Changes in the Oxygen Regime in the Deep Part of the Black Sea in 1980–2019

Purpose. Assessing changes in the oxygen regime of the deep-water part of the Black Sea under the influence of climatic and anthropogenic factors over the past 40 years is the goal of the work. Methods and Results. For the analysis, the expedition data (2015–2019) and those from the Databank of the Marine Hydrophysical Institute, Russian Academy of Sciences, (1980–2013) were used. The data for the deep-water part of the Black Sea (the depths exceeding 200 m) were selected from the array. The data on hydrophysical and hydrochemical parameters were subjected to expert assessment, and those including random errors in the values were excluded from the array. Then the average profiles of temperature, salinity, oxygen concentration, oxygen saturation, and nitrates concentration were plotted in the density scale (σt). Averaging was carried out by the inverse distance method followed by additional smoothing by the low-frequency filtering method. Conclusions. Against the background of the tendency of temperature increase in the upper layers of the water column and decrease of winter convective mixing intensity, the oxygen supply diminishes in all the layers of the Black Sea aerobic zone. Having been analyzed, of the data for the 1980–2019 period showed that at the present stage, a "regime shift" resulting from the joint effect of climate changes and anthropogenic load took place in the ecosystem of the deep-water part of the Black Sea. Decrease in the oxygen saturation of water throughout the entire thickness of the aerobic zone shows that the process of the Black Sea basin eutrophication constitutes a significant factor affecting oxygen dynamics in the Black Sea waters.

Changes in the Oxygen Regime in the Deep Part of the Black Sea in 1980–2019

Purpose. Assessing changes in the oxygen regime of the deep-water part of the Black Sea under the influence of climatic and anthropogenic factors over the past 40 years is the goal of the work. Methods and Results. For the analysis, the expedition data (2015–2019) and those from the Databank of the Marine Hydrophysical Institute, Russian Academy of Sciences, (1980–2013) were used. The data for the deep-water part of the Black Sea (the depths exceeding 200 m) were selected from the array. The data on hydrophysical and hydrochemical parameters were subjected to expert assessment, and those including random errors in the values were excluded from the array. Then the average profiles of temperature, salinity, oxygen concentration, oxygen saturation, and nitrates concentration were plotted in the density scale (σt). Averaging was carried out by the inverse distance method followed by additional smoothing by the low-frequency filtering method. Conclusions. Against the background of the tendency of temperature increase in the upper layers of the water column and decrease of winter convective mixing intensity, the oxygen supply diminishes in all the layers of the Black Sea aerobic zone. Having been analyzed, the data for the 1980–2019 period showed that at the present stage, a “regime shift” resulting from the joint effect of climate changes and anthropogenic load took place in the ecosystem of the deep-water part of the Black Sea. Decrease in the oxygen saturation of water throughout the entire thickness of the aerobic zone shows that the process of the Black Sea basin eutrophication constitutes a significant factor affecting oxygen dynamics in the Black Sea waters.

Transfer of free methane by gas bubble streams from anaerobic to aerobic waters of the Black Sea

“Breath of earth” in the form of methane gas bubble streams from a seabed (methane seeps, bubble emanations) is a planetary phenomenon that was noticed only at the end of the XX century. The study of this phenomenon, being an important link in processes of lithosphere, hydrosphere, atmosphere, and biosphere interaction, is relevant to date. In this work, methane fluxes were determined in the known area of intense methane occurrences of biogenic nature, geographically tied to Dnieper River paleochannel in the northwest of the Black Sea. Bubbling (free) methane flux from anaerobic to aerobic waters in the active methane seeps area of Dnieper River paleochannel in the depth range of 140–725 m is estimated averagely as 1.2·10³ m³·km−2·year−1 (STP), or 2.8 % of bubbling methane emitted from a seabed. The value of the investigated flux was 4.2 % of the specific flux of bubbling methane to a water column on shelf depths (less than 140 m) in the same area. Methane flux estimate, obtained in this work, seems to be a significant environmental factor in conditions of strong stratification of Black Sea waters, where methane transfer by gas bubble streams is the main mechanism for introducing deep-water methane into biogeochemical cycles and carbon transformation processes of Black Sea aerobic zone.

