Search results

Filters

  • Journals
  • Authors
  • Keywords
  • Date
  • Type

Search results

Number of results: 11
items per page: 25 50 75
Sort by:

Abstract

Changes in the amount of basic nitrogen fractions (total, protein and non-protein nitrogen) were studied in an annual cycle. Significant seasonal changes were noted, minima occurring in Antarctic winter and maxima during spring-summer season. These changes are due mainly to high fluctuations of water content in krill in the annual cycle.
Go to article

Abstract

The article presents the procedure for how to establish a mathematical model of nitrogen oxides formation based on the theory of dimensional analysis. The model is based on selected physical quantities (parameters) measurable during regular operation of a heat generation plant. The objective of using dimensional analysis to describe nitrogen oxides formation is to show that between operating parameters of the combustion equipment and the NOx formation there is a significant correlation. The obtained results, which are further described in this article, have proved this fact. The obtained formula expressing nitrogen oxides formation, based on dimensional analysis, applies universally to any boiler fuelled by coal, gas or biomass. However, it is necessary to find C, m, n constants for the formula by experiment, individually for each type of boiler and used fuel. The experiment is based on on-line measurements of selected operational parameters for a given boiler, combusting a certain type of fuel with its actual moisture content and calorific value. The methodology, described in this article, helps to find relationships between the operational parameters and the formation of NOx emissions for a particular furnace. The developed mathematical model has been validated with boilers fuelled by black coal and biomass. Both the results obtained from direct measurements of NOx in both types of boilers, and the results obtained by calculation using equation based on the dimensional analysis, are in a very good accord. When burning coal, the variation between NOx expression from the model and the on-line measurements ranges between -12.23 % and + 9.92 %, and for burning biomass between -0.54 % and 0.48 %. The intention of the authors is to inform the professional community about the suitability of the dimensional analysis to describe any phenomena for which there is currently no exact mathematical formulation based on differential equations or empirical formulas. Many other examples of dimensional analysis applications in practice may be found in the work of Čarnogurská and Příhoda (2011).
Go to article

Abstract

The study of groundwaters was carried out in two different forest ecosystems of Słowiński National Park: Vaccinio uliginosi-Betuletum pubescentis and Empetro nigri-Pinetum in the period of 2002-2005. Differences were found in the position of the groundwater table and in the concentrations of nitrogen and phosphorus compounds in the investigated forest associations. In the Vaccinio uliginosi-Betuletum pubescentis association the groundwater table was found on average at a depth of -73.3 cm, while in Empetro nigri-Pinetum at -90.2 cm. No statistically significant effect of precipitation on the position of the groundwater table was found in this study. Statistical calculations (U Mann-Whitney test) for groundwaters in the analyzed forest associations showed statistically significant differences in the dynamics of concentrations of total nitrogen (T-N), organic nitrogen (Norg.), nitrate nitrogen (N-NO3 ), total phosphorus (T-P), organic phosphorus (Porg.) and the level of groundwaters.
Go to article

Abstract

Primary or secondary sewage sludge in medium and large WWTP are most often processed by anaerobic digestion, as a method of conditioning, sludge quantity minimization and biogas production. With the aim to achieve the best results of sludge processing several modifications of technologies were suggested, investigated and introduced in the full technical scale. Various sludge pretreatment technologies before anaerobic treatment have been widely investigated and partially introduced. Obviously, there are always some limitations and some negative side effects. Selected aspects have been presented and discussed. The problem of nitrogen has been highlighted on the basis of the carried out investigations. The single and two step - mesophilic and thermophilic - anaerobic waste activated sludge digestion processes, preceded by preliminary hydrolysis were investigated. The aim of lab-scale experiments was pre-treatment of the sludge by means of low intensive alkaline and hydrodynamic disintegration. Depending on the pretreatment technologies and the digestion temperature large ammonia concentrations, up to 1800 mg NH4/dm3 have been measured. Return of the sludge liquor to the main sewage treatment line means additional nitrogen removal costs. Possible solutions are discussed.
Go to article

