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CONTENTS
ISSN 1648–4363 Water Management Engineering, 2(5), 2005, 5–14 © Lithuanian University of Agriculture © Water Management Institute of Lithuanian University of Agriculture EFFECT OF THE LAKE ON HYDROCHEMICAL REGIME IN THE BASIN Arvydas Povilas MALIŠAUSKAS The distribution of nutrients and dissolved main ions salts contained in water was studied in hydrographic complex of the lake Lėnas basin. The complex comprises a shallow 2.2-m deep 245-ha lake, its tributary with a drained polder arranged in the valley nearby the lake, and its effluent with the area of 38.5 km2. Runoff from the lake lasts on the average 237 days per year. The amounts of main ions contained in drainage water and in water of the tributary and the effluent were on the average 537 mg/l, 396 mg/l and 267 mg/l respectively. Annual ions runoff much depends on water runoff and water circulation velocity in the lake. During the year with 10% precipitation probability, ions runoff in the tributary was 2–3 times higher (82 t·km-2) than in the year of 70–80% precipitation probability (44 t·km-2). Ions runoff in the effluent was 42% lower compared with the runoff of ions in the tributary. In drainage water the highest concentrations of phosphorus and nitrogen were observed; in water outflow from the forest P and N concentrations were 2–3 times lower. The lowest P and N concentrations were determined in effluent water of the lake. On the average 0.12 kg/ha of total N and 16.0 kg/ha of nitrogen are leached with drainage water from agricultural land use areas every year. The amounts of those elements transported with water of the tributary into the lake are 2–3 times less. The lake retains about 84% of nitrate nitrogen, 60% of total nitrogen, 71% of phosphate phosphorus and 56% of total phosphorus. Keywords: balance, basin, lake, main ions, nutrients. Dr. Arvydas Povilas Mališauskas, senior researcher, Water Protection Department, Water Management Institute of Lithuanian University of Agriculture. Research interests – environmental engineering and landscape management, hydrotechnics and hydrology. Address: Parko 6, Vilainiai, LT–58102 Kėdainiai district, Lithuania. Phone: +370 347 6 80 09. E-mail: a.malisauskas@water.omnitel.net. Received 12 2005. SSN 1648–4363 Water Management Engineering, 2(5), 2005, 15–24 © Lithuanian University of Agriculture © Water Management Institute of Lithuanian University of Agriculture ANALYSIS OF VARIATION IN NITROGEN AND PHOSPHORUS CONCENTRATION IN THE NEMUNAS RIVER Antanas Sigitas ŠILEIKA*, Saulius KUTRA, Kazimieras GAIGALIS, Laima BERANKIENĖ, Aušra ŠMITIENĖ The present study estimates the changes in nitrogen and phosphorus concentrations in 11 monitoring stations along the Nemunas River. Three periods have been evaluated: the Soviet rule period of 1986–1991, the transfer period to market economy of 1992–1996, and the post-reform period of 1997–2002. PO4-P concentration decreased at least 2 times from the first to the third period along the Nemunas River. The most significant decrease is observed at the mouth of the Nemunas River, where the flow weighted concentration decreased from 0.22 to 0.03 mg l-1. The decrease of PO4-P concentration is attributed to the reduction of concentrated pollution and number of animals. NH4-N emission from cities determined high riverine concentration (0.41 mg l-1 at the river mouth) during the first period, but the concentration has settled down at a level of 0.12 mg l-1 in the third period. NO3-N concentration increased up to 2.9 times along the river from the first to the third period. An insignificant increase in NO3-N concentration downstream cities indicates that the most significant changes have occurred in catchments. The highest increase in concentration is observed after entering the Nevėžis River. The statistical analysis confirms that NO3-N and PO4-P concentrations in the Nemunas River monitoring sites differ significantly among the study periods. Keywords: concentration, nitrogen, phosphorus, runoff, the Nemunas River. *contact person Dr. Antanas Sigitas Šileika, director of Water Management Institute of the Lithuanian University of Agriculture. Research interests – environmental engineering and landscape management, GIS, environmental monitoring, water quality assessment. Address: Parko 6, Vilainiai, LT–58102 Kėdainiai district, Lithuania. Phone: +370 347 6 81 00. E-mail: sigitas@water.omnitel.net. Dr. Saulius Kutra, the head of Water Protection Division, Water