Membrane Technologies In Wastewater Treatment: A Review - MDPI
membranesReviewMembrane Technologies in Wastewater Treatment:A ReviewElorm Obotey Ezugbe *and Sudesh RathilalDepartment of Chemical Engineering, Faculty of Engineering and the Built Environment, Durban University ofTechnology, Durban 4000, South Africa; rathilals@dut.ac.za* Correspondence: elormezugbe.ee6@gmail.com; Tel.: 27-642661348 Received: 2 April 2020; Accepted: 27 April 2020; Published: 30 April 2020Abstract: In the face of water shortages, the world seeks to explore all available options in reducingthe over exploitation of limited freshwater resources. One of the surest available water resourcesis wastewater. As the population grows, industrial, agricultural, and domestic activities increaseaccordingly in order to cater for the voluminous needs of man. These activities produce large volumesof wastewater from which water can be reclaimed to serve many purposes. Over the years, conventionalwastewater treatment processes have succeeded to some extent in treating effluents for dischargepurposes. However, improvements in wastewater treatment processes are necessary in order to maketreated wastewater re-usable for industrial, agricultural, and domestic purposes. Membrane technologyhas emerged as a favorite choice for reclaiming water from different wastewater streams for re-use.This review looks at the trending membrane technologies in wastewater treatment, their advantagesand disadvantages. It also discusses membrane fouling, membrane cleaning, and membrane modules.Finally, recommendations for future research pertaining to the application of membrane technologyin wastewater treatment are made.Keywords: membrane technology; wastewater; potable water; fouling1. IntroductionAll activities of mankind are water dependent. With the increase in human population, tonsand tons of wastewater are produced everyday across the domestic, industrial, and agriculturalsectors. Freshwater resources, however, do not get replenished to accommodate the ever-increasingpopulation and its water usage needs. This has led to intense competition and unfair distribution ofthe limited freshwater resources among the various sectors. Consequently, many people around theworld, especially in developing countries, lack access to potable water. Again, agricultural activitiesare heavily affected, as farms lack access to enough water resources for all year-round irrigation andlivestock production. The evidence of these situations is seen across the world, especially in the MiddleEast, Africa, Asia, and Latin America. The facts are glaring, such as 2.1 billion people living withoutsafe drinking water at home, and nearly four billion people experience severe water scarcity during atleast one month of the year [1,2].Wastewater generation is inevitable as it forms an integral part of the value chain in all sectors oflife. In the oil refinery industry, every one barrel of crude oil processed generates about 10 barrels ofwastewater [3]. In an infrastructure report by the South African Institution of Civil Engineers, titledSAICE Infrastructure Report Card for South Africa, 2011, it was noted that an average of 7589 mega litersper day of wastewater is transported across South Africa [4]. All these wastewaters are clean waterwith contaminants. With efficient wastewater treatment, freshwater resources can be supplemented,and potable water can be made accessible to all. This seems to be the most obvious way of dealingwith water scarcity [5].Membranes 2020, 10, 89; membranes
Membranes 2020, 10, 892 of 28In this vein, several efforts have been made over the years to introduce various wastewatertreatment technologies such as conventional filtration, coagulation-flocculation, and biological treatmentsystems among others. There is also improvement of already existing technologies to meet currentdischarge or reuse standards. One of the wastewater treatment technologies that have seen a majorboost over this period is membrane technology. Membrane technology has grown significantly in thelast couple of decades due to the benefits it offers in water and wastewater treatment. With significantreduction in the size of equipment, energy