Abstract

There are certain well-known methods of diminishing concentrations of nitrogen compounds, but they are ineffective in case of nitrogen-rich wastewater with a low content of biodegradable carbon. Partial nitritation followed by anaerobic ammonium oxidation (Anammox) process appear to be an excellent alternative for traditional nitrification and denitrification. This paper presents the feasibility of successful start-up of Anammox process in a laboratory-scale membrane bioreactor (MBR). It was shown that the combination of membrane technology and Anammox process allowed to create a new highly efficient and compact system for nitrogen removal. It was possible to achieve average nitrogen removal efficiency equal to 76.7 ± 8.3%. It was shown that the start-up period of 6 months was needed to obtain high nitrogen removal efficiency. The applied biochemical model of the Anammox process was based on the state-of-the-art Activated Sludge Model No.1 (ASM 1) which was modified for accounting activity of autotrophs (nitrite-oxidising bacteria and nitrateoxidising bacteria) and anammox bacteria. In order to increase the predictive power of the simulation selected parameters of the model were adjusted during model calibration. Readjustment of the model parameters based on the critically evaluated data of the reactor resulted in a satisfactory match between the model predictions and the actual observations.
Go to article

Abstract

Organic carbon, nitrogen, and phosphorus in the soils of the High Arctic play an important role in the context of global warming, biodiversity, and richness of tundra vegetation. The main aim of the present study was to determine the content and spatial distribution of soil organic carbon (SOC), total nitrogen (N tot ), and total phosphorus (P tot ) in the surface horizons of Arctic soils obtained from the lower part of the Fuglebekken catchment in Spitsbergen as an example of a small non−glaciated catchment representing uplifted marine terraces of the Svalbard Archipelago. The obtained results indicate that surface soil horizons in the Fuglebekken catchment show considerable differences in content of SOC, N tot , and P tot . This mosaic is related to high variability of soil type, local hydrology, vegetation (type and quantity), and especially location of seabird nesting colony. The highest content of SOC, N tot , and P tot occurs in soil surface horizons obtained from sites fertilized by seabird guano and located along streams flowing from the direction of the seabird colony. The content of SOC, N tot , and P tot is strongly negatively correlated with distance from seabird colony indicating a strong influence of the birds on the fertility of the studied soils and indirectly on the accumulation of soil organic matter. The lowest content of SOC, N tot , and P tot occurs in soil surface horizons obtained from the lateral moraine of the Hansbreen glacier and from sites in the close vicinity of the lateral moraine. The content of N tot ,P tot , and SOC in soil surface horizons are strongly and positively correlated with one another, i.e. the higher the content of nutrients, the higher the content of SOC. The spatial distribution of SOC, N tot , and P tot in soils of the Hornsund area in SW Spitsbergen reflects the combined effects of severe climate conditions and periglacial processes. Seabirds play a crucial role in nutrient enrichment in these weakly developed soils.
Go to article

Abstract

In the paper, a numerical simulation of the co-combustion process of sewage sludge gasifi cation syngas in a hard coal-fi red boiler was done. Two different syngases (SS1 and SS2) were taken in consideration. Additional (reburning) fuel was injected into the combustion chamber, which was modeled as a plug fl ow reactor (PFR). The molar fl ow rates ratio of reburning fuel is assumed to be 5.0%, 7.5%, 10.0%, 12.5% and 15.0% of the whole exhaust. The simulations were conducted for constant pressure equal to 1atm for temperatures range from 600 to 1400 K. It was assumed that a fl ue gases which enters the reburning zone contains 300 ppm of NO and that during combustion only NO is formed without other NOx. Results show that that gas from sewage sludge gasifi cation gives reburning effi ciency of up to 90%. Calculation shows also an optimum value of temperature reburning for gas from sewage sludge gasifi cation which is equal to 1200 K. The type of the sewage sludge has no strong infl uence on the NO reduction.
Go to article

