Table 3.10
(continued)
Index
Parameter
Application limits
Sub-index function
Weight
Aggregation function
Water-quality
classification
Liou
Dissolved oxygen
(mg/L)
>6.5 IDO
¼ 1 4.6–6.5
IDO
¼ 3
–
IWQI
¼
1
4 :
P
4
i¼1 I
i
<2
¼ good
2–3
¼ slightly polluted
3.1–6
¼ moderately
polluted
>6
¼ very polluted
2–4.5 IDO
¼ 6
<2 IDO
¼ 10
BOD5 (mg/L)
<3 IBOD
¼ 1
3–4.9 IBOD
¼ 3
5–15 IBOD
¼ 6
>15 IBOD
¼ 10
Suspended solids
<20 ISS
¼ 1
(mg/L)
20–49 ISS
¼ 3
50–100 ISS
¼ 6
>100 ISS
¼ 10
Ammonia nitrogen
<0.5 INH3-N
¼ 1
(mg/L)
0.5–0.99 INH3-N
¼ 3
1–3 INH3-N
¼ 6
>3 INH3-N
¼ 10
84
H. A. Aziz et al.