I. Procedures to calculate K
oc
1. Assume n number of solutions with initial concentration
in the interested range for the compound and in contact
with m grams of soil.
2. Based on Freundlich model, calculate the total mass
sorbed onto the soil particles in each solution (Xl)
using the Freundlich sorption coefficients obtained
from the batch study with sludge.
3. Calculate the total mass sorbed onto the soil particles
in each solution (X2) using the Freundlich sorption
coefficients obtained from the batch study without
sludge.
4. The difference between X1 and X2 is the amount sorbed
to the organic carbon (o.c.) in the added sludge.
5. Use (X1-X2) values to calculate the equilibrium
concentrations (Ce)
n
6. Based on the values of [(X1-X2)/o.c.] and (Ce) an
isotherm can be constructed and K can be calculated.
oc
II. A program for equilibrium concentration calculations:
10 INPUT M,V,CO
20 READ KF,B
30 REM M=mass of soil (g), V=volume of solution (ml),
CO=initial concentration (mg/l), B=exponent,
KF=Freundlich sorption coefficient, X= total mass of
compound sorbed onto soil
40 H=CO*V/25 : X2=0
60 X1=X2 : X2=X1+H
70 IF CO<=X2/V THEN GOTO 140
100 Y1=M*KF*(CO-X1/V)^B-X1
110 Y1=M*KF*(CO-X2/V)^B-X2
120 SG=Y1*Y2 : IF SG>0 THEN GOTO 60
140 X=(X1+X2)/2 : ER=ABS((X2-X1)/2)
150 Y=M*KF*(CO-X/V)^B-X
160 IF Y=0 THEN GOTO 290
170 IF ER<=0.00001 OR (ER/X)<=0.00001 THEN GOTO 290
180 IF Y1*Y <0 THEN GOTO 200
190 X1=X : GOTO 140
200 X2=X : GOTO 140
290 CE=CO-X/V
300 PRINT KF, B, CE, X : GOTO 20
400 DATA KF(1), B(1), KF(2), B(2), ......, KF(n), B(n)