Krzysztof W. Szewczyk

Monitoring of periodic anaerobic digestion with flow-through array of miniaturized ion-selective electrodes.

In the last few years Electronic tongues (ETs) based on various sensor arrays were applied to the monitoring of various fermentation processes, as devices capable of fast, inexpensive, automated and on-line control. In this work a novel application of ET is proposed--flow-through array of miniaturized ion-selective electrodes (ISEs) was used for the analysis of samples obtained during anaerobic digestion (methane fermentation) performed in periodic conditions. The samples were classified according to their Chemical Oxygen Demand (COD) and Volatile Fatty Acid (VFA) content. Moreover, for this application a novel design of ISEs was developed, which is fully compatible with flow-through modules for sensor measurements.

Inertial deposition of particles in the human branching airways

Abstract The theoretical model of inertial deposition of aerosol particles in the human upper tracheobronchial tree and in ideal models of bifurcation is presented. The calculated efficiencies of particle deposition are compared with data from the literature for deposition in hollow casts of the tracheobronchial tree and in models of human branching airways.

Development of a Dichotomous-Flow Quantitative Fit Test for Half-Mask and Full-Facepiece Respirators

A new method to quantitate the fit of elastomeric half-mask and full-facepiece air-purifying respirators was developed. In this method the two flows, cartridge flow and leak flow, are separate. The air-purifying cartridges of the respirator are attached to a reference respirator. A selected flow equivalent to the inhalation flow of the wearer is drawn through the cartridge pair: A feedback system consisting of a pressure controller and a control valve is used to set the pressure drop in the mask on the subjects face equal to the pressure drop in the reference mask. The faceseal leak flow is measured while the subject holds his or her breath for a short period of time. The ratio of total flow (cartridge flow+leak flow) to leak flow is a measure of fit and is defined as the flow fit factor. Aerosol fit factors and flow fit factors were determined using sampling probes in three mask locations: top, center, and bottom. A Kruskal-Wallis test showed that aerosol fit factors obtained from the three locations we...

Modelling of a batch anaerobic digestion

Modelling of a batch anaerobic digestion The Anaerobic Digestion Model no 1 (ADM1) has been implemented to simulate batch fermentation. The pH changes and inhibition of the fermentation have been studied. The model has been used to investigate the effects of substrate composition and concentration as well as the composition of the microorganism population on the course of fermentation. The overload of a reactor has been discussed.

Size Characteristics of Particles Released from Broths

Abstract The release of aerosols from aerated liquids is of environmental concern when the liquid contains potentially hazardous contaminants. The aerosol generated by the aeration of a fermentation broth was measured in a vessel of 0.1 m3 total capacity. The influence of air flow rate, agitation rate, and diffuser diameter on the size distribution and particle number concentration was investigated. Aerosols in the size range of 0.8–15 μm were measured by an Aerodynamic Particle Sizer. Measured particles were in the respirable size range and were large enough to carry bacteria. It was found that the composition of the particles was close to that of solid residues after water evaporation. The particle concentration in the air stream depended directly on the broth concentration. Particle volume release rates on the order of 16 mm3/m2˙min were observed for superficial air velocities of about 0.2 cm/s and liquid agitation rates of 75 and 130 rpm. The mean size of the particles increased with increasing agitat...

Application of flow-injection potentiometric system for determination of total concentration of aliphatic carboxylic acids

In this work, flow-injection system with potentiometric detection was tested for determination of total carboxylic acid concentration. Detection part of the examined system consists of ion-selective electrodes (ISEs) with polymer membranes of different compositions. First electrode is based on Zr(IV)-tetraphenylporphyrin as ionophore selective towards carboxylic acid anions, the membrane of second one contains only liphophilic anion exchanger - tridodecylmethylammonium chloride. Final response of the system is a result of combination of EMF signals from both electrodes. Combination of two detectors enables significant decrease of differences between potentiometric signals induced by mixtures of studied anions of various concentrations as compared to results obtained only with metalloporphyrin-based ISE. The use of anion-exchanger based detector allows for elimination of the influence of aliphatic carboxylic acids lipophilicity. Proposed potentiometric flow-injection system was employed for determination of short-chain aliphatic carboxylic acids (so-called VFA - volatile fatty acids) in samples originating from an anaerobic digester. Results obtained for these relatively complicated samples are in good agreement with results obtained with the use of reference colorimetric method. Linear response towards carboxylic acids was observed in the concentration range of 10(-4) to 10(-2)mold m(-3), with the slopes in the range of -110 to -150 mV dec(-1) (for acetate(-) and butyrate(-), respectively). System enables for determination of about 6 samples per hour. Life time of ISEs average about 2 months.