CHAPTER – VIII
SEWAGE POLLUTION
185
Introduction
Sewage
is
water-carried
waste,
in
either
solution
or
suspension that is intended to flow away from a community. It is
known as waste water flows, sewage is the used water supply of the
community. It is more than 99.9% pure water and is characterized
by its volume or rate of flow, its physical condition, its chemical
constituents, and the bacteriological organisms that it contains.
Depending on their origin, wastewater can be classed as sanitary,
commercial, industrial, agricultural or surface runoff.
The spent water from residences and institutions, carrying
body wastes, washing water, food preparation wastes, laundry
wastes, and other waste products of normal living, are classed as
domestic or sanitary sewage. Liquid-carried wastes from stores and
service establishments serving the immediate community, termed
commercial wastes, are included in the sanitary or domestic sewage
category if their characteristics are similar to household flows.
Wastes that result from an industrial process or the production or
manufacture of goods are classed as industrial wastes. Their flows
and strengths are usually more varied, intense, and concentrated
than those of sanitary sewage. Surface runoff, also known as storm
flow or overland flow, is that portion of precipitation that runs
186
rapidly over the ground surface to a defined channel. Precipitation
absorbs gases and particulates from the Atmosphere, dissolves and
leaches materials from vegetation and soil, suspends matter from
the land, washes spills and debris from urban streets and highways,
and carries all these pollutants as wastes in its flow to a collection
point.
Waste water from all of these sources may carry pathogenic
organism that can transmit disease to humans and other animals,
contain organic matter that can cause odor and nuisance problems
of receiving water bodies, and can lead to eco toxicity. Excessive
deposition
of
chemical
nutrients
in
water
bodies
is
called
eutrophication. It is one of the numerous problems created by
sewage water pollution. Degradation of the quality of water,
reduction in the number of fish and increase in BOD, are the effects
of
eutrophication.
.
The toxins released into the rivers through sewage
water are consumed by fishes and other organisms, thus increasing
the possibility of these toxins entering the food chain. Coral reefs are
affected by sewage pollution the world over. The sewage water that is
dumped in the oceans, affects the coral reefs to a great extent. The
toxins present in the polluted
water in habit the growth of corals.
Proper collection and safe, nuisance-free disposal of the liquid
187
wastes of a community are legally recognized as a necessity in an
urbanized, industrialized society
(1).
"Sewage" and "Sewerage" may be
used interchangeably, but elsewhere they retain separate and
different meanings - sewage being the liquid material and sewerage
being the pipes, pumps and infrastructure through which sewage
flows.
(2)
Water
bodies
in
their
natural
form
contain
chemical
compounds such as the bicarbonates, nitrates, chlorides, sulphates,
etc. However, various problems arise with the increase in the
amount of these compounds. The water becomes unsuitable for
drinking and irrigation. Total Dissolved Solids (TDS) in water should
be less than 500mg/gram, for it to be considered potable. Water
which contains salts is not useful for irrigation either. Utilization of
such water leads to the salinization of the soil, which in turn lead to
soil erosion.
Mains water supplied to households is used for many
purposes, other than drinking and food preparation, notably bathing
and showering, toilet flushing and the washing of utensils, dishes
and clothes. Except where main drainage is not installed, the used
water gravitates to the local sewer and becomes „sewage‟.
Domestic wastewater will contain both solid and dissolved
pollutants including faecal matter, paper, urine, sanitary items, food
188
residues and a variety of other contaminants. The sewer network
will usually also receive waste waters from office and commercial
properties and from industrial premises. Rainwater from roofs and
roads may also drain into the sewer network.
The combined flow from these various sources travels through
the sewer system and ultimately to a „sewage works‟ where it
receives treatment before discharge of the treated effluent to a
stream, river, estuary or the sea.
Collecting and treating wastewater has been even more
beneficial to human health than the health service because it
stopped water-borne diseases such as cholera and typhoid.