Management Institute of the Lithuanian University of Agriculture. Research interests – environmental engineering and landscape management, GIS, pollution modelling, application of remote sensing method. Dr. Kazimieras Gaigalis, the head of Water Resources Sector, Water Management Institute of the Lithuanian University of Agriculture. Research interests – hydrology, water flow and quality monitoring. Dr. Laima Berankienė, senior researcher, Water Protection Division, Water Management Institute of the Lithuanian University of Agriculture. Research interests – environmental engineering and landscape management, hydrology, pollution of rivers. Aušra Šmitienė, Ph. D. student, Water Management Institute of Lithuanian University of Agriculture. Research interests – water quality modelling in small agricultural watersheds. Received 12 2005. SSN 1648–4363 Water Management Engineering, 2(5), 2005, 25–32 © Lithuanian University of Agriculture © Water Management Institute of Lithuanian University of Agriculture CALIBRATION AND VERIFICATION OF DRAIN WATER DISCHARGE BY THE SOILNDB MODEL UNDER LITHUANIAN CONDITIONS Aušra ŠMITIENĖ, Martin LARSSON, Kazimieras GAIGALIS*, Giedrius BAIGYS The SOILNDB model is a management-orientated model based on widely known mechanical research-orientated sub-models SOIL and SOILN designed to simulate soil water and nitrogen fluxes. The SOILNDB model is used to determine the best management – orientated decisions by obtaining knowledge about the factors determining nitrogen leaching from the soil profile. This paper presents the first attempt to simulate drain water discharge by the SOILNDB model in the Graisupis river watershed in Lithuania, which makes it possible to use the model for determination of nitrogen leaching coefficients in the future. The model was first applied and calibrated for the Pikeliai fields for the year 2000 to 2004 and then validated for other crop rotation in the Lipliūnai field for the period 1996–2000. Calibration of the model by changing the parameters governing crop water uptake, evapo-transpiration and groundwater flow improved model efficiency for daily drain water discharge from 0.30 to 0.44 and the efficiency for monthly discharge from 0.53 to 0.64 in the Pikeliai fields. The simulated annual drain water discharge matched the measured discharge values very well and the efficiency of the model for annual drain water discharge was from 0.94 to 0.97 for the Pikeliai fields and 0.64 for the Lipliūnai field. The simulated mean annual drain water discharge for the Pikeliai fields was 156 mm initially and 159 mm after the calibration, which was close to the measured discharge of 164 mm. For the validation at the Lipliūnai field, the simulated discharge was 180 mm and the measured one was 174 mm. These results indicate the ability of the model to predict water discharge with the SOILNDB model, which is essential for further simulation of nitrogen leaching with the SOILNDB model in Lithuania. Keywords: calibration, drain water discharge, SOILNDB model. *contact person Aušra Šmitienė, Ph. D. student of the Water Management Institute of Lithuanian University of Agriculture. Research interests – water quality modelling in small agricultural watersheds. Dr. Martin Larsson, researcher at the Division of Water Quality Management, Department of Soil Sciences, Swedish University of Agricultural Sciences. Research interests – modelling of N and P losses from arable land at different scales. Dr. Kazimieras Gaigalis, the head of Water Resources Laboratory, Water Management Institute of Lithuanian University of Agriculture. Research interests – hydrology, water flow and quality monitoring. Address: Mituvos 9, LT–50134 Kaunas, Lithuania. Phone/fax: + 370 37 33 12 70. E-mail: gaigalis@water.omnitel.net. Giedrius Baigys, Ph. D. student of the Water Management Institute of Lithuanian University of Agriculture. Research interests – water protection, non-point source pollution. Received 12 2005. SSN 1648–4363 Water Management Engineering, 2(5), 2005, 33–42 © Lithuanian University of Agriculture © Water Management Institute of Lithuanian University of Agriculture IMPROVEMENT OF EXPERIMENTAL INVESTIGATIONS OF SEDIMENT LADEN FLOW Alfonsas RIMKUS, Saulius VAIKASAS* Due to the disadvantages of up-to-date theory of suspension flow, the experimental investigations on its further development have still been performed in many hydraulic laboratories all over the world. Usually, the sediment motion theory and empirical data are combined in