requirement and low capital cost, membrane technologyoffers many prospects in wastewater treatment [6]. According to Singh and Hankins [7], membranetechnology has the potential of bridging the economical and sustainability gap, amid possibilities of lowor no chemical usage, environmental friendliness and easy accessibility to many. That is, membranetechnology has proven to be a more favorable option in wastewater treatment processes in recent times.Even though membrane technology is not a new invention, the varying nature and complexity ofwastewater makes room for more improvements, in terms of efficiency, space requirements, energy, qualityof permeate, and technical skills requirements. Again, there is continuous modification of membranemodules and membrane elements to enhance the reduction in membrane fouling, which is a majorchallenge for membrane processes. The possibility of combining two or more membrane processes witheach other, or with other forms of technology like coagulation or adsorption, in a hybrid fashion is alsocontinuously being explored, developed and applied in many wastewater treatment facilities [7–9].This paper reviews the application of membrane technology in wastewater treatment. It considersthe advantages and the disadvantages of these processes. Again, the paper touched on some generalterms like membrane modules and their applications, concentration polarization, membrane fouling,and membrane cleaning techniques. It also discusses the prospects of membrane technology.2. Membrane Technology for Wastewater TreatmentBasically, a membrane is a barrier which separates two phases from each other by restrictingmovement of components through it in a selective style [10]. Membranes have been in existence sincethe 18th century. Since then, a lot of improvements have taken place to make membranes better suitedfor many different applications [11].Characteristically, membranes can be classified as isotropic or anisotropic. Isotropic membranes areuniform in composition and physical structure. They can be microporous; in which case their permeationfluxes are relatively high compared to when they are nonporous (dense) where their application ishighly limited due to low permeation fluxes. Isotropic microporous membranes are widely applied inmicrofiltration membranes. Anisotropic membranes on the other hand are non-uniform over the membranearea and are made up of different layers with different structures and composition. These membraneshave a thin selective layer supported by a thicker and highly permeable layer. They are particularlyapplied in reverse osmosis (RO) processes [12,13].In terms of membrane material make up, membranes are classified as either organic or inorganic.Organic membranes are made from synthetic organic polymers. Mostly, membranes for pressure drivenseparation processes (microfiltration, ultrafiltration, nano filtration and reverse osmosis) are madefrom synthetic organic polymers. These include polyethylene (PE), polytetrafluorethylene (PTFE),polypropylene, and cellulose acetate among others [14]. Inorganic membranes are made from suchmaterials as ceramics, metals, zeolites, or silica. They are chemically and thermally stable and usedwidely in industrial applications like hydrogen separation, ultrafiltration, and microfiltration [13,15].Movement of media through the membranes is based on different driving forces. There are equilibriumbased membrane processes, non-equilibrium based membrane processes, pressure driven and nonpressure driven processes [16]. The schematic diagram below (Figure 1) shows a summary of some of thesetechniques according to their driving forces. These membrane techniques are discussed individually below.