Sewage Treatment
Treatment of sewage is essential to ensure that the receiving
water into which the effluent is ultimately discharged is not
significantly polluted. However, the degree of treatment required will
vary according to the type of receiving water. Thus, a very high
degree of treatment will be required if the effluent discharges to a
fishery or upstream of an abstraction point for water supply. A lower
level of treatment may be acceptable for discharges to coastal waters
where there is rapid dilution and dispersion.
189
Effluent Standards
Standards for the quality of effluents from sewage works
discharging to rivers and coastal waters have been applied in the UK
since early in the last century but the EC Urban Waste Water
Treatment (UWWT) Directive 1991(8) now defines standards for
sewage effluents discharging to rivers, estuaries and coastal waters.
Sewage treatment involves:

The removal of solids by physical screening or sedimentation

The removal of soluble and fine suspended organic pollutants
by biological oxidation and adsorption processes. Both forms
of treatment produce sludge as by-products and these have to
be treated and used or disposed of in an economical and
environmentally acceptable way. (See the description below on
sludge treatment.)
The following describes a typical sewage treatment sequence
which is illustrated in Figure 1. In practice, there are many process
variations employed according to locality and the standard of
effluent required.
Preliminary Treatment
Screening:
Large solids (plastics, rag, toilet paper residues) are
removed first by mechanical screens. Traditionally, screening was
190
used to remove only large solid material (> 25-30mm) in order to
protect downstream operations. Nowadays, much finer screens
(6mm mesh) are commonly employed to remove smaller inert solids.
The material retained („screenings‟) is usually washed to remove
faecal matter and then compressed for disposal to landfill or to an
incinerator.
Grit removal:
At the next preliminary stage, fine mineral matter (grit and
sand), originating mainly from road runoff, is allowed to deposit in
long channels or circular traps. The retained solids are removed
and usually sent to landfill for disposal.
Storm water diversion channel
At times of rainstorms, the flow of sewage into the works may
be too high to be accommodated by the downstream treatment
stages. In these circumstances, some of the flow may be diverted at
this point to storm tanks where it is stored temporarily before
returning it for treatment when the flow subsides.
At times of rainstorms, the flow of sewage into the works may be too
high to be accommodated by the downstream treatment stages.
191
Fig 1
This diagram shows a typical sewage treatment process.
192
In these circumstances, some of the flow may be diverted at
this point to storm tanks where it is stored temporarily before
returning it for treatment when the flow subsides. In extreme rainfall
events an overflow of effluent from the storm tanks may pass
directly to a watercourse.
Primary Treatment
Primary sedimentation
The sewage passes into large sedimentation tanks to provide a
quiescent settlement period of about 8 hours. Most of the solids
settle to the bottom of the tanks and form a watery sludge, known as
„primary sludge‟, which is removed for separate treatment. The
sewage remaining after settlement has taken place is known as
„settled sewage‟.
Secondary (biological) treatment:
Settled sewage then flows to an aerobic biological treatment
stage where it comes into contact with micro-organisms which
remove and oxidise most of the remaining organic pollutants.
At smaller works, the biological stage often takes the form of a
packed bed of graded mineral media through which the sewage
trickles and on the surfaces of which the micro-organisms grow. At
193
most larger works, the sewage is mixed for several hours with an
aerated suspension of flocs of micro-organisms (known as the
activated sludge process). As well as removing most of the polluting
organic matter, modern biological treatment can, where necessary,
remove much of the nitrogen and phosphorus in the sewage, thus
reducing the nutrient load on the receiving waters.
Final settlement
Following secondary (biological) treatment, the flow passes to
final settlement tanks where most of the biological solids are
deposited as sludge (secondary sludge) while the clarified effluent
passes to the outfall pipe for discharge to a watercourse. In the case
of the activated sludge process, some of the secondary sludge is
returned to the aeration tanks for further contact with the sewage.
The secondary sludge from biological treatment also requires
separate treatment and disposal and may be combined with the
primary sludge for this purpose.
Tertiary treatment
In circumstances where the highest quality of effluent is
required, a third (tertiary) stage of treatment can be used to remove
most the remaining suspended organic matter from the effluent
before it is discharged to a watercourse.