order to obtain the calculation methods necessary for practical needs. However, the laboratory investigation methods and experimental equipment as well as the contemporary methods of the analysis of measurement data have certain disadvantages that reduce the quality and reliability of experimental data. The paper analyzes the most important shortcomings that are to be eliminated. The improvement of future investigations requires their thorough study. The studied imperfections include: insufficient stabilization of suspended sediment distribution in the water flow along the experimental channels, non-homogeneity of experimental sediments when the received hydraulic characteristics are considered as a function of average diameter of investigated sediments, and the application of simplified formulas for the reduction and analysis of experimental data, when complex processes are investigated. Keywords: distribution study, experiments, sediment motion. *contact person Dr. habil. Alfonsas Rimkus, freelance researcher, Exploitation Laboratory, Water Management Institute of Lithuanian University of Agriculture. Research interests – hydraulics of hydrostructures, river bed processes. Dr. habil. Saulius Vaikasas, senior researcher, Exploitation Laboratory, Water Management Institute of Lithuanian University of Agriculture. Research interests – environmental engineering and landscape management, hydraulic modeling, river bed processes. Address: Parko 6, Vilainiai, LT–58102 Kėdainiai district, Lithuania. Phone: +370 347 6 81 09. E-mail: s.vaikasas@delfi.lt. Received 12 2005. ISSN 1648–4363 Water Management Engineering, 2(5), 2005, 43–49 © Lithuanian University of Agriculture © Water Management Institute of Lithuanian University of Agriculture ASSESSMENT OF NITROGEN AND PHOSPHORUS LOAD IN THE MINIJA RIVER CATCHMENT Antanas Sigitas ŠILEIKA, Kazimieras GAIGALIS, Aušra ŠMITIENĖ*, Giedrius BAIGYS Improvement of surface water quality can only be achieved when knowing the magnitude of pollutants originating from various pollution sources in a watershed. The presented investigation of nutrient loads from different diffuse and point sources was performed in the Minija River catchment. Nitrogen and phosphorus load coming through drainage runoff from crop fields, losses from animal farms, runoff from forests, discharges from Plungė wastewater treatment plant (WWTP), discharges from scattered dwellings and by direct atmospheric deposition on surface water bodies was evaluated. Measured water runoff as well as nitrogen and phosphorus leaching coefficients for various crop groups and N and P losses from animal husbandry were used for the investigation. The results showed that crop fields are considered as the major source of nitrogen pollution in the watershed. 57–64% of nitrogen load originated in the crop fields. The highest phosphorus load was determined from point sources: Plungė WWTP and scattered dwellings, which were the source of 19–26 and 31–40% of phosphorus respectively. In the Minija River catchment the total load from the investigated sources was 513.3–764.1 tonnes per year-1 of nitrogen and 32.38–42.39 tonnes per year-1 of phosphorus in 2001–2003. Keywords: load, nitrogen, phosphorus, pollution sources, the Minija River. *contact person Dr. Antanas Sigitas Šileika, director of Water Management Institute of the Lithuanian University of Agriculture. Research interests – environmental engineering and landscape management, GIS, environmental monitoring, water quality assessment. Dr. Kazimieras Gaigalis, the head of Water Resources Sector, Water Management Institute of the Lithuanian University of Agriculture. Research interests – hydrology, water flow and quality monitoring. Aušra Šmitienė, Ph. D. student, Water Management Institute of Lithuanian University of Agriculture. Research interests – water quality modelling in small agricultural watersheds. Address: Mituvos 9, LT–50134, Kaunas, Lithuania. Phone: + 370 37 31 12 63. E-mail: ausrac@kaunas.init.lt. Giedrius Baigys, Ph. D. student, Water Management Institute of Lithuanian University of Agriculture. Research interests – water protection, non-point source pollution. Received 12 2005. ISSN 1648–4363 Water Management Engineering, 2(5), 2005, 50–59 © Lithuanian University of Agriculture © Water Management Institute of Lithuanian University of Agriculture EFFICIENCY OF NITROGEN REMOVAL IN CONSTRUCTED WETLANDS Constructed wetlands (CW) is one of wastewater treatment methods described as plant soil filters. CW may be