Applications of reverse osmosis to complex industrial wastewater treatment

Desalination, 48 (1983) 171--187

Elsevier Science Publishers B.V., Amsterdam -- Printed in The Netherlands

APPLICATIONS OF R E V E R S E OSMOSIS TO COMPLEX I N D U S T R I A L WASTEWATER T R E A T M E N T

C.S. SLATER, 1 R.C. AHLERT, 2 AND C.G. UCHRIN 3 1 Chemical Engineering Department, Manhattan College, Manhattan College Parkway, Riverdale, N Y 104 71 (USA) 2 Department o f Chemical and Biochemical Engineering, P.O. Box 909, Piscataway, N J 08854 (USA) 3Department o f Environmental Sciences, P.O. Box 231, New Brunswick, N J 08903 (USA)

(Received December 2, 1982; in revised form March 7, 1983)

SUMMARY Methods f o r t r e a t m e n t of hazardous and complex, aqueous industrial wastes are o f great current interest. Reverse osmosis (RO) has been shown t o be an efficient and cost effective process step for renovation of a broad range o f c o m p l e x industrial wastes. The success of RO in large-scale desalination and municipal wastewater t r e a t m e n t has led m a n y industries to view this t e c h n o l o g y as a means of pollution abat em ent and cost savings t h r o u g h reuse. Applications include r enovat i on of effluents f r o m t he chemical, textile, petrochemical, electrochemical, pulp, paper and food industries. Also, treatm e n t o f landfill leachate with RO is showing promise as a means of avoiding groundwater and surface water contamination.

INTRODUCTION The purpose o f this paper is to overview the application of reverse osmosis (RO) t e c h n o l o g y t o the t r e a t m e n t of c om pl ex industrial wastewaters. Within their c o n t e x t , a u t h o r views on t h e use o f RO steps in pollution a b a t e m e n t and water reuse processes have been considered and several have been n o t e d explicitly. T r e a t m e n t applications have been grouped by industry, i.e., chemical, textile, electroplating and metal finishing, pet rol eum and petrochemical, pulp and paper, and f o o d and beverage. Other industries t h a t yielded few references to RO applications have been com bi ned in a separate miscellaneous section. Th e subjects of specific organic substance rejection and landfill leachate t r e a t m e n t are discussed in separate sections. The inclusion of the t opi c of specific organic c o m p o u n d rejection is an a t t e m p t t o relate RO rejection 0011-9164/83/$03.00

© 1983 Elsevier Science Publishers B.V.

172

C.S. SLATER, R.C. AHLERT AND C.G. UCHRIN

mechanics for organics to the treatability of complex wastewater, i.e., industrial effluents. However, a detailed analysis of specific solute rejection and membrane properties was deemed beyond the scope of this paper. and membrane properties was deemed b e y o n d the scope of this paper. Landfill leachates are accorded separate discussions because of the intense concern for these hazardous and potentially toxic residuals, in the United States. In m a n y respects, leachates are broadly comparable to high-strengtil, complex industrial waste streams. Some reference to the experience of the present authors, together with the observations of several others, is well warranted. Desalination of seawater or brackish water has been omitted from this paper. This topic is so extensive that it requires a lengthy separate review. Those interested in this topic should consult the Proceedings of the International Congress on Desalination and Water Reuse, 1981, as included in Desalination, Vols, 38 and 39, as well as References 1 through 4.

NON-INDUSTRIAL APPLICATIONS Desalination of seawater and brackish water has been the principle historic focus o f RO application. Success in desalination has encouraged consideration of RO for other non-industrial purposes. Substantial research has been directed at municipal wastewater treatment and renovation of secondary and tertiary effluents for c o m m u n i t y reuse, as drinking and/or irrigation water. These topics are considered very briefly in the following sub-sections. Municipal wastewater treatment In addition to the research on industrial wastewater treatment, much effort has been directed to municipal wastewater treatment. The main uses o f RO in this area have been for the treatment of secondary and tertiary effluents. However, some work has been done on primary effluents and digester supernatant, also. Strauss [5] cites increased interest in RO wastewater separations. A system, in use since 1978, treats secondary effluent to produce a permeate with 20--30 mg/1 of TDS. The units have a 98.9% solids rejection capability and operate with continuous water recovery of 70%. Some early work on RO treatment of a variety of municipal wastewaters is described by Fisher and Lowell [6]. They considered flat plate and tubular cellulose acetate membranes for treatment of raw sewage, primary effluent, anaerobic digester supernatant and secondary effluent. Flux was maintained for primary and secondary effluents over an operating period of 20 days, but the flux depended greatly on wastewater composition. Flux dropped to almost zero after two days of operation with digester supernatant. The great degree of fouling observed with both raw sewage and digester filtrate was due to the high level of fine suspended and colloidal matter in these wastes. Lim and J o h n s t o n [7] concluded t h a t nutrients, i.e., nitrate, phosphate