Tertiary treatment is
194
effected by sand filters, mechanical filtration or by passing the
effluent through a constructed wetland such as a reed bed or grass
plot.
Sludge Treatment
All methods of sewage treatment generate organic sludges (or
„biosolids‟) as by-products and these must be managed separately
from the liquid sewage
(9).
Raw (untreated) sludges have a very high
oxygen demand and must not be allowed to enter the water
environment.
All methods of sewage treatment generate organic sludges (or
„biosolids‟) as by-products and these must be managed separately
from the liquid sewage
(9).
Raw (untreated) sludges have a very high
oxygen demand and must not be allowed to enter the water
environment. Sludge also contains pathogenic organisms.
There is, therefore, a need to deal with them in a way that
permits their ultimate disposal in an environmentally acceptable
and sustainable manner. The sludge „route‟ selected for a given
sewage treatment works will depend on several factors including its
location, the availability of suitable farm land, the characteristics of
the sludge and the overall cost.
195
Sludges produced by sewage treatment are organic in nature and
contain useful amounts of plant nutrients such as nitrogen,
phosphorus and essential trace elements.
Therefore, the first objective should be to utilise the sludge as
a fertiliser or soil conditioner on agricultural land. In fact, some 60
per cent of the sludge produced in the UK is (after appropriate
processing) recycled to farms.
Agricultural use of sludge is
regulated by government controls and by codes of practice designed
to protect the quality of the soil, its crops and the health of human
and animal consumers of such crops.
(10,11)
The location of some sewage works is unsuitable for the
sludges they produce to be used in agriculture (e.g. not enough
farmland or too much manure from farm animals) and for these the
most frequent „route‟ is incineration with land filling of the ash.
Landfill is an alternative but sludge is seldom land filled in the UK.
Either of these options is regulated strictly in the UK to minimize
environmental impact. While these two options account for most of
the remaining 40 per cent of UK sludge‟s, there are also other minor
uses for sludge, for example as a garden fertilizer, to make compost
or as a fertilizer for crops which are subsequently used as fuel at
power generating stations.
196
In their initial form, most raw (untreated) sludges have a high water
content (96-99%), are putrescent and have an offensive odour. They
will also contain a variety of human and animal pathogens derived
from the contributing population.
Various forms of treatment may be used to achieve volume
reduction by removing some of the water content. Odour and
pathogen reduction is achieved by stabilization and disinfection
processes. In recent years, the control of odour emissions to the
atmosphere has become an important requirement of sludge
treatment.
The following outlines the more common types of sludge
treatment employed, of which various combinations are used
according to the end product required.
Primary consolidation
As a first stage of treatment, sludge is passed through stirred
tanks or subjected to centrifugation to reduce its water content and
volume by up to 50 per cent. The separated liquor is returned to the
sewage flow for treatment and the consolidated sludge passes
forward for further processing.
197
Anaerobic digestion
Anaerobic digestion (AD) has been practiced for more than 150
years. It is not new but still has huge unrealized potential if
regulations did not inhibit co-digestion of wastes. In this process,
consolidated liquid sludge is retained in an airtight tank (digester)
and maintained at 35 deg. C for 12-20 days. Under the anaerobic
conditions in the tank, various pathogens break down about half of
the sludge organic matter and convert it into a gas containing about
65 per cent methane.
The gas is used to heat the digester and, in some cases, also
to fuel gas engines to generate electricity. The sludge resulting from
anaerobic digestion is much less offensive in odour than the
untreated raw sludge and, with certain restrictions
(9),
is generally
suitable for use in agriculture in liquid or solid form. Further
consolidation of sludge after digestion, to reduce its volume, is a
common practice.
Mechanical dewatering
Either untreated or digested sludge may be converted from a
liquid to a sludge „cake‟ by treating it first with a conditioning
chemical which releases much of the water initially bound to the
organic matter. Much of the free water is then removed from the
198
sludge in a filter press, a belt filter or a centrifuge. The resultant
sludge cake will have only 20 per cent of the volume and weight of
the original sludge, thereby reducing subsequent handling and
transport costs. The conversion of sludge to a solid form is essential
prior to its disposal to landfill.
