No abstract

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.

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.

In recent decades, minimization and recycling/reuse policies were introduced to reduce the quantities of generated waste and for alternative waste recovery. Organic wastes represent 46% of total global solid waste. Possible uses of organic wastes include using it as fertilizer and amendment for soil, for energy recovery and for the production of chemical substances. Sewage sludge disposal and reuse are identified as future problems concerning waste. The total amount of sludge generated in the entire world has increased dramatically, and this tendency is expected to increase significantly in the years to come. In most developed countries, special attention is given to sewage sludge treatment in order to improve the quality and safety of using it on the ground surface. Sewage sludge pyrolysis is considered an acceptable method, from an economic and ecological perspective, for the beneficial reuse of sewage sludge. This method has many advantages because, during the pyrolysis process, the sludge volume is reduced by 80%, pathogenic agents and hazardous compounds from sewage sludge are eliminated, metals are immobilized in solid residue and organic and inorganic fractions are immobilized in a stabilized form of pyrolytic residues (biochar). The biochar generated by sewage sludge pyrolysis does not contain pathogenic agents and is rich in carbon and nutrients.

In this paper, a comprehensive review on greywater is presented. Emphasis is given to the techniques used to treat and recover greywater, and special emphasis is placed on the risk of the existence of the novel coronavirus “SARS-CoV-2” in greywater and the possibility of its spread via the reuse of this water. In general, greywater is considered wastewater collected from domestic sources, with the exclusion of toilet water (which is considered as blackwater). Greywater represents 50 to 80% of the total volume of wastewater all over the world. This review provides various aspects related to greywater, such as origins, characteristics, and existing guidelines for greywater proper treatment and reuse. Several approaches and techniques have been developed to study the performance of different greywater treatment systems. These methods are critically discussed in this article. In the context of sustainable development, water management, and taking into account the scarcity of water resources, particularly in arid and semi-arid areas, the use of treated greywater is one of the alternatives methods that can reduce the burden of withdrawals from the resource. In addition, some successful examples of greywater valuation experiences in Tunisia were examined.