Möglichkeiten der Nachreinigung von Abwässern aus der Kunstlederproduktion mit Hilfe von Algen

In the production of a special artificial leather (BAREX) in the CSSR wastewaters containing dimethylformamide (DMF) and dimethylamine (DMA) are produced. Investigations have shown that cultures of algae (Scenedesmus quadricauda) are able to use the two substances as a nitrogen nutrient source after a time of adaptation. In the course of the reactions of decomposition the pH-value plays an important part, since at increased values ammonia is released, which has a temporarily inhibitory effect on the production of algae masses and daughter cells. This detrimental effect can be considerably reduced by aeration with carbondioxide containing (3%) air. Since the production of algal biomass is restricted by a phosphorus deficiency, too, a combined treatment with municipal sewage is very advantageous, according to the results from investigations.     

Möglichkeiten der Nachreinigung von Abwässern aus der Kunstlederproduktion mit Hilfe von Algen,Teil 2

The attempt was made to use the alga Scenedesmus quadricauda for the purification of wastewaters from the production of artificial leather. The dimethylamine contained in these wastewaters is continuously decomposed and the remaining nitrogen-containing residuals are used as a nutrient source for the production of algal biomass. In continuous experiments with original wastewaters, dimethylamine and its metabolites showed a pronounced inhibiting effect. In practice, a longer retention time in the reactors as well as a sufficient share of municipal wastewater are required in order to avoid a limiting of growth due to a phosphorus deficiency. The second part of this paper is concluded by information about other investigations performed by us on the purification of artificial leather wastewaters with the aid of the biological nitrogen elimination under specific conditions with a successful denitrification of up to 95%.     

Ökotechnologischer Einsatz von höheren Wasserpflanzen in stehenden und gestauten Gewässern — Möglichkeiten,Grenzen

Species of macrophytes which are suitable for the biogenic aeration of the hypolimnion by macrophytes must reach positive balances of the net primary production at a high development of populations also at low light intensities and temperatures (winter). Elodea canadensis, Juncus bulbosus and Littorella uniflora from suitable sites were exposed after holding at different water depths, and the biomass development was investigated in relation to the radiation intensity. Parallel to that, the net primary production was determined in dependence on the light intensity in the bottle experiment by air-conditioned laboratory experiments (oxygen method). Elodea canadensis has been found to be suitable for the ecotechnological application to more eutrophic waters with neutral pH, especially because of the low light compensation point of the net primary production. Colonization with Juncus bulbosus, however, seems to be possible only in the acidophilic range (pH<7), whereas Littorella uniflora is not suitable for floating vegetation covers because of the higher light compensation point for a hypolimnetic colonization and the linkage to the substrate.     

Bestimmung von Spurenelementen in Gewässern mittels Flotationsspektralphotometrie am Beispiel des Arsens

Highly sensitive and selective methods for the determination of trace elements in waters and solutions are made possible by the combination of flotation and spectrophotometry (flotation spectrophotometry). The basis for it are multiply charged anion complexes of the analyte, which form sparingly soluble ion association complexes with singly charged basic dye cations in aqueous solution. Intense shaking of the aqueous solution with an organic solvent (having a low dielectric constant) results in the accumulation of these ion association complexes at the interface or on the vessel walls (flotation step). After separating the ion association complexes from the liquid phases, they are dissolved and dissociated in a polar organic solvent and the absorbance of the basic dye ions is measured as a function of the concentration of the analyte. By the example of the trace determination of arsenic in natural water, the possibilities of analytical chemistry by combination of flotation steps and spectrophotometry are demonstrated. According to the arsenic content, its determination can be performed by flotation spectrophotometry with crystal violet (detection limit 50 ng/ml As), by an indirect determination of arsenic via flotation spectrophotometry of molybdenum in the dodecamolybdoarsenic acid (detection limit 1 ng/ml As) or by the combination of collector precipitation of arsenic with zirconium hydroxide followed by froth flotation and flotation spectrophotometry as the determination technique (detection limit 0.05 ng/ml As). The reproducibilities of these variants are indicated and their accuracy is checked by comparison of methods.     

Untersuchungen zum Schadstoffpotential von Wasserwerksschlämmen

Investigation on the Pollution Potential of Waterworks Sludges Several contaminated sludges from water treatment plants with known or estimated concentrations of trace elements were investigated for their leaching characteristics and long-term stability using standard and advanced test procedures. Potentially hazardous elements in the sludge are zinc, nickel, and arsenic with concentrations of up to 1.2 g/kg dry matter (mass). Preliminary sorption tests with synthetic sludge components like iron hydroxide, manganese oxide, silicate clay minerals, and chitine powder as a model organic component showed that Cu is associated with the organic phase wheras arsenic is predominantly bound to the iron oxide minerals. The recently suggested pH_stat test procedure was used to assess the leaching characteristics of metals at typical pH values. This procedure was compared with the DEV-S4 test, the current standard test in Germany, consisting of a simple lixiviation of the solids with water, without pH control. The pH_stat test yields results which are much better to interprete than those obtained by the DEV-S4 procedure. The iron and manganese sludges are well buffered against changes in pH and redox potential so that low pH values and/or reducing conditions can hardly occur. Thus, in deposited material a sudden leaching of heavy metals is unlikely and due to the presence of iron and manganese oxides the pentavalent arsenic is protected against conversion into the highly mobile trivalent form at neutral to low pH. Co-deposition with reducing organic matter and alkaline stabilisation material or waste (like fly ash) could influence the binding properties and should be strictly avoided.     

Pestizidbestimmung im Wasser – gegenwärtige Möglichkeiten und künftige Entwicklungen

Summary: In the drinking-water regulation of the Federal Republic of Germany limit values in the range of 0.1 μg/l are established for pesticides. Identification and quantitative determination of pesticides in this concentration range require a very high expenditure concerning analysis, devices and equipment, analytical methods having been available so far only on a limited scale. The sum limit value of 0.5 μg/l pesticides may create special difficulties. In general, in view of the approx. 300 possible substances first of all a screening has to be proposed concerning the exceeding of limit values based on knowledge from the catchment area and its potential loading as the first step of investigation. Suitable methods of determination are partly available in gas chromatography and high-pressure liquid chromatography. Promising in the future development are the biochemical methods of enzyme inhibition (cholinesterase) and of immunoassay with radioactive and enzyme labelling. Nevertheless, for the foreseeable future standard methods will be available only for approx. Two thirds of the total of 300 substances, so that discussing the effectiveness of the limit values should be carried on.     

Gewässergütebewertung und Bewertung von Abwasserfahnen in Rhein und Main auf der Basis mikrobieller Enzymaktivitäten

Quality Mapping of Surface Water and Assessment of Treated and Untreated Waste-water Inputs into the Rhine and Main River Based on Microbial Enzyme Activities Microbial enzyme activities are used for an extension of the traditional quality mapping of surface water. In the following study, the enzymatic parameters were proved and validated on samples from various creeks and rivers in Baden-Württemberg and on samples gathered from the Rhine and Main Rivers (Germany). The test parameters should also be used for the control and the preservation of the capacity of the biological self-purification, which is the only natural and essential process in drinking-water conditioning of surface water. Main subject of the surveys was the development of criteria for an assessment of the measured enzymatical inhibition effects. Therefore, classes of inhibition and indices of inhibition are defined.