free-water surface wetlands, the so-called macrophytes filters (MF); another type of CW are subsurface flow filters including filters of vertical flow (VF) and horizontal flow (HF). To evaluate nitrogen (N) removal efficiency, the database of the studies on different construction of CW collected within the period of 1995–2005 was used. The best N removal efficiency is observed in filters of horizontal flow. N removal in filters of vertical flow is less efficient; the worse N removal efficiency is observed in macrophytes filters. When filter load according to total nitrogen (TN) is 1.5 g/m2/d, N removal efficiency is 39.6% and 24% in filters of horizontal and vertical flow respectively; while in macrophytes filters N removal efficiency is only 16.8%. This implies that N removal efficiency is 1.6 times higher in horizontal flow filters than in those of vertical flow, and 2.4 times higher than in macrophytes filters. Considering different seasons of the year, N removal efficiency in HF and VF filters in winter was the same as in summer. In MF N removal efficiency was equal to zero in winter, while in the warm period of the year it was 16%. As the study data shows, after treatment in filters NO3-N contained in wastewater is detected in different forms. NH4-N is prevailing in HF and MF, while in VF filters NO3-N is dominant. Increasing TN concentrations contained in water outflow from HF predetermine higher NH4-N amounts. If water outflow in HF contains 10 mg/l of TN, NH4-N makes up 50%; if it contains 50 mg/l of TN, then NH4-N makes up 76%; meanwhile NO3-N concentration remains unchanged (on the average 0.7 mg/l). Increasing filter load in MF does not result in significant changes in NH4-N concentration that makes up 80% from TN. If water outflow in VF contains 50 mg/l of TN, NO3-N makes up 60%; if it contains 100 mg/l of TN, then NO3-N makes up 85%; meanwhile no significant changes are observed in NH4-N concentration (only up to 2 mg/l). During the cold period of the year a slight increase in NH4-N contained in water outflow from VF filter after the treatment process is observed. If in the warm period of the year NH4-N concentration makes up only 0.6%, then in winter it makes up even 8.3% from TN amount. Keywords: constructed wetlands, nitrogen, wastewater treatment. *contact person Valerijus Gasiūnas, senior researcher, Water Management Institute of Lithuanian University of Agriculture. Research interests – natural wastewater treatment methods. Address: Parko 6, Vilainiai, LT–58102, Kėdainiai, Lithuania. Phone: +370 347 6 80 20, fax: +370 347 6 81 05. E-mail: v.gasiunas@water.omnitel.net. Zenonas Strusevičius, the head of Wastewater Treatment Laboratory, Water Management Institute of Lithuanian University of Agriculture. Research interests – natural wastewater treatment methods. Received 12 2005. ISSN 1648–4363 Water Management Engineering, 2(5), 2005, 60–66 © Lithuanian University of Agriculture © Water Management Institute of Lithuanian University of Agriculture TREATMENT OF WASTEWATER IN MILK COLLECTING STATION Simanas AŠKINIS The paper presents the results of studies on the treatment of wastewater in experimental treatment facilities in a milk collecting station. The treatment process of wastewater was as follows: aeration–flocculation device – sedimentation pond – two-stage constructed wetlands. In milk collecting stations the pollution of wastewater is particularly high – it exceeds the pollution of domestic wastewater 2–4 times. The average pollution according to BOD5 was 821 mgO2/l, however the fluctuation range was rather wide (from 369 to 1388 mgO2/l). At the onset of the studies, the discharge of wastewater inflow into the treatment facilities was 5 m3/d, but soon it reached 12.5 m3/d due to the increasing amounts of received milk. The laboratory investigations have shown that the primary treatment with quicklime (1 kg/m3) reduces wastewater pollution by 54%, while the treatment with coagulant “ZETAG 8660” (4 g/m3) reduces it by even 68%. Under the industrial conditions such results were not obtained in the first stage of the treatment process: the amount of BOD5 contained in wastewater decreased only by 27.2%, the amount of suspended sediment was reduced by 48.1%, the amounts of Ntotal and Ptotal decreased by 15.8% and 27% respectively. Such results much depended on the air temperature, inaccurate dosage of chemicals as well as on the insufficient capacity of reaction and sedimentation reservoirs for 2.5 times higher amount of wastewater. However, despite