Classes Of Organic Micropollutants Research Articles

Characteristics and evaluation of natural attenuation processes for organic micropollutant removal during riverbank filtration

In industrialized and urban areas, surface waters are to a high level exposed to anthropogenic environmental impacts and are therefore often contaminated with a wide spectrum of organic trace compounds. Riverbank filtration is a well established technique in Europe and is most often used as an important component of the multiple-barrier system. During its underground passage, surface water undergoes a diversity of physical, biological and chemical processes, improving water quality significantly and adjusting it in ideal cases to the quality of natural groundwater. By means of examples taken from recent research projects and related to organic micropollutants currently under discussion, this contribution will report on characteristics of riverbank filtration with regard to its purification capacity for different classes of organic micropollutants.

Factors affecting the removal of organic micropollutants from wastewater in conventional treatment plants (CTP) and membrane bioreactors (MBR)

As a consequence of insufficient removal during treatment of wastewater released from industry and households, different classes of organic micropollutants are nowadays detected in surface and drinking water. Among these micropollutants, bioactive substances, e.g., endocrine disrupting compounds and pharmaceuticals, have been incriminated in negative effects on living organisms in aquatic biotope. Much research was done in the last years on the fate and removal of those compounds from wastewater. An important point it is to understand the role of applied treatment conditions (sludge retention time (SRT), biomass concentration, temperature, pH value, dominant class of micropollutants, etc.) for the efficiency of conventional treatment plants (CTP) and membrane bioreactors (MBR) concerning the removal of micropollutants such as pharmaceuticals, steroid- and xeno-estrogens. Nevertheless, the removal rates differ even from one compound to the other and are related to the physico-chemical characteristics of the xenobiotics.

Organic micropollutants on river sediments from Rio de Janeiro State, Southeast Brazil.

The paper is a contribution for the knowledge upon concentrations and fate of different kinds of organic micropollutants in Tropical River system from a very industrialized region in Brazil. The presented data was obtained during three years of an International Research Project between Brazilian and Dutch institutions. The sediments were sampled at the Paraiba do Sul-Guandu river watershed, the most important watercourse of Rio de Janeiro state, where up 90% of the population depends on its water for domestic uses. After extraction with non-polar solvents in a hot sohxlet device and clean up using chromatographic columns, three classes of organic micropollutants were analyzed: organochlorine insecticides (OCs), polychlorinated biphenyls (PCBs) and polynuclear aromatic hydrocarbons (PAHs). The organochlorines, including the PCBs were scarcely present in the collected samples probably reflecting the restrictions of use of this class of compounds in the Brazilian market. However, the PAHs levels were high at the vicinity of a huge steelworks located in the city of Volta Redonda. This contamination is probably due to the massive use of coal in the above-cited metallurgical plant.

PCDD/PCDF formation and destruction during co-firing of coal and RDF in a slag forming combustor

Environmental aspects related to the co-firing of pulverized coal and RDF (refuse derived fuel) in a slag forming combustor have been investigated with regard to specific combustion parameters and fuel type. Three classes of organic micropollutants have been considered: PCDD (polychlorodibenzodioxins), PCDF (polychlorodibenzofurans) and PAH (polycyclic aromatic hydrocarbons). The emissions from coal/RDF combustion (40% RDF) have been compared with those from the plant fired with pulverized coal alone. In order to follow the thermal and oxidative history of the investigated organic compounds, samples of flue gases were collected at the exit of the slagging combustor but before the boiler entrance, and at the boiler outlet stack.

Organic Micropollutants in Dutch Coastal Waters

During six cruises in the period August 1983 - July 1984, water samples were collected at nine locations in the Southern North Sea in order to assess the level of contamination with some classes of organic micropollutants for which presently little information is available. Thirty-one individual compounds (chlorobenzenes, chloronitrobenzenes, nitrotoluenes, halogenated aliphatic hydrocarbons, alkylbenzenes, polycyclic aromatic hydrocarbons) were measured. Concentration levels were found to be in the lower ng/1 (ppt) range: frequently close to the blank levels or below the limits of detection. Statistical data analysis revealed that both spatial and temporal variations were significant for nearly all parameters, and that nearly all parameters were significantly correlated with each other as well as with the salinity. Using principal components analysis, variations in the contamination with trace organics can be semi-quantitatively described with one component only. The highest concentrations were observed in the coastal waters north of the Rhine/Meuse estuary. Concentrations gradually decrease in northerly direction and sharply fall in seaward direction. It is proposed that the observed concentration levels are the result of two physical phenomena: (i) mixing of relatively uncontaminated water from the Atlantic Ocean with polluted water from the Rhine/Meuse estuary, and (ii) air-sea exchange by volatilization-, dry- and wet deposition processes.