Discharges Of Hazardous Substances Research Articles

Bayesian estimation and reconstruction of marine surface contaminant dispersion

Discharge of hazardous substances into the marine environment poses a substantial risk to both public health and the ecosystem. In such incidents, it is imperative to accurately estimate the release strength of the source and reconstruct the spatio-temporal dispersion of the substances based on the collected measurements. In this study, we propose an integrated estimation framework to tackle this challenge, which can be used in conjunction with a sensor network or a mobile sensor for environment monitoring. We employ the fundamental convection-diffusion partial differential equation (PDE) to represent the general dispersion of a physical quantity in a non-uniform flow field. The PDE model is spatially discretised into a linear state-space model using the dynamic transient finite-element method (FEM) so that the characterisation of time-varying dispersion can be cast into the problem of inferring the model states from sensor measurements. We also consider imperfect sensing phenomena, including miss-detection and signal quantisation, which are frequently encountered when using a sensor network. This complicated sensor process introduces nonlinearity into the Bayesian estimation process. A Rao-Blackwellised particle filter (RBPF) is designed to provide an effective solution by exploiting the linear structure of the state-space model, whereas the nonlinearity of the measurement model can be handled by Monte Carlo approximation with particles. The proposed framework is validated using a simulated oil spill incident in the Baltic sea with real ocean flow data. The results show the efficacy of the developed spatio-temporal dispersion model and estimation schemes in the presence of imperfect measurements. Moreover, the parameter selection process is discussed, along with some comparison studies to illustrate the advantages of the proposed algorithm over existing methods.

ASSESSMENT OF RIVER SEDIMENT QUALITY ACCORDING TO THE EU WATER FRAMEWORK DIRECTIVE IN MOUNTAINOUS FLUVIAL CONDITIONS. A CASE STUDY IN THE UPPER TISA AREA, DANUBE RIVER BASIN

Discharge of hazardous substances (HSs) in hydrographic basins represent a danger to aquatic biological activity and water supplies and can severely pollute surface water sediments. The increase of pollution in the Danube Basin requires the implementation of systematic monitoring and evaluation of the sediments quality as dictated by the EU Water Framework Directive. For this system development, applicable in mountainous conditions, the Upper Tisa region in the northwest part of Romania on the border with Ukraine, Hungary and Slovakia was selected as a test area. Sampling of overbank (floodplain) sediment, river bottom sediment and suspended sediment was carried out at 10 locations in the test area in order to analyze the concentration and distribution of eight metal(oid)s (Cu, Pb, Zn, Cd, Hg, Ni, Cr and As), in addition to 3 organic components (anthracene, fluoranthene, benzo(e)pyrene) as hazardous substances (HSs). The sediment quality assessment was carried out according to the 2013/39/EU Directive and EU Water Framework Directive standards. Most of the analyzed HS concentrations in river bottom sediment and overbank (floodplain) sediments fall within the limits of environmental quality standards (EQS). As, Cu, Pb, and Zn tend to exceed the EQS at some locations. The highest exceedances were recorded for Pb, for which contents of up to 987 mg/kg were detected. The highest contents were found in the overbank sediments sampled, and the lowest in river bottom sediments, which may indicate historical pollution. Mercury contents in overbank sediment samples exceed all standards, while cadmium content is below the international standards. Anthracene, fluoranthene and benzo(e)pyrene concentrations in overbank and bottom sediments comply with international standards. A few samples in suspended sediments slightly exceed the lowest environmental standard value (i.e., Romanian normal value). HS concentrations remain low in the suspended sediments showing that it is not the main transport route for pollution in this area. HS contents decrease gradually from upstream to downstream due to dilution along the river course. In the last testing point at Someș Aciua, the concentration of metal(oid)s measured in the sediments remain below the EQS limit values, thus there is no risk of transboundary pollution. The main source of metal(oid) contamination is historic base-metal ore mining and the associated mine waste sites in the Baia Mare and other mining areas scattered around the whole region. The main source of the studied organic compounds is the incomplete or low-temperature coal combustion processes that occur in households in rural areas

Сравнение выпарных установок с механической компрессией пара и установок с применением парогенератора

