Microbial BOD biosensor for wastewater analysis
Date
2011-03-04
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Abstract
Üheks oluliseks näitajaks vesikeskkonna saastumise hindamisel on summaarne parameeter biokeemiline hapnikutarve (BHT), mis iseloomustab orgaaniliste biolagunevate ühendite sisaldust vees. Traditsioonilise BHT analüüsiga mõõdetakse hapniku kontsentratsiooni vähenemist orgaaniliste ühendite biokeemiliseks lagundamiseks vesilahuses 5- või 7-päevase inkubatsiooniperioodi jooksul, mis on liiga pikk aeg reoveepuhastite operatiivseks juhtimiseks ning saastatud vesi võib jõuda looduslikku suublasse juba enne analüüsitulemuste selgumist. Käesolevas töös uuritud biokeemilise osisena immobiliseeritud mikroorganisme sisaldavast membraanist ja signaali detekteerijana amperomeetrilisest hapnikuandurist koosneva BHT biosensoriga saadakse analüüsitulemus kuni 1 tunni jooksul. Lisaks sellele on BHT biosensori eelisteks kompaktsus, kaasaskantavus ja suhteline lihtsus kasutamisel mõõteseadmena.
Koostatud BHT biosensori väljundsignaali uurimise tulemusena töötati välja matemaatiline mudel mittestatsionaarsete protsesside iseloomustamiseks, mille väljundparameetreid saab kasutada biolagunevate orgaaniliste ühendite kontsentratsiooni määramiseks ning samaaegselt ka BHT biosensori väljundsignaali ajalise stabiilsuse hindamiseks. BHT biosensori väljundsignaali saab kalibreerida ja selle tulemusi saab vastavalt kasutada proovide BHT7 määramiseks kolme erineva meetodiga – väljundsignaali statsionaarsete muutuste järgi, signaali muutuse maksimaalse kiiruse järgi ja matemaatilise mudeli parameetri alusel. Nimetatud meetoditega uuriti BHT biosensori väljundit olmereovee ja raskeltlaguneva reovee, st toiduõli tööstuse väljavoolu ja olmereovee segu BHT7 sisalduse määramiseks.
Monitoring and quantitative measurement of pollutants are integral parts of any sustainable environmental policy or programme. Soluble biodegradable organic solutes are important pollutants in wastewater and industrial effluents, and are normally measured collectively and expressed as concentration index known as biochemical oxygen demand (BOD). The BOD7 is essentially a measure of the amount of dissolved oxygen required for the biochemical oxidation of organic solutes in 7 days. BOD biosensors have been developed for more time-effective determination of complex parameter BOD of wastewater samples. The purpose of current thesis is an extensive study of microbial BOD biosensor response to provide output parameters suitable for calibration and wastewater analysis, and also to find out optimal construction details of the device. Extensive analysis and study of BOD biosensor output signal has resulted in a mathematical model that allows response curve reconstruction and good quality curve fitting procedures, with parameters indicating the relationship between response and organic substrate concentration and the stability of the BOD biosensor signal in time. Constructed BOD biosensor which output signal is recorded according to the study can be calibrated for the determination of BOD7 in wastewater samples by three different methods of data treatment – steady state output, dynamic response and results of modelling by curve fitting of normalized data. Broader concentration range, shorter response as well recovery times are the favours of dynamic condition compared to stabilized method. Curve fitting procedure of output signal takes into account various sources of experimental noise providing reliable data for an improved concurrence of BOD biosensor response and BOD7 values compared to aforementioned methods.
Monitoring and quantitative measurement of pollutants are integral parts of any sustainable environmental policy or programme. Soluble biodegradable organic solutes are important pollutants in wastewater and industrial effluents, and are normally measured collectively and expressed as concentration index known as biochemical oxygen demand (BOD). The BOD7 is essentially a measure of the amount of dissolved oxygen required for the biochemical oxidation of organic solutes in 7 days. BOD biosensors have been developed for more time-effective determination of complex parameter BOD of wastewater samples. The purpose of current thesis is an extensive study of microbial BOD biosensor response to provide output parameters suitable for calibration and wastewater analysis, and also to find out optimal construction details of the device. Extensive analysis and study of BOD biosensor output signal has resulted in a mathematical model that allows response curve reconstruction and good quality curve fitting procedures, with parameters indicating the relationship between response and organic substrate concentration and the stability of the BOD biosensor signal in time. Constructed BOD biosensor which output signal is recorded according to the study can be calibrated for the determination of BOD7 in wastewater samples by three different methods of data treatment – steady state output, dynamic response and results of modelling by curve fitting of normalized data. Broader concentration range, shorter response as well recovery times are the favours of dynamic condition compared to stabilized method. Curve fitting procedure of output signal takes into account various sources of experimental noise providing reliable data for an improved concurrence of BOD biosensor response and BOD7 values compared to aforementioned methods.
Description
Väitekirja elektrooniline versioon ei sisalda publikatsioone.
Keywords
doktoritööd, dissertatsioonid, reovesi, biokeemiline hapnikutarve