (mass%) Model Solution Independent Ingredient Aqueous Solution Sample No No.1 No.4 No.5 No.6 Oleic acid Triethanolamine Sodium sulfonate POE (EO5) alkylether Chlorinated paraffin (Cl = 50) Mineral oil Water (deionised water) type Feed volume (mass%) Model Solution Independent Ingredient Aqueous Solution Sample No No.2 No.7 No.8 No.9 Recinoleric acid Octanoic acid Triethanolamine Sodium sulfonate POE (EO5) alkylether Chlorinated paraffin (Cl=50) Water (deionised water) When results were confirmed with the properties [TOC, COD, BOD] of treated permeated, the varied greatly by type. In the model it was found to be about 97% for the emulsion type, 70% for the soluble type and 44% for the type. A similar trend was found for the independent ingredient aqueous (Table 2.4-2). 4

5 Table Model Solution, of Independent Ingredient Aqueous Solution, Permeated Solution Properties TOC Sample No. Permeated Treatment COD Sample No. Permeated Treatment Solution unit: ppm 10 Solution 59,560 25,060 13,990 7,885 11,300 4,097 9,300 2,174 3,487 11,470 1,713 7,459 7,848 1, ,726 1, , % 70.2% 43.9% 83.0% 93.0% 96.6% 70.7% 13.8% 98.2% 36.9% Solution unit: ppm 10 Solution 7,700 11,200 4,160 4,400 11,300 1,020 6,100 4,320 1,170 3, ,435 3, ,590 3, , % 69.3% 19.4% 86.9% 93.0% 91.9% 73.9% 26.4% 98.5% 40.1% BOD Sample No. Permeated Treatment Solution unit: ppm 10 Solution 4,400 5,300 3,400 2,300 1, ,000 3,900 2,300 4, ,300 1, , , % 75.5% 50.0% 75.7% 84.5% 83.3% 83.7% 28.2% 96.1% 41.9% (For sample No.1 to 3, model by each type, For No.4 to 10, independent ingredient aqueous ) Next, an evaluative analysis of the property of each ingredient by independent ingredient was made through TOC measurement. The properties of each ingredient are shown in Table and Figure It was discovered that in cases in which TEA [triethanolamine] is included, such as triethanolamine, octanoic acid/triethanolamine, or dodecane 2 acid/ triethanolamine, the properties are inadequate. However, the s of oleic acid/triethanolamine and of recinoleric acid/triethanolamine are relatively high. Considering that the percentage of fatty acid/triethanolamine was neutral equivalence in each sample, it was confirmed that the efficiency of fatty acid/amine salt varies with the type of fatty acid. The of POE (EO5) alkyl ether was higher than anticipated, and in the of waste water containing nonionic type emulsifier, the unit used in the research was found to be effective. 5

6 Table Treatment Property of Each Ingredient (TOC - PPM/Sample 1,000 PPM) Before After Treatment Oleic acid/tea % Sodium sulfonate % POE(EO5) alkylether % Chlorinated paraffin % Mineral oil % Recinoleric acid/tea % Octanoic acid/tea % Triethanolamine (TEA) % Dodecane 2 acid/tea % Treatment Oleic acid /TEA Sodium sulfonate POE(EO5) alkylether Recinoleric acid/tea Octanoic acid/tea TEA Dodecane 2 acid/tea Figure Treatment Rate of Each Ingredient 2.5 Impact of Abrasive Powders and Other Impurities on Membrane Treatment Aluminum powder and machine oil were delibely mixed in water-soluble lubricant [emulsion type, soluble type], and evaluations were made of the impact on membrane and of the properties of permeated. (1) Impact of Abrasive Powder (Aluminum) on Membrane Treatment Aluminum powder of grain size 1,000A was mixed in water-soluble lubricant at 100 ppm and 500 ppm, and impacts on membrane were compared in terms of time and flow volume index (FLUX). In addition, an analysis was done on metal in permeated in order to investigate metal permeation. It was found that there is no clogging in membrane even with aluminum mixed in, and all permeation of metal powder could not be noted by naked eye observation. There was also no change in FLUX (Figure 2.5-1) index. In a quantitative analysis of metal in permeated, approximately 8.5 ppm was detected with the soluble type. 6

