Wastewater Treatment Technology – AOP - Cinkarna Celje PDF
Preview Wastewater Treatment Technology – AOP - Cinkarna Celje
Wastewater Treatment Technology – AOP Table of Contents Cinkarna Celje and green technologies...................................................................................................4 Ultrafine titanium dioxide as water treatment catalyst..........................................................................4 Magnetic photocatalyst (MP)..................................................................................................................5 The efficiency of the MP in comparison to other photocatalysts...........................................................5 Wastewater treatment technology using MPs.......................................................................................6 Wastewater treatment.......................................................................................................................6 Retrieving and re‐using MPs...............................................................................................................6 Development approach to the custom‐made solution for the user...................................................6 MP technology advantages in comparison to other AOP technologies.............................................7 MP technology limitations..................................................................................................................8 General information concerning photocatalysis – MP energy source....................................................8 AOP globally – overview..........................................................................................................................9 Existing AOP technologies.....................................................................................................................10 References.............................................................................................................................................10 33 Cinkarna Celje and green technologies Ultrafine titanium dioxide as water treatment catalyst Ultrafine TiO produced by Cinkarna Celje (CCA 100 AS, CCA 100 BS and 200 BS) has photocatalytic 2 features, which is characteristic of titanium dioxide nano particles. This characteristic is used in wastewater treatment because, in order to work, the method only needs ultrafine TiO and UV light. 2 This method is classified among the more advanced oxidation treatment techniques (AOP – Advanced Oxidation Processes). AOP treatment methods are used globally, mainly in order to remove small amounts of health hazardous pollutants, some of which are even toxic for municipal treatment plants (e.g. hormone disruptors, pesticides, etc.) and thus need to be treated using other methods before they are released into municipal waters. This method is also useful for the pre‐treatment of certain types of polluted waters where complex molecules are broken up into smaller and less hazardous ones, making water more biologically degradable. Advanced oxidation processes are being used for the treatment of industrial wastewater more often than ever. Ultrafine TiO is characterized by non‐selective removal of a wide range of pollutants. In 2 cooperation with universities (the University of Ljubljana, Maribor and Nova Gorica), institutes (Jožef Štefan Institute, Institute of Chemistry), and healthcare organizations, we monitored the efficiency and selectivity of our material using some of the most advanced techniques, which gives us a better overview over the treatment process efficiency. Among all of the advantages of wastewater treatment using titanium dioxide nano particles, the main issue is removing them from water once the treatment process is concluded. In order to achieve the maximum efficiency of the material, the particles need to be suspended in polluted water, in contrast to some products, in which the catalyst layer is applied on solid carriers (smaller specific surface of the active material in comparison to suspended particles). Our company has developed a treatment technology using a composite catalyst with titanium dioxide nano particles bound to magnetic nano particles. The advantage that our solution has over other competing products on the market is the technology of material separation from treated water, which only takes place if an external magnetic field is present (without using additional energy), enabling the removal of the catalyst after water treatment (recycling). At the same time, the material keeps its large specific surface due to the suspended catalyst particles. The most common areas of application [1]: textile wastewater, food industry wastewater, pharmaceutical wastewater, ballast water (disinfection – environmental requirements), closed‐loop water (microorganism removal, cooling water conditioning). 