Quantifying the Benefit of a Dynamic Performance Assessment of WWTP

In this work a comprehensive analysis of the environmental impact of the operation of a wastewater treatment plant (WWTP) using different control strategies is carried out considering the dynamic evolution of some environmental indicators and average operation costs. The selected strategies are PI (proportional integral) control schemes such as dissolved oxygen control in the aerobic zone (DO control), DO control and nitrates control in the anoxic zone (DO + NO control) and regulation of ammonium control at the end of aerobic zone (Cascade SNHSP) commonly used in WWTPs to maintain the conditions that ensure the desired effluent quality in a variable influent scenario. The main novelty of the work is the integration of potential insights into environmental impact from the analysis of dynamic evolution of environmental indicators at different time scales. The consideration of annual, bimonthly and weekly temporal windows to evaluate performance indicators makes it possible to capture seasonal effects of influent disturbances and control actions on environmental costs of wastewater treatment that are unnoticed in the annual-based performance evaluation. Then, in the case of periodic events, it is possible to find solutions to improve operation by the adjustment of the control variables in specific periods of time along the operation horizon. The analysis of the annual average and dynamic profiles (weekly and bimonthly) of environmental indicators showed that ammonium-based control (Cascade SNHSP) produce the best compromise solution between environmental and operation costs compared with DO control and DO + NO control. An alternative control strategy, named SNHSP var Qcarb var, has been defined considering a sequence of changes on ammonium set-point (SNHSP) and carbon dosage (Qcarb) on different temporal windows. It is compared with DO control considering weekly and bimonthly profiles and annual average values leading to the conclusion that both strategies, Cascade SNHSP and SNHSP var Qcarb var, produce an improvement of dynamic and annual average environmental performance and operation costs, but benefits of Cascade SNHSP strategy are associated with reduction of electricity consumption and emissions to water, while SNHSP var Qcarb var strategy reduces electricity consumption, use of chemicals (reducing external carbon dosage) and operation costs.

Efeito agudo de diferentes métodos de musculação

Objetivo: Analisar o efeito agudo de diferentes métodos de musculação. Métodos: Participaram deste estudo 10 mulheres praticantes de musculação a partir de 12 meses, com idade 27,6 ± 6,5 anos. As participantes em cada sessão de treinamento utilizaram métodos de treinamento resistido, e analisaram a frequência cardíaca e a percepção subjetiva de esforço (PSE). Resultados: Os métodos Drop-Sets (DS), Repetições Forçadas (RF) e Super Lento (SL) são mais vigorosos na PSE pela prática e também promovem maior aumento na frequência cardíaca em comparação com os outros métodos de treinamento de força analisados. Ainda, observa-se que os mesmos métodos DS, RF e SL encontram-se entre 63-74% FCmáx. Conclusão: Os métodos de treinamento resistido Repetições Forçadas e Super Lento são mais eficientes caso o objetivo do cliente seja o trabalho na zona aeróbia.Palavras-chave: treinamento de resistência, exercício, força muscular. Palavra-Chave: Treinamento de Resistência. Exercício. Força Muscular. ABSTRACT Objective: To analyze the acute effect of different methods of bodybuilding. Methods: Ten women practicing bodybuilding participated in this study from 12 months, with ages ranging from 27.6±6.5 years. The participants in each training session used resistance training methods and analyzed the heart rate and subjective perception of effort (SPE). Results: The Drop-Sets (DS), Forced Repetitions (FR) and Super Slow Strength (SS) methods are more vigorous in SPE by practice and also promote a greater increase in heart rate compared to other methods of strength training analyzed. Furthermore, the same DS, FR and SL methods are found to be between 63-74% HRmax. Conclusion: Resisted Forced and Super Slow Strength resistance training methods are more effective if the client's goal is work in the aerobic zone. Keywords: Resistance Training. Exercise. Muscle Strength.