RO IN INDUSTRIAL WASTEWATER TREATMENT

173

and ammonia, can be separated from raw and secondary municipal wastewaters b y cellulose acetate membranes. Phosphate removals that approach 100% have been demonstrated; ammonia and nitrate rejections averaging 85 and 86%, respectively, were observed. The target species of municipal wastewater coagulation, i.e., aluminum, iron, and sulfate ions, were reduced to 97%. Calcium and chloride removals were 92 and 83%, respectively. Throughout four months of pilot plant operation, permeate flux varied b u t averaged 0.41 m3/m 2 d. It was maintained by various physical and chemical cleaning techniques. Membrane fouling was found to be more pronounced for membranes with low rejection capability. The effect o f axial velocity on membrane flux and fouling in primary effluent treatment was studied b y Thomas and Mixon [8]. Separation utilized cellulose acetate membranes with an initial flux of 1.6--8.1 m3/m 2 d, operating at 5,520--6,900 kN/m 2. Flux decline was shown to be dependent on axial velocity. Below 0.25--0.38 m/s, fouling was severe. Above this value, flux decline was not evident. An o p t i m u m velocity range of 0.25--0.50 m/s was established as a standard operating condition. The use of pretreatment in t h e successful membrane renovation of raw domestic sewage was demonstrated b y Besik [9] who used physiochemical coagulation. Membrane fluxes o f 0.24--0.41 m3/m 2 d were maintained with tubular cellulose acetate membranes. Separation efficiency remained high. Pretreatment is seen as the critical step in municipal wastewater separation; it is necessary to maintain high flux from the start of operation [10, 1 1 ] . Secondary effluent has been evaluated with tubular, hollow fiber, and spiral w o u n d membranes. Various combinations of treatment methods, prior to RO, i.e., sand filtration, granular activated carbon, chlorine addition, and coagulation, significantly extend membrane life. Van den Hovel et al. [12] cite RO as an excellent method of concentrating municipal wastewater prior to anaerobic digestion. The average flux through tubular cellulose acetate membranes did not decrease during their experiments. Conductivity rejection averaged 97%; the primary effluent was reduced from 1380 to 300 pSI cm. The organic parameter of choice, COD, was reduced from 290 to 0--4 mg/1; BOD was reduced from 110 mg/1 to below detectable limits. Water reuse

Direct reuse o f wastewaters after RO has been practiced primarily in the industrial c o m m u n i t y ; it is a pollution abatement tool and an economical w a y to conserve process water. A major use, for example, is in agriculture for crop irrigation, to cut the cost o f water supply. Although some countries are planning total reuse systems for drinking water, utilizing RO technology, limited i m p l e m e n t a t i o n of direct wastewater reuse systems has occurred in the United States [ 1 3 ] . Uses of RO for water reuse after municipal and industrial wastewater treatment is discussed in the appropriate sections, as noted. Water Factory 21 in Orange County, California is one of the largest ad-

174

C.S. SLATER, R.C. AHLERT AND C.G. UCHRIN

vanced municipal wastewater treatment facilities in the world. It processes 56,800 m3/d of secondary effluent to within drinking water standards. The effluent from this facility is injected into groundwater wells to replenish the aquifer and retard seawater intrusion. In addition, 22,700 m3/d of tertiary effluent with 1100 mg/1 of TDS is treated to 40 mg/l by RO [14--16].

INDUSTRIAL WASTEWATERAPPLICATIONS

General Shuckrow et al. [17] compiled studies on RO treatability of industrial wastewaters containing a wide range of contaminants. A study of eighteen various industrial wastes showed nominal 95% removal of an average waste TOC of 72 mg/1. COD removal reported in this study was above 90%. For the organic species evaluated in this study, benzene rejection averaged 59%; bis(2-ethylhexyl)phthalate, 67%; acenapthene, 73%; phenol, 25%; and methylene chloride, 10% (Table 1). Rejection of inorganic contaminants such as selenium, arsenic, and cyanide were 77, 92 and 42%, respectively. They also document studies on reverse osmosis renovation of specific organic and inorganic species such as alcohols, aliphatics, amines, aromatics, ethers, halocarbons, metals, pesticides, and phenols [18].

Specific Organic Rejection Duvel and Helfgott [19] studied the specific RO rejection of organics found in industrial wastes. This study pointed out that, with cellulose acetate membrane systems, large macromolecular species are rejected almost completely. On the other hand, low molecular weight organics exhibit variable rejection, depending to some extent on the carbon chain length of the species. "In a homologous series, solute rejection increases as the number of carbon atoms, or the molecular weight increases." This was not found to be the complete answer because steric configuration, branching, and overall molecule geometry play important roles in determining rejection. Increased branching was found to overshadow molecular weight, as was shown with the isomers of pentanol. About 40% of linear 1-pentanol was rejected in RO, 3-methyl-l-butanol and 3-pentanol gave 60--70% rejection, and the highly branched 2-methyl-2-butanol and 2,2~limethyl-l-propanol exhibited close to 90% rejection. In addition to molecular weight and geometry, the chemical characteristics of a molecule, e.g., ability to form hydrogen bonds, are important in determining permeability. "Alcohols, amines, amides, and carboxylic acids are capable of both donating and accepting protons; therefore, they form strong hydrogen bonds. In consequence, they permeate membranes better than do esters, aldehydes, ketones, and sulfones, which can only act as proton acceptots." Carboxylic acids show the least rejection because they have the strongest hydrogen bonding ability of the compounds mentioned.

RO IN I N D U S T R I A L W A S T E W A T E R T R E A T M E N T LO O00~ Ob

UO UD

A

A

17 5

A

AA

AA

~'-LO

AA

AA

AA

A

0 0

~q

b~ 0 0

S~V~

0 h~ Z 0

<

Z © © z

0 Ch

Z < Z © © ~,..-,

0 ~ ~

<

~ -'-

.-' ~ ' ~

~"~

" " ~

"

