Hidrológiai Közlöny 1972 (52. évfolyam)

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

Horváth I.: Recirculation in activated — sludge treatment Hidrológiai Közlöny 1972. IV. sz. 437 G *e 3.3 Organic suspended solids in the effluent Assuming steady conditions Eq. (3) is solved for (A-B

fB

g)G

l Ge=1 -Br relating G

c to A. The values of RQ or II

F and GL or G

R

, respectively, are found from Eqs. (7) and (9) as RQ = GL — OR-G L — Ge

( 1 — lib') — It FGR Gn-Gj, _ AGl—GP 't F — s i /- y , G

K(R

Q+R

F) + G

e(l-R

F) 1 +BQ Ql(1+BQ)-G.(1-RF) Rq+RF (10) (11) (12) (13) It should be noted that neglecting both endogenous respiration and removal of excess sludge {k

e—0; R

f—

0), Eqs. (6), (8) and (9) reduce the equations derived by Herbert [2]. The above equations have been adojited by several authors in the field of sewage treatment technology, first of all for the analysis of the effect of detention time. With A=

0; (G

e=

0; R

F=0) Eqs. (10) and (12) yield the relationships applied by Hörler [4]. 3.4 Specific rate of sludge growth Under steady conditions is expressed from Eq. (2) directly. ri—AD + k

e. (14) With k

e=

0, Eq. (14) can be rewritten to give the relationship applied by Schulze [5]. 3.5 Sludge age and excess sludge Sludge age can be found from the relationship [1] G

L VL-GL 1 h = Gjsz Q„(Gc+B

fGR) N-ke whence — in the konwledge of Eqs. (9) and (14) the simple expression ,

k=Al) Ik Ce ~c

n 1 n ( r< ma

x _ . J :

m \Al) + ke J (IT) 4. Analysis of the mathematical relationships on the basis of test data Test data have been used to plot some of the relationships formulated above. As a starting basis, the kinetic constants determined from VITUKI-measurements were used [1]. Values of the parameters and kinetic constants are as follows : Co—

72.5 mg/1; K

m=

21.« mg/1; r

i

m„=0.155h '; /ie—0.0029 h y

A=0.673. On the figures the factor .4 has been plotted as (he dependent variable. The parameter I) is that corresponding to 2, 5 and 10 hours detention time. The C

e vs. A relation is plotted in Fig. 2. In the case of C'c —oo and C

e—

0, resp. the characteristic extreme points and asymptotes of the curves are: (18a—b) and ^4—0, resp., or Z>=

0, 1 4

n max — ke . . ke -> ß , and A — —jy> resp. However, if A — then C

e — — Km, and C

e = K, n r resp. (18c

—d) k

e 1 In Fig. 3 the G

L vs. A relation is illustrated. The characteristic points and asymptotes of the curves are for G

L — oo

: r% max — I ,and A = lr, D • ö'

re8

pHowever, for GL= 0, and ^4 — 0, resp. (19a—b) rix K„ ~C~

n •k, - + 1 and n D ' f/h (si Km • ke \ GL = —J

— TV res

pt^ e \ ' i max A &) (19c—d) (15a) In f igures 4a

—b, the X

l

: vs. A relation is plotted. The characteristic points and asymptotes of the curves are: with X

k 1, of course, Eq. (18b) is obtained, while, if .4->-oo and ^4 = 0, or D—

0, then X

k=\ + Kn C n (lob) and is obtained. On the other hand, from Eq. (15a

—b) the quantity of excess sludge is

: =AD-GL • (16) X

k=\ — 1 C

c -, resp. (20a—b) 3.6 Efficiency of treatment From Eq. (6), the expression relating the efficiency of treatment to the recirculation factor can be formulated as which is also in accordance with Eq. (18c—d). In Fig. 4b a set of observation data have also been plotted. The data originate from an operational survey of the PÉCS-scwage treatment plant (22 000 cu.m/dav). Although the points scatter considerably they are seen to be concentrated around the theoretical curve. Averaging the values A and X

k from a record of two months, the points connected by a full line were plotted, approaching the theoretical curve fairly well. Instead of analysing further variables, the result of a series of hydraulic tests are shown in Fig. 6.