7 type Unit: ppm type Unit: ppm FLUX comparison Aluminum 500 ppm No metal powder 0:00 0:30 1:10 1:40 2:10 2:40 3:10 3:20 Time FLUX comparison 0:00 0:30 1:30 2:00 2:30 3:00 3:35 4:10 4:20 Time Figure Impact of Metal Powder Mixtures (FLUX: flow volume at 1 m 2 per hour) (2) Impact of Machine (Slide-way lubricant) on Membrane Treatment A water-soluble cutting oil and slide-way lubricant of different quality were forcibly mixed in water-soluble lubricant, and the impact on membrane was evaluated in terms of the properties of permeated. In the evaluation with s of different sliding oil mixture percentages [0, 1 and 5%], machine oil permeation was not noted by naked-eye observation and the s were colorless and transparent. The s of TOC, COD and oil in permeated were equivalent to measured values (Table 2.5-1), and it was thus determined that there is no impact. Table Comparison of Properties of Permeated Solution Mixed With Machine type unit: ppm type unit: ppm Mixture Mixture TOC COD volume volume TOC COD ,429 1, % % 3,567 1, % % 3,609 1, Secondary Treatment Property of Membrane-Treated Waste Water From research conducted thus far, it was determined that the s of BOD, COD and oil after UF membrane failed to match standards set by the Water Pollution Prevention Act. Consequently, experiments with secondary s generally conducted, such as chemical agent, adsorption or biological, became necessary. (1) Chemical agent The chemical agent (aluminum sulfate) generally used in wastewater underwent and evaluation by the method shown in Figure in UF membrane permeated and RO membrane permeated. 7

8 Although some effect was manifested by chemical agent secondary of UF membrane emulsion, there was virtually no reaction in the soluble. With RO membrane, was implemented under varied conditions (chemical agent quantities), but no improvements in properties were noted. The results of evaluation of chemical agent for UF membrane permeated and for RO membrane permeated from water-soluble lubricant are presented in Table Sample fluid Aluminum sulfate (120rpm, 15min) Figure Calcium-hydroxide (5% ) ph7 (120rpm, 15min) Paper filter (No.5A filter paper) 5000ppm Polymer (0.1% ) 5ppm Flow of Chemical Agent Treatment (120rpm, 5min) Water quality measurement Table Chemical Agent Treatment Properties UF membrane permeated RO membrane permeated type (5% ) ppm type (5% ) ppm Chemical Chemical UF RO agent Removal agent Removal membrane membrane PH PH TOC % TOC % COD % COD % type (3.3% ) UF membrane % Chemical agent Removal type (3.3% ) RO membrane % Chemical agent Removal PH PH TOC 2,941 2, % TOC % COD 1,300 1, % COD % % % (2) Adsorption (active carbon) Next, active carbon adsorption was implemented, and its effectiveness was evaluated. In this method, a cylindrical container was filled with 3 kg of active carbon, and experiments were conducted at a throughput flow volume of 20 to 30 ml/min. BOD, COD and oil s exceeded water quality standards only in the soluble type UF-membrane treated (Table 2.6-2). Nevertheless, because the ph value was outside the standard value, discharge after neutralization with sulfuric acid, etc., was required. With the soluble type UF-treated in question, although there were drops in measured values, the adsorption method was deemed unfeasible because ingredient s were excessive. 8

9 Table Active Carbon Treatment Properties UF membrane permeated RO membrane permeated type (5% ) ppm type (5% ) ppm UF Active RO Active Removal Removal membrane carbon membrane carbon PH PH TOC % TOC % COD % COD % BOD % BOD % % 34 1> 100% type (3.3% ) type (3.3% ) UF Active RO Active Removal Removal membrane carbon membrane carbon PH PH TOC 2,941 1,172 60% TOC % COD 1, % COD % BOD 1, % BOD % % 51 1> 100% (3) Biological oxidation The biological oxidation unit used in the R&D is based on the rotary disk catalytic oxidation method. In principle, the disk serves as a catalytic medium and it is rotated at a fixed circumferential speed. Microorganisms are propagated on this disk and brought into contact with a biological membrane and waste. Pollutant substances in the waste undergo biological oxidation and decomposition through repeated aeration in air. For the microorganisms, bacteria were obtained from public sewage facilities and cultured. Under continuous circulatory operation, it is possible to lower numerical values until wastewater standards are met (Table 2.6-3, Figure 2.6-2). Nevertheless, it is difficult to control the microorganisms in accordance with waste lubricant properties and fluctuations in volumes, so ongoing control is problematic. 9