0

o

E.-,

Z

176

C.S. SLATER, R.C. AHLERT AND C.G. UCHRIN

Fang and Chian [20] investigated the rejection of polar organic compounds from aqueous solution. Their study pointed to differences in rejection characteristics depending on membrane type. Thirteen low molecular weight polar organics with various functional groups (acid, aldehyde, amide, amine, ester, ether, ketone, phenol, alcohol) were tested at a concentration of 1,000 mg/1. Results showed that aromatic polyamide membranes gave an overall rejection of 50--75%; cellulose acetate membranes gave separations ranging only from 13--26%. Thus, in addition to dependence on the nature o f the molecule, membrane separation efficiencies depend on the characteristics of the membrane. Removal of specific organic c o m p o u n d s was the subject of a laboratory s t u d y b y Chian et al. [ 2 1 ] . RO was capable of removing better than 99% of fifteen major pesticides, including seven chlorinated hydrocarbons, four organophosphorus compounds, and four of other types. Wastewaters had concentrations of these pesticides ranging from 0.04 to 1.5 mg/1. Carcinogenic substances in industrial waste streams can be removed successfully b y RO [ 2 2 ] . Since most carcinogens are of high molecular weight and/or non-polar, membrane rejection theory suggests they should be removed. Two types of polyamide membranes were used in the separation studies, i.e., spiral w o u n d and hollow fiber units. An industrial waste stream suspected of containing carcinogens was treated initially b y ultrafiltration (UF), prior to RO. An RO feed TOC of 70 mg/1 was reduced b y an average o f 92.5% to 3.8 mg/1, with b o t h membranes studied. Individual carcinogenic species in a synthetic wastewater were studied. Overall rejection efficiencies for these chemicals, with spiral wound and hollow fiber modules were 85 and 82%, respectively. Removal efficiencies for high molecular weight species, such as methyl orange and malathion were high; removals were poorer for smaller species. Separation efficiencies for several c o m p o u n d s with water solubilities lower than 100 mg/1, i.e., polycyclic aromatic hydrocarbons, aromatic amines, and nitrosamines, were greater than 99%. The spiral w o u n d membrane showed no signs of fouling, while rejection b y the hollow fiber element declined slightly.

Chemical industry RO is one of the many process units used commercially to treat the chemical industry's varied wastewaters [23]. RO is usually combined with other physical separation techniques, as well as biological and physiochemical treatment, to produce effluents suitable for reuse, RO was found to be essential for the removal of dissolved solids from inorganic process waste streams treated previously biologically [24]. Biological treatment does not reduce high levels of dissolved salts. Gadjiev and Chian [25] demonstrated the utility of RO for removal of organic and inorganic species from aqueous wastes. The wastewater studied, eminated from an aerosol manufacturing plant and had a high concentration

RO IN INDUSTRIAL WASTEWATER TREATMENT

177

of dispersed oil. Chemical coagulation, followed b y sand filtration, appeared to be the most promising process for pretreating the waste to obtain efficient RO operation. Cellulose acetate membranes were rapidly destroyed b y an industrial waste containing 2000 mg/1 phenol [26]. A new phenol-resistantand-rejecting membrane, constructed o f polyvinylalcohol (PVA) resisted attack b y phenol at concentrations up to 50,000 mg/1, with rejections of 90-95%. Schrem and Lawson [27] employed RO units in a treatment scheme for wastewater from an organic chemical manufacturing plant. Initial activated sludge treatment reduced COD concentration to 180 mg/1. Treatment with activated carbon and multimedia filtration followed. RO further reduced COD to 4 mg/1; feed conductivity was lowered from 5,800 to 480 #S/cm. Tubular cellulose acetate membranes were used first in the unit, b u t could not a c c o m m o d a t e the extreme variations in temperature and pH. Spiral w o u n d polyamide units were installed; these could be operated over a pH range of 3 to 9 and at temperatures of 1 to 57°C. Over seven weeks of continuous operation, conductivity rejection averaged 92% at 80% water recovery. Although chloride rejection averaged only 78%, rejection of organic matter remained above 90%. Schrem et al. [28] concluded that RO has m a n y limitations in the removal of organics from chemical industry effluents. Fosberg et al. [29] examined the use of RO in conjunction with vapor compression evaporation in t h e treatment of industrial wastewaters. This syst e m was capable o f zero discharge; it utilized vapor compression evaporation o n RO retentate, in addition to final evaporation. Recoveries from the RO unit ranged from 40 to 90%, depending on TDS (1,000--35,000 mg/1). In one study o f a 10,000 mg/1 TDS chemical industry waste with high sodium, chloride, and sulfate, RO proved extremely cost effective, i.e., 2.6 kWh/m 3 of wastewater compared to vapor compression evaporation alone at 23 kWh/m 3.

Landfill leachate Chian and De Walle [30] demonstrated the effectiveness of RO in the treatment o f sanitary landfill leachate. They employed cellulose acetate and non-cellulose acetate membranes and obtained high TDS rejection (85--99%) and good to high TOC rejection (56--94%). They found that b o t h membrane t y p e and operating parameters effected organic removal. Utilizing a 13,000 mg/1 TOC leachate, an increase in pH from 5.5 to 8.0 increased TOC rejection b y a cellulose acetate membrane from 70 to 91.5%. A parallel, b u t not as significant an increase in TDS rejection was observed, also. Since most of the volatile acids present in sanitary landfill leachate have p K values b e t w e e n 4.7 and 4.9, the dissociation of these acids at pH 5.5 is incomplete. The increased quantity o f fatty acids dissociated b e t w e e n pH of 5.5 and 8.0 probably accounts for the increase in TOC rejection. The in-

178

c.s. SLATER, R.C. AHLERT AND C.G. UCHRIN

creased TDS rejection at higher pH is attributed to the increase in the degree o f dissociation of the organic acids at higher pH. Chian and DeWalle noted a decrease in rejection and flux with an increase in feed concentration and a decrease in operating pressure. Operating pressure was demonstrated to be an important parameter, since TOC and TDS rejection and flux increased with increasing pressure. In comparing cellulose acetate against a cross-linked polyethyleniminetolylene-2,4
RO IN INDUSTRIAL WASTEWATER TREATMENT

179

as TOC. An a t t e m p t was made to use a membrane with a lower rejection and higher flux. The flux did n o t increase significantly b y comparison with the previous membrane. Some signs of flux loss were seen with this module. However, this did not pose a problem in over 500 hours of total recycle operation. With this "loosely" cast membrane and higher solute concentrations, TDS rejection was only 88%. COD rejection was 65%, compared to the first experiment with 69% TOC reduction. Thus, even though solids rejection dropped, the level of organic removal paralleled that of the first experiment.

