Retrofitting Sea Cucumber Nursery Tanks to Recirculating Aquaculture Systems for Highly Intensive Litopenaeus vannamei Aquaculture

Designing good recirculating aquaculture systems (RASs) is challenging in shrimp aquaculture. In this study, two sets of RASs were constructed using sea cucumber nursery tanks for rearing Litopenaeus vannamei. Recirculating aquaculture was supported by key technologies such as sewage collection and aeration systems adapted to the rectangular tanks and technologies for the removal of sewage, shrimp shells, and dead individuals. Six-hundred and eighty-five thousand juveniles were selected for rearing in the newly constructed RASs, where the average stocking density was 1013 shrimp/m3. During the recirculating aquaculture period of 53 days, the water temperature of the tanks was 24–31 °C, the salinity was 25–32‰, the pH was 6.4–8.2, the DO was ≥ 4.9 mg/L, the concentration of total ammonia nitrogen (TAN) was maintained between 0.17 and 4.9 mg/L, the concentration of nitrite nitrogen (NO2-N) was between 0.12 and 4.7 mg/L, and the total number of Vibrio bacteria remained between 330 and 9700 cfu/mL. At the end of the experiment, the final average weight of individual shrimp was 13.43 g, and the average yield reached 12.92 kg/m3. The great improvement in growth performance marks a breakthrough in RAS technology of shrimp, and it supports the use of an innovative methodology for the retrofitting and utilization of idle sea cucumber nursery tanks.

Environmental toxicants evaluation in a modern monitoring system - Romanian monitox network area

In this paper a class consisting of 8 environmental toxicants were selected to assess Danube River water quality between Calarasi-Silistra sector until the river flow into the Black Sea, the Romanian Monitox Network Area. A comprehnsive comparison between 2 years of investigations in terms of nutrients contribution, such as different forms of nitrogen (ammonium nitrogen (N-NH4+), nitrite nitrogen (N-NO2-), nitrate nitrogen (N-NO3-), organic nitrogen, total nitrogen (TN)) and phosphorus (orthophosphate phosphorus (P-PO4 -3), total phosphorus (TP)), was made in order to provide information on the spatial and temporal variations of this river water quality. Sampling was performed according to European standards and quantitatively analysed using molecular spectrophotometry using UV VIS spectrophotometer Perkin Elmer Lambda 650S. The obtained results showed differences in nitrite nitrogen loads in surface water samples with higher values in the samples collected from the sampling points situated at the mouths of the Danube River into the Black Sea in 2020. Regarding quality classes, the surface waters were generally framed, in good quality class. The nutrients concentrations, combined in CCME WQI index, give an overview on surface water quality assessement in Romanian Monitox Network Area, with a good quality of Lower Danube (Constanta in 2019 and 2020) and fair quality of Danube Delta in 2020, but very closed to good quality.

HYDROCHEMICAL STATE OF RIVERS IN THE SEMI-DESERT ZONE OF THE EAST EUROPEAN PLAIN (THE ERUSLAN RIVER BASIN, THE LOWER VOLGA)

The results of the assessment of the hydrochemical state of the plain rivers of the Yeruslan basin flowing in the semi-desert region of the Russian Plain are presented. The priority pollutants that most often exceed the MPC for fisheries-related water bodies are: organic matter, total phosphorus, copper, and nitrite nitrogen. In some areas of small rivers, there is a very high level of contamination with trace elements such as copper (up to 80 MPC) and manganese (up to 38 MPC). The conducted studies, taking into account the literature data, allow us to assert that the pollution of rivers is chronic and is largely due to the peculiarities of the hydrogeological conditions of the territory.

