Determination of permissible concentrations of pollutants in the wastewater of the enterprise
Permissible concentrations (DC) of pollutants in wastewater from enterprises are determined based on the following conditions:
1. DC of a pollutant in the sewer network (at the outlet of the enterprise) is accepted according to Appendix 1 to the Rules for the acceptance of wastewater from enterprises into municipal and departmental sewerage systems in settlements of Ukraine.
2. DC of a pollutant in biological treatment facilities (at the entrance to these facilities) is determined by the formula:
, g/m3
where is the DC of the pollutant in the aerotank, g/m3 (accepted according to Appendix 2 to the Rules for the acceptance of wastewater from enterprises into municipal and departmental sewerage systems of settlements in Ukraine or according to the project of urban treatment facilities);
— average daily wastewater consumption at the inlet to the treatment plant, m3/day (equal to 500,000 m3/day);
— average daily consumption of wastewater from enterprises that may contain this pollution, m3/day (equal to 200000 m3/day, for chromium6+, chromium3+ and cadmium it is 100000 m3/day, for sulfides 50000 m3/day).
— concentration of a pollutant in domestic wastewater, g/m3.
3. The limits for the discharge of pollutants into the reservoir, which are set for Vodokanals by the bodies of the Ministry of Energy and Resources of Ukraine in permits for special water use. The DC of a specific pollution by the value of the total limit for its discharge into a reservoir is calculated by the formula:
,g/m3,
where , t/year - part of the limit, which falls on the domestic wastewater of the settlement;
365 is the number of days in a year;
Qxb is the average daily consumption of domestic wastewater in a given city, m3/day (equal to 300,000 m3/day);
— average daily consumption of wastewater from enterprises that may contain this pollution, m3/day (equal to 200,000 m3/day);
TOR - coefficient of efficiency of removal of this pollution at urban wastewater treatment plants (accepted according to Appendix 2 to the Rules for the acceptance of wastewater from enterprises into municipal and departmental sewerage systems of settlements in Ukraine or according to the project of urban wastewater treatment plants);
, t/year
where Qcommon — annual amount of wastewater;
MPCwaters — MPC of a pollutant in a reservoir for drinking and domestic water use, g/m3 (accepted according to Table 1 of SanPiN No. 4630-88) .
Of these three values, the smallest is set as DC.
The results of the DC calculation are shown in Table 4.4
Table 4.4 DC of pollutants in wastewater from the enterprise
|
Name of pollutant |
Cst |
DC1 |
WITHi |
DC2 |
MPC |
LPV |
KO |
TOR |
DC3 |
DCR |
|
pH |
6,5-9,0 |
— |
— |
— |
— |
— |
— |
— |
6,5-9,0 |
|
|
suspended solids |
500 |
— |
— |
30,75 |
— |
— |
0,95 |
360 |
360 |
|
|
BOD5 |
350 |
— |
— |
6 |
— |
— |
0,95 |
435 |
435 |
|
|
Oil products |
20 |
10 |
24,25 |
0,3 |
org |
4 |
0,85 |
4,16 |
4,46 |
|
|
Fats |
50 |
50 |
5 |
— |
— |
— |
— |
— |
5 |
|
|
sulfates |
400 |
500 |
800 |
500 |
org |
4 |
— |
775 |
400 |
|
|
chlorides |
350 |
350 |
500 |
350 |
org |
4 |
— |
482,5 |
350 |
|
|
surfactant |
— |
20 |
42,5 |
0,5 |
org |
4 |
080 |
0,5 |
0,5 |
|
|
Iron |
— |
2,5 |
3,25 |
0,3 |
org |
3 |
0,50 |
0,3 |
0,3 |
|
|
Copper |
— |
0,5 |
1,25 |
0,1 |
org |
3 |
0,40 |
0,408 |
0,408 |
|
|
Zinc |
— |
1,0 |
2,5 |
1,0 |
common |
3 |
0,30 |
3,5 |
2,5 |
|
|
Nickel |
— |
0,5 |
1,25 |
0,1 |
s-t |
3 |
0,50 |
0,49 |
0,49 |
|
|
Cadmium |
— |
0,01 |
0,05 |
0,001 |
s-t |
2 |
0,80 |
0,019 |
0,019 |
|
|
Chrome6+ |
— |
2,5 |
7,5 |
0,5 |
s-t |
3 |
0,50 |