Tex tile industry RO is an attractive m e t h o d for treating textile industry wastewaters to produce quality effluent for reuse [ 3 3 - - 3 7 ] . The concentrated feed from the separation can be reused to prepare d y e solutions and has been shown to be operationally feasible over a 15 m o n t h test period; recovery was 95% [38, 39]. E1-Nashar [40] found fouling to be a problem in textile wastewater treatment, due to organic and inorganic colloids in the dye systems. This problem can be remedied b y proper pretreatment and the permeate produced can be o f high enough quality to be reused in scouring, bleaching and finishing solutions [41]. g O operation at high temperature was demonstrated b y Gaddis et al. [42] ; t h e y recycled water and chemicals in a wet finishing operation. Jhawor and Sleigh [43] observed high removal of color and 95% TDS red u c t i o n in d y e plant waste treatment. RO was shown b y Gaddis and Spencer [44] to be useful for removal of toxic substances from textile process water. Only basic contaminant parameters were studied. Rejection of color was extremely good, i.e., >99%; rejection of total solids averaged 94% and rejection of ionic species averaged 95%. Results showed that chloroform, toluene, trichloroethylene, and methylene chloride were not rejected. Phenol and di-n-butyl phthalate exhibited a varied tendency to be rejected. Compounds that did display a tendency for rejection from textile wastewater were: bis(2-ethylhexyl)phthalate, dimethyl phthalate, b u t y l b e n z y l phthalate, diethyl phthalate, acenaphthene, anthracene, fluoranthene, pyrene, naphthalene, phenanthrene, chlorobenzene and ethylbenzene. Toxic metals present in low concentrations were rejected at high percentages, except for arsenic, which averaged 89%. Brandon and Gaddis [45] studied the use of RO in textile dyeing plants. Their study f o u n d that rejection of salts, organic species and toxic metals increased significantly over the first 100 hours of operation. This was due to the formation of a dynamic membrane, resulting in flux decline and improved separation efficiency, rather than decreasing efficiency through conventional fouling. Organic concentrations, reflected as CODs ranging from 1,300 to 1,900 mg/1, were reduced to 80 to 270 mg/1 at several plants. Feed TDS that averaged 3,000 mg/l was reduced to an average of 125 mg/1. Brandon [46] cites t h e great variety of dyes and finishes used in the tex-

180

C.S. SLATER, R.C. AHLERT AND C.G. UCHRIN

tile industry as a major problem in waste stream treatment. Although quite variable, COD averaged 300 mg/1, TOC 70 mg/1, TOC 880 mg/1, and color was 760 Pt-Co units in one study. Color rejection was 98--99% at water recoveries of 75--90%. TDS was reduced b y 95%; COD reduction was similar. Tubular and spiral w o u n d cellulose acetate and hollow fiber polyamide membranes operated for long periods of time. However, washing was needed to restore flux and rejection efficiency. Effluent from an acrylic fiber manufacturing plant can be treated successfully with several types of RO modules [ 4 7 ] . These industrial wastewaters contain high levels of sulfates, polymers, sulfites, oligimers, and acrylonitrile with sodium bisulfate (ASB complex). A typical, fiber waste stream has a COD of 1,000 mg/1 and TDS of 2,000 mg/1. Studies at 89--90% recovery produced permeate with low TDS and organic content; no fouling occurred over the operating period. Also, it was shown that rejection of higher molecular weight organic species was greater than for lower molecular weight alcohols, aldehydes, ketones, etc. COD rejection in excess of 90% was noted for tubular cellulose acetate and polyamide hollow fiber units. Solids rejection was 98% for the tubular units and 95% for the hollow fiber module. Additional research was conducted on a fiber finishing plant effluent containing non-ionic surfactants with low biodegradability [47]. This wastewater had a COD of 966 mg/1 and a TDS of 946 mg/1, slightly lower than in t h e previous study. At a recovery of almost 75%, COD and TDS rejections (comparing retentate to bulk permeate) were 99.7 and 96.5%, respectively. The concentration of surfactants in the bulk product was 3.5 mg/1, corresponding to a reduction of 99.6%.

Electroplating and metal finishing Because of the inherent disadvantages of end-of-pipe treatment, loss of valuable plating chemicals, cost of treatment chemicals, and cost of toxic sludge disposal, recycle and recovery methods employing RO have b e c o m e practical in the electroplating industry [48, 4 9 ] . Although other techniques are under development, RO is one o f the processes accepted for rinse water recovery [50, 5 1 ] . In these treatment and reuse systems, 90 to 95% recovery o f the water from plant operations has been achieved, together with separation of most metal species [52, 5 3 ] . McNulty et al. [55] evaluated a hollow fiber unit for treatment of rinse water from a Watts-type nickel electroplating bath. Rejections of nickel, total solids and conductivity were generally good. Nickel can be recovered efficiently from the rinse waters of these plating baths; cellulose acetate membranes reject nickel at levels of 99% [55, 5 6 ] . Tin-nickel plating wastes have been renovated successfully and reused, also [57]. Schrantz [58] describes how copper wastewater is recycled through a closed-loop RO system, at a plastics electroplating plant. Weekly copper consumption was reduced b y one-third. Copper cyanide rinse waters were treated b y RO, also, at t w o major plating companies; membrane life was a significant problem [59 ].

