Among chemical industries, petroleum refineries have been identified as large emitters of a wide variety of pollutants. Benzene, toluene, ethylbenzene, and xylene (BTEX) form an important group of aromatic volatile organic compounds (VOCs) because of their role in the troposphere chemistry and the risk posed to human health. A very large crude oil refinery of the Baltic States (200,000 bbl/day) is situated in the northern, rural part of Lithuania, 10 km from the town of Mažeikiai (Lithuania). The objectives of this study were: (1) to determine of atmospheric levels of BTEX in the region rural and urban parts at the vicinity of the crude oil refinery; and (2) to investigate the effect of meteorological parameters (wind speed, wind direction, temperature, pressure, humidity) on the concentrations measured. The averaged concentration of benzene varied from 2.12 ppbv in the rural areas to 2.75 ppbv in the urban areas where the traffic was determined to be a dominant source of BTEX emissions. Our study showed that concentration of benzene, as strictly regulated air pollutant by EU Directive 2008/50/EC, did not exceed the limit of 5 ppbv in the region in the vicinity of the crude oil refinery during the investigated period. No significant change in air quality in the vicinity of the oil refinery was discovered, however, an impact of the industry on the background air quality was detected. The T/B ratio (0.50-0.81) that was much lower than 2.0, identified other sources of pollution than traffic.

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Biological air treatment devices, biofilters, of four different structures with different origin charges, composed of natural zeolite granules, foam cubes and wood chips, were used for the experimental investigation. Biological and ad‐sorptive air treatment methods are employed to clean the air from volatile organic compounds by mixing foam and zeolite with wood chips. The use of complex cleaning technologies improves the efficiency of the device and extends the useful life of a charge. The investigation showed that microorganisms predominant in the process of biocleaning could also propagate in the charges of inorganic origin composed of natural zeolite. The dependences of biofilter treatment efficiency on the nature, concentration and filtration time of the fed pollutant were determined when cultivating associations of spontaneous microorganisms in a charge. The best filtration efficiency of the charge was achieved when acetone‐polluted air was fed into the device at a speed of 0.3 m/s. The treatment efficiency of a biofilter with a humidifying chamber reached 98% when cleaning the air from acetone with an initial concentration of the pollutant of 305 mg/m3. The cleaning efficiency of the device increases when reducing the concentrations of pollutants fed into the device and increasing the time of their filtration. Santrauka Eksperimentiniams tyrimams atlikti naudota keturi skirtingu konstrukciju biologiniai oro valymo irenginiai - biofiltrai su skirtingos kilmes ikrovomis, sudarytomis iš gamtines kilmes ceolito granuliu, porolono kubeliu bei medienos skiedru. Porolona ir ceolita maišant su medienos skiedromis, lakiesiems organiniams junginiams iš oro valyti taikomi biologinis ir adsorbcinis oro valymo metodai. Irenginio valymo efektyvumas pagerinamas bei ikrovos naudojimo trukme ilgeja naudojant kompleksines valymo technologijas. Ištyrus nustatyta, kad biologinio valymo procese vyraujantys mikroorganizmai gali daugintis ir neorganines kilmes ikrovose, sudarytose iš gamtinio ceolito. Ikrovoje kultivuojant savaiminiu mikroorganizmu asociacijas nustatytos biofiltru valymo efektyvumo priklausomybes nuo i irengini tiekiamo teršalo prigimties, koncentracijos, filtracijos laiko. Geriausiai ikrova filtravo 0,3 m/s greičiu i biofiltra tiekiama acetono garais užteršta ora. Šalinant iš oro acetona, kai pradine teršalo koncentracija 305 mg/m3, biofiltro su drekinimo kamera valymo efektyvumas sieke 98 %. Mažinant i biofiltrus tiekiamu teršalu koncentracijas bei didinant ju filtracijos laika irenginiu valymo efektyvumas dideja. Резюме Для экспериментальных исследований использовались четыре устройства для биологической очистки воздуха – биофильтры разных конструкций. Загрузку биофильтров составляли гранулы естественного цеолита, поролон и древесина, которые использовались для очистки воздуха от летучих органических веществ. В случае применения для очистки воздуха поролона и цеолита в смеси с древесиной применялся биологический и адсорбционный методы. Применение комплексных технологий способствует улучшению эффективности очистки воздуха и продлению срока применения загрузки. Исследования показали, что в процессе биоочистки микроорганизмы могут размножаться и в неорганической загрузке, состоящей из природного цеолита. Культивируя в загрузке ассоциации микроорганизмов, найдены зависимости эффективности биофильтра от характера загрязнителя, его концентрации, времени фильтрации. Лучше всего загрузка фильтровала воздух, загрязненный парами ацетона и подаваемый в установку со скоростью 0,3 м/с. Эффективность очистки воздуха от ацетона при начальной концентрации загрязняющих веществ в 305 мг/м3 для биофильтра с камерой увлажнения составляла 98%. При снижении концентрации загрязняющих веществ, подаваемых в биофильтр, и повышении времени фильтрации загрязненного воздуха эффективность установки увеличивается.