Evaporation is a process through which solvent is partially removed from solutions by subjecting the latter to evaporation. Aqueous solutions of solid materials are generally subjected to evaporation; however, other liquids may also serve as solvents. The solvent being removed is in this case in vapor form and is called secondary vapor. The vapor used for heating and evaporation is called heating steam. At present, evaporation plants are widely used in purification and concentration of industrial waste waters to obtain demineralized water and sludge, which makes it possible to set up a closed water cycle at a production enterprise, to exclude discharges of hazardous substances into water bodies, and to decrease the amount of discharged waste; in obtaining demineralized water; in desalination of seawater; in evaporation of various process solutions to the required concentration (aluminate solutions, mineral salt solutions, alkalis, acids and so on); in milk and food industries; and in medicine. As a rule, evaporation is performed by applying the heat of steam produced at a boiler house or a thermal power plant. Steam is an efficient heat carrier owing to its having high heat of condensation. In some cases, when evaporation has to be carried out at high temperature, furnace gases and high-temperature heating agents (diphenyl mixture, superheated water, or oil) are used. If it is necessary to evaporate liquids sensitive to temperature effects, special equipment for creating deep vacuum (steam-jet and water-jet vacuum pumps, mechanical vacuum pumps, and others) is used. As a result, evaporation can be carried out at 60 °С (in the milk industry) and even at 35°С (in medicine). In many cases, production sites do not have a steam source, and construction of new boiler houses is economically unprofitable or unfeasible for some or other reason. In such situations, an alternative heat source is selected subject to the operation conditions of a particular plant. Process circuit versions of evaporation plants with mechanical steam compression and plants using steam generators operating on different kinds of fuel are considered. The possibilities of using one or another version depending on the properties of treated process solutions, process implementation conditions, and the number of shells in the plant (one- or multi-shell evaporation) are studied. The net cost of one ton of steam is evaluated, and the equipment payback period is estimated.

Sustainability assessment of advanced wastewater treatment technologies

As a consequence of the EU Water Framework Directive more focus is now on discharges of hazardous substances from wastewater treatment plants and sewers. Thus, many municipalities in Denmark may have to adopt to future advanced treatment technologies. This paper describes a holistic assessment, which includes technical, economical and environmental aspects. The technical and economical assessment is performed on 5 advanced treatment technologies: sand filtration, ozone treatment, UV exclusively for disinfection of pathogenic microorganisms, membrane bioreactor (MBR) and UV in combination with advanced oxidation. The technical assessment is based on 12 hazardous substances comprising heavy metals, organic pollutants, endocrine disruptors as well as pathogenic microorganisms. The environmental assessment is performed by life cycle assessment (LCA) comprising 9 of the specific hazardous substances and three advanced treatment methods; sand filtration, ozone treatment and MBR. The technical and economic assessment showed that UV solely for disinfection purposes or ozone treatment is the most advantageous advanced treatment methods if the demands are restricted to pathogenic microorganisms. In terms of sustainability, sand filtration is the most advantageous method based on the technical and environmental assessment due to the low energy consumption and high efficiency with regards to removal of heavy metals.

Regulatory Requirements for Pulp and Paper Mill Effluent Control: Scientific Basis and Consequences

The Ministers' Declaration from the 2nd North Sea Conference recommended a goal to be set to diminish the discharge of hazardous substances via rivers by 50% over the next 10 years, e.g. to diminish the discharge of persistent halogenated compounds from pulp and paper mill effluents. The Paris Convention adopted this recommendation later. Based on a study conducted for the EEC Commission, we have arrived at the following conclusions to fulfil this goal. For historic reasons the regulation of the pulp and paper industry includes some parameters which may not be the most appropriate ones, e.g. BOD5 and AOX. To regulate the bleached pulp mills by AOX/TOC1 is not recommendable. PCDD/PDDFs are very difficult to regulate at present. Regulation of polychlorinated phenolics (PoCPs) in the effluent may prove to be a valid indirect measure of TCDD-equivalents, but this has yet to be proven. To ensure sufficient removal of hazardous compounds, we recommend that standards for TSS be stringent, as the major fraction of hazardous compounds is associated with suspended solids (including PoCPs and PCDD/PCDFs). Effluent control should be based on pH, COD (Chemical Oxygen Demand using dichromic acid), TSS (total suspended solids) and PoCPs. At present there are not sufficient data available to establish a regulation based on these parameters. So, further data should be obtained.