RO IN INDUSTRIAL WASTEWATERTREATMENT

181

Several different membrane materials were used successfully by McNulty and Hoover [60] to treat electroplating rinse water with high oxidation potential and extreme pH levels. A membrane cast of poly (ether/amide) on polysulfone was f o u n d to be superior to other membranes for separation of concentrated copper and zinc cyanide and chromic acid wastes at plating bath concentrations up to 25%. Cellulose acetate membranes failed because of operation outside their narrow operating pH range of 2.5--7.0. Treatment of citrate buffered gold plating rinse wastewater was successful with several types o f non-cellulose acetate membranes [61], i.e., aromatic polyamide, polybenzimidazolone and sulfonated poly-furfuryl alcohol applied to polysulfone. Cellulose acetate membranes failed to separate this plating rinse effluent; rejection was nil. Membranes other t h a n cellulose acetate produced rejections o f 75 and 99% for citric acid with five-fold concentration. Gold rejection was greater t h a n 92%, initially, b u t dropped as feed concentration increased. Using a multi-ion feed, such as the gold plating rinse containing a less permeable ion, i.e., citrate, improved the permeability of t h e more permeable ion o f like charge; gold cyanide [Au(CN)~ ]. This ionic interaction caused rejection to drop as the concentration of ions in the feed increased. Removal of toxic inorganic substances present in electrochemical industry wastewaters was summarized b y Kosarek [62]. RO is capable of removing the toxic metals, i.e., a n t i m o n y , arsenic, beryllium, cadmium, chromium, copper, lead, mercury, nickel, selenium, silver, thallium, and zinc, that along with cyanide can threaten drinking water supplies. All these species were rejected in excess of 90% {ionic removal). In addition to wastewater renovation, these expensive metals can be concentrated and rec'~aimed to reduce overall cost. Different polymeric membranes were shown to lead to varying levels of rejection. The presence of b o t h monovalent and multivalent species in a feed stream results in lesser rejection of the monovalent species, because of conservation of charge on b o t h sides of the membrane, pH is a major parameter affecting the ionization of dissolved constituents and, consequently, the rejection of these species. The greater the charge a wastewater species retains, the higher the rejection b y RO. Leightell [63] cites RO as a means of treating large quantities of wastewater containing a variety o f metals and chemicals, from metal finishing and machinery in the automobile industry. Marquardt [64] suggests t h a t RO is applicable to the treatment of sheet metal processing industry effluents.

Petroleum and petrochemical industry Muratova et al. [65] used RO to treat petrochemical wastewaters. A waste stream with a TDS of 1,200 mg/1 was reduced, by 70%, to 360 mg/1. COD was reduced from 49 to 24 mg/1. A marked decline in membrane permeability was seen after 70--80 hours of operation. The feasibility of applying RO to concentrate soluble coolant oils in a wastewater was demonstrated on

182

C.S. SLATER, R.C. AHLERT AND C.G. UCHRIN

a pilot plant scale [ 6 6 ] . After 3,000 hours of operation, data showed rejection o f oil and suspended material to b e nearly complete. A TDS of 1,400 mg/1 was reduced b y 97.2% to 30 mg/1; feed TOC of 2,000 mg/1 was reduced b y 97.5% to 50 mg/1. COD was reduced by 97.8%, from 6,900 mg/1 to 150 mg/1. A 99.7% rejection was possible for the oily constituents, enabling t h e 2,400 mg/1 feed to b e reduced to 6 mg/l. Effective treatment of petrochemical wastewater b y RO is made possible b y pretreatment [67]. Carbon adsorption was shown to remove excessive refractory organics, enabling RO to achieve COD removals in excess of 95%. Phenolic c o m p o u n d s observed in coal gasification plant wastewater were separated b y hydrous zirconium (IV) oxide membranes b y Klemetson [68]. With concentration variations from 1 to 400 mg/1, membrane operating parameters at pH of 5--11 were examined. Phenol reductions greater than 95% were obtained at fluxes greater than 4.1 m3/m 2 d. The kerosene acidwash water from an oil refinery was treated successfully in an RO system [69]. An influent COD of 6,780 mg/1 was reduced to 235 mg/1; feed conductivity of 16,000 pS/cm was reduced by 94.4%. Flux dropped by one-half after 20 hours of operation, remaining steady thereafter. An interesting effect was noted -- rejections improved at the lower flux. Average solids rejection was 95% for kerosene acid-wash water with an initial concentration of 14,000 mg/1. Petrochemical wastewaters have been treated for reuse by RO [70]. A plant, operating o n a zero discharge basis, uses membrane separation techniques on water for cooling towers, heat exchangers and steam generating systems.

Pulp and paper industry Treatment of pulp and paper industry effluent b y membrane separation techniques is reported b y Wiley et al. [71]. These wastewaters contain high concentrations o f color and organic matter. In one field study utilizing an RO membrane, fluxes averaged 0.41--0.73 m3/m 2 d, at a pressure of 4,140 k N / m 2 . To concentrate the feed, the operation was run at 50% recycle. This eliminated color and reduced COD 95%. RO units have been used to separate weak wastewaters from pulp and paperboard mills to form closed-loop recycle systems. In a pilot plant study, a feed stream with 10,000 mg/1 of dissolved solids was concentrated volumetrically b y 99%, producing a permeate o f extremely high quality [ 7 2 ] . Applications to in-plant wastewater control and reuse have been demonstrated, also, for semichemical pulp and paperboard mill wastes [73, 7 4 ] . Permeates from these systems can be used in bleaching operations [ 7 5 ] . White water from paper forming equipment can be separated b y RO, b u t only after fibers are removed to prevent fouling the modules [76]. Dytnerskii et al. [78] determined that elevated temperatures, i.e., > 4 5 ° C , can alleviate degenerative membrane fouling in the renovation of pulp wash wastewaters. Wash water is the product of dewatering operations on a high

RO IN INDUSTRIAL WASTEWATER TREATMENT

183

yield sodium sulfite semichemical pulp. Continuous operation of the RO unit, in conjunction with the dewatering operation, gave greater than 90% recovery of dissolved solids.

Food and beverage industry Jackson et al. [79] used RO in b o t h laboratory and field studies to treat soy whey. In a two-step membrane process, i.e., UF followed b y RO, t h e y produced low BOD effluent from a highly concentrated protein and sugar waste. RO has potential for use in the starch manufacturing industry for wastewater treatment [ 8 0 - - 8 2 ] . These wastes, largely from p o t a t o processing, contain protein, free amino acids, organic acids, sugars, inorganic acids, and other compounds. Extensive testing suggested that b o t h permeate and retentate can be reused. Spatz [83] cites RO applications in the f o o d industry as economically attractive for f o o d waste reclamation. A 2--3% sucrose and red d y e wastewater stream from a marashino cherry processing plant was separated; the sucrose and d y e were reused. A candy manufacturing facility employed RO to remove 99% of the BOD, sucrose (2--3%), glucose, and coconut oil from wastewater. Matz et al. [84] described treatment o f citrus fruit processing wastewater consisting o f pulp, sugar and other organic ingredients. High concentrations o f BOD and COD, and an acidic nature, prohibit direct discharge to municipal treatment facilities. A U F unit was used as pretreatment for the RO syst e m in an a t t e m p t to eliminate some of the foulants. A solids content of 31,900 mg/1 was reduced b y 98.6%, to 450 mg/1. A high COD of 34,000 mg/1 was reduced to 800 mg/1, corresponding to 97.6% rejection. Also, conductivity was reduced to 150--300 pS/cm. Flux decline was highly dependent on membrane characteristics and decreased rapidly with recovery. Sheehan and Greenfield [85] reviewed several studies of membrane application to the treatment o f brewery and distillery wastewaters. Stillage with a TOC of 12,000 mg/1 was treated b y RO and recycled back to the corn mashing stage, increasing overall yield. Another study examined stillage with a BOD of 10,000 mg/1; 80% was recovered, while producing a permeate of 600 mg/1.

