http://www.chemia.uj.edu.pl/~ictchem/book/20_szafnicki_1_ictm.pdfInternational audienceAn interactive pedagogical methodology, applied to industrial wastewater detoxication process (WWDP) is presented. It is based on a dedicated realor accelerated-time simulator, which can represent and simulate up to five interconnected Continuous Flow Stirred Tank Reactors (CFSTR), commonly used in continuous-flow detoxication processes of industrial sewage effluents. Various aspects of the WWDP, such as: environmental engineering, process modelling and control, real-time supervision, fault management, process optimization (efficiency, safety, operation costs), can be dealt with, either separately or within the same pedagogical module. The simulator has been developed in a freeware environment (Java) and can be used in cyber education via usual internet browsers

Narce, Cécile

Szafnicki, Konrad

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  Przykłady  kursów91Wykorzystanie technologii informatycznych w akademickiej dydaktyce chemiiTOWARDS AN INTERACTIVE PEDAGOGICALCSFTR-REACTORS SIMULATION TOOLAPPLIED TO INDUSTRIAL WASTEWATER DETOXICATIONKonrad Szafnicki*, Cécile NarceEcole Nationale Supérieure des Mines de Saint-Etienne – ENSM.SE158 cours FaurielF-42023 Saint-Etienne cedex 2 Francee-mail: konrad@emse.frTel. +33477420224, Fax. +33477420204*corresponding author.Key words: Industrial Wastewater Detoxication, CFSTR, real-time control, simulation,optimization.Abstract:An interactive pedagogical methodology, applied to industrial wastewaterdetoxication process (WWDP) is presented. It is based on a dedicated real-or accelerated-time simulator, which can represent and simulate up to fiveinterconnected Continuous Flow Stirred Tank Reactors (CFSTR), commonly usedin continuous-flow detoxication processes of industrial sewage effluents. Variousaspects of the WWDP, such as: environmental engineering, process modellingand control, real-time supervision, fault management, process optimization (efficiency,safety, operation costs), can be dealt with, either separately or within the samepedagogical module. The simulator has been developed in a freeware environment(Java) and can be used in cyber education via usual internet browsers.I. IntroductionIndustrial activities, paticularly surface treatment (electroplating) activities,generate significant volumes of wastewater (WW) which require specific and complexdetoxication before being rejected to the urban sewage network or to the environment.Environmental standards require that the concentrations of free cyanides (CN-)and heavy metal ions (e.g. Cr6+, Pb2+, Ni2+, Cu2+, Zn2+,...), at the outfall sewer, is lessthan the maximal admissible values, Table 1.The challenge depends on optimization of industrial wastewater detoxication, i.e.so that their detoxication efficiency and operating costs are both optimal.This paper presents a project concerning the development of an interactive pedagogicalmethodology, based on a simulation tool, dedicated to different audiences; such as:engineering students, continuing education or continuous professional training as wellas vocational training.92K. Szafnicki, C. NarceElement France, 1985 France/EU, 2006Al 5,0 5,0Cd 0,2 0,2CrVI 0,1 0,1CrIII 3,0 2,0Cr total 3,0 -Cu 2,0 2,0Fe 5,0 5,0Ni 5,0 2,0Pb 1,0 0,5Sn 2,0 2,0Zn 5,0 3,0CN- 0,1 0,1Table 1. Excerpt of the newest french environmental standard concerning – among others – the electroplating industry (Decree, 2006). Max. concentrations in mg/L.II. WWDP: a complex, hazardous processIndustrial WWDP involves several complex stages, which goal is to destroy orto modify toxic compounds into less toxic or extractable ones. For example: oxidation of cyanides into cyanates (Eq. 1.1 to 1.3), reduction of hexavalent chromium into trivalent chromium (Eq. 2.1 & 2.2), precipitation and flocculation of heavy metals in order to settle them, for example,under their hydroxide form ( Me(OH)n ), so as to generate sludges which may bedisposed in a dedicated landfill or utilized for colored metals recovery.Cyanide oxydation using sodium hypochlorite (NaClO, Javel) writes:NaCN + NaClO + H2O  CNCl + 2NaOH                                                 (1.1)If pH > 10,5 then almost instantaneously:CNCl + 2NaOH  NaCl + NaCNO + H2OCaution ! Gaseous CNCl is lethal !! Therefore, for safety, usually pH >> 11,5.Using hydrogen peroxide (H2O2):NaCN + H2O2  NaCNO + H2O                                                                 (1.2)(pHoptimal ~ 9,5, reaction is catalyzed by copper ions).Cyanide oxydation using persulfuric acid (H2SO5, Caro’s acid):NaCN + H2SO5  NaCNO + H2SO4                                                           (1.3)(pHoptimal > 9,5 ).93Wykorzystanie technologii informatycznych w akademickiej dydaktyce chemiiHexavalent chromium reduction using sodium bisulphite (NaHSO3):H2Cr2O7 + 3NaHSO3 + 3H2SO4  Cr2(SO4)3 + 3NaHSO4 + 4H2O                           (2.1)If pH < 2,5 then reaction is instantaneous. Critical threshold: pH > 3,5.Hexavalent chromium reduction using ferrous sulphate (FeSO4):H2Cr2O7 + 6FeSO4 + 6H2SO4  Cr2(SO4)3 + 3Fe2(SO4)3 + 7H2O              (2.2)(pHoptimal < 6 ).Usually generates significant amount of sludge (3-4 times more than Eq. 2.1).An industrial WWDP usually includes a set of continuous flow stirred tankreactors (CFSTR); in each CFSTR a particular detoxication stage is carried out, e.g.decyanidation, dechromation, neutralization, flocculation, etc. Fig. 1 (Degrémont 1991,Meinck et al. 1968-1977, Olsson & Newell 2001, SITS 2002, ...). Every mentionedstage is rather uneasy to operate, particularly as far as continuous flow wastewaterdetoxication is concerned. Moreover, the oxidation and reduction stages can behazardous, depending on the reactant used. The managers as well as the operatorsof WWDPs are therefore very much interested in a safe, efficient and economicaloperation of their processes.Figure 1. Picture of a part of an industrial WWDP. Arrows show effluents flow directions.[A] – acidic WW inflow. [BC] – alkaline – cyanidated WW inflow.DecyanidationNeutralizationFlocculationBCA94K. Szafnicki, C. NarceIII. Computer-aided WWDP simulation and optimizationThe ENSM.SE has been developing an integrated computer-based methodology,including a dedicated simulator of the detoxication process (Szafnicki & Narce 2006,Szafnicki et al. 2005, Szafnicki et al. 1998). The latter enables real- or accelerated-timesimulations of a set of CFSTRs, within a simulation tool as close as possibleto the real, industrial detoxication process, Fig. 2.The user can, for example, choose among different reactants (e.g. strong acids:HCl, H2SO4, or weak acids: CO2, ...) and modify the operation and/or controlparametres (e.g. volumes of CFSTRs, settings of pH-controllers, etc. ).The whole plant is simulated under real industrial constraints, for exampleby integrating real industrial data recorded in situ, on an operating WWDP (WW flow,pH, redox potential, temperatures, ...).Dedicated reactants-intake and consumption indicators provide information aboutthe detoxication costs and therefore the WWDP efficiency (e.g. volumes of detoxicatedWW, used reactants – volumes and prices, real-time control efficiency, etc.).IV. Applications in educationThe methodology – and the simulator – have already been successfully usedin student education (Licence and Master levels) as well as continuing education.Professional trainings (e.g. safety consciousness raising courses for galvanisation plantsoperators) on international level are being planned. Thanks to the dedicatedimplementation language: Java (www.java.com), which is available as freeware,the simulator can easily be used also for cyber education via any internet browser (IE,Nsc, Mozilla, Opera...).Figure 2. Multiple-CFSTR simulator main screen. The user interface is here in French; butit can be adapted and translated in real-time into other languages (English, German, Polish,Portuguese, Chinese... ).95Wykorzystanie technologii informatycznych w akademickiej dydaktyce chemiiDifferent aspects can be dealt with using this simulator; either separately or withinthe same course module, for example:• environmental engineering: industrial WW detoxication,• WW detoxication process (physical-chemical, continuous flow,...),• real-time process control applied to strongly non-linear dynamic process,• WW detoxication plant monitoring, supervision and optimization.AknowledgementsThis project is being partially financed by the Université Numérique Ingénierieet Technologie – UNIT ( www.unit-c.fr ) as well as by the Grande Ecole Virtuelle –GEV from the Groupe des Ecoles des Mines ( http://gemgev.industrie.gouv.fr ).Also great thanks to our long-standing industrial partners, for their kindcollaboration: Société SOFIPEM ( www.pem.fr ) and HEF-Techniques Surfaces( www.hef.fr ).CopyrightThe software has been registered at the APP (Agence pour la Protection desProgrammes) under the number: IDDN.FR.001.380028.000.R.P.2006.000.31235. It istherefore protected by international laws ( http://app.legalis.net/ ).References:Decree of June 30, 2006 (modif. of Sept. 26, 1985), On the surface treatmentwokrshops (NOR: DEVP0650366A) www.legifrance.gouv.frDecree of Sept. 26, 1985, On the surface treatment workshops.Degrémont 1991, Water Treatment Handbook, Ed. Degrémont, (1991; 6th ed.)Meinck, Stooff, Kohlschütter (1968-1977), Industrie-Abwässer, Masson.Olsson, Newell 2001, Wastewater Treatment Systems, IWA publ. (2001)SITS 2002, Surface Treatment - Wastewater Treatment, SITS, (2002)Szafnicki & Narce, 2006. Water Research, 40, n°3, (2006), 579-587Szafnicki et al. 2005, Control Engineering Practice, 13, n°6 (2005), 729–738Szafnicki et al. 1998, Water Research, 32, n°8, (1998), 2480-2490Wozny G., Ed. (2005), E-Learning in Process and Chemical Engineering. APractical Overview, VDI Verlag. ISBN 3-18-382803-0.

Towards an interactive pedagogical CFSTR-reactors simulation tool – Applied to industrial wastewater detoxication

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Towards an interactive pedagogical CFSTR-reactors simulation tool – Applied to industrial wastewater detoxication

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