such unfavourable conditions, this stage of treatment process was rather efficient: the pollution of wastewater with organic matter flowing into the stream did not exceed the maximum allowable rates. The average value according to BOD5 was 4 mgO2/l, the highest BOD5 value was 9.6 mgO2/l. From the environment protection point of view, it is particularly important that the removal of biogenic pollutants is quite sufficient in the wastewater treatment facilities. After the treatment process in wastewater treatment facilities the amount of Ntotal decreased by 82.4%, the amount of Ptotal was reduced by even 97.3%. During the first stage of treatment process, the amount of fat contained in wastewater is reduced by 29% (down to 178 mg/l). To ensure the efficient functioning of constructed wetlands, the amount of fat contained in wastewater should not exceed 50 mg/l. Therefore a special fat separator should be arranged and used in the first stage of the treatment process. The amount of suspended sediment contained in wastewater inflow into the first constructed wetlands was too high (227 mg/l). To avoid the colmatation, an additional sedimentation pond is to be arranged. Keywords: coagulants, constructed, primary treatment of wastewater, quicklime, treatment efficiency, wetlands. Dr. Simanas Aškinis, senior researcher, Water Treatment Laboratory, Lithuanian Institute of Water Management. Research interests – ecology and environmental engineering, the impact of handling and usage of slurry and wastewater on the environment, researches on the transformational processes of pollutants. Address: Parko 6, Vilainiai LT–58102, Kėdainiai district, Lithuania. Phone: +370 347 6 80 20. E-mail: s.askinis@takas.lt. Received 12 2005. ISSN 1648–4363 Water Management Engineering, 2(5), 2005, 67–77 © Lithuanian University of Agriculture © Water Management Institute of Lithuanian University of Agriculture THE EFFECT OF YEARLY WATER ABUNDANCE ON NITRATE NITROGEN RUNOFF FROM RIVER BASINS Saulius KUTRA, Laima BERANKIENĖ* The investigations of the effect of yearly water abundance on nitrate nitrogen runoff from river basins were performed in 25 rivers of Lithuania within the period of 1992 to 2004. No close relationship between the annual precipitation rate and the average nitrate nitrogen runoff from all rivers was determined. A specific linear dependence typical to each river basin as well as more or less significant dispersion of points exists between the river discharges and nitrate nitrogen runoff. The paper presents the main reasons that contribute to worse connection between river discharges and nitrate nitrogen runoff. Several groups of rivers were determined under the same dependence; only the fluctuation range of nitrate nitrogen runoff in dry and wet years was different. As the study results show, water abundance of a particular year is a very important factor regulating the leached amounts of nitrate nitrogen: in dry years the amount of nitrate nitrogen leached from the basin is limited by the lack of water, while in wet years the pollution level of the basin and conditions of nitrate nitrogen leaching process from the basin (arable land, drained land, karst region etc.) are more important. Therefore in very dry years the most intensive nitrate nitrogen runoff is observed in rivers of Western Lithuania (the Šyša, the Jūra, the Akmena, the Bartuva), and in wet years the highest amounts of nitrate nitrogen is leached by the rivers of Middle Lithuania (the Šušvė, the Mūša, the Kražantė, the Nevėžis). The river Tatula situated in karst region is exceptional – here nitrate nitrogen runoff is always highest compared to other rivers under investigation. The susceptibility of the basin (i.e., the difference of nitrate nitrogen runoff between wet and dry years) of Lithuanian rivers is changing from 1560 (in the Tatula) to 32 kg/km2 per year in rivers of south-eastern Lithuania; in rivers located in intensive farming areas in Middle Lithuania it is changing from 855 to 1112, in rivers of intensive farming areas in Western Lithuania the value reaches 585. In rivers flowing via territories with less intensive agricultural activity developed in Western and Middle Lithuania the susceptibility value is 416 kg/km2 per year. Keywords: discharge, nitrate nitrogen, runoff, yearly water abundance. *contact person Dr. Saulius Kutra, the head of Water Protection Department, Water Management Institute of Lithuanian University of Agriculture. Research interests – environmental