Polarographische Bestimmung von Nickel und Chrom in Klärschlämmen Polarographic Determination of Nickel and Chromium in Sewage Sludge

The contents of Ni and Cr in sewage sludge with high and low amounts of heavy metals were investigated by polarography. The DIN-digestion (aqua regia) was used, and the resulting solution was treated with H₂O₂/UV (90 °C, 60 min) for further destroying of the organic material. Besides, the solution of the DIN-digestion was examined with AAS (flame) and ICP-OES. With the determination of Ni it was shown that after digestion with aqua regia no further treatment with H₂O₂/UV is necessary. Contrariwise it was found that for the determination of Cr a H₂O₂/UV photolysis is necessary followed by further steps to get good agreement with AAS and ICP results as well as with the certified values of a sludge of the Community Bureau of Standards.     

TOC-Bestimmung in Schlämmen,Sedimenten und Schwebstoffen — Beschreibung des Verfahrens und begleitender Qualitätssicherungsmaßnahmen Determination of TOC in Sludge,Sediment and Suspended Solids — Description of the Analytical Procedure and Accompanying Quality Control Procedures

The total organic carbon (TOC) is calculated by subtracting the inorganic carbon (IC) from the total carbon (TC). For TC determination, the carbon in a sample is completely converted to CO₂ by decomposition/combustion in an oxygen stream. To determine IC, inorganic carbon (carbonate) is liberated by adding acid and by heating in an oxygen stream. In both cases, CO₂ is quantified by infrared spectrometry. To gain reliable and reproducable results for sludge, sediment and suspended solids, at least the following conditions have to be met: particle size has to be smaller than 200 μm; weightout has to be selected in such a way, that the signal area is not below and the signal maximum is not above specific instrument dependent parameters; combustion/decomposition has to be complete (TC: ≥ 1300 °C, no soot) and rules for analytical quality assurance must be followed. The TC quantification of calcium carbonate is used for system calibration. Daily working procedures include calibration checks by mean control charts for TC determination of calcium carbonate and IC determination of sodium carbonate as well as for control sediment TC and IC quantifications.     

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.     

Trends und Verteilungsmuster in der Schadstoffbelastung von Sedimenten aus östlichen Bundeswasserstraßen

Trends and Patterns in the Contamination of Sediments from Federal Waterways in Eastern Germany The following study presents a concept for a sediment pollution cadastre and the results of systematic investigations of sediment contamination for eight toxic heavy metals and arsenic, as well as for eight classes of organic priority pollutants in all together 21 reaches in the Elbe and Oder waterway systems. Based on data from the years 1991 to 1995; multivariate statistical evaluations were carried out to identify local and temporal trends in the overall contamination. It was possible to differentiate between more non-point and point sources of sediment contamination. Because of the closure of substantial parts of the industry in Eastern Germany and by common sanitation efforts of both the German and the Czech sides since 1990, the situation in the Elbe river system with respect to the heavy metals has improved markedly. For the Oder river system, a comparable trend does not exist yet, and the sediment contamination by heavy metals is stagnant there. As a consequence, the pollution situation in both German parts of the rivers has become similar except for mercury and arsenic. Regarding organic pollutants, the picture is quite different. With the exception of PAHs, Oder sediments are contaminated by organics only to a lower extent and compare better with the ones from unpolluted waters found in parts of Brandenburg and Mecklenburg-Western Pomerania than with those of rivers Elbe, Mulde, and Saale with its tributaries. On the one hand, organic pollution generally also decreased since 1991 in these rivers. On the other hand, due to continuing inputs from plants in the Czech Republic and from old contaminated sites, both in Czechia and Germany, a decreasing trend is not significant or cannot be found at all for such pollutants as HCB, PCBs, or PAHs. The general trends are discussed in detail, e.g., by comparison with quality targets for sediments and suspended matter, and illustrated at the example of individual contaminants being typical for the overall situation.     

Schnelle und einfache Methode zur In-situ-Bestimmung von Schwefelwasserstoff in Gewässern und Sedimenten

A direct potentiometric measurement chain (pH₂S-electrode) for in situ determination of H₂S in aquatic habitats is proposed which works like a conventional glass electrode chain but with Ag, Ag₂S as reference electrode. In the pH range ≤6 pS_tot can be determined irrespective of varying pH values. As there is no liquid junction most of the well-known interferences in pS-measurement chains with an external reference electrode with liquid junction are diminished or avoided. Four methods for calibration of the pH₂S-electrode are discussed.      

Chlorphenole und Nonylphenole in Klärschlämmen. Teil I: Vorkommen in Klärschlämmen westdeutscher Kläranlagen aus den Jahren 1987 bis 1989

Chlorophenols and Nonylphenols in Sewage Sludges. Part I: Occurence in Sewage Sludges of Western German Treatment Plants from 1987 to 1989 Sewage sludges originating from all western German states from 1987 till 1989 have been analyzed for two groups of organic pollutants, which are not specified in the German sewage sludge regulations (Klärschlammverordnung) from 1992: the isomeric 4-nonylphenols and the chlorophenols. The applied analytical methods are presented, as well as the analytical results. In almost all 149 analyzed samples nonylphenols could be found, at an average of 128.2 mg/kg dry matter. In the case of chlorophenols, pentachlorophenol was the most pronounced in respect to amount and to frequency of positive results: i.e. in 85 samples investigated, the mean value was 59.5 μg/kg. Results are reported in percentils. The data correspond to sewage sludges from the past and will be used as a guideline in evaluating all following studies of sludges. Investigations will be continued.     

Petrographische,mineralogische und chemische Untersuchungen an Sedimenten in den Deltabereichen von Schussen und Argen

Summary The influence of suspended matter from Argen and Schussen, two affluents to the Lake of Constance, on the mouth areas has been determined by means of sediment samples. The results of the granulometric analysis prove an evident primary division of the ground, which is disturbed by allochthone materials. With increasing amount of coarse-grained material the water content of the sediments is decreasing. Quartz, carbonates and feldspars predominate close to the mouth. With progressive distance from the mouth they are mixed and replaced more and more by clay minerals, coming from affluents of the vicinity too. According to these changes an increase of autochthone components (calcite) takes place. The results of the chemical analysis show a large-faced pollution of the sediments by organic matter. In contrast to carbon and nitrogen autochthone organic phosphorus is mineralized until the analytical limit. Therefore the C/P-relation oscillates with the station where the sediment sample has been taken, but the C/N-quotient is nearly constant. As a proof for pollution of the sediments by organic matter the determination of total-ammonium is adapted. A high concentration gradient exists between interstitial water and lake water. An exchange takes place mainly at areas with polluted sediments, because the density of the Tubificidae population here is high too.