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.

The biological air treatment method is based on the biological destruction of organic compounds using certain cultures of microorganisms. This method is simple and may be applied in many branches of industry. The main element of biological air treatment devices is a filter charge. Tests were carried out using a new-generation laboratory air purifier with a plate structure. This purifier is called biofilter. The biofilter has a special system for packing material humidification which does not require additional energy inputs. In order to extend the packing material's durability, it was composed of thermally treated birch fibre. Pollutant (acetone) biodegradation occurred on thermally treated wood fibre in this research. According to the performed tests and the received results, the process of biodestruction was highly efficient. When acetone was passed through biofilter's packing material at 0.08 m s−1 rate, the efficiency of the biofiltration process was from 70% up to 90%. The species of bacteria capable of removing acetone vapour from the air, i.e. Bacillus (B. cereus, B. subtilis), Pseudomonas (P. aeruginosa, P. putida), Stapylococcus (S. aureus) and Rhodococcus sp., was identified in this study during the process of biofiltration. Their amount in the biological packing material changed from 1.6 × 107 to 3.7 × 1011 CFU g−1.

The investigation was carried out using a biological air‐treatment device, i.e. a biofilter with an aeration chamber filled with water saturated with biogenic elements. To accelerate the absorption of organic compounds, air polluted with volatile organic compounds is directed to a water reservoir installed in the lower part of the filter where organic compounds are destructed. In the process of aeration, microorganisms propagate in the chamber, degrading part of pollutants to harmless products, carbon dioxide and water. Since all hydrocarbons are water‐soluble, the aeration chamber is the first phase in a hydrocarbon degradation process. Application of such a polluted air‐feeding model improves the sorption qualities of a charge. When relative air humidity reaches 100%, water‐drops evenly distribute over the entire surface area of the charge and improve the activity of microorganisms. Having passed through the aeration chamber, polluted air is filtered via charges of a different origin, composed of zeolite, foam, wood chips or their mixtures. The carried out experiment shows that the best charge filtering capacity is achieved when supplying air polluted with acetone at the rate of 0.1 m/s. At the initial pollutant concentration of 115 mg/m3 the biofilter treatment efficiency reached 96%. The aeration chamber installed in the biofilter increases both microbiological activity of the charge and air treatment efficiency. Santrauka Tyrimai atlikti naudojant biologinį oro valymo įrenginį – biofiltrą su aeracine kamera, pripildyta biogeninių elementų prisotinto vandens. Siekiant pagreitinti organinių junginių absorbciją lakiaisiais organiniais junginiais, užterštas oras nukreipiamas į filtro apatinėje dalyje įrengtą vandens talpyklą, kurioje vyksta organinių junginių destrukcija. Aeracijos proceso metu kameroje dauginasi mikroorganizmai. Jie suskaido dalį teršalų iki nekenksmingų produktų – anglies dvideginio ir vandens. Visi angliavandeniliai tirpūs vandenyje, todėl aeracinė kamera yra pirminis angliavandenilių skilimo proceso etapas. Taikant tokį užteršto oro tiekimo į įrenginį modelį pagerinamos įkrovos sorbcinės savybės. Santykinei oro drėgmei pakilus iki 100 %, vandens lašeliai tolygiai pasiskirsto per visą įkrovos paviršiaus plotą ir pagerina mikroorganizmų aktyvumą. Pratekėjęs aeracinę kamerą užterštas oras filtruojamas pro skirtingos kilmės įkrovas, sudarytas iš ceolito, porolono, medienos drožlių ir jų mišinių. Atlikus eksperimentinius tyrimus nustatyta, kad geriausiai įkrova filtravo 0,1 m/s greičiu į įrenginį tiekiamą acetonu užterštą orą. Esant pradinei šio teršalo koncentracijai 115 mg/m3 , valymo biofiltru efektyvumas siekė 96 %. Taigi biofiltre įrengta aeracinė kamera padidina įkrovos mikrobiologinį aktyvumą ir užteršto oro valymo efektyvumą. Резюме При выполнении экспериментальных исследований использовалось биологическое устройство для очистки воздуха – биофильтр с аэрационной камерой, заполненной водой и насыщаемой биогенными элементами. Для того, чтобы ускорить процессы абсорбции органических соединений, воздух, загрязненный летучими органическими соединениями, направлялся в резервуар с водой, установленный в низкой части фильтра, в котором органические соединения разрушались. В процессе аэрации в камере размножаются микроорганизмы, которые разрушают часть загрязнителей до безопасных продуктов: углекислого газа и воды. Так как все углеводороды растворимы в воде, в аэрационной камере происходит первоначальный процесс деградации углеводорода. При такой модели подачи загрязненного воздуха в устройство улучшаются сорбционные свойства загрузки. Когда относительная влажность воздуха достигает 100%, капли воды равномерно распределяются по всей площади поверхности загрузки и улучшают деятельность микроорганизмов. Пройдя через аэрационную камеру, загрязненный воздух фильтруется через загрузку различного происхождения, составленную из цеолита, поролона, щепы или их смесей. Эксперимент показал, что загрузка лучше всего фильтровала загрязненный ацетоном воздух, подаваемый в устройство со скоростью 0,1 м/сек. При начальной концентрации загрязнителя, равной 115 мг/м3 , эффективность биофильтра достигала 96%. Таким образом, установленная в биофильтре аэрационная камера увеличивает как микробиологическую активность загрузки, так и эффективность очищения воздуха.