engineering and landscape management, GIS, pollution modeling, application of remote sensing. Dr. Laima Berankienė, senior researcher, Water Protection Department, Water Management Institute of Lithuanian University of Agriculture. Research interests – environmental engineering and landscape management, hydrology, river pollution. Address: Parko 6, Vilainiai, LT–58102 Kėdainiai district, Lithuania. E-mail: berankiene@freemail.lt. Received 12 2005. ISSN 1648–4363 Water Management Engineering, 2(5), 2005, 78–85 © Lithuanian University of Agriculture © Water Management Institute of Lithuanian University of Agriculture INVESTIGATIONS ON THE REMOVAL OF BIOGENIC POLLUTANTS FROM WASTEWATER PRODUCED IN CATTLE SLAUGHTERHOUSE Zenonas STRUSEVIČIUS, Sigita Marija STRUSEVIČIENĖ* The paper describes the technology of wastewater treatment process and analyzes the removal of biogenic pollutants from wastewater when the wastewater is treated in several stages. As the results of the studies carried out in “Agaras” slaughterhouse have shown, the pollution of wastewater formed during the slaughtering process much depends on the applied slaughtering technologies: in the old slaughterhouse that was functioning until the year 2003 the pollution of wastewater with biogenic matter (Ntotal and Ptotal) was 630.0 and 40.0 mg/l, however, using the new technologies the average pollution of wastewater has decreased almost 2 times (Ntotal – 314.0; Ptotal – 26.8 mg/l). The wastewater of the slaughterhouse was pre-treated in a chamber of chemical reaction: here the wastewater was mixed with air and 0.6 kg/m3 of CaO and 4.0 gr/m3 of poly-electrolitical coagulant “Zetag 8660”, which resulted in the removal of Ntotal and Ptotal from wastewater on the average by 63.7% and 54%. After pretreatment in the primary treatment facilities, the wastewater is accumulated in the balancing ponds for about 60 days. Here the self-purification processes of wastewater is going on, during which on the average 12.1% of Ntotal and 21.3% of Ptotal pollutants are removed from the wastewater. During the biological treatment process in two-stage constructed wetlands, concentration of Ntotal and Ptotal decrease from 76.0 mg/l to 27.0 mg/l and from 6.4 to 0.7 mg/l respectively. Those values of wastewater outflow into the environment correspond to the environment protection requirements (Ntotal –30.0 mg/l, Ptotal – 4,0 mg/l). In constructed wetlands of horizontal flow nitrogen is removed under nitrification and denitrification conditions, therefore the Ntotal in wastewater outflow after the treatment contains about 40–50% of ammonia nitrogen the concentration of which exceeded the allowable rate during the study period and was 5.0 mg/l. The amount of ammonia nitrogen contained in wastewater after the treatment might be reduced having re-arranged the second stage of the treatment process into the filter of vertical flow where nitrogen would be removed under nitrification conditions. Keywords: biogenic pollutants, cattle slaughterhouse, wastewater. *contact person Dr. Zenonas Strusevičius, the head of Water Treatment Laboratory, Water Management Institute of Lithuanian University of Agriculture. Research interests – ecology and landscape management, the impact of handling of wastewater and manure on the environment, investigation of pollutant transformation processes. Dr. Sigita Marija Strusevičienė, scientific researcher, Water Treatment Laboratory, Water Management Institute of Lithuanian University of Agriculture. Research interests – ecology and landscape management, the impact of handling of manure, urine and wastewater on the environment. Address: Parko 6, Vilainiai, LT–58102 Kėdainiai district, Lithuania. Phone: +370 347 6 80 20. E-mail: zenonas@water.omnitel.net. Received 12 2005. ISSN 1648–4363 Water Management Engineering, 2(5), 2005, 86–92 © Lithuanian University of Agriculture © Water Management Institute of Lithuanian University of Agriculture CHANGES OF NITROGEN, PHOSPHORUS AND POTASSIUM AMOUNTS IN WATER AND SILT OF THE STREAMS LOCATED IN THE KARST ZONE Aurelija Rudzianskaitė*, Povilas Šukys The paper gives the data about the studies on water and silt characteristics of two streams (basin areas 1.63 and 2.02 km2) located on soils of the karst zone. Higher nitrate N concentrations have been derminated in water in the area of intensive land use as well as under the conditions of runoff formation after the dry period of the year; higher total P concentrations occurred when the soil experienced higher precipitation