Membranes 2020, 10, 893 of 28Membranes 2020, 10, x FOR PEER REVIEW3 of 30Figure1.1.SchematicSchematic representationrepresentation of someFiguresome DrivenMembraneMembrane ProcessesprocessesPressurefar thethe mostmost sprocessesPressuredrivendrivenmembranemembrane processesprocesses are by farininwastewaterpost-treatment ofof relyrelywastewatertreatment,treatment, fromfrom pretreatmentpretreatment to post-treatmentonThere areare fourfour suretotoachieveachieve separation.separation. Theremicrofiltrationnano filtrationfiltration RO).TheThemainmainmicrofiltration(MF),(MF), ultrafiltrationultrafiltration (UF), nanodifferencefrom theirtheir bybythesethese processes,processes, apart ovidesaasummarysummary ofof the main featuresporefeatures ofof thesethese processes.processes.Table1.1. SomeSome features of pressure.Tablepressure drivendriven ,18].* MWCORetainedPressureMembrane * ProcessDiameters (µm)Required (bar)Process (kilo Dalton)Dalton)MFMF100–500100–500(µm)10 1 –1010 –10 1(bar)1–31–3Membrane lity(L/m22 hh bar)bar)(L/mSolutes RetainedRetainedSolutesPorous,Porous, orasymmetricasymmetricsymmetric500Bacteria,fat, fat,oil, grease,Bacteria,oil,colloids,organics,grease, colloids,micro-particles150Proteins,pigments, oils,micro-particlessugar, organics,Proteins,pigments,microplastics500or symmetricUFUFNF20–1502–200.2–22–510 –1 310 3 –10 22–20NFRO10 3 –120–15010 3–10 210 4 –10 32–55–155–1515–75Micro porous,asymmetricMicro porous,asymmetrictight porous,asymmetric, thintightporous,film compositethinfilm composite15010–20organics,oils, sugar, organics,Pigments,sulfates, divalentmicroplasticscations, divalent anions,Pigments, sulfates,lactose, sucrose,divalentcations,sodium chloride10–20divalent anions,5–10All contaminantsincludinglactose, sucrose,monovalentionssodiumchlorideSemi porous,* MWCO Molecular weightcut off.All –210 4–10 3thin filmmonovalentionsAmong the pressure driven membrane processes, ROis highly known for its efficiency in separatingcompositesmall particles including bacteria andmonovalentions likesodiumions and chloride ions up to 99.5% [18].* MWCO Molecularweightcut off.RO has been at the forefront of water reclamation through wastewater treatment and desalination ofAmong the pressure driven membrane processes, RO is highly known for its efficiency inseawater for a long time. During reverse osmosis, a hydrostatic pressure is generated that is strongseparating small particles including bacteria and monovalent ions like sodium ions and chlorideenough to overcome the intrinsic osmotic pressure of the feed. This is against the natural osmosisions up to 99.5% [18]. RO has been at the forefront of water reclamation through wastewater
Membranes 2020, 10, 894 of 28process. For the complete process, water molecules are absorbed onto the membrane surface (underpressure). These molecules diffuse through the membrane material and finally desorb at the permeateside of the membrane for collection [19].Different combinations of these pressure driven membrane processes have been applied in differentwastewater treatment settings. In some cases, they serve as pre-treatment to other unit processes. In anexperiment, Nataraj, et al. [20] combined NF and RO to treat distillery wastewater in which an averageof 98% of contaminants (colour, total dissolved solids, chemical oxygen demand, and potassium) wereremoved successfully. In another application, UF and RO were combined in a pilot scale plant to treatwastewater from reactive dye printing. After the UF, the permeate still fell short of the discharge limits,however the RO permeate was fit for discharge and reuse. Contaminants such as urea, sodium alginate,reactive dye and oxidizing agents were successfully removed [21]. Several other instances of applyingthese pressure-driven membrane processes are shown in Table 2.Table 2. Some applications of pressure driven membrane processes in wastewater treatment.Pressure DrivenMembrane ProcessWastewater TreatedResults *ReferenceUFVegetable oil factoryCOD a (91%), TSS b (100%), TOC d(87%), PO4 3 (85%), Cl (40%)[22]MF-ROUrban wastewaterPesticides and pharmaceuticalsremoved to discharge limit[23]MFMunicipal wastewater(disinfection andphosphorus removal)Contaminants removed to belowdetection limit[24]MFSynthetic emulsifiedoily wastewater95% removal of organic contaminants[25]NF-RODumpsite leachate95% water recovery[26]UFPoultry slaughterhousewastewaterCOD and BOD removal 94%,fats (99%), suspended substances (98%)[27]NFTextileCOD (57%), color (100%), salinity (30%)[28]UF-ROMetal finishing industry90–99% removal of differentcontaminants[29]UF-ROOily wastewaterOil and grease (100%), TOC (98%), COD(98%), TDS e (95%), Turbidity (100%)[30]UF-NF/ROPhenolic