Cleaning up industrial emissions

Metallurgical plants are a significant source of atmospheric pollution, these facilities being responsible for 12-15% of the quantity of harmful substances introduced into the air. The production of steel in open-hearth (OH) furnaces, moreover, is one of the "dirtiest" metallurgical operations from an enviromnental standpoint. While the current level of OH steelmaking has maximized the productivity of OH furnaces, it has also brought an increase in the discharge of hazardous substances: dust and oxides of sulfur and nitrogen. Open-hearth shop No. 1 at the Karaganda Metallurgical Combine evaluated the dust content of the outgoing gases and their concentration of harmful substances. The study revealed the process factors responsible for the deterioration in pollution control in the shop. It turned out that the escape of gases through the charging doors and leaks in the furnace superstructure account for 5-20% of the emissions registered. Moreover, while the concentration of nitric oxide is not above the MPC (maximum permissible concentration) in every section of the shop, the concentration of sulfur dioxide ranges from 0 to25.4 mg/m 3 -- with the MPC being 10 mg/m 3. The concentration of sulfur dioxide at work stations in the shop is 13.1 mg/m 3. The highest concentration of dust (45 mg/m 3) was found in the area of the tap hole during tapping. The MPC is 4 mg/ m 3. Dust concentration on the working platform of the furnace during cold-charging reaches 13.2 mg/m 3. Uncontrolled emissions could be reduced by increasing the draft, but this would require more powerful ventilating equipment. Also, increasing the amount of cold air brought into the system increases heat losses, disturbs the slag regime, and entails the consumption of additional heat carrier. An alternative solution is to install an aerodynamic screen, hoods, and other devices to control gaseous emissions. The total amount of dust generated by OH steelmaking is reduced 7% when two-level lances are used to blow the metal. The reduced dust formation is accompanied by improved operation of the regnerators, flues, and waste-heat boiler. The level of cleaning of the flue gases (controlled emissions) depends on the efficiency of the electrostatic precipitators in the gas-cleaning system. Their efficiency ranges within 85-99%. The efficiency of the gas-cleaning system as a whole is adversely affected by an increase in the quantity of gas (gas velocity) and an increase in gas temperature at the system inlet. Factors which tend to increase dust generation are: a reduction in the bulk weight of the scrap charge; overheating of the charge before the hot-metal addition; oxygen-blowing of the metal when its carbon content is below 0.15%. These findings suggest that, from an environmental standpoint, it would be helpful to change the OH shop over to the production of killed and low-alloy steels. Unfortunately, the existing gas-cleaning systems do not ensure the removal of oxides of sulfur and nitrogen from the flue gases. Since sulfur in the charge and the fuel is one factor contributing to the formation of sulfur dioxide in the steelmaking process, emissions of SiO 2 could be reduced by using pig iron and fuel oil that are low in sulfur. The concentration of oxides of nitrogen in flue gases depends on the method used to reduce fuel consumption and the extent to which the steelmaking operation is being forced.

Control of Test Substances

The efficient control of chemicals during a nonclinical laboratory study is of the utmost importance from three main points of view: (1) integrity of the experiment, (2) safety of personnel, and (3) protection of the environment. While the general principles involved in chemical control may be set forth in formal GLPs, detailed problems concerning individual test substances can only be resolved by utilizing the competency and judgment of a researcher who possesses adequate analytical chemical methods. Integrity of an experiment requires knowledge of the identity, purity, and stability of the test substance, as well as its proper handling and storage and a knowledge of its chemical properties. Assurance of homogeneity, stability, and proper concentration of the chemical in the dosage form is also of primary importance. The development and use of adequate analytical chemical procedures for determining the test agent in human samples, air, clothing, and on work surfaces is necessary for the initiation of surveillance procedures to assure safety of personnel from exposure to the test substances. The environment must be protected from hazardous test substances by using adequate disposal techniques for the chemical and all contaminated materials. This usually involves development of wastewater cleanup systems and continuous monitoring of the effluent to prevent discharge of hazardous substances. Incineration is the most useful method for disposal of solids and highly contaminated liquids. Work from our laboratory, done during the past 5 years, provides an illustration of the important principles, problems, and pitfalls encountered in chemical control.