amount, particularly in summer. It was determined that the silt of the stream Bėrė (located in glacial lacustrine clay soils) contains 1.2–10 times more N compounds, 4.7 times more mobile P and 4.2 times more mobile K than that of the stream G-1 (located in moraine loam soils). This is because the studied elements are migrating together with clay and silt particles the larger amounts of which are determined in water of the stream flowing via glacial lacustrine clay soils. Increasing amounts of N compounds and K contained in the silt have a tendency to determine higher amounts of those compounds contained in the stream water. Stronger relationship (r2=0.53) has been determined between nitrate nitrogen contained in water and silt of the stream G-1 located in sandy loam soils. Such kind of relationship may be determined by large amounts of nitrogen transported with drainage water as well as nitrification processes occurring in silt. P contained in the silt may form dissoluble compounds; this might be due to the fact that larger amounts of P2O5 were contained in the silt, while less amounts of Ptotal were found in the stream water. Keywords: nitrogen, phosphorus, potassium, silt, streams of karst zone. *contact person Dr. Aurelija Rudzianskaitė, senior researcher, Geofiltration Research Department, Water Management Institute of Lithuanian University of Agriculture. Research interests – environmental engineering, the researches of stream, drainage and ground water regime and pollution. Address: Parko 6, Vilainiai LT–58102, Kėdainiai district, Lithuania. E-mail: aurelija@water.omnitel.net. Dr. Povilas Šukys, the head of Geofiltration Research Department, Water Management Institute of Lithuanian University of Agriculture. Research interests – environmental engineering, relations between the regime and pollution of surface and subsurface water. Received 12 2005. ISSN 1648–4363 Water Management Engineering, 2(5), 2005, 93–99 © Lithuanian University of Agriculture © Water Management Institute of Lithuanian University of Agriculture PECULIARITIES OF WATER RUNOFF AND POLLUTION IN STREAMS OF THE KARST REGION Povilas ŠUKYS*, Alvyda ŠAULIENĖ The paper analyzes the peculiarities of water pollution and runoff formation of two streams with the source in drained soils of different genesis in karst region. The average runoff height of the stream located in glacial-lacustrine soils exceeds drainage runoff nearly 1.1 times, while the average runoff of the stream flowing via moraine sandy light loams is 1.2 times lower than drainage runoff. As it was determined, the runoff of streams within a 1.5-km long strip below the effluent depends on drainage runoff by about 76–85%. Even in the area of stream source the stream water quality is strongly affected by drainage water. Self-purification process of streams is observed only in stream strips located in non-drained woody areas, and depends only on nitrogen compounds. Dissolved inorganic nitrogen (DIN) concentration is reduced on the average 1.7 times in a 1.5-km long strip from the stream source during the cold period of the year and 1.9 times during the vegetation period. No significant self-purification of the stream from K and P compounds was determined. Keywords: runoff, self-purification, stream, watershed. *contact person Dr. Povilas Šukys, senior researcher, Geofiltration Research Department, Water Management Institute of Lithuanian University of Agriculture, associate professor at Kaunas Technological University. Research interests – environmental engineering, relations between the regime and pollution of surface and subsurface water. Address: Parko 6, Vilainiai LT–58102, Kėdainiai district, Lithuania. Phone: +370 687 7 47 85. E-mail: lygis@water.omnitel.net. Alvyda Šaulienė, junior researcher, Geofiltration Research Department, Water Management Institute of Lithuanian University of Agriculture. Research interests – environmental engineering and landscape management, drainage runoff in karst soils. Received 12 2005. ISSN 1648–4363 Water Management Engineering, 2(5), 2005, 100–106 © Lithuanian University of Agriculture © Water Management Institute of Lithuanian University of Agriculture application of biosorption systems for ballast water treatment Viktoras RAČYS, Daina KLIAUGAITĖ, Irmantas VALŪNAS*, Inga URNIEŽAITĖ This article discusses the biosorption process applied for the treatment of wastewater contaminated with light-textured oil products. SC “Klaipėdos nafta”, which works in the field of transhipment of oil