United States Environmental Protection Agency Industrial Environmental Research Laboratory Cincinnati OH 45268 Research and Development EPA-600/S2-83-085 Jan. 1984 SER& Project Summary Polishing Industrial Waste Stream Effluents Using Fly Ash-Natural Clay Sorbent Combination Paul C. Chan, John W. Liskowitz, Mung-Shium Sheih, and Richard Trattner Described herein is a laboratory evaluation of the use of new, fly ash- natural clay sorbent combinations and, of the use of activated alumina for the polishing of industrial effluent containing fluorides and heavy metals. The work was conducted at the New Jersey Institute of Technology in Newark, New Jersey. The new sorbent materials studied were acidic and basic fly ashes and natural clays such as bentonite, bauxite, illite, kaolinite, zeolite, and vermiculite. Industrial waste effluents (3.8 x 106 liters per day) generated by the feldspar mining and processing industry contained significant concentrations of fluoride, iron, lead, chromium, and cadmium. In the laboratory evaluation, activated alumina treatment was included for comparison with the effectiveness and cost of treatment using the new sorbent combinations. The most effective new sorbent combination for the feldspar waste stream was a mixture of illite, basic fly ash, and lime. Lime was used to maintain a pH of 6.3. Fluoride and iron in the wastewater were reduced from concentrations of 17.5 mg/l and 4.5 mg/l to 1 mg/land 0.020 mg/l, respectively. Lead, chromi- um, and cadmium concentrations were reduced from 0.12 mg/l, 0.05 mg/l, and 0.15 mg/l to 0.013 mg/l, 0.015 mg/l, and 0.010 mg/l, respectively. While the treatment process was designed for maximum removal of fluoride, it also provided effective removal of the heavy metals. Maximum removal of fluoride was achieved at a pH of 6.3 with a minimum contact time of six hours between the sorbent and waste stream. Regeneration of the spent sorbent can be accomplished with 1% H2SO4- A 20% loss in sorbent capacity was observed after the first regeneration. Subsequent regenerations resulted in no further loss of sorbent capacity. Estimated materials costs for the illite/basic fly ash/lime sorbent combi- nations with spent sorbent regeneration are 13.3 cents per 3.8 x 103 liters (1000 gallons) of wastewater. The use of activated alumina with regeneration costs twice as much. Estimated materials costs for the illite/basic fly ash/lime sorbent combi- nation used once (without regeneration) are 45 cents per 3.8 x 103 liters (1000 gallons) of wastewater. Activated alumina without regeneration costs $4.95 per 3.8 x 103 liters (1000 gallons) of wastewater. Disposal of the spent illite/basic fly ash/lime sorbent combination, when no regeneration is done, should pose no problem. Repeated washing showed no significant loss of sorbed cations and anions. This report was submitted in fulfillment of Grant No. R-805666 by the New Jersey Institute of Technology under the sponsorship of the U.S. Environmen- tal Protection Agency. This report ------- covers the period October 1, 1977 to October 31, 1978, and work was com- pleted as of December 31, 1978. This Project Summary was developed by EPA's Industrial Environmental Research Laboratory. Cincinnati. OH, to announce key findings of the research project that is fully documented in 'Separate report of the same title (see Project Report ordering information at back). Introduction The objective of this laboratory investiga- tion was to establish the feasibility, both technically and economically of using inexpensive combinations of fly ash and clays as new sorbents for a polishing treatment of industrial wastewaters. The new sorbents have been found effective for removal of heavy metals, toxic anions, and organics from leachate that is generated from industrial sludges deposited in landfills (EPA-600/2-80- 052, June 1980). The present study explores the use of fly ash/clay sorbent combinations for a polishing treatment of an industrial effluent for the removal of fluorides and heavy metals. The wastewater used for this investiga- tion came from a feldspar mining and processing operation generating waste- water at a rate of 3.8 x 106 liters per day. The study was undertaken to investigate the removal of fluorides, heavy metals, and organics that may be present in significant concentrations in this waste stream. Materials and Methods Materials The sorbent materials selected for this investigation were fly ashes, zeolite, vermiculite, illite, kaolinite, bauxite, bentonite, and activated alumina, the latter for comparison purposes. The selection of these materials was based on economic considerations, availability, and potential for pollutant removal. Origin and preparation of sorbent materials is described in the final report. The wastewater used in this study resulted from mining and processing of feldspar ore. The wastewater was collected in five 5-gallon, lined drums and transported to the laboratory. Three shipments of the wastewater, three drums each time, were made during the one-year study. The results of the analysis of three separate shipments of wastewater are listed in Table 1. Table 1. Analysis of Feldspar Wastewater Concentration mg/l Contaminants F Cel CN SO, Ca Cd Cr Cu Fe Mg Ni Pb Zn COD pH Sample 1 4.0 27 0.0 64 5.2 0.009 0.007 0.035 1.8 1.7 0.054 0.019 0.054 14 5.5 Sample 2 17.5 32 0.009 82 6.7 0.007 0.008 0.047 4.5 3.7 0.044 0.013 0.076 20 4.9 Sample 3 5.8 39 0.008 57 11.3 0.015 0.05 0.02 0.3 1.9 0.15 0.12 0.18 18 6.3 Methods The investigation was performed in three different phases: (1) static studies, (2) dynamic studies, and (3) spent sorbent regeneration. 