Incineration
This involves the burning of sludge at 850-900 deg. C to
destroy its organic content and to leave a smaller residue of mineral
ash for final disposal, usually to landfill.
Incineration is only
suitable for large sewage works and is used when the option of
agricultural use of the sludge is not practicable. The process is
carried out under closely controlled conditions and is subject to
strict environmental regulation (the EU Waste Incineration Directive)
to ensure that ambient air quality is not compromised by the
combustion gases.
Thermal drying
Some sewage works in the UK employ thermal drying systems
to convert the sludge to pelletized or granular form comprising about
90 per cent solids. The heating involved also destroys pathogens.
Thermally-dried sludges are used in agriculture or for amenity uses
(for example, golf courses, parks and other amenity areas).
199
Pasteurization (disinfection)
To destroy all pathogens in liquid sludge, it is heated to about
70 0C for at least 30, minutes after which it is cooled and subjected
to anaerobic digestion. This combination of pasteurization and
digestion produces an „enhanced treated‟ product
(11)
which enables
it to be used more widely for various agricultural purposes.
Lime stabilisation
At some smaller works, lime is added to liquid sludge to raise its pH
to above 12.0 for several hours. The high alkalinity improves its
odour and eliminates pathogens.
Composting
A few sewage works compost sludge by the process of „windrowing‟.
The process generates heat and a rise in temperature in the
composting material causes pathogen destruction. The final product
may be suitable for amenity use.
200
Figure2
This diagram shows a typical sludge treatment sequence for production of an
„enhanced treated‟ sludge (biosolids) for use as fertiliser in agriculture. Many other
options are possible in practice
201
Treatment of Sewage Water
Sewage treatment is the process of removing the contaminants
from sewage to produce liquid and solid (sludge) suitable for
discharge to the environment or for reuse. It is a form of waste
management. A septic tank or other on-site wastewater treatment
system such as biofilters can be used to treat sewage close to where
it is created.
Sewage water is a complex matrix, with many distinctive
chemical characteristics. These include high concentrations of
ammonium, nitrate, phosphorus, high conductivity (due to high
dissolved solids), high alkalinity, with pH typically ranging between
7 and 8. Trihalomethanes are also likely to be present as a result of
past disinfection.
In developed countries sewage collection and treatment is
typically subject to local, state and federal regulations and
standards.
A system of sewer pipes (sewers) collects sewage and takes it
for treatment or disposal. The system of sewers is called sewerage or
sewerage system (see London sewerage system) in British English
and sewage system in American English. Where a main sewerage
system has not been provided, sewage may be collected from homes
202
by pipes into septic tanks or cesspits, where it may be treated or
collected in vehicles and taken for treatment or disposal. Properly
functioning septic tanks require emptying every 2–5 years depending
on the load of the system.
Sewage and waste water is also disposed to rivers, streams
and the sea in many parts of the world. Doing so can lead to serious
pollution of the receiving water. This is common in third world
countries and may still occur in some developed countries, where
septic tank systems are too expensive.
Conversion to fertilizer:
Sewage sludge can be collected through a sludge processing
plant that automatically heats the matter and conveys it into
fertilizer
pellets
(hereby
chemical detergents,
removing
possible
contamination
by
This approach allows to eliminate seawater
pollution by conveying the water directly to the sea without
treatment (a practice which is still common in developing countries,
despite environmental regulation). Sludge plants are useful in areas
that have already set-up a sewage-system, but not in areas without
such a system, as composting toilets are more efficient and do not
require sewage pipes (which break over time).
203
Electricity
Power can also be obtained from sewage water. The technique
uses Microbial fuel cells.