4 MMaaggnneettiicc pphhoottooccaattaallyysstt ((MMPP)) BByy ddeevveellooppiinngg oouurr oowwnn pprroodduucctt,, wwee ccoommbbiinneedd nnuummeerroouuss ppoossiittiivvee ffeeaattuurreess ooff tthhee mmeetthhooddss tthhaatt wweerree Mlliissttaeeddg aanbbeoovvteen iinni oofrroddteerro ttkoo abbeetnnaeelffiiittz tthhaeet mmoaarxx ii(mmMuummF ee)ff ffiicciieennccyy aanndd ssiimmpplliicciittyy ooff wwaasstteewwaatteerr ttrreeaattmmeenntt.. AA mmaaggnneettiicc pphhoottooccaattaallyysstt ((MMPP)) uusseess tthhee pphhoottooccaattaallyyttiicc pprrooppeerrttiieess ooff ttiittaanniiuumm ddiiooxxiiddee ttoo ddiissiinntteeggrraattee Z razvojem lastnega produkta smo združili več pozitivnih lastnosti zgoraj naštetih metod v prid čim večji ppoolllluuttaannttss aanndd tthhee mmaaggnneettiicc pprrooppeerrttiieess ooff tthhee ccaarrrriieerr ttoo rreeccyyccllee mmaatteerriiaall.. TThhee uullttrraaffiinnee ttiittaanniiuumm uddčiiioonxxkiioddveei,,t oCCsCCtAAi 11in00 00e AAnSSo,,s wwtahhviinccohhs iitssi uu sseečiddš čffeoonrr jppa rreeoppnaaerrsiinnngga žttehhneei hmm aavggonndee. ttiiMcc ppahhgnooettootncciaa ttfaaollyytossttk a((MMtaPPliz)),,a iitsso aCr lisn(okM aCFri)nn aki azCkrenolarjei š’čsa foCowetolnjke ap’str aoolidwtuinčcn pte.r oladsutcnto. s ti titanovega dioksida za razgradnjo onesnažil ter magnetne lastnosti nosilca za r ecikliranje materiala. Za pripravo magnetnega fotokatalizatorja uporabljamo lasten ultrafini titanov dioksid, tip CCA 100 AS. The efficiency of the MP in comparison to other The efficiency of the MP in comparison to other photocatalysts photocatalysts Učinkovitost MF v primerjavi z drugimi fotokatalizatorji AAtt CCiinnkkaarrnnaa CCeelljjee,, wwee hhaavvee bbeeeenn uussiinngg oouurr oowwnn mmeetthhoodd ffoorr ddeeccoommppoossiinngg ffoorrmmiicc aacciidd iinn oorrddeerr ttoo Zddaee ttdeeorrmmločiinneeev attnhhjeee eefffoffiitccoiieekanntccayyl iootsffk ttehh eeu ppčihhnookttooovccitaaottsaatlliyy ssuttp.. oTTrhhaeeb ddljaiiaamggrroaa mmv bbCeeinllookawwr nssihh ooCwwelssje tt hhineet eeeffrffniiccoii eemnncceyyt ooodff ovv aarrraiioozguurssa dnje ssaammpplleess ((MMPP,, tthhee ssuussppeennssiioonn,, aanndd tthhee ddeeppoossiittss oonn tthhee ggllaassss ooff oouurr pprroodduuccttss aanndd ccoommppeettiinngg pprroodduuccttss)) mravljinčne kisline. Na spodnjem grafu so prikazane učinkovitosti različnih vzorcev (MF, suspenzije in aass tthhee cchhaannggee ooff tthhee ccoonnvveerrssiioonn iinn aa cceerrttaaiinn ttiimmee ppeerriioodd.. nanosi na steklu lastnih ter konkurenčnih proizvodov) kot sprememba konverzije v časovni enoti. PhotPohcoatotacalytatliycti Hc CHOCOOOHH d deeggrraaddaatitioonn Photocatalytic HCOOH degradation 1 CCA 100 AS 0,8 CCA 200 BS 0,6 [H]/[Ho] MF CC 2.4.2013 0,4 Competing sample 0,2 in a CCsuoospmmenppseeiottiinnngg ssaammppllee iinn aa ssuussppeennssiioonn CCA 100 AS on plates 0 CCCCAA 110000 AASS oonn 0 2 4 6 Compppllaaetttieenssg sample on plates Time CCoommppeettiinngg ssaammppllee TTiimmee oonn ppllaatteess Graf 1: Hitrost razgradnje vzorcev TiO v suspenziji in na trdnih nosilcih ter MF v suspenziji. 2 DiDagiaragmra m1: 1d:e dgeragdraadtiaotnio snp sepeede odf oTfi OTi2O s2a smapmlepsle isn ian sau ssupsepnesniosnio ann adn odn o sno sliodl icda crrairerries rass a ws ewlle alls a Ms MP iPn a Najnižjo aktivnost izkazujeta vzorca, ki sta inns aaun ssepusesepnnesain osnniao nt rdnih nosilcih (CCA 100 AS na ploščah in konkurenčni vzorec na ploščah). Pri teh vzorcih je aktivna površina dosti manjša, kot v primeru sTTuhhseep elloonwwdieerassttn aaihcc ttniivvaiinttoiieedsse aalcrreeev nn. ooTtteiimcceeudd piinnri mtthheeer nssaaomm jepp alleeksst ittvhhnaaotts tww meerrneeo aagppopp nlliiieežjdda ,oo vnne ntthhdeea rss oojellii ddnj icchaaorrvrriioee rrossd ((sCCtCCraAAn j11e00v00a nAAjSSe po čooišnnč eppnllaajuttee sse aannnoddst ttahhveen occ.oo mmSuppseeptteiinnnggz ippjerr oolddauustccntti hoo nni npp llaakttoeenssk))..u IIrnne ntthhčneessihee sspaarmmoippzvlleeossd,, ottvhh eei zaakccattziivvueeje ssjouu rrffpaarccieem iiessr mmljivuuocc hha sskmmtivaanlllloeersr t, tthhaann iinn ssuussppeennddeedd nnaannoo ppaarrttiicclleess aanndd tthhee aaccttiivviittyy lleevveellss aarree ccoorrrreessppoonnddiinngg.. HHoowweevveerr,, tthheeiirr rreemmoovvaall iiss najhitrejšo razgradnjo mravljinčne kisline pa smo dosegli z magnetnim fotokatalizatorjem. ssiimmppllee.. TThhee aaccttiivviittyy ooff tthhee ssuussppeennssiioonnss ooff oouurr oowwnn pprroodduuccttss aanndd tthhee ccoommppeettiinngg pprroodduuccttss aarree ccoommppaarraabbllee.. TThhee ffaasstteesstt ddeeggrraaddaattiioonn ooff ffoorrmmiicc aacciidd wwaass aacchhiieevveedd wwiitthh aa mmaaggnneettiicc pphhoottooccaattaallyysstt.. 