Page 57 - GRIHA Manual Volume IV - Introduction to National Rating System
P. 57
48 Griha Manual: Volume 4
Efluent water quality standards
The Central Pollution Control Board has developed the National Standards for effluent under the
statutory powers of the Water (Prevention and Control of Pollution) Act, 1974. These standards were
notified by the Union Ministry of Environment and Forests, Government of India, under Section 25
of the Environment Protection Act, 1986.
Water quality standard plays an important role in the implementation of wastewater reuse policy
in various sectors. Standards are the basis on which the treatment levels and possible application
could be fixed. However, in India, wastewater reuse standards are only for agricultural use/irrigated
land. The other standards are for disposal of discharges into inland surface and public sewers as
given in Table 1.
Table 1 Standards for discharge of environmental pollutants elements
Sl. No. Parameters Discharge into
Inland surface Public sewers Land for irrigation
1 Suspended solids mg/l, maximum. 100 600 200
2 Particulate size of suspended solids Shall pass 850 micron sieve — —
3 pH value 5.5–9.0 5.5–9.0 5.5–9.0
4 Temperature Shall not exceed 5 C above the receiving — —
0
water temperature
5 Oil and grease mg/l, maximum 10 20 10
6 Total Residual Chlorine, mg/l, maximum 1 — —
7 Ammonical Nitrogen (as N) mg/l, 50 50 —
maximum
8 Free Ammonia (as NH3 ), maximum 5 — —
9 Biological oxygen demand (5 days at 20 30 350 100
0 C) mg/l, maximum
10 Chemical Oxygen Demand mg/l, 250 — —
maximum
11 Boron, mg/l, maximum 2
12 Total Coliform MPN/100 ml, maximum 10 000
13 Faecal coliform MPN/100 ml, maximum 5000
14 Faecal streptococci MPN/100 ml, 1000
maximum
Source: CPCB (1998)
The World Health Organization (WHO) recommends that treated wastewater for unrestricted
irrigation should contain less than 1000 number/100 ml faecal coliform and less than one helminth
egg per litre. This limit is suggested to be observed strictly to avoid any risk of transmitting parasites.
The MoEF /CPCB standards, however, give more flexibility ranging from 1000 mpn/100 ml to 10 000
mpn/100 ml (maximum permissible).
Solution
Basic principles of wastewater treatment
Depending on the reuse application/discharge of wastewater, it is necessary to treat raw wastewater
to meet specific needs and public safety. Pollutants in wastewater could be removed by physical,
Efluent water quality standards
The Central Pollution Control Board has developed the National Standards for effluent under the
statutory powers of the Water (Prevention and Control of Pollution) Act, 1974. These standards were
notified by the Union Ministry of Environment and Forests, Government of India, under Section 25
of the Environment Protection Act, 1986.
Water quality standard plays an important role in the implementation of wastewater reuse policy
in various sectors. Standards are the basis on which the treatment levels and possible application
could be fixed. However, in India, wastewater reuse standards are only for agricultural use/irrigated
land. The other standards are for disposal of discharges into inland surface and public sewers as
given in Table 1.
Table 1 Standards for discharge of environmental pollutants elements
Sl. No. Parameters Discharge into
Inland surface Public sewers Land for irrigation
1 Suspended solids mg/l, maximum. 100 600 200
2 Particulate size of suspended solids Shall pass 850 micron sieve — —
3 pH value 5.5–9.0 5.5–9.0 5.5–9.0
4 Temperature Shall not exceed 5 C above the receiving — —
0
water temperature
5 Oil and grease mg/l, maximum 10 20 10
6 Total Residual Chlorine, mg/l, maximum 1 — —
7 Ammonical Nitrogen (as N) mg/l, 50 50 —
maximum
8 Free Ammonia (as NH3 ), maximum 5 — —
9 Biological oxygen demand (5 days at 20 30 350 100
0 C) mg/l, maximum
10 Chemical Oxygen Demand mg/l, 250 — —
maximum
11 Boron, mg/l, maximum 2
12 Total Coliform MPN/100 ml, maximum 10 000
13 Faecal coliform MPN/100 ml, maximum 5000
14 Faecal streptococci MPN/100 ml, 1000
maximum
Source: CPCB (1998)
The World Health Organization (WHO) recommends that treated wastewater for unrestricted
irrigation should contain less than 1000 number/100 ml faecal coliform and less than one helminth
egg per litre. This limit is suggested to be observed strictly to avoid any risk of transmitting parasites.
The MoEF /CPCB standards, however, give more flexibility ranging from 1000 mpn/100 ml to 10 000
mpn/100 ml (maximum permissible).
Solution
Basic principles of wastewater treatment
Depending on the reuse application/discharge of wastewater, it is necessary to treat raw wastewater
to meet specific needs and public safety. Pollutants in wastewater could be removed by physical,