The present discussion on a case study:
Qualitative as well as quantitative nature of the domestic
sewage depends upon certain parameters such as the pattern of
water supply, food habits of the
people, community types,
population size, sewage collection system, etc. Characterization of
the sewage becomes essential for an effective and economical waste
management program and to choose the treatment processed,
deciding the extent of treatment methods and assessing the
beneficial uses of the wastes. Some heavy metals such as Zn, Pb,
which are present in lower concentration or below detection limits in
supply water, tend to increase more than 98% in used water (i.e.,
domestic sewage). Reasons for their increment in sewage are not
only because of domestic uses, but also from other sources. For
example, lead (Pb) may be entering into the sewage system through
dust fall, soil erosion, leaching, urban waste discharges and runoff
from streets and other surfaces. This toxic metal may cause anemia,
kidney disease and nervous disorders above the tolerance limits
0.05 mg/L. Similarly, zinc (Zn) is an essential element in human
metabolism. A child requires 0.3 mg of Zn/kg of body weight, the
204
deficiency of which may cause growth retardation. But excessive
concentration in the drinking water may cause undesirable aesthetic
effects. Characteristics of sewage from some Indian cities are shown
in Table 1.
Characteristics of effluent sample:
The study has been conducted during the pre monsoon
period, i.e. during the month of March and April 2011 in a
residential
area situated in Guntur town, Andhra Pradesh. The
main source of water supply in this area is by deep bore wells and
local municipality. The water supply system in this area is of
continuous type with discrete pumping system. The colony residents
are having their individual overhead tanks.
Average per-capita
water consumption in this community is 270 L/capita-day. From
this community, domestic or residential establishments contribute
the main waste water portion. It is mainly the spent water from
kitchens, bathrooms, lavatories etc. Domestic sewage water samples
were collected from 12 different resenditial areas of the town S1 Arundalpet, S2 - Brodipet, S3 - Koritipadu, S4 - Vidya Nagar, S5 Sambasiva Nagar, S6 - Chaitanyapuri, S7 - SVN Colony, S8 - Vdyog
Nagar Colony, S9 - JKC College Road, S10 - Kothha Peta, S11 - RTC
Bus Stand,
S12 - Reddy Palem (consisting open and deep bore
wells) as per standard procedures.
The samples were stored in
205
plastic bottles. Parameters like pH, conductivity. TDS, chlorides,
hardness were determined standard method.(3) The concentrations of
Fe, Pb, and Zn were determined with the help of atomic absorption
spectrophotometer). The results obtained are compared against
standards.
Results and Discussions:
The
result
obtained
during
the
course
of
present
investigations is given in Table‟s VI – 1 & 2.
pH and Conductivity:
One of the important factors in water quality management is
pH. The pH of domestic sewage from different Indian cities has
specified by WHO standards vary from 7.0 to 7.5. In the present
investigation the pH of the fresh well water samples are within the
limits [4]. The conductivity of the present water samples found varied
between 0.7 – 1.9 mhos. The reason of this is the contamination of
the sewage effluents by ionic pollutants like NaCl etc.
Colour and Odour:
Domestic sewage has a slightly alkaline condition and earthy
odor and a cloudy appearance. With lapse of time, due to microbial
action, it darkened in colour and the smell of the sewage became
more pronounced.
206
TDS and SS:
The total dissolved solids (TDS) in the domestic sewage is
found in the range 319-715 and 22-78 mg/L. A comparison between
the two results clearly indicates that the sewage effluents are
contaminated with water insoluble solids more than water-soluble,
solids. For different Indian cities as reported in the standard
literatures, the TDS pick-up in the domestic sewage is 400mg/L6.
The SS concentrations of the domestic sewage generally rages from
206 to 560 mg/L in different Indian cities whereas, the maximum
limit of SS in the effluent discharge as specified by standards is
100mg/L. Knowledge of the classification of these solids is
important, as it constitutes lad on biological treatment processes.
Chlorides, Nitrates and Hardness:
Chloride content of the water samples found in the range 32163 after domestic use. The reason for the sharp increment is that
the human excretions contain chlorides equal to the chlorides
consumed (commonly NaCl as common salt) with food and water.
