ASSESSMENT OF POLLUTION LOAD
WITH RESPECT TO HEAVY METALS FROM THE WASTEWATER OF SOME INDUSTRIAL AREAS OF
DELHI, INDIA.
Manju Rawat*, M.C.Z. Moturi1, V. Subramanian2
School of Environmental
Sciences, Jawaharlal Nehru University, New Delhi-110067. India.
1Kenya Industrial
Research and Development Institute (KIRDI). P.O. Box 30650 Nairobi, Kenya.
2Corresponding
Author: e-mail: subra@jnuniv.ernet.in,
Telfax: +91-11- 6106501.
ABSTRACT
Delhi with the population over 11
million has the highest cluster of small-scale industries in India. It
generates 2,270 million litres of wastewater, out of which 300 million litres
per day is industrial wastewater. Indiscriminate disposal of industrial
effluents by many of the units into surface water, and specifically into the
river Yamuna (a tributary of the Ganges and a major source of water in Delhi)
has been a cause of environmental degradation in recent years. In order to
study the pollution load with respect to heavy metals, wastewater samples were
collected thrice from seven industrial areas namely¾ Wazirpur, Badli, Naraina,
Patparganj, Okhla, Jhilmil, and Mayapuri during 1997 and 1998. The
concentration of heavy metals was measured using the GBC, Atomic Absorption
Spectrometer, Model 902. The samples were analysed for pH, EC, Fe, Mn, Cu, Zn,
Ni, Cr, Cd, Co and Pb. It can be observed that the low pH range often lead to
high dissolution thereby causing mobility of the toxic heavy metals. The
results were compared with the prescribed standards under the Indian Environment
(Protection) Act, 1986. The mean concentration values obtained were found to be
higher than the standards.
INTRODUCTION
Delhi, National Capital Territory (NCT) of India has
highest number of Small Scale Industries (SSI) in the country. There are 1,28,000
industrial units (Office of the Commissioner of Industries, Delhi, 1996)
present in twenty-eight industrial zones (NEERI Survey 1997). The waste
originates from many spheres of human activities (urban, municipal and
industrial sectors). The industrial wastes are considered to be more
troublesome as they contain many toxic metals and hazardous chemicals, which
are slow in degradation, thus causing hazards to human health, living organisms
and ecosystems (Gasana et al., 1997, Moore 1991, Shiv Kumar et al.,1997).
The nature of the industrial
activities operating in Delhi vary from fabrication of garments, dyeing,
electrical appliances, consumer electronics, printing and publishing, glass,
electroplating and steel processing. The waste emanating from these activities
is often disposed-off untreated. The wastewater are usually discharged into
open storm drains, which link-up with others, eventually emptying their
contents into the Yamuna. It is estimated that 2,270 million (Aggarwal, 1997)
of sewage and industrial effluents are discharged into the Yamuna river daily,
resulting in the deterioration of it’s water quality and aquatic flora and
fauna. This work seeks to study the nature and level of toxic heavy metals
arising from a cross-section of the zones representing the regional spread of
the industrial belt of Delhi (Figure 1).
METHODS
The wastewater samples were
collected from the seven industrial areas of Delhi. Sampling was done three
times in the year 1998-99 and samples were kept at 4oC temperature
to avoid further contamination and chemical changes in it. The wastewater
samples were treated according to the standard procedures (APHA, 1995). The
quantitative estimation of the toxic heavy metals was carried out using the
GBC, model 902 atomic absorption spectrophotometer.
RESULTS AND
DISCUSSION
The results are summarised in Table
1,2 and Figure 1 shows Delhi with study sites.
Table 1: Mean Heavy Metal Concentrations (mg/L) in Wastewater from some Industrial areas of Delhi, India.
|
Serial No. |
Site Ref: |
No. of Samples |
pH |
EC |
Fe |
Mn |
Cu |
Zn |
Ni |
Cr |
Co |
Cd |
Pb |
|
1 |
Standards* (for Inland surface water |
- |
5.5-9.0 |
- |
3 |
2 |
3 |
5 |
3 |
2 |
- |
2 |
0.1 |
|
2 |
JL |
41 |
6.8 |
3.4 |
31 |
2.0 |
1.5 |
1.3 |
0.9 |
0.2 |
0.19 |
0.09 |
0.65 |
|
3 |
PAT |
46 |
7.5 |
1.8 |
2.4 |
0.3 |
0.2 |
0.2 |
0.6 |
1.4 |
0.16 |
0.09 |
0.34 |
|
4 |
NAR |
32 |
7.4 |
1.6 |
1.6 |
0.6 |
0.3 |
0.2 |
0.6 |
0.5 |
0.20 |
0.09 |
0.47 |
|
5 |
MAY |
38 |
7.9 |
2.3 |
3.7 |
0.3 |
0.7 |
0.2 |
0.8 |
16 |
0.16 |
0.08 |
0.28 |
|
6 |
WAZ |
74 |
2.6 |
5.4 |
208 |
35 |
20 |
2.5 |
11 |
53 |
0.55 |
0.08 |
0.35 |
|
7 |
BAD |
37 |
2.7 |
2.9 |
212 |
39 |
17 |
5.3 |
6.1 |
21 |
0.36 |
0.07 |
0.66 |
|
8 |
OKH |
24 |
8.4 |
2.4 |
6.5 |
0.4 |
0.5 |
ND |
ND |
ND |
0.01 |
0.01 |
ND |
*Source - The
Environment (Protection) Act 1986, ND-Not Detected
JL- Jhilmil, PAT-
Patparganj, NAR- Naraina, MAY- Mayapuri, WAZ- Wazirpur, BAD- Badli, OKH- Okhla
Industrial Area.
