INVESTIGATION OF THE PROCESS OF PROCESSING LIQUID WASTE OF UREA PRODUCTION USING A BIOFILTER

The kinetic regularities of the recycling process of liquid waste of urea on the combined filter which contains the immobilized layer of enzymes at the process of their purification from the suspended substances, dissolved nitrate anions; the effect of pH on the filtration process are investigated and established in our research. A stable positive result was obtained on the filters with layers of: – oak and birch, the concentration of nitrate anions decreased from 12 to 0,06 — 0,05 mg/dm3 after 80 minutes of filtration. The content of suspended solids decreased from 37 g/dm3 to 6 — 7 g/dm3. At the same time, the increased content of tannins and the natural structure of oak and birch leaves contributes to the resistance of the leaf layer to fermentation processes, helps to use such kind of filter repeatedly. – linden and maple leaves, the concentration of nitrate anions decreased from 12 mg/dm3 to 0,08 mg/dm3 after 80 minutes of filtration. The content of suspended solids decreased from 37 g/dm3 to 15 g/dm3 after the third use of the filter, due to increased activity of microorganisms. At the same time, the natural structure of linden and maple leaves is thin, has a biofilm that is easily destroyed and accelerates the process of natural aerobic fermentation. The scientific substantiation of the direction of improvement of technology of processing of liquid waste with the increased content of nitrogen is executed. A bio filtration unit on a combined filter with a layer of oak and birch leaves with the use of an immobilized layer of enzymes is proposed. The combined filter consists of a layer of gravel, sand and dry oak and/or birch leaves. The enzyme Chymotrypsin at a concentration of 0,005 g/dm3 is fed into the formed bio filter from above. After 30 minutes, liquid waste with a temperature of 10 25 °С is gradually fed into the filter over 60 — 80 minutes. The initial concentration of suspended particles in liquid waste should not exceed a concentration of 37 — 40 g/dm3. It is determined that the optimal rate of processing of liquid waste of urea production is achieved in solutions with active reaction of hydrogen ions in the range of 6,5—7,3.

Fate of Particulate Matter Associated with Produced Water Discharge by Offshore Platforms in the Adriatic Sea (Mediterranean Sea)

In the Adriatic Sea (Mediterranean Sea), during monitoring of Production Water (PW) discharged from offshore platforms, high contamination levels of metals, PAH, and aliphatic hydrocarbons are detected in the sediment close to some installations. Here, we investigate for the first time, the transport and fate of the total suspended solids (TSS) associated with PW discharged by selected platforms, considering the separation of particulate matter from the water plume. We apply a 3D hydrodynamic model and a Lagrangian module to simulate the dispersion of PW suspended substances, then we relate the numerical results to the sediment contamination measured data. The TSS released with PW determines a negligible contribution along the water column and seems poorly related to the anomalies observed in the sediment contamination levels. This approach paves the way to assess the potential risks arising from TSS discharged with the PW on marine ecosystems and to optimize the environmental monitoring tools.

ECOLOGICAL EFFECTIVE TREATMENT OF INDUSTRIAL WASTEWATER FORMED IN THE OIL-PRODUCING INDUSTRY BY COAGULATION METHOD

Research work has been carried out on deep purification of water samples taken from industrial wastewater formed in the oil-producing industry containing hydrophilic and hydrophobic (oil-in-water and water-in-oil) emulsions from oil and organic suspended substances. Using the coagulation method developed by us, industrial wastewater samples were purified up to 100% from oil and suspended substances under optimal conditions. It has been substantiated that this method is of great economic and environmental importance. The applied coagulant and extractant meet the requirements of environmental safety

CONTENT OF SUSPENDED SUBSTANCES IN MACROPRIENT ESTUARIES OF THE WHITE AND BARENTS SEA RIVERS

The statistical characteristics of the content of suspended matter in the macrotidal estuaries of the Kuloi River with a lateral tributary of the Pocha, the Pyya River (White Sea) and the Chesha River in the Barents Sea. Their maximum values in the surface layers of estuarine waters due to the roiling of bottom sediments by tidal currents can reach a level of 500–4000 mg/l and even more. The typical range of fluctuations in the concentration of suspended matter in such river mouths will be 90–720 mg/l for taiga rivers and 200–1830 mg/l for tundra rivers. The higher turbidity of the estuarine waters of the tundra zone is associated with the degradation of its permafrost soils against the background of the observed climate warming. The relationship between suspended solids and salinity distribution at the mouths of small rivers may differ markedly from the conditions observed at the mouths of medium and large rivers.

