Hidrológiai Közlöny 1972 (52. évfolyam)

10. szám - Horváth Imre: A recirkuláció szerepe eleveniszapos szennyvíztisztító rendszerekben

438 Hidrológiai Közlöny 1972. 10. sz. Horváth I.: Recirculation in activated — sludge treatment D=0t1h —0=0,2/7": D=0,5h'' 1 0,5 Recirculation factor

; A H

1 ig. 2

—

4. Variation of C

E, GL and Xk as a function of recirculation factor A Recirculation factor, A Fig. 4a-b. Recirculation, R& Fig. 5. Variation of hydraulic efficiency as a f unction of If Q 0,5 0,0 Recirculation factor, A The data originate from tests performed with tap water and tracer material. The experimental equipment comprised a 125 lit. aeration tank (turbine aeration system), and a 60 lit. secondary settling tank (Dortmund type). The relationship between the hydraulic efficiency (ratio of the active to the total tank volume) and the factor RQ is illustrated. The maximum efficiency was found in the environment of Rq=1, which can naturally be considered as an empirical value. Lastly it should be mentioned that measurements have also been carried out in equipment of various sizes to determine a practical value of the factor A. In a laboratory scale model, small values of R

G could only be realised, because of the small thickening effect of the settling tank, as a result of which the value A varied between 4-I.o-h

—1.5. Evaluating the data of several months for a full-scale plant, A was found to vary between +0.5-;

—0.5, in general. It should be added that in the case of a full-scale plant Schulze calculated values of 0,149 -i-0,344. He also mentioned negative values for A [5]. Conclusions A

) The recirculation factor A determined by the parameters RQ and R

G is important in characterizing activated sludge sewage treatment technology. The