Comparison of aeration tank calculations using ASM2d and ATV models

Проведено сравнение результатов расчета аэротенков по модели ATV (Standard ATV-DVWK-A131 E «Dimension of Single-Stage Activated Sludge Plants 2000»), которая является стохастической «табличной» моделью, и по модели ASM2d, которая относится к теоретическим и описывает, в отличие от ATV, процессы биологической очистки сточных вод с помощью формул ферментативной кинетики. Расчеты выполнены для одних и тех же входных данных. Результаты расчетов показали существенную ограниченность использования модели ATV. Данная модель, как изначально указано авторами в ее описании, рассчитывает аэротенки только на единственное значение качества очищенной воды по аммонийному азоту 1 мг/л и не рассчитывает аэротенки на нитриты. Более того, сравнение ATVс ASM2d показало, что и достижение указанного качества очищенной воды по аммонийному азоту 1 мг/л возможно только при конкретных значениях кинетических констант, которые были определены авторами в данной статье, а изменение хотя бы одного из кинетических параметров сточных вод приводит к увеличению необходимого значения аэробного возраста активного ила и, как следствие, расчетного объема аэробной зоны на десятки процентов, что доказывает риск недостижения требуемого качества очищенной воды при использовании модели ATVдаже на концентрацию аммонийного азота 1 мг/л. С учетом того, что методика ATV не рассчитывает аэротенки на качество очищенных вод по нитритам, результаты проведенного нами расчета показывают, что предлагаемые в ATVзначения аэробного возраста активного ила 4,05 суток для температуры 17 ºС позволят достичь качество очищенной воды по азоту нитритов 0,35–0,52 мг/л N–NO2. Это доказывает невозможность использования ATV, если даны требования к качеству очищенной воды по нитритам. Авторами на основании проведенных расчетов сделаны выводы о риски недостижения качества очищенной воды по аммонийному азоту, как и 1 мг/л при использовании ATV, из-за того, что ATVявляется стохастической моделью, то есть все представленные в данной методике зависимости были определены для конкретных условий проведения работ. Более того, как и указано в описании ATV, данная методика применима, даже в ограниченных условиях, строго для городских сточных вод. Проведенные расчеты показали, что при наличии требований к качеству очищенной воды по нитритам, вне зависимости от значений требуемых концентраций нитритов, методика ATVне подходит вообще, при этом ASM2dс учетом того, что она основывается на формулах ферментативной кинетики, позволяет рассчитывать аэротенки на любое требуемое качество очищенной воды как по аммонийному азоту, так и по азоту нитритов и применима для любого типа сточных вод. A comparison is made of the results of calculating aeration tanks by ATV model (Standard ATV-DVWK-A131 E «Dimension of Single-Stage Activated Sludge Plants 2000»), that is a stochastic «table» model, and by ASM2d model, that is referred to as theoretical and describes, unlike ATV, biological wastewater treatment processes using enzymatic kinetics formulas. Calculations are performed for the same input data. The calculation results show essentially limited use of ATV model; this model, as originally given in the description of this model by the designers, provides for calculating aeration tanks only for a single value of the effluent quality in terms of ammonia nitrogen as 1 mg/l and does not provide for calculating aeration tanks in terms of nitrites. Moreover, the comparison of ATV and ASM2d show that achieving the specified quality of effluent in terms of ammonia nitrogen as 1 mg/l is possible only at specific values ​​of the kinetic constants determined by the authors in this article; whereas, any change in at least one kinetic parameter of the wastewater results in an increase in the required aerobic age of activated sludge and, as a consequence, in the calculated volume of the aerobic zone by tens of percent, which proves the risk of not achieving the required effluent quality while using ATV model even for ammonium nitrogen concentration of 1 mg/l. Taking into account the fact that ATV Method does not provide for calculating aeration tanks for the effluent quality in terms of nitrites, the results of our calculation show that the aerobic age of activated sludge of 4.05 days for a temperature of 17 ºС proposed in ATV will make it possible to achieve the effluent quality in terms of nitrite nitrogen, 0.35–0.52 mg/l N–NO2, proving the unavailability of ATV, if the requirements to the effluent quality in terms of nitrites are specified. The authors, on the basis of the calculations, make conclusions about the risk of failure to achieve the effluent quality in terms of ammonia nitrogen as well as 1 mg/l while using ATV, because ATV is a stochastic model, that is, all dependencies presented in this method have been determined for the specific operating conditions. Moreover, as specified in the ATV description, this method, even in limited conditions, is applicable strictly for urban wastewater. The calculations show that if there are requirements for the effluent quality in terms of nitrites, regardless of the required concentration value of nitrites, the ATV method is absolutely not suitable, while ASM2d, taking into account the fact that it is based on the formulas of enzymatic kinetics, provides for calculating aeration tanks for any required effluent quality in terms of both ammonium nitrogen and nitrite nitrogen and is applicable for any type of wastewater.