wastewaterfrom paper millCOD (95.5%), phenol (94.9%)[31]c* Note: a —chemical oxygen demand, b —total suspended solids, c —biochemical oxygen demand, d —total organiccarbon, e —total dissolved solids.As seen in most of the applications listed above, MF, UF, and NF usually serve as pretreatmentsteps to RO. This is to reduce fouling of the RO membrane and to enhance the maintenance of constantflux. This also serves as a multi-barrier treatment for removal of contaminants from wastewater [32,33].Pressure driven membrane processes have undoubtedly made water reclamation from wastewater agood option. However, the challenge still remains with the energy requirements due to the pressure.2.2. Forward Osmosis (FO)As shown in Figure 2, FO follows the natural osmosis process where water molecules are drawnfrom one solution to the other, through a semipermeable membrane. In this case a draw solution (DS),which is highly concentrated, is used to provide a concentration gradient to draw water molecules fromthe feed solution (FS). This gradient provides the needed osmotic pressure difference to drive watermolecules from the FS to the DS. This movement continues till an equilibrium of chemical potential is
Membranes 2020, 10, x FOR PEER REVIEW5 of 30As shown in Figure 2, FO follows the natural osmosis process where water molecules aredrawn from one solution to the other, through a semipermeable membrane. In this case a drawsolution (DS), which is highly concentrated, is used to provide a concentration gradient to drawMembranes 2020, 10, 895 of 28water molecules from the feed solution (FS). This gradient provides the needed osmotic pressuredifference to drive water molecules from the FS to the DS. This movement continues till anequilibriumchemicalpotentialis twaterreached[34]. ofUnlessfor nicheapplications,wherewater forbeingdrawnfrom the feedformsofbeingdrawntherefromisthefeedtheformsthe product,is alwaysthe need recoversfor a recoveryunit.theproduct,alwaysneedpartfor ofa recoveryunit. thereThis unitsimultaneouslyfresh waterThisregeneratesunit simultaneouslyfresh water and regenerates the draw solution [35].andthe draw recoverssolution [35].Figure 2.2. Schematic diagram of forward osmosis.FOfor thethe treatmenttreatment andand concentrationconcentration ofof differentdifferent streamsstreams ofof wastewater.wastewater.FO hashas beenbeen appliedapplied obicdigestercentrateinwhichanHolloway, et al. [36] applied FO in concentrating anaerobic digester centrate in which an RORO systemsystemwasSimilarly, York,York, etwas usedused toto recoverrecover andand reconstitutereconstitute thethe drawdraw solution.solution. Similarly,et al.al. [37][37] appliedapplied FOFO inin andROtorecoverandreconstitutelandfill leachate management using NaCl as a draw solute and RO to recover and reconstitute thethedrawUp toto 95%95% ofIn otheret al.draw solution.solution. Upof thethe permeatepermeate waswas recovered.recovered. Inother applications,applications, Zhang,Zhang, etal. .Hauptand Lerch[39] conducteda seriesacombined and Lerch[39] ityofFOinanautomobileproductionsiteandseries of FO experiments to investigate the applicability of FO in an automobile production sitedairyandindustry.Five differentwastewaterstreams streamswere utilizedturn, asinDSand asas FS.dairy industry.Five differentwastewaterwere inutilizedturn,DS Theseand aswastewaterFS. Thesestreamswere;streamswastewatertreatmentRO concentrate,brine, cathodicdip paintingwastewaterwere;wastewatertreatment cheeseRO concentrate,cheesebrine, fluentswerepainting rinsing water, paint shop pre-treatment wastewater and cooling water circulation water.usedas theseFS, 1 mol/LNaClsolutionusedas DS. NaClWhensolutionthey wereusedas DS,deionizedwasWhereeffluentswereused wasas FS,1 mol/Lwasusedas DS.When waterthey wastewatersforuseasDSorFS.Itwasused as DS, deionized water was used as FS. There was also the combination of two or morefoundout singwaterwereverywastewatersforcoolinguse as DSor FS.It was cunsuitableforrinsinguse as DSand werethereforebe appliedin FOin anautomobileIt wasdip paintingwaterverycannotunsuitablefor useas DSandthereforeproductioncannot be O in an automobile production site. It was however found out that