1. Static studies: The static studies evaluated the effectiveness of sorbents for removal of major contaminants from feldspar wastewater, the effect of pH on sorbent capacity, the relation between sorbent capacity and the desired effluent concentration, and the length of contact time between sorbent and wastewater. Sorbent materials were contacted with wastewater in an Erlenmeyer flask. 2. Dynamic studies: Lysimeter studies provided dynamic conditions to evaluate the removal capacity of the most effective sorbent mixture, illite/basic fly ash/lime, (determined as a result of static studies), for fluorides and iron present in the feldspar wastewater. Two different hydraulic systems were studied; gravitation- al flowandexpanded-bedflow. Lysimeters were constructed of Plexiglass* tubing, supported in a vertical position. In the gravitational flow operation, wastewater was fed to the top of the column. A constant hydraulic head was maintained in the lysimeters at all times, and the volume of wastewater through the packed sorbent material was continu- ously monitored. In the upflow expanded-bed operation, the wastewater was fed through the bottom of the bed at a velocity sufficient to expand the bed without loss of the sorbent in the overflow. 3. Sorbent regeneration: The spent regeneration studies were carried out Mention of tradenames or commercial products does not constitute endorsement or recommendation for use by the U.S. Environmental Protection Agency. under batch conditions. A 1% solution of sulfuric acid was used as the reagent. Results and Discussion Results of Static Studies The sorbent materials were examined for their effectiveness to remove fluoride and iron from wastewater because these two contaminants were present at highest concentrations in the feldspar wastewater (see Table 1). Both illite and kaolinite showed comparable removals in reducing the fluoride concentrations to below 1.5 mg/l (Figure 1). Basic fly ash was found most effective in reducing iron from 1.8 mg/l to 0.02 mg/l (Figure 2). The illite sorbent capacity for removal of fluoride shows dependence upon pH, with optimum pH for fluoride removal at pH of 6.3. The Kaolinite sorbent capacity for fluoride removal shows no dependence on pH (Figure 3). The sorbent capacity of a sorbent and for a given pollutant decreases as the initial concentration of the pollutant decreases in the waste stream. Under- standing the relationship between sor- bent capacity and desired effluent con- centration is important in estimating the amount of sorbent required to achieve the desired effluent concentration. A minimum contact time of six hours between the sorbents and feldspar wastewater is required to insure maxi- mum removals of fluoride. Results of Lysimeters Studies Based on the results of static studies, a mixture of 50% illite and 50% basic fly ash was selected for lysimeter studies to ------- i § i Wastewater Concentration = 4.0 mg/l Bentonite A Bauxite Fly Ash (Acidic) Fly Ash (Basic) O //lite A Kaolinite » Zeolite O Vermiculite I \ 20 4O 60 80 Sorbent Concentration in Wastewater, g/l 100 Figure 1. Fluoride treatment (batch conditions). determine that mixture's effectiveness in reducing both fluoride and iron to acceptable levels under dynamic (flowing) conditions. Gravitational Flows Experiments performed under gravita- tional flow operation showed that the sorbent particle size range influencedthe reduction of fluoride (best removals at small particle size ranges) but did not effect the removal of iron (Figure 4). Increases in sorbent particle size ranges allow larger flows, but at the same time it significantly decreases the effectiveness of the sorbent bed for removal of fluoride. Experiments with gravitational flow showed that very large flows cannot be handled by sorbent beds under gravitation- al feed. Thus, passing of the feldspar wastewater in the amount of 3.8 x 106 liters per day would be impractical. On the other hand, experiments with the upflow expanded-bed treatment showed that large volumes of wastewater can be easily treated in this way, and adequate contact time for the sorbent to interact with the wastewater can be maintained. Operation of the upflow expanded-bed in the illite/basic fly ash/lime sorbent mixture in the lysimeters resulted in reduction of fluoride levels from 5.8 mg/l to 1.5 mg/l in the feldspar wastewater (Figure 5). Another practical way of contacting sorbents with industrial wastewaters is by adding the illite/basic fly ash/lime mixture directly to the waste stream. The sorbents added to the waste can be removed in sedimentation basins, provided that adequate settling rates are encoun- tered. Settling tests carried out on the illite/basic fly ash/lime mixture showed that this particular mixture has compatible settling rates. The use of the new sorbent mixture without regeneration of the spent sorbent is economically and technically feasible. Conclusions 1. On the basis of laboratory tests, the illite/basic fly ash/lime sorbent com- bination appears to be effective for treating waste streams generated by the feldspar mining and processing industry. The sorbent combination can be added directly to the waste stream and the spent sorbent removed by sedimentation at a loading rate of 1.77 x 104 l/mVday (432 gal/ftVday). Also, the waste stream can be treated in a sorbent bed operated in an upflow expanded-bed mode. A six-foot-deep sorbent bed can treat the above flows at a loading rate of 7400 l/m2 (180 gal/ft2). This sorbent combination reduced the iron, lead, chromium, cadmium, and fluoride concentration to levels that are generally acceptable for potable water supplies. 