10 Table Course of Continuous Circulatory Treatment for Biological Treatment type (60L) + soluble type RO membrane permeated (15L) TOC measurement unit: ppm Measurement results Difference from Treatment previous result /day First day th day th day th day th day Physical property values after biological ppm Measured value PH 4.8 TOC 35 COD 25 BOD Biological oxidation (TOC comparison) Measurement results Treatment /day First day 4 th day 10 th day 12 th day 17 th day Figure Course of Continuous Circulatory Treatment for Biological Treatment (4) Reverse osmosis (RO) membrane UF-membrane permeated was subjected to secondary with RO membrane, and the properties of this permeated were evaluated. A tubular type RO membrane made of cellulose was used for. Results were about the same for both emulsion type and soluble type. In UF membrane plus RO membrane, the effect is great in emulsion type, and property is favorable. Among emulsion type s, there were levels of waste that match water quality standards, but in any case oil s failed to match standards. Even in the case of RO membrane permeated, the cannot be discharged as is (Table 2.6-4). 10

11 Table Properties of RO Membrane Permeated Solution type (5% ) unit: ppm UF membrane RO membrane Removal PH TOC 9, % COD 4, % 49, % type (3.3% ) UF membrane RO membrane Removal PH TOC 7,998 2, % COD 5,670 1, % 14, % UF treated adjusted to 7.0 Ph (Sulfuric acid application) 2.7 Tertiary Treatment (Post Treatment) Evaluations were made of chemical agent, adsorption, biological and RO membrane as modes of secondary. It was found that joint use of UF and RO membrane is ideal in consideration of routine maintenance, running costs, etc. Even with this combination, however, water quality standards were not met, and tertiary was deemed necessary. For tertiary, a spiral-type, high-molecular compound membrane was used together with an RO membrane of 99.5% NaCl blocking, and evaluations were made with several types of practical. Although there were small variations in measured values, depending on the test sample, BOD, COD and oil s satisfied water quality standards in all respects, and initial objectives could be reached. 2.8 Proposal of Optimum Unit and Treatment Conditions (1) Optimum Unit The optimum unit design was in the sequence: pre unit [oil/water separator, magnet paper filter] UF membrane RO membrane [polyolefin] RO membrane [high molecular compound membrane] (Figure 2.8-1). Because a single RO membrane unit can be used with both polyolefin and high molecular compound membrane, one unit is used jointly in the layout. 11

12 Flow Diagram of Water-soluble waste lubricant Treatment Circulation line UF membrane Circulation line RO membrane (polyolefin) PH adjustment /water separation tank Condensed waste Condensed Waste Intermediate tank Condensed waste Circulation line Intermediate tank Wastewater standards met? Condensed waste Wastewater tank RO membrane (high molecular compound membrane) Discharge, Reuse Condensed waste tank Industrial waste company Recycled as fuel depending on composition Figure Flow of Membrane Treatment Units Completion within a short time period was targeted for long-term operation of practical equipment. Practical equipment operations were implemented on a practical scale after a water-soluble waste lubricant actually in use on the market was loaded. As a result (Table 2.8-1), a high-standard evaluation could be obtained in which the can be reused or discharged into rivers, etc., because among permeated properties, BOD, COD and oil s matched water quality standards in all respects. [Water Pollution Prevention Act: COD 160 ppm, BOD 160 ppm, oil 5 ppm or less] Table Properties of Permeated Solution at Each Process UF membrane permeated Sample No. TOC BOD COD NO,1 14, ,800 3,160 NO,2 12, ,580 2,300 NO,3 46, ,860 2,560 NO,4 16,920 1,180 8,120 1,180 RO membrane permeated (cellulose) TOC BOD COD RO membrane permeated (high molecular compound membrane) TOC BOD COD