Miscellaneous applications Rouse [86] has shown RO to be technically feasible for the removal of heavy metals from acid coal mine drainage. Mine drainage containing copper, zinc and other valuable metals can be separated b y RO and processed for recovery of metals. High quality water, for reuse as process water, can be produced. Wilmount et al. [87] cites RO as a viable process for the removal of trace elements from acid mine drainage. RO is very effective in rejecting arsenic, cadmium, chromium, copper, nickel and zinc; it is relatively in-

184

C.S. SLATER, R.C. AHLERT AND C.G. UCHRIN

effective in rejecting boron. A 15 m3/d (product flow) spiral w o u n d RO unit was employed, with a lime pretreatment system in their study. Laboratory investigations have shown that cellulose acetate membranes are capable o f concentrating and removing dilute nitration acid from munitions plant wastewater [88]. Military wastewaters as well as those from a nuclear weapons plant have been treated and reused [89, 9 0 ] . Dagon [91] reviewed wastewater treatment technology for photographic processing effluents. RO is an accepted process for silver recovery, fixer reuse, bleach regeneration and color developer regeneration. RO separation of industrial wastewater from a photographic proce~ ~ing plant was d o c u m e n t e d b y Diagnault [ 9 2 ] . Rejection o f silver complex from this waste stream was 99%; iron removal averaged 98.4%. In addition to metal removal, BOD and COD concentrations were lowered substantially. Caprio et al. [93] cite the usefulness of RO in treating wastewater from an electronics plant for reuse. With hollow fiber polyamide membranes, high rejections were noted for a majority of ionic species present. TOC rejection was only 39%. Calcium, magnesium and sulfate were reduced b y 99%; fluoride was reduced b y 68%. Flux dropped over the operating period and, even with frequent washings, could not be restored to original levels. Calcium, iron and aluminum were found to be the principal foulants, b u t small amounts o f silica, chromium, copper, magnesium and fluoride were found in membrane residue, also. Beasley [94] describes t h e use of RO membranes for treatment of electronics plant wastes; studies examined the applicability of spiral w o u n d and hollow fiber modules. Warnke et al. [95] describe an industrial wastewater system utilizing an RO unit to treat an electronics plant evaporation pond effluent containing high levels of dissolved metals. RO helped to reduce water use, improve reclaimed water quality, and reduce waste discharges that interfered with production. Industrial wastewater from an aircraft maintenance and operations facility was treated with a system using RO as an integral step [96]. This industrial waste has high inorganic and organic species levels, including acids, caustics, salts, oil, detergents, heavy metals, chromates and cyanides. Pretreatment b y alum coagulation and flocculation prior to RO separation, removed suspended solids and greatly reduced membrane fouling. A wastewater TDS of 545 mg/1 was reduced to 17 mg/1 and all metal species were reduced below limits of detection, including sulfate which was originally 340 mg/1. After 1,600 hours o f operation, there was no indication of detrimental effects on t h e membrane. An RO system was used to treat wastewater from an electropainting process [ 9 7 ] . The unit separates acrylic paint and associated solvents from water; b o t h can b e reused in the process. This eliminates the need to discharge these wastes to a municipal wastewater facility. The permeate from this process contains less than 0.4% of the acrylic paint ingredients.

RO IN INDUSTRIAL WASTEWATER TREATMENT

185

CONCLUSIONS T h e a p p l i c a t i o n o f R O to w a s t e w a t e r t r e a t m e n t in six m a j o r industrial c a t e g o r i e s has b e e n r e v i e w e d in detail. Landfill l e a c h a t e is a c o m p l e x , hazard o u s residual t h a t c a n b e p r i m a r i l y o f industrial origin; l e a c h a t e s are o f part i c u l a r i n t e r e s t b e c a u s e o f t h e p o t e n t i a l f o r c o n t a m i n a t i o n o f surface w a t e r a n d g r o u n d w a t e r . I n all cases, R O is o n e s t e p in a t r e a t m e n t t r a i n or p r o c e s s . H o w e v e r , as a s e p a r a t i o n o p e r a t i o n it has s h o w n , p h y s i c a l a n d e c o n o m i c eff e c t i v e n e s s f o r r e m o v a l o f b o t h inorganic salts a n d organic species. Success c a n n o t b e r e p o r t e d t o b e universal; fouling, b o t h organic a n d inorganic, are o b s e r v e d a n d i n t e r f e r e n c e b e t w e e n solutes in c o m p l e x w a s t e w a t e r s are n o t u n c o m m o n . T h e s e p a r a t i o n o f specific organic c o m p o u n d s has a b e a r i n g o n t h e e v a l u a t i o n o f c o m p e t i t i o n in m u l t i - c o m p o n e n t s o l u t i o n s . R O s h o w s p r o m i s e in m a n y a p p l i c a t i o n s . With increasing costs o f w a t e r s u p p l y a n d process w a t e r t r e a t m e n t , R O f o r w a s t e w a t e r r e n o v a t i o n a n d r e u s e can compete economically to meet feed water requirements. Regulation of w a s t e disposal a n d p u b l i c c o n c e r n f o r c h e m i c a l landfilling a n d d u m p i n g increase i n t e r e s t in recycling, also. In c o n j u n c t i o n w i t h c o a g u l a t i o n , flocculat i o n , f i l t r a t i o n , b i o d e g r a d a t i o n a n d o t h e r o p e r a t i o n s , R O is a useful a d j u n c t t o w a s t e w a t e r t r e a t m e n t p r i o r t o e i t h e r r e c y c l e , safe disposal or t r a n s f e r t o c o n v e n t i o n a l m u n i c i p a l s e c o n d a r y s y s t e m s . O f t e n R O has b e e n f o u n d t o b e e f f e c t i v e in c o n c e n t r a t i o n a n d r e c o v e r y o f valuable solutes, as well as w a t e r renovation.