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The environmental legislation and strict enforcement of environmental regulations are the tools effectively used for developing the market of materials for environmental protection technologies.Sustainability criteria shift environmental engineering systems to more sustainable-material-based technologies. For carbon-based medium materials in biofiltration, this trend results in attempts to use biochar for biofiltration purposes. The paper presents the analysis of biochar properties based on the main criteria for biofiltration medium integrating the environmental quality properties of biochar, following the European Biochar Certificate guidelines. Three types of biochar produced from feedstock of highly popular and abundant types of waste are analysed. A systematic approach was applied to summarize the results. The lignocellulosic type of biochar was found to be more competitive for use as a biofiltration medium than the types of biochar with high ash or lignin content.

In this study, different types of magnetic biochar nanocomposites were synthesized using the co-precipitation method. Two biochar materials, namely, sewage sludge biochar and woodchips biochar, were prepared at two different temperatures, viz., 450 and 700 °C. These biochars were further modified with magnetic nanoparticles (Fe 3 O 4 ). The modified biochar nanocomposites were characterized using field emission–scanning electron microscopy (FE-SEM), X-ray diffraction (XRD), transmission electron microscopy (TEM), Brunauer–Emmett–Teller (BET), SQUID analysis, X-ray photoelectron spectroscopy (XPS), and Fourier-transform infrared spectroscopy (FTIR). The potential of prepared adsorbents was examined for the removal of hexavalent chromium (Cr(VI)) and Acid orange 7 (AO7) dye from water as a function of various parameters, namely, contact time, pH of solution, amount of adsorbents, and initial concentrations of adsorbates. Various kinetic and isotherm models were tested to discuss and interpret the adsorption mechanisms. The maximum adsorption capacities of modified biochars were found as 80.96 and 110.27 mg g -1 for Cr(VI) and AO7, respectively. Magnetic biochars showed high pollutant removal efficiency after 5 cycles of adsorption/desorption. The results of this study revealed that the prepared adsorbents can be successfully used for multiple cycles to remove Cr(VI) and AO7 from water. Graphical Abstract Electronic supplementary material The online version of this article (10.1007/s11356-020-09275-1) contains supplementary material, which is available to authorized users.

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Industry, transport and unsustainable agriculture result in the increased quantity of wastewater, release of nutrients and emission of carbon dioxide that promotes eutrophication of water bodies and global climate change. the application of microalgae for phycoremediation, their biomass use for human needs may increase sustainability and have a positive effect on the regional development. The experiments were carried out in order to establish the feasibility of treating the local municipal wastewater with microalgae consortia and their biomass potential for biofuel production. The results revealed that Chlorella/Scenedesmus consortium eliminated up to 99.7–99.9% of inorganic phosphorus and up to 88.6–96.4% of inorganic nitrogen from the wastewater within three weeks. The ammonium removal was more efficient than that of nitrate. Chlorella algae grew better in diluted, while Scenedesmus – in the concentrated wastewater. The consortium treated wastewater more efficiently than a single species. The maximum biomass (3.04 g/L) of algal consortium was estimated in concentrated wastewater. Algae accumulated 0.65–1.37 g of CO2/L per day in their biomass. Tus, Chlorella/Scenedesmus consortium is a promising tool for nutrients elimination from the local wastewater under the climatic conditions specific to Lithuania. However, none of the two species were able to accumulate lipids under the nitrogen starvation conditions.