In Romania, over 40 % of the population lives in rural areas where wastewater infrastructures are poor or missing. Development of infrastructure in water supply and sewerage is essential for improving living conditions and human health. To solve the problem of domestic wastewater treatment in the areas where only decentralized sewage treatment systems can be implemented, compact installation that operating as a Sequencing Batch Reactor (SBR) process can be used. Unlike the conventional biological mechanical wastewater treatment systems, in which the process is divided into several basins, the treatment system that uses the SBR process segregates the treatment process by working times. Therefore, the compact installation that uses SBR process is among the most effective alternatives to the conventional wastewater treatment with low flow. To ensure a high degree of treatment in small treatment plants which operates by SBR process, it is essential to identify the correlations among some parameters, such as: qualitative and quantitative characteristics of the influent, construction characteristics of the treatment system and operating factors. The main direction of this research aims at identifying the mathematical model able to describe the heat balance for a SBR used in a small municipal wastewater treatment plant. Moreover, the theoretical model was correlated with the numerical values obtained during 30 days of measurements and monitoring of a small wastewater treatment plant used to treat real municipal wastewater. The installation used in this research was used in real condition to obtain the values as close to reality for the component of the heat balance.
Techniques for the treatment of polluted soils have as main objective the destruction, elimination or immobilization of pollutants. In situ soil flushing, which is based on the extraction of contaminants from the soil with water or other proper aqueous solutions is carried out by the permeation of the extraction fluid through soil layers. In this paper, an experimental setup was exploited for soil remediation based on the principle of in situ soil flushing for ensuring a high efficiency of treatment. Correlations were identified among soil properties that influence the treatment process, structural characteristics of the installation of remediation and operating parameters. The theoretical and experimental research of the soil depollution process presented in this paper constitutes an attempt to offer, by means of detailed analysis, constructive and functional dependences, which can set the basis for the design of new depollution technologies or modernization of the older systems.
In order to accomplish the water quality standards required for a specific use, the continental surface water is treated through a sequence of operations and unit processes. The treatment technological flowsheets carry out, partially or totally, the removal of various pollutants, every treatment step being used for improving one or more qualitative parameter. The treatment scheme is specific to water source type and water use. One of the basic operations for water treatment is the filtration, which is influenced by a series of parameters. The present paper aims at identifying the influence of the granular filtering material on the removal of solids in suspensions that are found in water in concentrations between 5 -50 mg/L. In order to accomplish the experimental program, the studies were carried out using three types of filtering materials with various shapes of granular particles, respectively: quartz sand, perlite and anthracite. Using this types of materials were constituted Granular filters with different thicknesses of the filtering layer were used at different water flow rates. The type of granular filtering material with the highest degree of retention of solids was identified and recommended for large scale application.
In many industrial applications most of the solid particles are separated by size and for this purpose there are used the oscillating sieves. The separation process based on sieves is a complex one and it depends on several factors, such as the properties of solid particles submitted to the separation process and on the operating regimes of the separating equipment. We have studied the separation process of the behaviour of solid particles on a flat oscillating surface by drawing up a series of mathematical models aiming at identifying the solid particle trajectory. This paper presents a study performed at the "Vasile Alecsandri" University in Bacau, aiming at determining the travel paths of the real particles compared to the ideal particle travel path. In order to determine the behaviour of the solid particles on oscillating surfaces within the experimental measurements we have used a blind screen. The experiments have been performed on a laboratory bench with flat oscillating sieves. The movement of the solid particle on the working surface has been monitored by two cameras positioned on perpendicular planes, the system aiming at obtaining the spatial trajectory of the particle on the operating surface. Films obtained from the experimental measurements have been processed using the SynthEyes software, resulting *.txt files, which contain the necessary data in order to visualize the trajectory of a particle studied on a working plan. By combining the two paths it was possible to view the three-dimensional trajectory of the solid particle. During the study, we have aimed to determine the trajectory for different types of particles, namely: ideal spherical particle, particle with cube form, various other forms of real particles: soy, pod and grain. Within the experimental measurements, we have also studied the solid particle behaviour for different operating conditions, like different angles of work surfaces and different operating modes of the block sieves. After processing the data obtained from experimental measurements one could calculate the velocity of solid particle on a flat oscillating surface.
Nowadays, when the problem of environmental protection is quite stringent, the producers are concerned to bring on the market products, which have reduced environmental impact. In their turn, the consumers have become more aware and selective in purchasing products or services. Due to the financial crisis, consumers buy less but they are asking for quality and environmental friendly products. Under these circumstances the producers must find solutions in order to satisfy the consumers' requirements. According to market survey the significant progress has been made in the production of green products so that they reduce the environmental impact, taking into account a part or the whole lifecycle of the product. In free consecutive years gradually the companies are oriented to obtain various certifications for the products and services they offer. One of the most important and successful certification schemes identified by survey is the European eco-label. However, there are a number of other widely accepted and successful labels that are also analyzed in the present study. The survey objective was to identify green products on the Romanian market and to monitor their evolution. The present paper presents the results of three years market research focusing on product categories that include eco-labeled products.
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.
After any treatment process of wastewater results residual sludge that is characterized depending on the type of the wastewater or by the sludge treatment type. The sludge treatment process can be divided in three important stages: the preliminary stage (with the sludge thickening), the stabilization stage, and the dewatering stage. The paper shows the results of the research for the identification of the most efficient organic cationic flocculants, which might be used within the process of thickening or dewatering of the sludge, resulting from the municipal wastewater treatment. Considering this, the study aimed to identify the most efficient flocculants, from Zetag category, used for municipal sludge treatment in the thickening and dewatering process. The main parameters studied during the laboratory tests were: size of the flocs, the filtrate and the sludge cake consistency. Also, the experimental results had industrial applications with a real testing of the studied flocculants in a municipal wastewater treatment plant.
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