5 Wastewater treatment technology using MPs The treatment technology includes two main stages: 1. Wastewater treatment, 2. Retrieving and re‐using MPs. Wastewater treatment The catalyst, the amount of which is determined beforehand by a lab device (the concentrations tend to range between 20 and 250 mg/L), is dispersed in the water that we wish to treat. A pump then moves the water including the suspended MP particles through a UV reactor (see Figure 1) where the pollutant degradation takes place. The residence time changes according to the water pollution level, pollutant type, and required treatment level. The residence time is determined according to the type of the water pollutant – the degradation level is measured as the change of COD and BOD values. In the event of more complex pollutants, 5 more complex analytical methods are applied that help us precisely determine the concentration of the selected pollutant. Polluted water inflow Treatment cycle description: 1. Polluted water is put into the mixer Mixer reactor, reactor UV reactor 2. the catalyst is added to the polluted water, 3. the water with the catalyst circulates through the UV reactor, 4. the treated water flows out through Magnetic separator the magnetic separator, Treated water 5. the catalyst is recycled. outflow Figure 1: Depiction of treatment plant operation Retrieving and reusing MPs The catalyst is prepared in the form of a water suspension which is added to wastewater. After the reaction is concluded, the treated water with the MP is led through a magnetic separator (MS). The separation is performed on the basis of magnetism and does not require an additional energy source. After the separation process is concluded, the catalyst remains in the separator. The treated water is pumped out of the system (Figure 2) and replaced with new wastewater that first needs to circulate through the separator to collect the catalyst particles. The treatment and recycling stages are then interchanged until all of the water that is brought to the system is treated. Development approach to the custommade solution for the user The vision of the company is to use its own high‐tech products with the purpose of reducing harmful substances in the environment. The development of the wastewater treatment application using a magnetic photocatalyst requires a solution custom‐made for the buyers because the application 6 depends on the water pollutant type. There is a pilot device set up at the company which demonstrates the treatment technology using various types of wastewater. Table 1: The level of the degradation of industrial wastewater sample with a magnetic photocatalyst. 54.21 – 23 Jan 2012 BOD5 mg/L O2 27 COD mg/L O2 165 UV 0,1 TiO2 – 24 Jan 2012 BOD mg/L O2 <3.0 LOD# COD mg/L O2 57 Optimal process parameters need to be determined for the selected wastewater: catalyst concentration, residence time, batch/continuous operation, UV strength input, etc. Cinkarna Celje constructed its own mobile laboratory device that enables capacity calculations. Later, this data helps us calculate the parameters for the needs of the industrial plant (Figure 2). Figure 2: The mobile pilot device When determining the efficiency of the degradation of more complex pollutants, sample analyses need to be carried out by means of chromatography in combination with a mass spectrometer. CLP Semivolatiles Calibration Mix is used as a standard mix of pollutants that are degraded with more difficulty. MP technology advantages in comparison to other AOP technologies The synthesis of innovative material made it possible for us to develop a new wastewater treatment technology that has some key advantages over competing technologies: 7 - MP particles are dispersed in polluted water and thus have a significantly larger specific surface in comparison with catalysts that are fixed on reactor or carrier surfaces, - during the treatment reaction, no substances need to be added to enable the pollutant degradation reaction, - in order to function, the technology only uses UV energy and MPs, - the catalyst is recycled following each treatment cycle, - MPs cause the degradation of a wide range of organic pollutants (hormone disruptors, pesticides, antibiotics, carbohydrates, phenols, bacteria, algae, etc.), - MPs degrades microorganisms and not merely deactivates their reproduction, - the catalyst is not harmful to the environment and people. MP technology limitations - the water pH value needs to be between 3 and 9, - the water may not include any non‐dissolved pollutants1, - the oxygen concentration in the water needs to be as close as possible to saturated concentration, - water temperature may not be higher than 45 °C, - this technology is more suitable for lower concentration pollution, except in the case of specific pollutants where the highest efficiency level is achieved. General information concerning photocatalysis – MP energy source The term photocatalysis denotes types of reactions that take place in the presence of light and a catalyst. Ultrafine titanium dioxide needs a UV light source for its functioning. This light then induces the process of charge separation in material a – TiO is a semi‐conductor that becomes charged 2 under the influence of UV light with specific energy. The electrons and electron holes that are created due to the migration of electrons contribute to the creation of active radicals. On the surface of the catalyst, the electrons and electron holes react with oxygen and water molecules. The products of this reaction are hydroxyl and superoxide radicals that trigger the degradation of pollutants in water [2]. Oxidant Oxidation Potential (eV) •OH 2.80 O 2.07 3 H O 1.77 2 2 Hydroperoxyl Radicals 1.70 Permanganate 1.67 Chlorine Dioxide 1.50 Chlorine 1.36 O 1.23 2 Table 2: The comparison of oxidation potential values of individual oxidants [3]. 