cathodic dip painting rinsingprovedwellpaintas FSshopwhen1 mol/L NaClwastewaterwas used asDS andcanasthereforein anwasautomobilewater andpre-treatmentprovedwellFS whenbe1 utilizedmol/L NaClused newasfoundtobepromisingforuseasinDS and can therefore be utilized in an automobile production site in wastewater s.cheese brine was found to be promising for use as DS in dairy wastewater treatment. Thus, FO wasOtherof FO ininwastewatertreatmentare shownin Table 3.Other applications of FO infoundapplicationsto be applicablethe treatmentof sforSustainableWaterTreatment”, Shen, et al. [46] noted thatwastewater treatment are shown in Table 3.the method for fresh water recovery after FO is greatly dependent on the kind of draw solute used. Wheremonovalent ions such as sodiumchloride formof the drawsolution, RO is mostly employedTable 3.andApplicationsof FOpartin wastewatertreatment.for the recovery whereas multivalent ions, hydrophilic nanoparticles, micelles and polyelectrolyteswould require membranes with larger pore sizes like ultra-filtration or nano filtration. FO has severaladvantages. The process does not require external pressure (especially for niche applications of FO),
Membranes 2020, 10, 896 of 28which makes energy consumption lower compared to pressure driven processes. Fouling reversal andwater cleaning is also easier due to the use of osmotic pressure for separation. Flexibility in choosingdraw solution makes it easy to customize products, either for freshwater recovery or for other purposeslike pharmaceuticals and beverage production in which case properties of products are maintained,since no pressure or heat is applied. Furthermore, the regeneration and reuse of DS is advantageous insaving cost. Challenging (highly concentrated) FS are better treated with FO. For example, for a highlysaline feed, more energy would be required by RO to overcome the osmotic pressure, hence making thechoice of FO a better one [46–49].Table 3. Applications of FO in wastewater treatment.ApplicationDraw Solute UsedResultReferenceRaw municipal wastewaterNaCl, MgCl2Up to 70% water recovery[40]Coke-oven wastewaterNaCl, MgSO2 andCaCl2 ·H2 O (0.4–2.5 M)96–98% removal of cyanide, phenolsand COD[35,41]Reduction in volume of gasfield produced water1 M NaCl50% of volume reduced[42]Coal mine wastewaterdesalinationMore saline mine wasterMore than 80% of volume of minewater recovered[43]Sewage (primary effluent)NaCl, MgCl2 ·6H2 OLow water recovery due to internalconcentration polarization and fouling[44]Domestic wastewaterNaCl (35 g/L)Over 90% contaminant removal[45]With all these promising features of FO, it has some drawbacks that require attention. Apart fromniche applications of draw solution, where the draw solute forms part of the final product, furtherseparation is needed to recover fresh water. Low permeate flux due to concentration polarization(CP) is another drawback with FO. This CP affects the net osmotic pressure, hence reducing permeateflux. Again, energy requirements for FO increases with decreasing molecular weight cut off (MWCO).This is because regeneration of draw solutes would require membranes with smaller pores and morepressure like RO. This in effect increases the overall energy requirements [46–49].Draw Solution Selection and Recovery for FO System: As afore-mentioned, FO systems dependon concentration gradients to cause the movement of water molecules. This concentration gradientis provided by the draw solution (DS). Draw solutions are formed when draw agents or solutes arehomogeneously dissolved in water to form solution [50]. Draw solutions play a significant role in FOprocesses, as they influence permeation flux and cost of regeneration [51]. Many draw solutions exist.Typical properties of draw solutions include the following; they are characterized by high osmoticpressure, which is their most important feature. Again, DS should have low reverse solute diffusion toFS and should be easily regenerated [49]. It is also important that DS is non-toxic, highly stable andhighly soluble in water to avoid precipitation [52]. Generally, draw solutes come in different formsviz organic (sucrose, glucose, fructose, EDTA, sodium polyacrylate, sodium