13 (2) Treatment Conditions From the impact of dispersed emulsifier on membrane, an evaluation was made of the relationship between fatty acid and amine salt. 1) Fatty acid and amine salt (impact of fatty acid length) A sample in which the mol ratio of fatty acid and triethanolamine is roughly fixed was subjected to UF membrane, and the property declined in the sequence: oleic acid, lauric acid and octanoic acid. Treatment property is improved to about the level at which a long-chain fatty acid is used (Figure 2.8-2). Treatment % Recinoleric acid Lauric acid Dodecane 2 acid Octanoic acid Figure Treatment Rates of Fatty Acid and Amine Salt 2) Treatment property of RO membrane (cellulose) The results of RO membrane of samples 4, 5, 7 and 8 show that the property of RO membrane is higher than that of UF membrane (Table 2.8-2). Permeated of 1% triethanolamine was in the range of 10 to 20 ppm. A slightly lower value was obtained through joint use of fatty acid and triethanolamine, but the difference was small, and it was found that ingredient impact was greater with UF membrane than with RO membrane. Table Properties of RO Membrane Permeated Solution of Independent Ingredient Aqueous Solution Sample No.4 Sample No.5 10% aqueous 10% aqueous Permeated Permeated PH PH TOC 7, TOC 3, COD 4, COD 11, BOD 2,300 - BOD 1,100-1, Measurement impossible Sample No.7 Sample No.8 5% aqueous 5% aqueous Permeated Permeated PH PH TOC 9, TOC 2, COD 6, COD 4, BOD 6,000 - BOD 3,900-7,

14 3. Results of Empirical Research Optimum conditions were established in accordance with the composition of each water-soluble lubricant, and the impact of each type of water-soluble lubricant composition on membrane property was clarified. In this way, advances were made in R&D for the provision of water-soluble lubricant of high applicability with respect to membrane property. (1) Comparison of properties of stock and permeated UF membrane blocks out high molecular substances from permeated, and the treated did not meet wastewater standards. Because of particle diameter, a higher removal was obtained in the emulsion type than in the soluble type. (2) Analysis of metal in stock and permeated Heavy metals such as Ba, K, Mg and Fe are effectively removed but there is an impact on membrane service life and fouling. (3) Impact of dispersed emulsifier on membrane 1) In seeking to determine the impact of oil agent ingredients on membrane property, it was discovered that a nonionic emulsifier can be used as emulsifier even though traditionally it use as such has been restricted because its aggregate property is inferior. It was also demonstd that the degree of freedom in the formulation of lubricant prescription can be elevated. 2) With a nonionic emulsifier having a property of 95% or more, it was found that the system used in the present research is effective. 3) Sulfonate emulsifier exhibits a property of 95% or more. 4) Fatty acid amine salt emulsifier exhibits a of 80% or more in the case of long-chain fatty acid salt, and 20% or less in the case of medium chain fatty acid salt. It was found that property varies greatly with fatty acid chain length, and this outcome is highly interesting. 5) The of triethanolamine was found to be low at approximately 20%. (4) Impact of abrasive powders and other impurities on membrane Experiments disclosed that mixtures of abrasive powder and machine oil (sliding surface oils) have no impact on permeated s. (5) Secondary property of membrane-treated wastewater 1) As modes of secondary, chemical agent, adsorption and biological all have shortcomings. Respecting with RO membrane (cellulose), it is necessary to use UF and RO membrane jointly. 2) As modes of tertiary, high molecular compound membrane and membrane with a NaCl blockage of 99.5% complied with water quality standards. 14

15 (6) Proposal of optimum unit and conditions Optimum unit A compact facility was employed encompassing pre unit, UF membrane, RO membrane (cellulose) and RO membrane (high molecular compound). Treatment conditions 1) As for the impact of fatty acid and amine salt (carbon length of fatty acid), in the case of with UF membrane of samples in which the mol ratio of fatty acid and TEA is roughly fixed, property declines in the sequence: oleic acid, lauric acid and octanoic acid. Treatment property improves to about the level when long-chain fatty acid is used. 2) RO membrane (cellulose) exhibited a higher property than UF membrane. It was also found that ingredient impact is greater with UF membrane than with RO membrane. 3) Concerning reuse of permeated, it was discovered that emulsification stability is favorable when membrane permeated is used as diluted water. In conventional by chemical agent, emulsification stability can be obstructed by inorganic salts in the treated water, but when permeated water obtained by the present method is used, this risk is avoided. The method is thus considered highly effective for reducing wastes. 4. Synopsis (1) With relatively compact facilities employing membrane technology, a technique for purification of water-soluble lubricant was established, and water quality standards could be met adequately. (2) The impact of lubricant composition was researched and indexes for the provision of water-soluble lubricant of high suitability to membrane could be obtained. (3) In order to have the technique disseminated among regular companies, it must be confirmed that the technique is effective against all the diverse types of cutting fluid on the market. In addition to regular research aimed at the aforesaid confirmations, R&D is scheduled to be continued with reference to membrane service life and economy. Copyright 2001 Petroleum Energy Center all rights reserved. 15