1 In the event of non‐dissolved substances, preliminary filtration is required. 8 REDUCTION Conduction band Electron excitation Photon absorption Valence band OXIDATION UV photon Figure 3: Depiction of the photocatalysis process on TiO nano particle4. 2 AOP globally – overview The technology of advanced oxidation methods has been known in the world for approximately 20 years. Nowadays, mainly the combination of UV light and an oxidation agent is used for wastewater treatment, and not so much any individual methods. Photocatalysis with titanium dioxide is an AOP wastewater treatment method that requires a UV light source for its functioning. In addition to the strength of the UV light source, the lifespan of UV light bulbs is also very important from the technoeceonomic point of view. In practice, this lifespan is 12 to 18 months if used 24/7. Equipment costs are calculated on the basis of the amount of wastewater and the desired effect of the degradation of the pollutant (power input). The largest users of UV equipment are municipal treatment plants that need UV light for tertiary treatment (systems with a flow rate of a few hundred m3/min). The MP technology is an upgrade of the UV water treatment/preparation system that combines the removal of microorganisms and the degradation of toxic substances which may not be degraded using standard methods or the removal of which is not economically viable. The use of MP treatment technology also makes sense for users who already have set‐up UV disinfection/wastewater treatment systems because it reduces the residence time (saves energy) or increases the level of treatment, even up to 40 percent2. However, the main advantage that the use of the MP technology has over other technologies is that the use of MPs does not require the addition of chemicals or other substances in order to achieve the desired treatment effect. The largest AOP water treatment systems are currently in the USA (the removal of NDMA, 1,4‐ dioxane) where treatment costs are already approximately 0.01 EUR/m3 of wastewater [5]. 2 The percentage of the increased treatment effect depends on the type of water. 9 The application for ballast water treatment is also very interesting. In the future, this application will be required by law. There are systems on the market that provide the removal of all microorganisms with the help of TiO UV technology [6]. 2 This application is also suitable in the field of providing drinking water. Within the projects of the European research inititative Seventh Framework Programme, the photocatalytic removal of various pollutants that affect the end quality of drinking water is being tested [7]. Existing AOP technologies AOP or advanced oxidation processes consist of a dozen pollutant removal technologies, in which hydroxyl radicals serve as the active medium. The methods are separated according to the source of the formation of OH* radicals [8]: - TiO2 photocatalysis, - ozonization, - UV disinfection, - UV wastewater treatment, - the application of hydrogen peroxide (H O ), 2 2 - Fenton/Photo‐Fenton reaction, - various combinations of the above methods. References [1] Mohajerani M, Mehrvar M., Ein‐Mozaffari F. An overview of the integration of advanced oxidation technologies and other processes for water and wastewater treatment. International journal of Engineering 3, 120 (2009). [2] Chong M. N., Jin B., Chow C., Saint C. Recent developments in photocatalytic water treatment technology: A review. Water research 44, 2997 (2010). [3] Sharma S., Ruparelia J.P., Patel M.L. A general review on advanced oxidation processes for waste water treatment. International conference on current trends in technology, Nuicone (2011) [4] http://projekti.gimvic.org/2009/2a/kataliza/fotokataliza_teorija.html (6 June 2013). [5] Kaneko M., Okura E. Photocatalysis Science and Technology. Springer, Japan, 2002. [6] Matheickal J., Raaymakers S. 2nd International ballast water treatment R&D symposium. Globallast monograph series 15 (2003). [7] http://www.observatorynano.eu/project/ (6 June 2013). [8] Kommineni, S. et. al. 3.0 Advanced Oxidation Processes. http://www.nwri‐ usa.org/pdfs/TTChapter3AOPs.pdf (11 June 2013). 10
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