Pool-spetsiifiliste BHT biosensorite uurimine biosensor-riviks

Väitekirja elektrooniline versioon ei sisalda publikatsioone.Reovee reostuse taset määratakse selle biokeemilise hapnikutarbe alusel (BHT). BHT iseloomustab hapniku hulka, mis on vajalik proovis leiduva orgaanilise aine biokeemiliseks lagundamiseks. Kuigi BHT analüüs ei ole spetsiifiline ühelegi saasteainele, on see siiski väga oluline üldine indikaator aine potentsiaalsest keskkonnaohtlikkusest pinnavetele. Paraku kulub analüüsi tulemuste saamiseks 5 või 7 päeva ning seetõttu on reoveepuhastusseadmete juhtimine selliseid teste kasutades väga keeruline. Antud probleemi lahendamiseks koostati lihtsad ja usaldusväärsed pool-spetsiifilised BHT biosensorid, mis võimaldasid tulemuse saada vähem, kui 30 minutiga. Antud biosensoritega oli võimalik hinnata BHT-d, mis oli põhjustatud raskesti lagundatavatest ühenditest, mille suhtes nad olid pool-spetsiifilised. Samas kui universaalne biosensor ja biosensorid, mis on pool-spetsiifilised mõnele teisele raskesti lagundatavale ühendile, ei määranud seda ja alahindasid proovi BHT7 umbkaudu selle raskesti lagundatava ühendi poolt tekitatud BHT väärtuses, 10-25%. Kuigi biosensorid alahindasid enamike reaalsete tööstuslike reoveeproovide BHT7, võimaldasid pool-spetsiifilised biosensorid siiski saada täpsemaid tulemusi kui universaalne biosensor, mis alahindas proovi BHT7 suuremas ulatuses. Seega on pool-spetsiifilised biosensorid sobivamad BHT mõõtmiseks tööstuslikes reovetes, kui universaalne biosensor, kuid ainult juhul, kui on olemas eelinfo proovi koostise ja päritolu kohta, mis võimaldab valida sobiva pool-spetsiifilise biosensori. Antud probleem lahendati erinevate pool-spetsiifiliste biosensorite ühendamisega sensor-riviks – „bioelektrooniliseks keeleks“. Selle sensor-rivi signaali analüüsiks rakendati mitmemõõtmelise andmete analüüsi meetodeid. Antud meetodite rakendamisel võimaldas PCA eristada proove nende koostise ja BHT7 väärtuse alusel ning PLS võimaldas märgatavalt paremini hinnata proovide BHT7 väärtusi kõigis proovides.Pollution load of wastewaters is determined on the basis of their biochemical oxygen demand (BOD) which measures the oxygen required for the biochemical degradation of organic material. Although the BOD test is not specific to any pollutant, it continues to be one of the important general indicators of the substance potential to be an environmental pollutant for surface waters. However, it takes 5 or 7 days to gain results and management of wastewater treatment facilities can be very difficult using this kind of tests. To address this limitation, simple and reliable semi-specific BOD biosensors were constructed which enabled us to gain results within less than 30 minutes. In addition, these biosensors can measure BOD derived from refractory compounds to which they are semi-specific. Therefore, better estimation of BOD is gained. On the other hand, universal biosensor and biosensors not semi-specific to that certain refractory compound cannot detect it and thus, underestimate the BOD7 of the sample to the extent made up by this compound, 10-25%. Although biosensors underestimated the BOD7 of most real industrial wastewater samples, the semi-specific biosensors still produced better correlation of sensor-BOD and BOD7 in real samples than universal biosensor which underestimated the BOD7 of samples to a greater extent. Therefore, semi–specific biosensors are more appropriate for measuring BOD in specific industrial wastewaters than universal biosensor. However, it is vital to have a prior knowledge about samples composition and origin to select the suitable sensor. This problem was overcome by using different biosensors as an array – bioelectronic tongue - and application of multivariate data analysis. Qualitative information was extracted by using PCA, which enabled us to distinguish different samples by their composition and BOD7 values. In addition, PLS was used for quantitative analysis which resulted in good correlation of sensor-BOD and BOD7 in all samples

Perennial Grasses as a Substrate for Bioethanol Production

One of the possible choices as a biomass for lignocellulosic bioethanol production are different perennial grasses. Cultivating this type of biomass has many advantages in terms of natural diversity and landscape protection. In this study, mixture of red clover and timothy grass was used as a feedstock to investigate its potential as a substrate for bioethanol production. Traditional three step bioethanol production process was used in combination with NED pretreatment. The results show at all pretreatment temperatures similar glucose concentrations and hydrolysis efficiencies, which varied from 4.3 to 5.1 g/l and 15.2 % to 17.7 %, respectively. The ethanol yield, on the other hand, decreased as the pretreatment temperature increased. However, the mass balance revealed that when using this kind of feedstock, 3.3-4.0 g ethanol could be produced from 100 g of biomass. The overall efficiency and yield of the process was lower than expected due to pretreatment, which might not have been suitable for soft biomass