2. Reliance upon gravitational flow through the sorbent bed is impractical for treatment of a feldspar waste stream. The permeability of sorbents limits the treatment to loadings as low as 575 l/m2/day/ (14 gal/ftVday). A sorbent bed with surface area of 6.7 x 103 M2 (7.2 x 104ft2) would be required to avoid ponding at a 3.8 x 106 I/day / (1MGD) flow rate. 3. Increasing the gravitational flow through a sorbent bed by increasing the particle size in the bed is not practi- cal for treating large volumes of wastewater. An increase in the parti- cle size results in a decrease in the vol- ume of wastewater that can be treated with a given weight of sorbents. Ap- ------- 0.7 0.6 > c I s p § 0.5 0.3 u 3 1 0.2 0.7 Influent concentration =1.8 mg/l % Fly Ash (Acidic) Fly Ash (Basic) A Kaolinite D ////te I I I _L _L _L Figure 2. 20 40 60 SO Sorbent Concentration in Wastewater, g/l Iron treatment (batch conditions). 100 The difference is primarily associated with the use of NaOH in the regenera- tion of activated alumina. 6. It appears that the spent sorbent com- bination may be disposed of easily. The sorbent contaminants do not seem to pose any threat to ground or surface waters. Repeated washing of different amounts of sorbents did not indicate any fluoride concentration above 1.1 mg/l in the rinse water. This elimi- nates the problem associated with the disposal of a metal hydroxide as CaF2 sludge from the regeneration process. However, replenishing the spent sor- bents with unused sorbents raises the treatment costs to 45 cents per 3.8 x 103 liters. Disposal of spent activated alumina without regeneration would amount to $4.95 per 3.8 x 103 liters. Recommendations The results of this investigation show that, on a laboratory scale, the use of clay/fly ash sorbent combination for polishing the fluoride, iron, lead, chromi- um, and cadmium in waste stream flows from the feldspar mining and processing operation is both technically and econom- ically feasible. An industrial-scale project should be undertaken with the cooperation of Federal agencies to demonstrate the use of the fly ash/clay sorbent combination for polishing the heavy metal-# and fluoride-bearing waste streams on an industrial scale. The development of inexpensive treat- ment technology would benefit industries that have treatment facilities but require additional polishing of their effluents for removal of heavy metals and fluoride to meet state and federal guidelines. parently, the advantage of the in- creased pore volume of the bed by in- creasing the particle size is offset by a reduction in the sorbent capacity due to the decrease i n particle surface area encountered with the larger particles. 4. The conditions required for maximum removal of the fluoride also provide ef- fective treatment of iron, lead, chromi- um, and cadmium present in the feld- spar waste stream. The maximum sor- bent capacity for the removal of fluo- ride occurs at a pH of 6.3, with a con- tact time of six hours between the sor- bents and wastewater. The material costs associated with the use of the illite/basicfly ash/lime sor- bent for treating 3.8 x 103 I (1000 gal- lons) of feldspar waste stream with re- generation is estimated on the basis of laboratory scale testing to be one third that associated with the use of acti- vated alumina. These costs amount to 13 cents per 3.8 x 103 and 45 cents per 3.8 x 1031 for the sorbent combination and activated alumina, respectively. ------- 0.5 0.4 1 I °'3 0.2 0.1 D Illite A Kaolinite 5 pH Figure 3. pH effect on sorbent capacity for fluoride (batch conditions). ------- 20 I 12 U § § 4 1.0 Influent Concentration =17.4 mg/l Particle Size > 0.042 cm O Particle Size > 0.042 cm A 0.021 cm < Particle Size < 0.042 cm A 0.021 cm < Particle Size < 0.042 cm O Particle Size < 0.021 cm Particle Size < 0.021 cm 6 8 10 Volume Treated, Liters 12 14 16 Figure 4. Fluoride removal dependence on sorbent particle size (gravitational flow). I, L i 2 § o Influent Concentration = 5.8 mg/l Figure 5. 20 40 60 80 100 Volume Treated, Liters Fluoride treatment (expanded bed flow). 120 140 160 ------- Paul C. Chan, John W. Liskowitz, Mung-Shium Sheih, and Richard Trattner are with the New Jersey Institute of Technology, Newark, NJ 07102. Mary K. Stinson is the EPA Project Officer (see below). The complete report, entitled "Polishing Industrial Waste Stream Effluents Using Fly Ash-Natural Clay Sorbent Combination," (Order No. PB 83-259 663; Cost: $10.00, subject to change) will be available only from: National Technical Information Service 5285 Port Royal Road Springfield. VA 22161 Telephone: 703-487-4650 The EPA Project Officer can be contacted at: Industrial Environmental Research Laboratory U.S. Environmental Protection Agency Cincinnati, OH 45268 United States Environmental Protection Agency Center for Environmental Research Information Cincinnati OH 45268 Official Business Penalty for Private Use $300 USS ENVIR2PROTECTION AGENCY CHICAGO IL 60604 U.S. GOVERNMENT PRINTING OFFICE: 1964-759-102/841 ------- |