Verfahren zur Nitrateliminierung im Gewässer

In a storage reservoir with a hypolimnic volume of 3.5 hm³ the water contains 40 mg/l nitrate. A straw bale of 60 by 20 by 1.5 m was introduced as a reactor. Hypolimnic water having been polluted with a waste product of the fatty acid synthesis (30 … 20% formic, acetic, propionic, butyric and valeric acids) were pumped through it. By the use of a total of 43.8 t fatty acid mixture from June to August an additional oxygen depletion of 14 t O₂ is achieved and 49 t NO₃^? are removed at the same time. The ammonium concentration did not increase, the NO₂^? concentration, however, rose to 12 … 13 mg/l NO₂ at times. The fatty acids were used up save 0.1 mg/l. The increase of the NO₂^? concentration, of the number of germs and of the iron, manganese and phosphorus back solution due to the controlled anaerobic conditions is the drawback of the process.     

Die EG‐Wasserrahmenrichtlinie: Ausweisung und Bewertung künstlicher und erheblich veränderter Gewässer

Designation and Assessment of Artificial and Heavily Modified Water Bodies under the EC Water Framework Directive The EC Water Framework Directive allows the Member States to designate artificial and heavily modified water bodies under specific conditions. For those water bodies the ecological assessment and the resulting programmes of measures will be based on the “maximum ecological potential” as reference conditions and not on the “high ecological status”, which has to be used for natural water bodies. Such designation is possible only, if the hydromorphology of the water bodies concerned has been substantially changed in character to maintain specified uses. The criteria for the designation are fulfilled, if restoration measures needed to meet the high ecological status would have significant adverse effects on the uses and if no other better environmental options would exist to maintain the specified uses. In late 1999 the EC‐Working Group on Heavily Modified Water Bodies (HMWB) has been established to develop criteria for the designation of artificial and heavily modified water bodies as well as for the determination of the maximum ecological potential. The working group has produced the guidance document “Identification and Designation of Artificial and Heavily Modified Water Bodies” in November 2002, which has been agreed by the European Water Directors on 21 November 2002 in Copenhagen. The guidance document is focusing on two time borders, the provisional identification of heavily modified water bodies until 2004 and the legally binding designation as artificial and heavily modified in the first river basin management plan in 2009 at the latest. The guidance document considered the main findings of 34 case studies for rivers, lakes, transitional and coastal waters carried out in 11 European countries. The results of the case studies as well as a summarizing synthesis were used as a fundamental basis to produce the guidance document. The practical examples given by the case studies were compiled as a toolbox which supplements the guidance for the purpose of its better application.     

Modellierung und Simulation des Phytoplanktongehaltes in einem eutrophen Fließgewässer

The model structure contains three compartments which are described by single models and are multiplicatively combined into an overall model of the net production of phytoplankton, the sedimentation of algae and the grazing by zooplankton being taken into account as loss quantities. The radiation and nutrients available (N, P, Si) are represented by Fourier models; the same holds for the water temperature. The light and temperature dependence of the growth rate are described by exponential equations, the nutrient dependence is described by the Monod statement. When the half-saturation constants and the sinking losses of the seasonally prevailing algae groups are taken into account, besides the total net production also the seasonal succession of the biomass of the different algae groups can be simulated realistically.     

Qualitätsanforderungen an Oberflächengewässer: Zielvorgaben,Qualitätsziele und chemische Gewässergüteklassifizierung

Quality Requirements for Fresh Waters: Water Quality Targets, Water Quality Objectives, and Chemical Water Quality Classification In the Federal Republic of Germany, water quality requirements for the protection of inland surface waters against hazardous substances are formulated on the basis of a quality targets derivation concept developed jointly by the Federal Government and the Federal States. The quality requirements were termed “water quality targets” in order to make it clear that the values derived are orientational values rather than legally binding limit values. The international comparison of quality requirements for surface waters shows that, on the whole, the national quality targets ensure a high level of protection. According to present scientific knowledge, impairments of uses, such as supply of drinking water, or risks to aquatic communities need not to be expected if the quality targets are complied with. A comparison of water quality data with the water quality targets makes it possible, on the one hand, to identify those substances whose inputs must be further reduced; on the other hand, it also shows that, for a number of substances, there is no need at present for concern over their adversely water quality. A further differentiation of the aquatic hazard potential of pollutants allows a water quality classification system to be developed on the basis of the quality targets derivation concept. The basic elements of this water quality classification system are presented, and its application is explained by way of examples.     