Engineered Nanoparticles with Decoupled Photocatalysis and Wettability for Membrane-Based Desalination and Separation of Oil-Saline Water Mixtures

Membrane-based separation technologies are the cornerstone of remediating unconventional water sources, including brackish and industrial or municipal wastewater, as they are relatively energy-efficient and versatile. However, membrane fouling by dissolved and suspended substances in the feed stream remains a primary challenge that currently prevents these membranes from being used in real practices. Thus, we directly address this challenge by applying a superhydrophilic and oleophobic coating to a commercial membrane surface which can be utilized to separate and desalinate an oil and saline water mixture, in addition to photocatalytically degrading the organic substances. We fabricated the photocatalytic membrane by coating a commercial membrane with an ultraviolet (UV) light-curable adhesive. Then, we sprayed it with a mixture of photocatalytic nitrogen-doped titania (N-TiO2) and perfluoro silane-grafted silica (F-SiO2) nanoparticles. The membrane was placed under a UV light, which resulted in a chemically heterogeneous surface with intercalating high and low surface energy regions (i.e., N-TiO2 and F-SiO2, respectively) that were securely bound to the commercial membrane surface. We demonstrated that the coated membrane could be utilized for continuous separation and desalination of an oil–saline water mixture and for simultaneous photocatalytic degradation of the organic substances adsorbed on the membrane surface upon visible light irradiation.

Is the Microfiltration Process Suitable as a Method of Removing Suspended Solids from Rainwater?

Due to climate change and anthropogenic pressure, freshwater availability is declining in areas where it has not been noticeable so far. As a result, the demands for alternative sources of safe drinking water and effective methods of purification are growing. A solution worth considering is the treatment of rainwater by microfiltration. This study presents the results of selected analyses of rainwater runoff, collected from the roof surface of individual households equipped with the rainwater harvesting system. The method of rainwater management and research location (rural area) influenced the low content of suspended substances (TSS < 0.02 mg/L) and turbidity (<4 NTU). Microfiltration allowed for the further removal of suspension particles with sizes larger than 0.45 μm and with efficiency greater than 60%. Granulometric analysis indicated that physical properties of suspended particles vary with the season and weather. During spring, particles with an average size of 500 μm predominated, while in autumn particles were much smaller (10 μm). However, Silt Density Index measurements confirmed that even a small amount of suspended solids can contribute to the fouling of membranes (SDI > 5). Therefore, rainwater cannot be purified by microfiltration without an appropriate pretreatment.

A combination of reverse osmosis and electrodialysis to improve water recovery in industrial wastewater

The article discusses in detail the membrane processing of complex systems, reverse osmosis (RO) and electrodialysis (ED) membranes. Currently, the development of industrial wastewater treatment technologies is of great interest to many researchers. This is due to the fact that the food, pharmaceutical and chemical industries are becoming increasingly important in our lives, while exacerbating one of the most serious environmental problems, environmental pollution from industrial wastewater, which contains harmful substances in high concentrations. This study is devoted to the analysis of a new technology for the extraction of complex components from industrial wastewater, combining reverse osmosis and electrodialysis. Reverse osmosis systems are pressure controlled membrane separation processes. In contrast, an electrodialysis system is an electrochemical process that is commonly used industrially under normal atmospheric pressure. However, such membrane processes have a significant drawback, the working membranes are contaminated with suspended substances in the wastewater and lose their activity. Therefore, to maintain the activity of the membranes for a long time, it is necessary to pre-treat wastewater by removing suspended solids. The analysis of the recovered components opens up new perspectives for the recovery of industrial wastewater. There is a wide range of methods for pretreatment of water for reverse osmosis and electrodialysis. Ultrafiltration (UF) followed by reverse osmosis is an important process for separating organic and inorganic compounds from wastewater. This article discusses some of these methods. In conclusion, it should be noted that electrodialysis demonstrates remarkable technical advantages in the treatment of concentrated solution after RO.

ON THE SNOW COVER CHEMICAL COMPOSITION IN THE BOLSHEKHETSIR NATURE RESERVE (KHABAROVSK TERRITORY)

This paper presents the results of the snow cover chemical composition monitoring at the Bolshekhetsir nature reserve, conducted in March 2017, in terms of pH, specific conductivity, salinity, major ions, biogenic and suspended substances.

