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.     

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.     

Ein Beitrag zur Bestimmung von partikulärem organischen Kohlenstoff in Wasserproben

The method after Strickland and Parsons is modified for fresh water as follows: filtration on glass-fibre paper, oxidation with K₂Cr₂O₇ in cone. H₂SO₄ for 2 h at 130 °C, dilution to 2.5 times the volume by aqua dest., centrifuging-off of the turbidity and extinction measurement at 445 nm against the blank value, the sample solution being balanced to the transmission of 100% (extinction = 0). Here, the following calibration line holds for the concentration C and the quantity of oxidation solution Ox: C = E_1cmc · 0.162 · Ox, C in mg filter. The oxidation solution contains 4.8 g K₂Cr₂O₇ as dissolved in 20 ml aqua dest. and made up with conc. H₂SO₄ to 11. With 5 ml of this solution one is able to determine 0.05 … 1 mg C/filter. Calibration is performed with 125 mg/l glucose solution. Comparative investigations have shown a good agreement with elementary-analytically obtained measured values. The occurring errors have been determined mainly by sampling. In the range of very small values we have to take into account a blank value of the filter due to the adsorption of dissolved organic substances on the filter.     

Hydrochemische Ergebnisse zur Aufbereitung stark belasteter Oberflächenwässer und Uferfiltrate mit Kalkhydrat,Teil 1

Several laboratory-scale-tested variants of the treatment of organically loaded surface water samples with hydrated lime are described. Possibilities of the additional application of magnesium, aluminium and iron salts and of the anionic polymer “activated silicic acid” are discussed. The aim has been a considerably reduced application of metallic salts and precipitants at a maximum adsorption of organic pollutants. Another factor influencing crystallization and double hydroxide formation consists in low water temperatures, < 8°C. With the aid of a magnetic treatment disturbing effects were avoided and even increases of the rates of growth and sedimentation were achieved.     

On-Line Monitoring mit Biosensoren am Gewässer zur ereignisgesteuerten Probenahme

Biosensors for On-Line Monitoring of Waterways for Sample Taking Aimed at Relieving Disturbances. There is a generally accepted need for rapid, simple and low cost online water quality monitors. Besides the chemophysical analytical methods the biological and biochemical methods are of increasing importance for the integral monitoring of pollutants. Electrodes made up of cyanobacteria, i.e. Synechococcus, for immediate detection of acute toxic effects of pollutants, are used as a biosensor. The measurements of the photosynthetic electron transport system PETS under alternating light–dark conditions, are conducted in a flow-through cell against reference electrodes (Ag/AgCl). A mediator (Fe(II)/Fe(III)) makes the flow of current possible. The time which the electrode takes to react is about two minutes, and a multiple confirmed result is available after ten minutes (Detection limit for Atrazine = <20 μg/L Atrazine). Similar investigations were done with an E. coli-electrode.