Organic matter in drinking water is determined by applying indirect determination methods used for quantitative measurements such as total organic carbon (TOC), chemical oxygen demand (COD), and biochemical oxygen demand (BOD). These analyses require expensive devices, harmful chemical reagents, and are time consuming. Standard water quality tests are inconvenient during start-up or reconstruction of drinking water treatment plants as samples need to be transported to a laboratory and no on-line measurements on plant performing efficiency are available. For practical purposes, less sophisticated and faster methods to determine organic matter are required. One of the methods could be ultraviolet absorption of water at 254 nm wavelength (UV254). It is a technically simple and fast method for determining natural organic matter, requiring neither expensive measurement equipment nor chemical reagents. The present article aims at investigating the possibilities of practical applications of UV254 method to determine the concentration of natural organic matter in ground water. The research proved good correlation between TOC and UV254, as well as between CODMn and UV254. The outcomes of the research indicate that UV254method can be successfully applied to determine natural organic matter concentrations in ground water. Santrauka Organinės medžiagos požeminiame vandenyje nustatomos netiesioginiais kiekybiniais bendrosios organinės anglies (BOA), cheminio deguonies suvartojimo (ChDSMn) ir biocheminio deguonies suvartojimo (BDS) metodais. Šioms analitėms nustatyti būtini brangūs prietaisai, kenksmingi cheminiai reagentai, tyrimai ilgai trunka. Diegiant naujus geriamojo vandens gerinimo įrenginius ir atliekant įrenginių paleidimo, derinimo bei eksploatavimo proceso efektyvumo vertinimą, minėtuosius geriamojo vandens tyrimus nepatogu ir brangu atlikti, todėl šiais atvejais reikia paprastesnio ir greitesnio organinių medžiagų nustatymo metodo. 254 nm bangos ilgio (UV254) ultravioletinių spindulių absorbcija yra techniškai paprastas, spartus organinių junginių koncentracijų nustatymo metodas, jį taikant nebūtina brangi tyrimų įranga bei cheminiai reagentai. Šio darbo tikslas buvo ištirti UV254 metodo tinkamumą organinių junginių koncentracijoms nustatyti požeminiame vandenyje. Atlikus tyrimus apibrėžtos priklausomybės tarp BOA ir UV254 bei tarp ChDSMn ir UV254. Remiantis tyrimų rezultatais galima teigti, kad ultravioletinių spindulių absorbcijos metodas gali būti sėkmingai taikomas organinių junginių koncentracijoms požeminiame vandenyje nustatyti.

No abstract

Microorganisms can reproduce only in such substrata which contain a certain amount of water and dissolved nutritious substances. Therefore, it is necessary to search for such charges that are distinguished by a large filtering surface and good humidity‐retaining properties. In experiments three types of materials ‐ wood, zeolite and foam ‐ were used as a charge for the biological air‐cleaning process. The charges were mixed up to maintain humidity necessary for the microorganisms in the biofilter as long as possible. The charges were placed into three different cassettes in the biofilter. The wood charge consisted of wood chips of 10–15 mm and that of zeolite contained 10–12 mm of zeolite granules. The foam rubber was cut into separate cubes each having the dimensions of 30×30×20 mm. Dependence of the charge humidity on the airflow rate, temperature, time and charge thickness was determined in the work. During the experiments the airflow rate reached 0.1–0.6 m/sec., and the temperature ranged from 15 to 35 °C. Foam showed the best sorption properties, but a better distribution of humidity was found in the wood‐chip charge.

Experimental tests used a biofilter, a biological air treatment device, filled with a packing material of different origins. With the aim of achieving a higher treatment effectiveness of the device the filter was filled with a packing material composed of zeolite granules, foam cubes, wood chips and barks. Pollutant adsorption, absorption and biodegradation processes take place during biological air cleaning by applying different packing materials. As tests have shown, microorganisms predominant in the process of biocleaning can also propagate in the packing materials of inorganic origin composed of natural zeolite and foam. Through the cultivation of spontaneous microorganism associations the research determined the dependences of biofilter packing material's humidity, porosity, pressure drop and treatment effectiveness on the device's operation time. As proved by tests, when applying these packing materials a high air cleaning efficiency remains for quite a long period of time and varies from 88 to 98 %. As the tests have shown, the acetone adsorbed in zeolite pores was not discharged into the ambient air within the entire period of 900 days. This allows a conclusion that the desorbed acetone was degraded by microorganisms. After 900 days of device's operation effectiveness fell to 88%. A decrease in effectiveness resulted from diminished water retention of the packing material. Such a decrease was predetermined by a reduced fraction of the packing material, which results from pollutant degradation and the impact of microorganisms.

Recent studies in the area of biological air treatment in filters have addressed fundamental key issues, such as a biofilter bed of different origin composed of natural zeolite granules, foam cubes and wood chips. When foam and zeolite are mixed with wood chips to remove volatile organic compounds from the air, not only biological but also adsorption air purification methods are accomplished. The use of complex purification technologies helps to improve the efficiency of a filter as well as the bed service life of the filter bed. Investigations revealed that microorganisms prevailing in biological purification, can also reproduce themselves in biofilter beds of inorganic and synthetic origin composed of natural zeolite and foam. By cultivating associations of spontaneous microorganisms in the filter bed the dependencies of the purification efficiency of filter on the origin, concentration and filtration time of injected pollutants were determined. The highest purification efficiency was obtained when air polluted with acetone vapour was supplied to the equipment at 0.1 m/s of superficial gas velocity. When cleaning air from volatile organic compounds (acetone, toluene and butanol), under the initial pollutant concentration of ~100 mg/m 3 , the filter efficiency reached 95 %.