A better efficiency of the reservoirs of water is a prerequisite to meet the arising requirements. The order of application of the water-reservoirs in the GDR in dry a tmospheric conditions is 90 a, ', , and in normal atmospheric conditions about 44 o/o, (REICHELT). A better application of the water will be reached by intensifying the clarification plants whereby the energy consumption will be reduced simultaneously. I n 1980 the energy consumption was 570000 kWh for 106 m3 of sewage.The behaviour of the current of the aqueous phases in two biological clarification plants with different operating conditions was studied using radio-tracer techniques. ( K~N N E C K E ,OTTO and HECHT; OTTO e t al.) The task was to improve the run of the process. The schemes of both the examined clarification plants are given in fig. 1. The clarification plant I consists of two settling pools, pool I being furnished with a n airing impeller was working like an activated sludge chamber. The volume of inlet was 730 m3/h, the velocity of flow into pool I averaged 50 cm/s, t'hat into pool I1 100 cm/s. 30*

An analytical registration of P-transport processes in intact sediment cores from the shallow reservoir Radeburg I1 (near Dresden, Saxonia, Germany) was possible by application of KH232P04 and followed by sequential P-fractionation (PSENNER et al. 1984). Under oxygen free conditions and sufficient nitrate supply an activity accumulation was found in the uppermost sediment horizon. Nitrate influences above all the BD-fraction (reductant soluble P), so that an interaction between nitrate and the iron binding system could be proved. It could be shown by means of activated sludge (a model object for microbial polyphosphate accumulation from a lab plant qualified for biological P-and N-elimination) that added KH232P04 was bound within 5 h to about 75 % in the NaOH-fraction. The saturation of iron compounds in the activated sludge took place immediately after KH23*P04 had been added. In the same time the portion of the microbial immobilization of added 32P amounted to 7 % in the high-iron sediment from the Radeburg reservoir, whereas evidently in the heat-and HgCI2-sterilized sediments this portion was additionally ascertained in the BD-fraction, too,

Ein Vergleich der 14C‐Isotopeneffekte bei der Verseifung von Benzoesäure‐benzylester und der Cannizzaro‐Reaktion mit Benzaldehyd führt zur Ablehnung eines intramolekularen Reaktions‐mechanismus. Für die Cannizzaro‐Reaktion des Benzaldehyds, p‐Chlor‐benzaldehyds und Thiophen‐aldehyds‐(2) wird der kinetische 3H‐Isotopeneffekt bestimmt. Die Reaktionsge‐schwindigkeit der Cannizzaro‐Reaktion des Benzaldehyds erhöht sich vom Lithiumhydroxid zum Cäsiumhydroxid. Für den Ablauf der Cannizzaro‐Reaktion nach III. Ordnung wird ein Chelatmechanismus vorgeschlagen.

S'LlUL?>L@r?J:The behaviour of the herbicide bromoxynil (3,5-dibromo-4-hydroxybenzonitrile), labelled with 82Br, is investigated in a n activated sludge plant on the laboratory scale with municipal wastewater. Only 5 o/o of bromoxynil present in a concentration of 5 mgil are degraded after preadaption of activated sludge for some weeks. The known hydrolysis products 3,5-dibromo-4-hydroxybenzamide and 3,5-dibromo-4-hydroxybenzoic acid were identified as degradation products. I n addition, 1.9$0.9 O/o of the quantity of R2Br appeared in the solution as Br-by debromination. Moreover, a pronounced adsorption of the active substance on activated sludge occurs. I t s activity amounts to about 130 o ! ,, of the initial activity of the solution.

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