REFERENCES 1. Anon., Chem., & Eng. News, Feb. 4 (1980) 26. 2. Anon, Municipal Waste Water Reuse News, 54 (1982) 23. 3. Y. Kunisada, H. Kaneda, M. Hirai and Y. Murayama, Desalination, 30 (1979) 337-342. 4. D. Pepper, Desalination, 38 (1981} 403--417. 5. S.D. Strauss, Power, February 1981, pp. 99--101. 6. B.S. Fisher and J.R. Lowell, Jr., Report to EPA on FWQA Program 1720 DUD, Contract 14-12-553, 1970. 7. M.S. Lira and H.K. Johnston, JWPCF, 48 (1976) 1820. 8. D.G. Thomas and W.R. Mixon, I&EC: Proc. Res. & Dev., 11 (1972) 339. 9. F. Besik, Water & Sewage Works, Oct. (1972) 76--79, 82--85. 10. J.E. Cruver and I. Nusbaum, JWPCF, 46 {1974) 301. 11. D.F. Boen and G.L. Johnnsen, EPA-600/2-74-077, 1974. 12. J.C. Van denHuvel, R.J. Zoetemeyer and C. Beolhouwer, Biotech. & Bioeng., 23 (1981) 2001--2008. 13. E..J. Middlebrooks, ed., Water Reuse, Ann Arbor Science, Ann Arbor, MI, 1981. 14. D.G. Argo, OWRT PB-300, July 1979, p. 602. 15. P.K. Allen and G.L. Elser, Desalination, 30 (1979) 23. 16. D.G. Argo and J.G. Moutes, JWPCF, 51 (1979) 590. 17. A.J. Shuckrow, A.P. Pajak and J.W. Osheke, EPA-600/2-81-019, 1981. 18. A.J. Shuckrow, A.P. Pajak and C.J. Touhill, EPA-530/SW-871, 1980.

186

C.S. SLATER, R.C. AHLERT AND C.G. UCHRIN

19. 20. 21. 22.

W.A. Duvel and T. Helfgott, JWPCF, 47 (1975) 57--64. H.H.P. Fang and E.S.K. Chian, Envir. Sci. & Technol., 10 (1976) 364--369. E.S.K. Chian, W.N. Bruce and H.H.P. Fang, Envir. Sci. & Technol., 9 (1975) 52--58. W.G. Light, Chemistry in Water Reuse, Vol. 1, W.J. Cooper, ed., Ann Arbor Science, Ann Arbor, MI, (1981), p. 352. J.W. Sidwick, Prog. Water Technol., 10 (1978) 443. L.J. Ricci, Chem. Eng., 83 (1976) 86. V.G. Gadjiev and E.S.K. Chian, Proc. 31st Indus. Waste Conf., Purdue Univ., Lafayette, IN, 1976, p. 956. S. Peter, N. Hese and R. Stefa, Desalination, 19 (1976) 161--167. M. Schrem and C.T. Lawson, Indus. Water Eng., 14 (1977) 16--18. M. Schrem, P.M. Thomasson, L.C. Boone and L.S. Magelssen, EPA-60012-79-184, 1979. T.M. Fosberg, D. Mukhopadhyay, T.M. O'Neil and R.C. Whalen, Chem. Eng. Prog., 77 (1981) 63--67. E.S.K. Chian and F.B. DeWalle, EPA-60012-77-186b, 1977. C.S. Slater, M.K. Walter, J. McCarthy and P.D. Ranzetta, USEPA/OHMSB Report #14, Contract #CR807805010, 1982. C.S. Slater, C.G. Uchrin and R.C. Ahlert, J. Env. Sci. & Health, Part A. Env. Sci. & Eng., 18 (1983} 125--134. G.J. Parish, Amer. Dyestuff Rept., 65 (1979) 27. Anon., Inter. Dyer and Textile Printer, 157 (1977) 170. C.A. Brandon and J.J. Porter, EPA-600]2-76-060, 1976, p. 157. C.A. Brandon and J.L. Gaddis, Textile World, 128 (1978) 68. J.E. Matthews, EPA-60012-80-183, 1980. J.J. Porter and C.A. Brandon, Chemtech, June, 1976, p. 402. C.A. Brandon and J.J. Porter, EPA-600]2-76-060, 1976, p. 157. A.M. E1-Nasher, Desalination, 20 (1977) 267. C.A. Brandon, J.J. Porter and D.K. Todd, EPA-60012-78-047, 1978. J.L. Gaddis, C.A. Brandon and J.J. Porter, EPA-600/7-79-131, 1979. M. Jhawar and J.H. Sleigh, Textile Indus., 139 (1975} 60. J.L. Gaddis and H.G. Spencer, EPA-60012-79-104, 1979, pp. 107--114. C.A. Brandon and J.L. Gaddis, Desalination, 23 (1977) 19--28. C.A. Brandon, Indus. Water Eng., 12 (1975176), 14--18. P. Mappelli, M. Santori, A. Chiolle and G. Gianotii, Desalination, 24 (1978} 155-173. K.J. McNulty and J.W. Kubarewicz, EPA-60018-79-014, 1979, p. 88. J.E. Warnke, K.G. Thomas and S.C. Creason, Proc. 31st Indust. Waste Conf., Purdue Univ., Lafayette, IN, May 1976, p. 525. H.S. Skovronek and M.K. Stinson, EPA-600]J-77-056a, 1977. R.L. Goldsmith, J. Eng. for Indus., 97 (1975} 238. R.K. Chalmers, Chem. and Indus., 12 (1978) 544. S.S. Kremen, C. Hayes and M. Dubos, Desalination, 20 (1977) 71. K.J. McNulty, R.L. Goldsmith and A.Z. Gollan, EPA-600]2-79-039, 1977. A. Golomb, Plating, 57 {1970) 1001. A. Golomb, Paper No. 3, 6th Int. Water Poll. Res. Conf., June 1972. Y. Koyama, M. Ishikawa, H. Enomoto, M. Nishimura and A. Kakagawa, J. Metal Fin. Soc. Japan, 26 (1977) 437. J. Schrantz, Indus. Fin., 1 (1975) 30. K.J. McNulty, R.L. Goldsmith, A. Gollan, S. Houssain and D. Grant, EPA-6-]2-77170, 1977.

