The industrial development, the demographic growth and the limitation of the natural regions have determined a continuous degradation of the water quality due to high concentrations and complexity of pollutants from the wastewater. The centralized and decentralized treatment systems apply treatment procedures and techniques which can be complementary in solving the environmental pollution problems due to wastewater. In the present paper a three-dimensional mathematical model was elaborated based on the experimental data obtained in a wastewater treatment plant with sequential operation, correlating the treatment degree with independent variables such as the temperature of the wastewater and the treatment duration, respectively. The mathematical model was developed and verified by using a specialized software, Table Curve 3D .The model was based on experimental data obtained by using a low capacity treatment plant, with a sequential operation, in a Sequencing Batch Reactor (SBR) type and the real domestic wastewater.
The most important aspect of the national environmental policy concerns air pollutant emission decrease. The studies led in order to identify the atmospheric pollution sources have revealed that the energy sector is one of the biggest pollutants in the economy. Given the negative impact of the pollutant emissions on the environment and the possibility of closing the large combustion plants in case necessary measures to comply with the legal regulations in the field are not taken will significantly reduce the amount of air pollutants from these installations. This paper presents a case study regarding the monitoring of emissions from the large combustion plants on the platform of S.C. CET S.A. in Bacau.
Air quality in urban areas mostly depends on the type and size of industrial activities, traffic intensity, municipal and industrial waste management. In addition to these factors, air quality in urban areas also depends on the size and quality of green areas, population density, geographic and climatic conditions. This paper reveals the correlations between air quality aspects in Bacau City, Romania (related to 2011) and the most representative climatic factors that influence the pollutant dispersion. The correlation was made based on data resulted from the analysis of ammonia (NH 3 ) concentrations and their variations in the case of accidental pollutions caused by an important chemical plant located in the south-east of Bacau City, Romania
This paper presents a study concerning the noise level in an enclosure, perceived through the envelope of the building, as a result of the activities carried outside the enclosure. The building chosen for measurements was a teaching laboratory designed for applicative activities and equipped with installations and devices used in laboratory work. To establish the sound pressure level transmitted from outside the building to inside, three types of noise sources were established: a diffuser, a group of people who discuss, and the rainfall intensity on the roof of the enclosure. Measurements were performed both inside and outside the building in different points. The impact on indoor activities due to noise from the outside has been evaluated. The results on the sound pressure level perceived inside the enclosure indicate that the sound pressure level varies depending on the intensity of the outdoor activities.
Air pollution has a significant impact on human health and natural ecosystems. The principal gaseous pollutants compounds result from different types of combustion processes. In this category there are included carbon monoxide (CO), carbon dioxide (CO2), nitrogen oxides (NOx), dust and hydrocarbons. Nitrogen oxides are a group of highly reactive gases, which contain nitrogen and oxygen in varying amounts. Most of the nitrogen oxides are colorless and odorless gas. This paper highlights the connections between air quality aspects in Bacau city by analysis of variance for the nitrogen oxides (NOx) concentration and the most representative climatic factors. We used data recorded during 2010 at the Bacau Meteorological Station and at the air quality monitoring stations. These data were used to establish connections between cases where maximum allowable concentration are exceeded for nitrogen oxides (NOx) and the variation of climatic factors. The analyzed climatic factors were: air temperature, atmospheric pressure, atmospheric humidity, solar radiation, wind speed and direction. Some conclusions of this paper have shown that the wind can intensify the action of the pollutant or a rapid dispersion. Wind direction influences the air quality in a specific urban area based on the shape and size of the city, the type and distribution of the main sources of pollution and geographic location. In the warm seasons in Bacau, strong solar radiation plays an important role in the activation of chemical reactions in the air due to pollution, especially with nitrogen oxides, which reacts with atmospheric oxygen, causing a complex series of photochemical reactions.
One way to reduce the level of pollution resulting from industrial activities is the implementation of methods for purifying gases from production processes. A process step in the production of ammonia is the recovery of ammonia in the form of ammonia solution (or ammonia water, a product which can be marketed). This process also allows the recovery of hydrogen. This paper shows the effectiveness of the purge gas separation system in the production of ammonia by: the recovery of ammonia as ammonia solution, separation and re-introduction of hydrogen into the synthesis gas, as well as the re-introduction other waste gases into the re-combustion process. The selectivity for hydrogen allows its retention in the pores of wood fiber membranes and its exit through the hydrogen nozzle set at the base of the hydrogen separator. The unabsorbed gas is fed back to the installation into the combustion system. The almost full recovery of the ammonia can take place by washing the purge gas in a scrubber with demineralized water resulting in a 6-7000 L/h amount of ammonia solution with variable concentration. The hydrogen recovery from the purge gas and the recycling in the synthesis and combustion system with a 93% percentage results in 40 to 50 tons/day plus in the ammonia production.
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