Table 2: Mean Annual
Fluxes of Heavy Metal (Kg/yr) in
Wastewater from some Industrial Areas of Delhi, India.
|
Site Ref: |
JL |
PAT |
NAR |
MAY |
WAZ |
BAD |
OKH |
Mean |
|
Discharge Rate(m3/h) |
660 |
360 |
871 |
431 |
662 |
428 |
257 |
Annual Flux |
|
Fe |
181003 |
7590 |
11991 |
13803 |
1204935 |
795710 |
14696 |
318532 |
|
Mn |
11759 |
795 |
4671 |
1185 |
201751 |
145307 |
801 |
52324 |
|
Cu |
8729 |
531 |
2571 |
2486 |
116891 |
62646 |
1072 |
27847 |
|
Zn |
7417 |
669 |
1220 |
604 |
14439 |
19736 |
ND |
7348 |
|
Ni |
5039 |
1755 |
4402 |
2933 |
63712 |
22880 |
ND |
16787 |
|
Cr |
1194 |
4331 |
3861 |
60607 |
305972 |
78605 |
ND |
75762 |
|
Co |
1083 |
491 |
1502 |
596 |
3188 |
1359 |
32 |
1179 |
|
|
519 |
273 |
660 |
296 |
484 |
258 |
14 |
358 |
|
Pb |
3730 |
1069 |
3599 |
1070 |
2053 |
2461 |
ND |
2330 |
ND-Not Detected, JL- Jhilmil, PAT- Patparganj, NAR- Naraina,
MAY- Mayapuri, WAZ- Wazirpur, BAD- Badli, OKH- Okhla Industrial Area.
The mean pH of wastewater in these industrial zones varies from
3- 8. Jhilmil, Partparganj, Naraina, and Mayapuri have showed pH 6-8 and within
prescribed standards (The Environment Act, 1986), whereas Badli and Wazirpur
had pH as 2.6 and 2.7 respectively (Table 1), which is much below the standards
for disposal to surface water. The low pH is due to the pickling industries.
Iron was found in very
high concentration of in Badli (212 mg/L) and Wazirpur (208 mg/L) compared to
other industrial zones. Jhilmil 31 mg/L, Okhla 7 mg/L and Mayapuri 4 mg/L Fe in
their wastewater (Table 1), which is higher than the standards prescribed for
disposal. The concentration of Mn varies from 0.3- 39 mg/L. Badli,
Wazirpur and Jhilmil have showed Mn higher than the prescribed limits. This high value Fe and Mn in Badli, Wazirpur
and Jhilmil is due to steel processing industries in these zones.
Mean concentration of Cu
varies from 0.2 to 20 mg/L and Zn ND to 5 mg/L. Wazirpur have showed highest
concentration of Cu 20 mg/L, followed by Badli (17 mg/L). All other industrial
areas have Cu within norms of their discharge (Table 1).
Mean concentration of Ni
and Cr vary from ND- 11 and ND-52 mg/L respectively. Ni was found in
higher concentration than the prescribed standards (Table 1) in Wazirpur (11
mg/L) and Badli (6 mg/L), whereas Cr concentration was 53 mg/L Wazirpur, 21
mg/L Badli, 16 mg/L in Mayapuri. The source of Ni and Cr in the wastewater is
Ni-Cr alloy electroplating industries (CPCB, 1986 report).
Cupper, Cd and Pb were estimated in lower concentration than other heavy
metals (Table 1). Concentration of Co 0.01- 0.6, Cd 0.01-0.09 and Pb ND-0.7
mg/L. Cd was found within the norms of discharge, whereas Pb was found crossing
detection level of 0.1mg/L in all the
study sites. The concentration of Pb may be due to some Pb battery based units
or heavy vehicular transaction for industrial activities.
The pollution load is
assessed with respect to heavy metals from these seven industrial zones (Table
1). Its found that Fe (318532 Kg/yr) is released in maximum mean concentration
followed by Cr (75762 Kg/yr), Mn (52324 Kg/yr), Cu (27847 Kg/yr), Ni (16787
Kg/yr), Zn (7347 Kg/yr), Pb (2330 Kg/yr), Co (1179 Kg/yr) and Cd (358 Kg/yr).
It is clear from the study that the industries are primarily the major source
of heavy metals in the environment compared to domestic and agricultural
wastes.
CONCLUSION
From the results
presented in this paper, it is clear that the wastes discharged from Wazirpur
and Badli industrial areas have low pH values and were associated with significantly
higher concentrations of heavy metals. This was to be expected since low pH is
associated with high levels of dissolution and mobility. In addition, high
metal concentrations in the waste suggest a low level of production efficiency,
resulting in a significantly high loss of metals as waste. The contents of the
metals examined generally exceded the recommended levels for wastewater
discharge in surface water. The metal concentrations still present in the
wastewater was high enough to cause serious harm to aquatic life and to the
large population of humans who depend upon the Yamuna river for their
survival.
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