and its products in Lithuania, has installed biosorbers for the treatment of ballast and bilge water from the vessels. Biosorption process comprises the integrated effect of granular absorbent carbon (GAC) and other particular micro organisms. Comparing with the treatment efficiency of other methods, this wastewater treatment method is more advanced to be applied for the treatment of such kind of wastewater. Wastewater is pumped into biosorbers for the flotation process. After the pre-treatment process the wastewater contains only 2 mg/l of total petroleum hydrocarbons (TPH). Then the wastewater is directed into biosorbers. At the onset of operation of the biosorbers the wastewater treatment efficiency is 0.2 mg/l according tp TPH. To ensure the control of the process, principal parameters are determined: sorption capacity of absorbent carbon, biomass amount and enzymatic activity of the micro organisms. The relation between those parameters and wastewater treatment efficiency according to TPH was established. The results obtained support the theory of biosorption process and the applicability of the process for the treatment of wastewater containing high concentrations of polluted with light-textured oil products. The article also presents principle technological solutions and parameters of the biosorbers in SC “Klaipedos nafta”. Keywords: ballast and bilge water treatment, biosorption application, petroleum hydrocarbons treatment, wastewater treatment efficiency. *contact person Dr. Viktoras Račys, assoc. prof. in Kaunas Technological University, Department of Environmental Engineering. Research interests – common and special wastewater treatment technologies, water quality improvement and management of solid wastes. Mag. Daina Kliaugaitė, PhD student in Kaunas Technological University, Department of Environmental Engineering. Research interests – common and special wastewater treatment technologies, water quality improvement. Mag. Irmantas Valūnas, PhD student in Kaunas Technological University, Department of Environmental Engineering. Research interests – common and special wastewater treatment technologies, water quality improvement. Address – Radvilėnų 19, LT–50254, Kaunas, Lithuania. Phone: +370 37 30 01 82. Fax: +370 37 30 01 52. E-mail: Irmantas.Valunas@ktu.lt. Mag. Inga Urniežaitė, PhD student in Kaunas Technological University, Department of Environmental Engineering. Research interests – common and special wastewater treatment technologies, water quality improvement. Received 12 2005. ISSN 1648–4363 Water Management Engineering, 2(5), 2005, 107–112 © Lithuanian University of Agriculture © Water Management Institute of Lithuanian University of Agriculture Analysis of Lithuanian River Channels Bed Stability (Referring to Grishanin Number) Saulius Vaikasas*, Narimantas ždankus This paper reviews the estimation of river channel bed-formation processes in Lithuania on the basis of the integrated hydraulic and morphological criterion – Grishanin numbers MG and MA. It has been established that MG expresses river flow scouring and transporting capacity, MA – riverbed ability to resist the scour. The Grishanin number depends on hydraulic parameters of river flow and expresses the ratio of kinetic and potential energies of it. The MA number depends on morphological characteristics of the river channel, first of all on the size and uniformity of ground particles, and their ability to form a bed armouring layer. It was evaluated by Grishanin number that the equality MG @ MA expresses the river flow – bed interaction equilibrium condition. According to our research, Lithuanian rivers may be classified into erosive straight channels with alternating bars, adaptive channels, stable highly meandering channels (with flow–resistant bed), and stable main channels can be found. Keywords: application of Grishanin criterion, stability of Lithuanian river beds. *contact person Dr. habil. Saulius Vaikasas, senior researcher, Exploitation Laboratory, Water Management Institute of Lithuanian University of Agriculture. Research interests – environmental engineering and landscape management, hydraulic modelling, river bed processes. Address: Parko 6, Vilainiai, LT–58102 Kėdainiai district, Lithuania. Phone: +370 347 6 81 09. E-mail: s.vaikasas@delfi.lt. Prof. habil. dr. Narimantas Ždankus, head of Geo-engineering Department, Kaunas Technological University. Research interests – fluid mechanics. Received 12 2005. |
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