Abstract

Due to insufficient operation efficiency, the studied treatment plant has undergone modernization. The aim of this study was to assess whether this modernization improved quality of the STP effluent and water quality in the receiver. The research period of fifty months covered time before and after the modernization. Samples were collected in four sites – upstream and downstream of the STP and by the sewage discharge. Electrolytic conductivity, water temperature and pH were measured onsite. Chemical analyzes were based on ion chromatography and determined the concentration of NH4+, NO3-, NO2-, PO43-, TDS. Microbiological analysis comprised serial dilutions to assess the number of mesophilic and psychrophilic bacteria and membrane filtration to enumerate E. faecalis, total and fecal coliforms as well as total and fecal E. coli. Values of most analyzed parameters did not improve after the modernization, or improved for a very short period of time (NH4+), while some of them even increased, such as PO43-, total and thermotolerant coliforms and E. coli. The maximum value of thermotolerant E. coli reached nearly 7 million CFU/100 ml and was observed after modernization. Also at the sites situated downstream of the STP some of analyzed parameters increased. The conducted modernization did not improve the quality of treated sewage and even a further deterioration was observed. It could have been a result of rapidly growing number of tourists visiting the studied area, thus generating large amounts of sewage causing STP overload coupled with poor water and wastewater management. Significant percentage of unregistered tourists hinders proper assessment of the STP target efficiency.
Go to article

Abstract

The paper addresses the effect of a compost prepared from tobacco wastes with an admixture of bark and straw on the enzymatic activity and certain chemical properties of a grey-brown podzolic soil amended with that compost. The study was conducted under the conditions of a pot experiment in which the soil material was collected from the surface horizon of the grey-brown podzolic soil. The effect of the application of the compost was compared with soil without such amendment. The test plant was maize cv. Kosmo 230. Fertilisation of the light soil with the compost studied caused changes in the enzymatic activity of the soil that were related both to the dose of the compost and to the kind of enzyme studied. With increase in the dose of the compost there was an increase in dehydrogenase activity (highest dose) and a significant decrease in the activity of acid phosphatase. Moreover, it was observed that tobacco compost was a significant source that enriched the light soil in organic matter, total nitrogen, and available forms of phosphorus, magnesium and potassium, which was evident in increased yields of maize grown as the test plant. Significant correlations were also demonstrated between a majority of the biochemical and chemical parameters, which indicates that those parameters characterise well the biological properties of a grey-brown podzolic soil amended with tobacco compost.
Go to article

Abstract

The aim of this study was to determine the impact of the temperature of wastewater in a biological reactor with activated sludge and the BOD5/N-NH4 ratio in the influent to the treatment plant on nitrification efficiency and the concentration of ammonium nitrogen in treated wastewater. Tests were carried out in a household wastewater treatment plant which collects and treats sewage from a school building and a teacher’s house. During the 3-year study, large fluctuations in the sewage temperature in bioreactor were noted which was closely related to the ambient temperature. There were also large fluctuations in the concentration of organic matter and the concentration of ammonium nitrogen in inflowing sewage. The influence of wastewater temperature in the bioreactor and the BOD5/N-NH4 ratio on the concentration of ammonium nitrogen in treated wastewater was determined using Pearson’s linear correlation. A statistical analysis showed that a 1°C decrease in the temperature of wastewater in the bioreactor increased the concentration of ammonium nitrogen in treated wastewater by 2.64 mgN-NH4·L-1. Moreover, it was found that nitrification depended on the ratio of BOD5 to the concentration of ammonium nitrogen in wastewater flowing into the bioreactor. An increase in the BOD5/N-NH4 ratio by 1 value led to a 5.41 mgN-NH4·L-1 decrease in the concentration of ammonium nitrogen.
Go to article

This page uses 'cookies'. Learn more