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Biodiesel use in local public transport could be especially significant in improving air quality in cities. The purpose of the experiments described in this paper was to evaluate the various (10, 20 and 50%) blends of biodiesel with diesel in the context of the engine and pollution aspects. As regards the experimental use of these findings on municipal buses, these experiments were the first reference in Hungary. The ages (15-20 years) and types of buses (Ikarus-280, Ikarus-260) used in the experiments are still common vehicles in Hungarian public transport. During our measurements, there was a significant difference between the change in fuel consumption of articulated and solo buses in traffic when compared to test bench measurements. The proportion of the engine performance reduction is nearly the same as that for biodiesel share in the blends. Most pollutants were decreasing (both at idle and full rpm), but this reduction is not directly proportional to the increase of the blending percentage. However, as for CO2, emission increase was observed in the case of idle rpm in comparison to normal diesel operation, even though this phenomenon was not due to biodiesel use, but the catalytic converter and the fact that biodiesel was used for the first time in the engine concerned. Highlights (for review) Highlights1. Our experiments in this topic were the first references in Hungary.2. Biodiesel use results 13.3% increase in the fuel consumption of articulated buses.3. Increasing the proportion of biodiesel results to similar decrease in performance. 4. All pollutants except for CO 2 showed a reduction.5. The extent of this reduction is not proportional to share of blended biodiesel.

Crystallization as the most widespread purification, separation, and morphology-determining method is a critical technology that could be made safer and more economical by using continuous crystallization alternatives. Accordingly, this study aims to develop the continuous crystallization method for direct processing of a flow reaction mixture of acetylsalicylic acid (ASA) and to provide pure, homogeneous crystalline products for further formulation steps. The solid−liquid separation and the purification of the acetylsalicylic acid from the multicomponent mixture were accomplished in a single stage mixed suspension mixed product removal (MSMPR) continuous crystallizer equipped with an overflow and an inner buffer element to ensure the representative withdrawal of the product suspension. The effect of process parameters such as the operating temperature and the length of residence time (RT) on product quality and quantity were studied at two and three levels, respectively. Investigating these parameters, we found that higher operating temperatures (25 °C) and longer residence time (47 min) favor appropriate purity (>99.5%), and narrow crystal size distribution. By reducing the operating temperature (2.5 °C), the yield improved slightly (approximately 77%) and polydisperse products were characterized. The developed crystallization process can link the flow synthesis with the continuous formulation, and consequently serves a further step toward end-to-end production.

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The treated effluent of the Southpest Wastewater Treatment Plant is discharged into a small, low-flow branch of the Danube susceptible to eutrophication. The first, high-load activated sludge system with a hydraulic retention time of 2.5 hrs in the aerated basins, was installed here in 1966. The paper presents the evolution of the technology by illustrating the effects of the different changes carried out since 1991. Reconfiguration of the existing activated sludge basins connected originally in parallel into an arrangement of tanks in series increased the settleability of the sludge as well as the efficiency of COD removal significantly. Introduction of an anaerobic zone preceding the aerated basins facilitated biological excess phosphorus removal with a consequent release in the thickener and digester. Introducing lime addition into the recycled sludge processing wastes significantly improved the performance of the system. However, since there had been no provision built for eliminating the nitrate content of the recycled sludge, efficiency of phosphorus removal proved to be dependent on the eventually occurring nitrification. In order to achieve both an effective nitrogen and phosphorus removal the current technology established in 1999 applies a nitrification and a denitrification filter following the activated sludge unit and uses precipitation for phosphorus removal.