Реагентная очистка различных видов сточных вод трехкомпонентной композицией

Представлены результаты экспериментальных исследований реагентной очистки сточных вод трехкомпонентной композицией (коагулянт, флокулянт, щелочной реагент), которые проводились в ООО «ДальВОДГЕО». Экспериментально подобрано соотношение реагентов в композиции, причем флокулянт растворяется в кальцинированной соде и вводится после коагулянта. Испытания на стоках от пищевых производств (с высоким содержанием органических и минеральных взвешенных веществ) при недостаточном щелочном резерве подтверждают большую эффективность очистки и меньший объем осадка в случае применения композиции по сравнению с раздельным вводом реагентов. Ключевые слова: сточные воды, интенсификация реагентной очистки, коагулят, флокулянт, подщелачивающий реагент, коагулирующая-флоккулирующая щелочная композиция The results of experimental studies of reagent wastewater treatment with a three-component composition (coagulant, flocculant, alkaline reagent), which were carried out at DalVODGEO LLC (from 2015 to 2018, when one of the authors, S.B. Kundenok, worked as a chief project engineer in this organizations), then jointly with the Far Eastern Federal University (2017–2020). The ratio of reagents in the composition was experimentally selected, and the flocculant is dissolved in soda ash and introduced after the coagulant. Tests on effluents from food production (with a high content of organic and mineral suspended substances), with an insufficient alkaline reserve, confirm the greater efficiency of purification and a smaller volume of sediment in the case of using the composition in comparison, with the separate injection of reagents. Keywords: waste water, intensification of reagent treatment, coagulum, flocculant, alkalizing reagent, coagulating-flocculating alkaline composition Contribution of the authors: the authors contributed equally to this article. The authors declare no conflicts of interests.

Results of monitoring of Lake Khanka in 2016–2018

Представлены результаты гидрохимических исследований озера Ханка в 2016–2018 гг. В 2015–2016 гг. съемки проводились в период максимального уровня озера. С 2017 г. наблюдалось снижение его уровня. Пространственное распределение температуры воды в целом не менялось из года в год, но при этом изменялись значения температуры. Так, температура воды в 2018 г. в течение всего сезона была выше на 1–2°. Содержание питательных веществ и растворенного кислорода во многом зависело от стока бытовых отходов пос. Камень-Рыболов, стока вод с рисовых чеков, от интенсивности стока впадающих в озеро рек и продукционных процессов. Цветение фитопланктона происходило даже зимой подо льдом, что подтверждалось высоким содержанием растворенного кислорода (до 180 %) под слоем льда. Вместе с тем содержание кислорода зимой в 2016 г., когда уровень озера был самым высоким, было несколько ниже, чем в последующие годы. Подобные межгодовые изменения отмечались и в колебаниях концентрации кремния. Зимой биологическое потребление кислорода (БПК5) также было высоким (6.53 мл/л), что указывало на активное разрушение органических веществ. Питательные вещества меняли свое соотношение в течение года из-за различных источников их поступления в определенные сезоны. Но в целом их значения и соотношение не имели значительных межгодовых колебаний. Наибольшие концентрации минерального азота и фосфора наблюдались осенью, вероятно, из-за сброса воды с рисовых плантаций. Сделан вывод о том, что высокие значения концентрации питательных веществ, БПК5 и содержания взвешенных веществ характерны для озера Ханка и не были обусловлены повышением его уровня. The results of the hydrochemical investigations of the Lake Khanka in 2016–2018 are presented. In 2015–2016, the surveys were carried out in the period of maximum level of the Lake. From 2017, its level recession was observed. The spatial distribution of the water temperature has generally remained the same each and every year but, at that time, the temperature values have changed. So, for example, the water temperature for the entire length of season in 2018 was higher by 1–2°. The content of nutrients and dissolved oxygen has largely depended on the household waste flow of the Kamen-Rybolov settlement, water flows from the rice checks as well as on flow intensity of the rivers falling into the Lake and production processes. The phytoplankton bloom was observed even in winter under the ice which was confirmed by the high content of the dissolved oxygen (up to 180‰) under the ice layer. At the same time, in winter of 2016 when the Lake level was highest the content of oxygen was slightly lower than in the subsequent years. The similar interannual changes were also noted in the silicon concentrations. In winter, the biological oxygen demand (BOD5) was also high (6.53 ml/l), which has pointed to the active destruction of the organic matter. The nutrients have changed their proportions throughout the year due to different sources of their entry during particular seasons. However, their values and proportions had basically no considerable interannual fluctuations. The highest concentrations of the mineral nitrogen and phosphorus were observed in autumn, probably, due to water discharge from the rice paddies. The conclusion was drawn that the high concentrations of nutrients, BOD5 and content of the suspended substances are characteristic of the Lake Khanka and were not caused by rise in its level.