Vorkommen und Bewertung polyzyklischer aromatischer Kohlenwasserstoffe in einem mit kommunalen und industriellen Abwässern belasteten Fließgewässer

The river with a catchment of 5,400 km² is investigated over a length of 230 km at seven stations for the total concentration of six polycyclic aromatic hydrocarbons (PAH) and the total of three carcinogenic polycyclic substances (CPS) in the water by means of thin-layer chromatography. The maximum load occurs in the lower course downstream of large industrial wastewater introduction points with 5.1 μg/l polycyclic aromatic hydrocarbons, whereas in the upper course the maxima are at 2 … 3 μg/l polycyclic aromatic hydrocarbons for a mainly municipal pollution. The average daily load increases from 0.146 kg/d PAH and 0.048 kg/d CPS to 4.168 and 1.401 kg/d, respectively. In the flowing water there cannot be observed any self-purification concerning these substances, by an interconnected storage reservoir seston is reduced and thus also the PAC-concentrations are reduced by 50 … 60%. The PAH-concentration shows a significant positive correlation with the COD-Mn and the ammonium concentration. There is also a good agreement between the concentrations measured and the concentrations calculated from the wastewater load in the longitudinal section of the river.     

Hydrochemische Ergebnisse zur Aufbereitung stark belasteter Oberflächenwässer und Uferfiltrate mit Kalkhydrat. Teil 2

Continuing the first part on this subject, the results of precipitation experiments are described by the example of the removal of humic acid and lignosulphonic acid. Moreover, to increase the number of process variants and in accordance with process methods after Haberer, there is proposed a two-stage chemical treatment, inter alia. According to the latest findings, already at the first stage a metallic salt dosing should be done, so that the purification effect can be improved. This new technique, termed “combination stage flocculation”, is based on new findings concerning the solubility behaviour of aluminium compounds at higher pH-values in the presence of magnesium salts, when slightly soluble aluminium-magnesium double hydroxides originate.     

Mobilisierbarkeit von hydrophoben organischen Schadstoffen in belasteten Böden und Abfällen. Teil II: Mobilisierbarkeit von PAK,PCB und Phenolen durch reale Wässer

Mobilization Potential of Hydrophobic Organic Compounds (HOCs) in Contaminated Soils and Waste Materials. Part II: Mobilization Potential of PAHs, PCBs, and Phenols by Natural Waters To evaluate the hazard potential of organic pollutants in a soil, the mobilization potential of polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), and phenol derivatives in different waters was ascertained by elution experiments and compared to common elution procedures. Furthermore, dissolved organic matter from different sources was examined with regard to its influence on solubility. The results of the elutions pointed out that depending on the composition of the water sample, the leaching behaviour of the PAHs and PCBs is very different and is determined not only by the concentration of the dissolved organic carbon (DOC) but particularly by its quality. The separation of DOC-associated and “free” dissolved pollutants with the solid-phase extraction on C18-reversed phases revealed the responsibility of the sorption of the pollutants to the DOC for their solubility and mobilization. Moreover, an increase of association of pollutants to the DOC was observed with growing hydrophobicity corresponding to their octanol/water partition coefficient K_ow. The comparison of the elutions showed that the exclusively used S4-elution (German standard DIN 38414 part 4) is not appropriate to evaluate the mobilization of hydrophobic organic pollutants realistically. The eluted PAHs (PCBs) of the S4-elution were exceeded in landfill leachate by a factor of 7 (7), in the pond water by a factor of 9 (15), and in the compost saturation extract even by a factor of 35 (56). In contrast, a realistic “worst-case” leaching could be simulated with a tensidic SDS-solution corresponding to an elution process evaluating the mobilization of organic pollutants. The DOC of real waters and surfactants has little influence on the mobilization of the comparatively polar phenols. Concerning a “worst-case” evaluation of mobilization, the S4-elution under alkaline conditions is doubtlessly useful for water-soluble phenols.