lignin sulfonate (NaLS),etc.), inorganic (NaCl, MgCl2 , Na2 SO4 , KCl, KNO3 , etc.), magnetite nano particles (Fe2 O4 ), gases andvolatile compounds (ammonia and CO2 ), [53,54]. The kind of draw solute recovery method to employdepends on the nature of the draw solute used. In general, membrane separation (RO, NF, UF, MD)processes are preferred for salt-based draw solute recovery. For gases and volatile compounds suchas SO2 , NH3 /CO2 thermal separation is used. Other methods include precipitation for sulphate basedraw solutes like Al2 (SO4 )3 , Mg(SO4 ), Cu(SO4 ) and stimuli based recovery process for hydrogels andmagnetite nano particles [55,56]2.3. Electro-Dialysis (ED) and Electro-Dialysis Reversal (EDR)Electro-dialysis and electro-dialysis reversal are processes that combine electricity and ion-permeablemembranes to separate dissolved ions from water. These processes make use of an electric potential to
Membranes 2020, 10, x FOR PEER REVIEW7 of 302.3. Electro-dialysis (ED) and Electro-dialysis Reversal (EDR)Electro-dialysis and electro-dialysis reversal are processes that combine electricity and7 of 28ion-permeable membranes to separate dissolved ions from water. These processes make use of anelectric potential to transfer the ions from a dilute solution to a concentrated solution through anion-permeableAs shownin Figure solution3, duringthe electrodialysis, twotypes of [57].iontransferthe ions membranefrom a dilute[57].solutionto a concentratedthroughan ion-permeablemembraneexchangemembraneare used.One isdialysis,permeableto anionsrejectsmembranecations andthe otherAsshown inFigure 3, duringthe electrotwo typesof ionandexchangeare used.One otwostreamsofsolutions.Theconcentrateandpermeable to anions and rejects cations and the other is permeable to cations and rejects anions. There arethe diluate(feed).ofWhenelectriccurrentis passedthe(feed).system,Whenions fromthecurrentdiluateismigratealsotwo streamssolutions.Theconcentrateandthroughthe diluateelectricpassedinto the concentrateoppositelychargedmembranes(cations migrateto oppositelythe cathodechargedwhilesthroughthe system, throughions fromthe diluatemigrateinto the onsarethenretainedbythepositivelychargedmembranes (cations migrate to the cathode whiles anions migrate to the anode). The cations are thenanion-exchangemembrane(AEM).Likewise, theanions (AEM).are retainedbythetheanionscation-exchangeretainedby the e mdepletedofionswhiletheconcentratestreamby the cation-exchange membrane (CEM). The outcome of this is a feed stream depleted of ions whilethebecomesrichinions[58,59].concentrate stream becomes rich in ions [58,59].Membranes 2020, 10, 89Figure 3. Schematic diagram of ED.Figure 3. Schematic diagram of ED.EDR involves the periodic reversal of the electrodes of the membrane and hence reversingEDR involvesthe periodicreversalof the electrodesandhence streamsreversingthe movementof ions.This causesconcentratedstreamsoftothebemembranediluted rated, hence reducing fouling of the membrane [60]. ED and EDR have been applied in manyconcentrated,hence treatment.reducing foulingthe membrane[60]. EDand EDR have been applied in manywaysin wastewaterTable 4ofshowssome commonapplications.waysEDin ons.and EDR are very useful in wastewater treatment mainly to remove total dissolved solids(TDS) and other ionized constituent particles. ED and EDR have very high-water recovery rate andTable 4. Application of ED and EDR in wastewater treatment.require little pretreatment for feed water. There is also less membrane fouling due to process reversaland the technologycan be combined with renewable energyResultsources ationTreatment of almond industry94% recovery of water[61]energy is proportionalwastewaterto the ions that are removed. This would then be very expensive to operate.The process also does not remove non-ionizedcompoundssubstancessuch ascarbon,viruses and bacteria,70-90%removal ofandTDS,total inorganicwhichare veryofharmful.Thisimplies thatcationsa post treatmentwouldbe required,would makeTreatmentuniversitysewageand anions.23–52%removal whichof COD,[62] theprocess expensive. Furthermore, due to the generationof chlorinegas attheTOCanode, corrosion can setBOD, colour,turbidityandin [7,57–59].
