Papers by Keyword: Nitrogen Removal

Abstract: The research presents the results of data analysis on degassing of wheel grades of steels in a tank degasser with a capacity of 120 tons, operated at the JSC “Ural Steel”. The volume of the analyzed sample included 754 steels for railway wheels (steel grades “2” and “T” according to State standard GOST 10791-2011) weighing more than 80 thousand tons received in November-December 2019.It was established that in order to guarantee the production of hydrogen content of less than 1.5 ppm and nitrogen before 0.007%, it is necessary to carry out vacuum treatment of metal with overheating of 110-130^°C at the residual pressure of up to 3 mbar for 20-25 minutes and argon flow rate of at least 0.05 m³/ton. The regression equation was obtained, which allows to predict the results of degassing, as well as select the values of vacuum treatment parameters in order to achieve a given content of dissolved gases - hydrogen and nitrogen.

Abstract: Performance of activated sludge wastewater treatment plants are mainly dependent on bacterial growth, which is limited by many factors. These factors include availability of suitable substrate, limiting nutrients, environmental conditions, and energy. In activated sludge model no. 3 (ASM3), constituents in wastewater are divided into two main categories: carbonaceous compounds and nitrogenous compounds, which are further subdivided depending on their solubility and biodegradability. These compounds are not mutually independent; hence, the fate of one compound in the biological processes is affected by one or more of the other compounds. In this study, a steady-state analysis was conducted to investigate the effect of initial readily biodegradable substrate, oxygen, ammonia nitrogen, nitrite plus nitrate, and heterotrophic organisms’ concentrations on the effluent concentrations of readily biodegradable COD and nitrogen compounds. The studied ranges of the selected wastewater state variables were identified based on literature surveys including previous studies concerning domestic, industrial, and synthetic wastewaters. The results proved that the effluent readily biodegradable substrate and ammonia nitrogen concentrations are reduced as the initial dissolved oxygen and nitrite plus nitrate concentrations are increased. Moreover, better nitrification-denitrification process is achieved at lower initial readily biodegradable concentration leading to lower nitrite plus nitrate concentrations.

Abstract: Ultra-low sulfur diesel (ULSD) is obtained by Light Gas Oil (LGO) and Light Cycle Oil (LCO) feedstocks (middle fractions from distillate petroleum). In addition to the environmental requirements related to the production of fuels with a lower content of nitrogen, technical specifications refineries also stimulate the need to remove such compounds. Nitrogenous compounds, for example, are strong inhibitors for hydrodesulfurization reactions. As Brazilian oil has a high amount of nitrogen compounds, an alternative process for nitrogen removal has been investigated, such as adsorption. In this paper, the nitrogen removal was investigated. The adsorption tests were carried out in a shaking water batchs, by performing kinetic and isotherm tests. Two commercial clays were used: Fuller's earth and bentonite.

Abstract: The purpose of this experiment was to study the inoculation and start-up, domestication and cultivation of ANAMMOX system and the stable operation after the successful start-up. The experiment used the activated sludge SBR reactor and artificial raw water. The inoculated sludge included nitrification sludge, anaerobic sludge and garden soil exudate. The ANAMMOX s ystem was s uccessfully started on the 114th day after the inoculation. The removal ratio of NH4+-N, NO2-, and NO3- -N mostly was 1:2.8～3.6:0.2～1.8. It could be inferred that in addition to Anammox phenomenon, there was other denitrification process without the participation of external carbon sources in the system In the stable operation period, the sludge was flocculent, and the flocs were dispersed, irregular shaped. The sludge was mixed with a large number of red, dark red particles.

Abstract: Activated sludge systems operate at low DO concentration can save aeration energy and enhance the treatment performance. To explore the effect of DO control strategies on the settleability of activated sludge, different DO control strategies were carried out in a step-feed anoxic/oxic reactor treating domestic wastewater. The result shows that low DO concentration is not the single reason to filamentous bulking. To achieve long-term system stabilization and avoid serious filamentous bulking, feedforward-feedback DO control strategy may be a feasible and good choice.

Abstract: Anaerobic ammonium oxidation (anammox) process is a heated researched biotechnology for nitrogen removal in wastewater. The application of the process is limited due to its long start-up time and sensitivity to organic matters. This paper discussed the effects of butyrate on anammox process. The nitrogen removal rate of anammox process was elevated at low butyrate content (1 mmol/L) and decreased at high butyrate content (3 mmol/L). NH₄⁺-N:NO₂^--N:NO₃^--N:butyrate ratio was 1:1.25:0.08:0.04 and 1:7.26:0.10:1.85 when butyrate concentration was 1 mmol/L and 3 mmol/L.

Abstract: In order to study combination effect of aquatic plants for the purification of eutrophic wastewater, research was carried out in greenhouse with water hyacinth (Eichhornia crassipes), hornwort (Ceratophyllum demersum L) an water milfoil (Myriophyllum verticillatum L). In the treatment of water hyacinth + water milfoil , the removal efficiency of ammonium nitrogen (NH₄⁺-N), nitrite nitrogen (NO₃^--N) , total nitrogen (TN), total phosphorus (TP) and COD was 74.7%, 61.7%, 65.6%, 73.8% and 50.8% respectively. And that of water hyacinth + hornwort was 79.0%, 52.6%, 67.5%, 46.2% and 56.9%. The combination of different aquatic plants have better removal efficiency than single species. Water milfoil showed good removal ability for the eutrophication pollutants, such as nitrogen and phosphorus, while hornwort was good at the purification of COD.

Abstract: MBR technology for sewage treatment has the advantages of high volumetric load, good treatment performance and so on. But the MBR technology also has the shortage of membrane fouling. So this study selected the control method of fixing combination packing added in the MBR reactor, so as to reduce the membrane pollution, at the same time in the reactor to create the environment of coexistence of anaerobic and aerobic for biological denitrification. Through the research of the pollutants removal efficiency and the membrane pollution, it was founded that this method can remove 85-95% of COD and ammonia nitrogen. Effluent COD concentration generally is about 25mg/L, and the minimum of it is less than 10 mg/L. Effluent ammonia nitrogen is generally less than 10 mg/L. The minimum effluent concentration of ammonia nitrogen was less than 1 mg/L. The removal rate of total phosphorus was between 30-45%.

Abstract: As human activities continue to alter the global nitrogen cycle, the ability to predict the impact of increased nitrogen loading to river systems is becoming more and more important. Nitrogen retention is of particular interest because it is through its combined processes that local and downstream nitrogen concentrations are reduced. To determine the potential for N removed from Feng River network, we used stream chemistry and hydrogeo-morphology data from 17 stream and river sites to estimate NO₃^-–N removal in Feng River system of China. We used a N removal model to predict NO₃^-–N input and removal in December of 2011. NO₃^-–N input ranged from 0.06 to 20 kg km^-1d^-1in the Feng River system. Cumulative river network NO₃^-–N input was 446 ton year^-1 in dry season in whole water system. NO₃^–N removal based on the model ranged from 0.04 to 4.2 kg km^-1d^-1 December of 2011 for Feng River. Cumulative river network NO₃^-–N removal predicted by the model was 58 ton year^-1 in dry season. Proportional NO₃^–N removal (PNR) ranged from 0.2 to 0.6 in this time. PNR was negatively correlated with both stream orders.

Abstract: The article touches upon methods and technologies of nitrogen removal. Characteristic features, necessary conditions and technological schemes are listed. There are also ways to intensify existing methods are shown.