When collecting oil products from a water surface water soaking is unavoidable. It makes a sorbent sink into water and reduces its capacity to take oil products. Previous experiments have revealed [15] that a biosorbent made of moss growing in Lithuania absorb oil products efficiently from a water surface but water soaking is high (14 g of water / g of a sorbent). To reduce water soaking a biosorbent should be impregnated or modified in another way. Impregnation results in occurrence of certain substances in a sorbent that increase pollution, if the sorbent is left in nature. One of the most perspective ways of modification without extra chemical substances is thermal modification. During heating chemical changes (dissociation of‐COOH and ‐OH free radicals) occur in a biosorbent, which have an influence on the combining of water molecules. A reduced number of these free radicals results in a reduced amount of soaked water. A biosorbent made of moss is very flammable, so definition of a sufficient and safe heating temperature and heating time is very important.
Bottom ash (BA) is the main residue left by municipal solid waste incineration (MSWI). As the circular economy is strengthened, the use of BA in civil engineering is increasing, but its successful use is hampered by heavy metal leaching. In this study, we investigated the influence of natural weathering (6 months) on the stabilization of heavy metals (Cu, Zn, and Pb) with different particle sizes in MSWI BA. Natural weathering is the most popular and cost-effective treatment method for BA. During this process, calcium carbonate (CaCO3) is produced, which causes a reduction in heavy metal leaching. We used the following methods in the analysis: The fractionation of BA, XRF, and XRD; an extraction test (LST EN 12457-2:2003); and AAS. The results showed that the concentrations of all elements in BA decreased during natural weathering. An analysis of the mineralogical composition showed a very high (>20%) content of calcium carbonate (CaCO3). The calcium carbonate content increased by 3.2% during weathering because the Ca(OH)2 in fractions <5.6 mm and <40.0 mm was hydrolyzed to CaCO3. Our analysis showed that the metal concentrations (Cu and Pb) in untreated MSWI bottom ash eluate exceeded the limit values, and thus it cannot be used in civil engineering. After three months of stabilization, the heavy metal concentrations were less than the limit values.
Abstract. The problem of noise is topical not only in Lithuania but the world over as well. The northern part of Klaipėda city is distinct for its industry and heavy traffic in the streets. Noise research was carried out in 17 selected measurement locations in the northern part of Klaipėda city. Noise measurements were taken in May, June, July, August, September, October and November. The measurements were made three times during the day: in the day time from 6 a.m. till 6 p.m., in the evening from 6 p.m. till 10 p.m. and at night from 10 p.m. till 6 a.m. The locations of the measurements are marked on the map. In order to distinguish the source of bigger noise between industry and transport, the northern part was divided into two belts. Industry is prevalent in the first belt, whereas the main troublemakers in the second belt are motor vehicles. The measured noise level is compared with permissible standards in measurement locations, where noise level is usually exceeded, and the analysis of noise levels is presented. In order to show the spread of noise in Klaipėda at all three times of the day more vividly, maps of isolines were compiled. Keywords: noise level, the highest permissible noise level, equivalent permissible noise level.
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