3,92 |
3,92 |
|
|
Chrome3+ |
— |
0,1 |
0,5 |
0,05 |
s-t |
3 |
0,50 |
0,39 |
0,39 |
|
|
Ammonia nitrogen |
— |
30 |
45 |
1,0 |
s-t |
3 |
0,60 |
1,0 |
1,0 |
|
|
Nitrites |
— |
3,3 |
8,25 |
3,3 |
s-t |
2 |
— |
8,09 |
8,09 |
|
|
Nitrates |
— |
45 |
45 |
45 |
s-t |
3 |
— |
110,25 |
45 |
|
|
Phosphates |
— |
10 |
10 |
3,5 |
common |
4 |
20 |
3,5 |
3,5 |
|
|
Sulfides |
1,5 |
1,0 |
2,5 |
common |
3 |
— |
1,5 |
|||
|
Fluorides |
— |
— |
— |
1,5 |
— |
— |
— |
— |
1,5 |
We will assess the quality of wastewater according to the calculated allowable concentration. The results of the evaluation in table. 4.5
Table 4.5 Evaluation of wastewater quality according to the calculated DC
|
No. p / p |
Name of indicator |
Concentration, mg/l |
Grade |
|||
|
Permissible |
Actual |
|||||
|
KK-7A |
KK-19 |
K-19 |
||||
|
1 |
pH |
6,5-9,0 |
6,8-7,87 |
6,5-7,21 |
7,1-8,9 |
+ |
|
2 |
suspended solids |
360 |
350,0 |
322,3 |
154,0 |
+ |
|
3 |
BOD5 |
435 |
112,0 |
85,4 |
359,2 |
+ |
|
4 |
Oil and oil products |
4,46 |
4,3 |
1,98 |
4,0 |
+ |
|
5 |
Fats |
5,0 |
50,0 |
2,5 |
1,0 |
— |
|
6 |
sulfates |
400 |
206,0 |
288,0 |
365,0 |
+ |
|
7 |
chlorides |
350 |
231,0 |
208,0 |
322,0 |
+ |
|
8 |
surfactant |
0,5 |
0,194 |
0,11 |
0,18 |
+ |
|
9 |
Iron |
0,3 |
0,01 |
0,25 |
0,07 |
+ |
|
10 |
Copper |
0,408 |
0,02 |
0,005 |
0,005 |
+ |
|
11 |
Zinc |
2,5 |
0,05 |
0,002 |
0,004 |
+ |
|
12 |
Nickel |
0,49 |
0,2 |
0,08 |
0,09 |
+ |
|
13 |
Cadmium |
0,019 |
0,01 |
0,009 |
0,009 |
+ |
|
14 |
Chrome 3+ |
3,92 |
0,02 |
0,01 |
0,01 |
+ |
|
15 |
Chrome6+ |
0,39 |
0,002 |
0,002 |
0,002 |
+ |
|
16 |
Ammonia nitrogen |
1,0 |
0,9 |
0,7 |
0,02 |
+ |
|
17 |
Nitrites |
8,09 |
0,04 |
1,7 |
2,64 |
+ |
|
18 |
Nitrates |
45 |
0,95 |
4,24 |
12,65 |
+ |
|
19 |
Phosphates |
3,5 |
3,1 |
2,55 |
1,8 |
+ |
|
20 |
Sulfides |
1,5 |
1,5 |
1,2 |
1,5 |
+ |
|
21 |
Fluorides |
1,5 |
0,16 |
0,9 |
1,1 |
+ |
According to the calculation of permissible concentrations, the wastewater of the enterprise does not correspond to the following indicators: fats.
Calculation of auxiliary parameters
one). Definition of the Chezy coefficient:
C=() Rv,
Where R is the hydraulic radius, m (for summer conditions R = Нср);
Y is the coefficient determined by the formula 1.3 Psh;
Psh is the roughness coefficient of the river bed;
C is the Chezy coefficient, m/s.
=1,3*1,05=1,36
C \u003d () * 31.36 \u003d () * 4.08 \u003d 3.7 m1 / 2 / s
2).Determination of the coefficient of turbulent diffusion:
D = g*VWed*HWed/(37*Pw*С2)
Where D is the coefficient of turbulent diffusion;
g is the free fall acceleration, m/s2;
HWed — average depth, m;
Vcp is the average velocity of the river flow, m/s;
Pw is the roughness coefficient of the river bed;
WITHm — Shezy coefficient, m1/2/s.
D===0.03
3). Determination of the coefficient taking into account the hydraulic conditions in the river:
=, where:
— coefficient taking into account the hydraulic conditions in the river;
J is the meanness of the river - 1.3;
- coefficient depending on the place of wastewater discharge = 1.5;
D is the turbulent diffusion coefficient;
g - free fall acceleration, m/s;
=1,3*1,5*=0,46
4). Definition of mixing ratio:
=-2, where:
is the mixing ratio;
is the base of the natural logarithm, e = 2.72;
L is the distance from the outlet to the section under consideration, m; L =500 m,
Q - river flow rate, m / min;
— coefficient taking into account the hydraulic conditions in the river.
=
5). Determination of the dilution factor:
n=, where:
P - dilution ratio;
q - waste water consumption, m / min;
Q - river flow rate, m / min;
— mixing ratio.
n=
Thus, we have determined the coefficients that will help in further calculations.