Non-Parametric Analysis of Nitrogen Trends in the form of Nitrate and Nitrite in Rivers and Streams of the Contiguous United States for 1990-2019

Nitrogen and phosphorous support the ecosystem by supplying nutrients to algae and aquatic plants. Having them in excess results in the eutrophication of waters creating quality problems. In the past, nitrogen has been widely investigated for wells in the context of groundwater flow. However, a national-scale nitrogen assessment in rivers and streams has not received enough attention. In this research, the Wilcoxon rank sum test, as a non-parametric hypothesis testing method, has been applied to nitrogen concentration in the form of nitrate-nitrogen and nitrite-nitrogen in rivers and streams of the Contiguous United States. This approach was particularly selected because of the non-normal and positively skewed nitrogen levels occurring in the surface flow. This method was able to identify the impaired body of waters as well as quantify the confidence, significance, and errors involved. The Northern Appalachians (NAP), Northern Plains (NPL), and Xeric (XER) ecoregions were worsening in the nitrogen-nitrate condition with NAP, and XER needed immediate actions. The nitrite-nitrogen condition did not pose an immediate threat, so mitigation plans should focus more on nitrate-nitrogen remediation. It was shown that the method was superior to the two-sample t-test by yielding lower type II errors.

INFLUENCE OF THE PREDECESSORS ON ELEMENTS OF FERTILITY SOILS AND EFFICIENCY SUMMER WHEATS IN A STEPPE ZONE OF REPUBLIC ТUVА

Проблема и цель. Целью исследований явилось изучение влияния предшественников и применения минеральных удобрений на основные элементы плодородия почвы, урожай яровой пшеницы и его качества. Методология. Для достижения цели исследования и ответа на поставленные исследовательские вопросы было проведено опытно-экспериментальное исследование. Опыты проведены в степной зоне Республики Тыва в 2019-2020 гг., на темно-каштановых, среднесуглинистых почвах, в трехпольном севообороте с короткой ротацией (чистый пар-пшеница-пшеница; чистый пар-многолетние травы-пшеница; чистый пар-овес-пшеница), бессменная пшеница, на двух фонах химизации: без применения минеральных удобрений (контроль, фон 0), с применением минеральных удобрений (фон 1). Результаты. Результаты исследований показали, что влажность почвы по чистому пару по всходам яровой пшеницы была на 16,5 % больше, чем после других предшественников. В период уборки пшеницы влажность почвы повысилась только на вариантах с применением минеральных удобрений. Выявлено, что в период вегетации пшеницы наибольшее содержание нитратного азота отмечено после многолетних трав, где азота нитратов было на 3,3-4,7 мг/кг больше, чем на контроле. Внесение минеральных удобрений способствовало росту содержания нитратного азота в почве к фазе всходов на 8,3-38,0 %, кущения и уборки – в 1,2-1,7 раза, в зависимости от различных предшественников. Заключение. В результате исследований было установлено, что высокое содержание азота в почве влияет на урожайность и продуктивность яровой пшеницы. При использовании в качестве предшественника многолетних трав средняя урожайность яровой пшеницы составляет 1,63 т/га, содержание белка в зерне – 16,6 %. Посев яровой пшеницы после овса обеспечивает получение зерна с содержанием белка – 15,4 %. Применение удобрений увеличивает урожайность пшеницы в среднем по опыту на 34,2 %. Problem and aim. By the purpose of researches was to establish infuence of the predecessors, application of mineral fertilizers on basic elements of fertility of ground, crop summer wheats and his quality. Methodology. To achieve the aim of the research and answer the questions an experimental study was carried out.The experiences are carried out in a steppe zone Republic of Тuvа in 2019-2020, on dark-chestnut, medium loamy soils, in three-feld crop rotation with short rotation (pure pairs-wheat-wheat; pure pair-longterm grass-wheat; pure pairs-oat-wheat) permanent wheat, on two chemistry backgrounds: without application of mineral fertilizers (control, background 0), with application of mineral fertilizers (background 1). Results. The results of researches have shown, that the humidity of ground till a pure pair on shoots summer wheats was on 16,5 % more, than after other predecessors. During harvest wheats the humidity of ground has raised only on variants with application of mineral fertilizers. It was found that during the growing season of wheat, the highest content of nitrate nitrogen was observed after long-term grasses where nitrite nitrogen was higher by 3,3 – 4,7 mg/kg than in the control. Is revealed, that the best predecessor ensuring nitrate by nitrogen crops summer wheats, in conditions of a steppe zone of region are the long-term grass. The entering of mineral fertilizers promoted growth of the contents nitrate of nitrogen in ground to a phase shoots on 8,3- 38,0 %, (tillering?) and harvesting - in 1,2-1,7 times, depending on the various predecessors. Conclusion. As a result of research it was found, that the high contents of nitrogen in ground infuences productivity and efciency summer wheats. At use as the predecessor of long-term grass the average productivity summer wheats makes 1,63 t/hа, contents of fber in a grain – 16,6 %. The crop summer wheats after oats provides reception of a grain with the contents of fber – 15,4 %. Application of fertilizers increases productivity wheats on the average by experience by 34,2 %