Membranes 2020, 10, 898 of 28Table 4. Application of ED and EDR in wastewater treatment.ApplicationResultReferenceTreatment of almond industry wastewater94% recovery of water[61]Treatment of university sewage70-90% removal of TDS, total inorganic carbon,cations and anions. 23–52% removal of COD,BOD, colour, turbidity and TOC[62]Tertiary treatment of municipal wastewater100% effectiveness in treatment to meet dischargestandards and removal of Cl , Mg2 , Ca2 [63]Treatment of drainage wastewater foragricultural purposesRemoval of heavy metals and Na up to 99%[64]Treatment of tannery wastewater92–100% removal of COD, color, NH3 -H, Cr.[65]Removal of heavy metals (* Cd and * Sn) fromelectroplating industry wastewaterSuccessful removal of Cd (74.8%) and Sn (64.5%)[66]Treatment of wastewater from the China SteelCorporation wastewater treatment plant92% desalination rate, 98% Cl removal, 80% SO4removal and 51% removal rate of COD[60]* Cd Cadmium, * Sn tin.2.4. PervaporationThis separation technique combines membrane permeation and evaporation to separate liquidmixtures based on a preference. As shown in Figure 4, the liquid mixture is fed to the membrane onthe one side while the permeate evaporates on the other side [68]. During this process, sorption of thepermeate in the upstream occurs. By this, the more permeable component of the liquid mixture is sorbedonto the membrane (nonporous polymeric membrane or molecularly porous inorganic membrane).These components then diffuse through the membrane under the influence of a concentration gradient ofthe diffusing species and subsequently evaporate at the downstream phase of the membrane. The vaporis then condensed and recovered as liquid. This mode of mass transport across the membrane is knownMembranes 2020, 10, x FOR PEER REVIEW9 of 30as the solution–diffusion model [68,69].Figure 4. Schematic diagram of Pervaporation.Figure 4.mainlySchematicdiagram of Pervaporation.This technology has been appliedin ethanol-waterseparation. It is, however, being exploredfor wastewater treatment in many areas of production.This technology has been applied mainly in ethanol-water separation. It is, however, beingexplored for wastewater treatment in many areas of production.Edgar, et al. [70] applied pervaporation in micro irrigation of plants from wastewater. In theexperiment, a dense hydrophilic pervaporation membrane was placed at vantage positions in thesoil. Synthetic wastewater in a feed tank was circulated over the membranes where the permeateflux and enrichment of the wastewater (contaminant rejection) were monitored. The results showedthat
boost over this period is membrane technology. Membrane technology has grown significantly in the last couple of decades due to the benefits it offers in water and wastewater treatment. With significant reduction in the size of equipment, energy requirement and low capital cost, membrane technology offers many prospects in wastewater treatment [6].
tivated sludge process and membrane technology has been recognized as a technology for advanced wastewater treatment. In membrane bioreactor technology, the membrane separation technology and bio- organic combin a-tion are new technologies of wastewater treatment. It utilizes membrane separation activated sludge and bio-
Principal Notation xv List of Acronyms and Abbreviations xvii 1 What is Domestic Wastewater and Why Treat It? 1 Origin and composition of domestic wastewater 1 Characterization of domestic wastewater 2 Wastewater collection 5 Why treat wastewater? 5 Investment in wastewater treatment 6 2 Excreta-related Diseases 8
Introduction to Wastewater Treatment Bruce J. Lesikar Professor Texas AgriLife Extension Service Overview ¾What is wastewater? ¾Why are we concerned about wastewater? ¾The big picture. ¾Goals for wastewater treatment are evolving ¾How do we implement our infrastructure? ¾Wastewater Treatment Processes - The end result is based upon your design
4 Wastewater Treatment ANNUAL REPORT 2020 Wastewater Treatment Process 1. INFLUENT PUMP STATION Wastewater from the serviced area in Thunder Bay enters the Water Pollution Control Plant at the Influent Pump Station (IPS) where five pumps are available to deliver the wastewater to the preliminary treatment process. The wastewater then flows by .
Wastewater treatment plants : wastewater resource recovery facilities ? NITROGEN and PHOSPHOROUS The process is distinguished by the fact that municipal sewage sludge from wastewater treatment plants with simultaneous phosphate elimination with iron salts could be used without any changes in the process of wastewater treatment.
Natural Technologies of Wastewater Treatment February 2014 w w w . g w p c e e . o r g 1 1 Preface Natural ecosystems have been used for wastewater treatment for centuries. However, this "treatment" has often represented only an uncontrolled wastewater disposal and, as a result, many valuable ecosystems have been irreversibly damaged.
3.5 million people that still discharge their wastewater directly to rivers and lakes, rather than to improve the industrial wastewater treatment further. The treatment rate of the industrial wastewater has reached 97%, but the municipal wastewater treatment rate has only reached 70%.
Artificial Intelligence of December 2018 [5] and in the EU communication on Artificial Intelligence for Europe [6], including billions of Euros allocated in the Digital Europe Programme _ [7]. This is due to potential economic gains (e.g. see OECD reports on AI investments [8] and on AI patents [9]), as well as economic risks (such as the issue of liability – Liability for Artificial .