The Role of Ionic Liquids in the Lignin Separation from Lignocellulosic Biomass

Lignin is a natural polymer, one that has an abundant and renewable resource in biomass. Due to a tendency towards the use of biochemicals, the efficient utilization of lignin has gained wide attention. The delignification of lignocellulosic biomass makes its fractions (cellulose, hemicellulose, and lignin) susceptible to easier transformation to many different commodities like energy, chemicals, and materials that could be produced using the biorefinery concept. This review gives an overview of the field of lignin separation from lignocellulosic biomass and changes that occur in the biomass during this process, as well as taking a detailed look at the influence of parameters that lead the process of dissolution. According to recent studies, a number of ionic liquids (ILs) have shown a level of potential for industrial scale production in terms of the pretreatment of biomass. ILs are perspective green solvents for pretreatment of lignocellulosic biomass. These properties in ILs enable one to disrupt the complex structure of lignocellulose. In addition, the physicochemical properties of aprotic and protic ionic liquids (PILs) are summarized, with those properties making them suitable solvents for lignocellulose pretreatment which, especially, target lignin. The aim of the paper is to focus on the separation of lignin from lignocellulosic biomass, by keeping all components susceptible for biorefinery processes. The discussion includes interaction mechanisms between lignocellulosic biomass subcomponents and ILs to increase the lignin yield. According to our research, certain PILs have potential for the cost reduction of LC biomass pretreatment on the feasible separation of lignin

The Efficiency of Nitrogen and Flue Gas as Operating Gases in Explosive Decompression Pretreatment

As the pretreatment process is the most expensive and energy-consuming step in the overall second generation bioethanol production process, it is vital that it is studied and optimized in order to be able to develop the most efficient production process. The aim of this paper was to investigate chemical and physical changes in biomass during the process of applying the explosive decompression pretreatment method using two different gases—N2 and synthetic flue gas. The explosive decompression method is economically and environmentally attractive since no chemicals are used—rather it is pressure that is applied—and water is used to break down the biomass structure. Both pre-treatment methods were used at different temperatures. To be able to compare the effects of the pretreatment, samples from different process steps were gathered together and analysed. The results were used to assess the efficiency of the pretreatment, the chemical and physical changes in the biomass and, finally, the mass balances were compiled for the process during the different process steps of bioethanol production. The results showed that both pre-treatment methods are effective in hemicellulose dissolution, while the cellulose content decreases to a smaller degree. The high glucose and ethanol yields were gained with both explosive pretreatment methods at 175 °C (15.2–16.0 g glucose and 5.6–9.0 g ethanol per 100 g of dry biomass, respectively)

Characterisation of Electrochemical Sensor-Array for Utilisation in Construction of BOD Bioelectronic Tongue

There is need to rapidly measure biochemical oxygen demand (BOD) to estimate organic pollution in wastewater. Biosensors are able to estimate BOD values within 5–30 minutes, but they have some limitations that can be overcome with biosensor-array. This work used sensor-array, which consists of 8 × 3 electrodes. The working electrode was inner Pt circle electrode, counter electrode was a Pt band electrode and the reference electrode was a silver wire. The potentiostat was used to record cyclic voltammetry and chronoamperometry. The pumping speed was set at 1.5 cm3 min−1 or higher, to avoid the interference. Next, sensor-array was tested to measure different oxygen amounts and calibrated accordingly. Lastly, Pseudomonas putida membranes were calibrated and used to estimate BOD value. The calibration gave linear range up to 85 mg L−1 of BOD and sensitivity from 0.0018 to 0.0068. Real industrial wastewater, from lignocellulosic bioethanol production, was used to test the biosensor-array. It underestimated BOD values from 8 to 37 %. This biosensor-array allows to measure BOD value in less than 15 minutes

Second-generation bioethanol production: A review of strategies for waste valorisation

This paper reviews second-generation biofuel production chain and focuses on its energetic, economic and environmental impacts. The biggest challenge in the production of bioethanol from lignocellulosic material refers to the biomass waste that is left over after the separation of bioethanol in the distillation process. This waste still has high energetic value and could be further utilised to add value to the production chain. Furthermore, the environmental impact of untreated waste from bioethanol production is very high, which also requires attention. Anaerobic digestion of bioethanol production waste has been proposed as a possible solution to utilise the energetic potential of this waste and lower its environmental impact.

Biomass Pretreatment with the Szego Mill™ for Bioethanol and Biogas Production

Results from an investigation of the mechanical size reduction with the Szego Mill™ as a pretreatment method for lignocellulosic biomass are presented. Pretreatment is a highly expensive and energy-consuming step in lignocellulosic biomass processing. Therefore, it is vital to study and optimize different pretreatment methods to find a most efficient production process. The biomass was milled with the Szego Mill™ using three different approaches: dry milling, wet milling and for the first time nitrogen assisted wet milling was tested. Bioethanol and biogas production were studied, but also fibre analysis and SEM (scanning electron microscope) analysis were carried out to characterize the effect of different milling approaches. In addition, two different process flows were used to evaluate the efficiency of downstream processing steps. The results show that pretreatment of barely straw with the Szego Mill™ enabled obtaining glucose concentrations of up to 7 g L−1 in the hydrolysis mixture, which yields at hydrolysis efficiency of 18%. The final ethanol concentrations from 3.4 to 6.7 g L−1 were obtained. The lowest glucose and ethanol concentrations were measured when the biomass was dry milled, the highest when nitrogen assisted wet milling was used. Milling also resulted in an 6–11% of increase in methane production rate during anaerobic digestion of straw

INDO-NORDEN - a consortium for developing holistic processes and land use practices for clean energy

201

Utilization of Barley Straw as Feedstock for the Production of Different Energy Vectors

202