THE PROBLEM OF ENVIRONMENTAL POLLUTION IN THE MEDITERRANEAN SEA ALONG THE COAST OF TURKEY

Turkish coastline neighbor to the Mediterranean Sea faces serious problems such as eutrophication and diffuse pollution. Among diffuse pollution, the leading actor is intensive agriculture. This research focuses on four developed cities, Antalya, Mersin, Adana, and Hatay, along the Turkish Mediterranean shoreline. The inadequate sewage system and insufficient treatment plants lead to eutrophication in populated cities. In the year 2017, in Turkey's Mediterranean region, Aksu, Manavgat, Göksu, Seyhan, Ceyhan, and Asi rivers were monitored. Concentration values for BOD5, Total Phosphorus, Nitrite Nitrogen, and Nitrate Nitrogen parameters were determined. This study observes the pollution status of the rivers according to the Turkish Water Pollution Control Regulation. One sample T-Test determined the actual pollution potentials of the rivers. Besides, uncontrolled heavy metal and toxic emissions from industry are essential problems.

Effect of ElasticFiller on Pollutant Removal in Each Compartment of ABR

This study was aimed to explore the effect of elastic filler on pollutant removal in each compartment of anaerobic baffled reactor (ABR), ABR with elastic filler, and ABR without elastic filler were compared. The result showed that elastic filler increased the removal rate of chemical oxygen demand (COD) and suspended solid (SS) in the first compartment, decreased the removal rate of COD and SS in the second and third compartments, and had little effect on the removal rate of COD and SS in the fourth compartment. Elastic filler increased the increase rate of ammonia nitrogen in the first and second compartments, decreased the increase rate of ammonia nitrogen in the third and fourth compartments; elastic filler had little effect on the nitrate nitrogen, nitrite nitrogen, total nitrogen and total phosphorus in each compartment of ABR. In general, elastic filler could improve the removal rate of COD and SS of ABR but had little effect on the increase rate of ammonia nitrogen, the removal rate of nitrate nitrogen, nitrite nitrogen, total nitrogen and total phosphorus. Elastic filler slightly increased the concentration of formic acid, acetic acid, propionic acid, and butyric acid in the first compartment of ABR, and slightly decreased the sum of formic acid and acetic acid in the second, hird and fourth compartments. Elastic filler did not change the composition of dissolved organic matter (DOM)in each compartment of ABR, but changed the kinds and contents of aromatic proteins, soluble microbial products and humic acids in each compartment of ABR. Elastic filler had little effect on ABR in the removal of aromatic proteins, but they could improve the removal rate of soluble microbial products and humicacids. Elastic filler slightly increased the degree of DOM humification (or maturity) in ABR effluent, but did not change the main source of humus like substance and DOM in ABR effluent.