23. 24. 25. 26. 27. 28. 29. 30. 31. 32. 33. 34. 35. 36. 37. 38. 39. 40. 41. 42. 43. 44. 45. 46. 47. 48. 49. 50. 51. 52. 53. 54. 55. 56. 57. 58. 59.

RO IN INDUSTRIAL WASTEWATER TREATMENT

187

60. K.J. McNulty and P.R. Hoover, EPA-600/2-80-084, 1980, p. 5. 61. C. Kanizawa, H. Masuda, M. Matsuda, T. Nakane and H. Akami, Desalination, 27 (1978) 261--272. 62. L.J. Kosarek in Chemistry in Water Reuse, Vol. 1, W.J. Cooper, Ed., Ann Arbor Science, Ann Arbor, MI, 1981, pp. 261--280. 63. B. Leightell, Chem. and Ind., June 1974, p. 437. 64. K. Marquardt, Baender Bleche Rohre, 15 (1974) 161. 65. N.G. Muratova, V.B. Sherchenko, G.F. Stychinskii, A.V. Dolganova and I.N. Smirnov, Int. Chem. Eng., 19 (1979). 66. M. Ghassemi, K. Yu and S. Quinlivan, EPA-600/2-81-213, 1981. 67. M.A. Zeitoun, C.A. Roorda and G.R. Powers, EPA/2-79-021, 1979. 68. S.L. Klemetson, EPA-60017-78-063, 1978. 69. R. Matz, E. Zishner and A. Herscovici, Desalination, 24 (1978) 113--128. 70. B.A. Carnes, D.L. Ford and S.O. Brady, Complete Water Reuse -- Industry's Opportunity, New York, NY, 1973, p. 407. 71. A.J. Wiley, L.E. Dambruch, P.E. Parker and H.S. Dugal, TAPPI (1978) 61. 72. D.C. Morris, W.R. Nelson and G.O. Walraver, EPA]12040, FUB 01172, 1972. 73. D.C. Morris, G.O. Walraver and S.L. Browa, Industrial Process Design for Pollution Control, AIChE, New York, NY, 1975, p. 11. 74. M. MacLeod, Pulp and Paper, 48 (1974) 62. 75. P.H. Claussen, Proc. 63rd Annual Mtg. Canad. Pulp and Paper Assoc., Montreal, Canada, February 1977, p. B125. 76. B. Brown, B. Crouse, D. Etter and W. Schattner, Research Disclosure No. 142 (1977) 46. 77. Y.I. Dytnerskii, A.A. Swittsor, Y.K. Romanko, Y.N. Zhilin and Y.P. Semenov, Bumazhnaya Promyshlennost, 7 (1972) 22. 78. A.J. Wiley, K. Scharpf, I. Bansal and D. Arps, Proc. TAPPI Env. Con., Houston, TX, 1972, p. 149. 79. G. Jackson, M.W. Stawiarski, E.T. Wilhelm, R.L. Goldsmith and W. Eykamp, AIChE Syrup. Ser., 70, 1974, p. 514. 80. F.K. Besik, Water and Poll. Control, 197 (1969) 24. 81. F.K. Besik, Water and Poll. Control, 107 (1969) 47. 82. W.L. Porter, J. Siciliano, S. Kruclik and G. Heisler, Mere. Sci. Tech. Proc. Symp., Columbia, OH, October 1969, p. 220. 83. D.D. Spatz, Proc. AIChE Mtg., St. Louis, MO, May 1972. 84. R. Matz, E. Zisner and G. Herscovici, Desalination, 24 (1978) 113--128. 85. G.J. Sheehan and P.F. Greenfield, Water Res., 14, (1980) 264--265. 86. J.V. Rouse, J. Env. Eng. Div., ASCE, 102 (1976) 934. 87. R.C. Wilmoth, J.L. Kennedy, J.R. Hell and C.W. Stvewe, EPA-60017-79-101, 1979. 88. V.J. Ciccone, Water Res. Bull., 12 (1976) 625--638. 89. Anon., Env. Sci. & Tech., 7 (1973) 485. 90. B.L. Kelchner, Rocky Flat Reports No. RFP-2479, 1976. 91. T.J. Dagon, J. Appl. Photo. Eng., 4 (1978) 62. 92. L.G. Diagnault, J. Appl. Photo. Eng., 3 (1977) 94--96. 93. C. Caprio, M.D. Beasley and L. Luttinger, Indus. Water Eng., 14 (1977) 24--30. 94. M.D. Beasley, Proc. 32nd Indus. Waste Conf., Purdue Univ., Lafayette, IN, 1978, p. 630, 95. J.E. Warnke, K.G. Thomas and S.C. Creason, Chem. Eng., 84 (1977) 75. 96. H.P. Roth and P,V. Ferguson, Desalination, 23 (1977) 49--63. 97. Anon., Water and Waste Treat., 20 (1977) 54.