Table 7.2 Wastewater maximum quality limits (mg/L except where otherwise stated) in Oman
Parameter
Standards (See
Table 7.3)
A
B
Biochemical oxygen demand (BOD) (5d@20
C)
15
20
Chemical oxygen demand (COD)
150
200
Suspended solids (SS)
15
30
Total dissolved solids (TDS)
1500
2000
Electrical conductivity (EC) (micro S./cm)
2000
2700
Sodium absorption ratio (SAR) (The effect of Sodium on soil absorption) 10
10
pH (within range)
6–9
6 –9
Aluminum (as Al)
5
5
Arsenic (as As)
0.100
0.100
Barium (as Ba)
1
2
Beryllium (as Be)
0.100
0.300
Boron (as B)
0.500
1
Cadmium (as Cd)
0.010
0.010
Chloride (as Cl)
650
650
Chromium (total as Cr)
0.050
0.050
Cobalt (as Co)
0.050
0.050
Copper (as Cu)
0.500
1
Cyanide (total as CN)
0.050
0.100
Fluoride (as F)
1
2
Iron (total as Fe)
1
5
Lead (as Pb)
0.100
0.200
Lithium (as Li)
0.070
0.070
Magnesium (as Mg)
150
150
Manganese (as Mn)
0.100
0.500
Mercury (as Hg)
0.001
0.001
Molybdenum (as Mo)
0.010
0.050
Nickel (as Ni)
0.100
0.100
Nitrogen: Ammoniacal (as N)
5
10
: Nitrate (as NO 3 )
5 0
5 0
: Organic (Kjeldahl) (as N)
5
10
Oil and grease (total extractable)
0500
0.500
Phenols (total)
0.001
0.002
Phosphorus (total as P)
30
30
Selenium (as Se)
0.020
0.020
Silver (as Ag)
0.010
0.010
Sodium (as Na)
200
300
Sulfate (as SO 4 )
400
400
Sulfide (total as S)
0.100
0.100
Vanadium (as V)
0.100
0.100
Zinc (as Zn)
5
5
Faecal coliform bacteria (per 100 mL)
200
1000
Viable nematode ova (per litre)
<1
<1
7 A Two-Stage Constructed Wetland Design Integrating Artificial Aeration and. . .
201