TREATMENT CHARACTERISTICS AND OPERATIONAL PARAMETERS OF A NEWLY DEVELOPED REACTOR WITH SLUDGE SEPARATION FILTER AND AIRLIFT PUMP FOR CARBON AND NITROGEN REMOVAL

Nutrient removal from sewage is one of the most urgently required issues from the viewpoint of prevention of eutrophication and preservation of water quality for water supply system. Among several nutrient removal methods, biological treatment, which is a modified activated sludge system is widely applied. However, biological nitrogen removal process, which consists of nitrification and denitrification steps, needs opposite operations at several stages such as necessity of oxygen and requirement of electron donor of organic compounds. In this study, treatment characteristics of a reactor with both sludge separation filter and airlift pump are investigated. This reactor has sludge separation filter in the middle part and airlift pump that supplies oxygen and circulate liquid from aerobic zone to anoxic zone in order to cut down the required energy. From laboratory scale experiments, design and operational parameters are investigated and it is shown that NH4-N loading rate of 35 mgN/(L-media･hr) at aerobic zone and DO loading rate of less than 0.15 kgDO/(kgMLSS･d) to anoxic zone are required for stable treatment.

Study on De-Nitrification of Improved Step-Feed Progress

Improved step-feed de-nitrification progress combined with biological fluidized bed was introduced in this study. The progress had good performance and capacity of de-nitrification and organic matter. The experiment result showed that the de-nitrification efficiency of the improved biological fluidized bed with step-feed process was higher than the fluidized bed A/O process under the same water quality and the operating conditions. When the influent proportion of each segment was equal, the system showed good nitrogen removal efficiency with the change of influent C/N ratio, HRT and sludge return ratio. The removal rate of TN reached up to 88.2%. It showed that the simultaneous nitrification and de-nitrification phenomenon happened in the aerobic zone. The nitrogen removal mechanism was also studied.

Experimental Study on the Plasticizer Wastewater Treatment by UASB-A/O Process

Plasticizer wastewater of high concentration was experimentally studied by the process of pretreatment of acidification demulsion and Fe-C micro-electrolysis and combined process of UASB and A/O aiming at the CODCr removal in this work. The result showed that the CODCr removal rate of pretreatment process arrived at 56.2% after Fe-C micro-electrolysis reaction of 160 min on the optimal condition of pH 3.5 of acidification demulsion and 1:1.2 of the Fe/C ratio, and meanwhile improved the biodegradability of wastewater. On the other hand, UASB-A/O process could afford 80~85% of the CODCr removal rate under the optimized condition of temperature 30~35 °C, HRT 48h, pH 6.5 for UASB and HRT of aerobic zone 10~12 h, DO of about 3mg/L for A/O basin. The whole system could run at the total CODCr removal rate of 94.53~96.36%, and the system effluent CODCr was 500 mg/L or less.

Nutrient Removal and Denitrifying Phosphate-Removal Bacteria Content in the Modified Oxidation Ditch

The flashboard was installed in the circulation compartment of the modified oxidation ditch in order to regulate the mixed reflux from aerobic zone to anoxic zone. The differences of the nutrient removal efficiencies and the phosphate-removal bacteria content were researched before and after flashboard installation. The results showed that the average removal efficiencies of COD, NH4+, TN, TP were 93.3%, 87.1%, 78.1% and 96.0% respectively, and the proportion of denitrifying phosphate-removal bacteria (DPB) to total phosphorus accumulating organisms were 46.1% after the flashboard installation. However, the average removal efficiencies of COD, NH4+, TN, TP were 91.2%, 82.7%, 67.2% and 86.4% respectively, and the proportion of denitrifying phosphate-removal bacteria to total phosphorus accumulating organisms were 17.54% before the flashboard installation. So, the modified oxidation ditch with flashboard could enrich denitrifying phosphate-removal bacteria and and improve the nutrient removal efficiencies.

The optimization of a mathematical simulation program to describe the nitrogen removal of the oxidation ditch process

To achieve new emission standards and enhance the denitrification of the oxidation ditch in the Handan West Sewage Treatment Plant, this research used the ASM Bio-P model based on self-made simulation software to study the optimum operation of the denitrification efficiency. The results indicate that:1) the volume of the aerobic zone was increased and the volume ratio between aerobic and anoxic zones was controlled to approximately 3:1; 2) the concentration of the dissolved oxygen (DO) in the aerobic zone was increased and was controlled at 1 mg/L in summer and 3 mg/L in winter; 3) the proper sludge retention time (SRT) was controlled and was maintained at 15 d in summer and 20 d in winter; and 4) the appropriate reflux ratio was controlled to 100% and 50% for summer and winter, respectively. The COD, TN, NH3-N and TP in the effluent reached the first (B) standard of the Discharge Standard of Pollutants for Municipal Wastewater Treatment Plant (GB18918-2002).