This amount averages from 8gm of chloride/person/day. The range
of chloride concentration in the domestic sewage in different Indian
cities has been reported as 40 to 352 mg/L(5) This parameter may
not pose a problem in the conventional water treatment process.
207
The nitrate - nitrogen concentration in the water samples has
been found out to be (in the range 21-44 mg/L) after domestic use.
This may be due to the presence of urea [CO(NH2)2] which is the
major source of nitrogen in the domestic sewage. Generally, the
nitrate pick-up in the Indian domestic sewage has been reported as
20-40mg/L[6]. The present value lies slightly excess than the
standard value.
The total hardness concentration in the well water is found in
the range of 220 to 426 mg/L. The reason for this hardness may the
underground rock characteristics with which the well water is in
contact with. Increase is due to addition of certain compounds
(which may impart hardness) after domestic use of the water. This
parameter also does not pose problems in the congenital water
treatment process. Generally the total hardness pick-up in the
domestic sewage for the Indian cities is reported as 25 mg/L[6], but
in our present investigation it is found as 99mg/L. It may be due to
the reason that the sampling was done during pre-monsoon period,
so the sewage sampled was raw and highly concentrated.
Biochemical oxygen demand (BOD):
The BOD of the sewage obtained in the range of 40 to 74
g/capita-day (present investigation), whereas, in India. Which is
above reported value for different domestic sewage is 45-54
g/capita-day. The probable reasons for this slightly higher value
208
may be that the sampling was conducted in the pre monsoon period,
so the sewage was raw and concentrated. Since the 5-day BOD
value depend on the read ion rate constant K, determination of its
value is important for extrapolating the ultimate oxygen demand (Lo)
of the waste. The ultimate BOD of the sewage was found out to be
283 mg/L. A high BOD value may pose a great problem for the
conventional water treatment processes, as it constitutes a high
load.
Chemical oxygen demand (COD):
The COD of the domestic sewage comes found in the range of
299 to 411 mg/L in the present study. Generally the range of the
COD for the Indian domestic sewage is about 1.6 to 1.9 times the
value of BOD. In the present study, COD coming to be in the range
of 1.7 to 1.9 times the value of BOD.
If the ratio between COD to BOD is known, it becomes easier
to assume the value of BOD of the sewage in a very short time. The
ratio will vary from one waste to other and will change for the same
waste as it is subjected to various treatment operations.
Heavy Metals:
A high iron (Fe) content of >2 mg/L imparts a taste to drinking
water besides leaving stains on laundry and plumbing fixtures. The
ground water used for drinking in some villages of Delong Block in
Coastal Orissa was shown to contain Fe 0.6 to 38.8 mg/L[7]. In the
209
present work, the maximum Fe constant in the drinking water
measured 0.16 mg/L, which is not very high. In the domestic sewage
the iron content is < 0.006mg/L. The reason of such increment can
be attributed due to the fact that water being stored in the overhead
iron tanks before being supplied. The maximum permissible limit of
Zn in the drinking water is 5 mg/L. In the present study, the Zn as
well as Pb content lies within the prescribed limit.
In case of
domestic sewage the range was found to be from 0.009 to 0.01
mg/L.
Conclusion:
A comparative study of the data presented in Table -1 & 2
indicates that the sewage becomes polluted with ionic and organic
pollutants. Organic pollutants like NH4-N, P, COD and BOD show
higher concentration which actually implies that these parameters
are generally absent in drinking water and even a slight increment
would result in higher value. The movement of these ionic and
organic pollutants through the soils enhances the possibility of the
contamination of the underground water resources. So, the
necessary measures have to be taken to treat and dispose the
sewage properly and safely to prevent pollution.
210
Table V-1: Analysis of sewage waters collected on 15-03-2010
Parameter
S1
S2
S3
S4
S6
S7
S8
S9
S10
S11
S12
7.70
7.45
7.62
7.52
7.0
7.81
7.85
7.63
7.70
7.25
7.29
7.34
Electrical
1.2
Conductivity
1.3
1.6
1.8
1.1
1.4
1.6
1.3
1.2
1.3
1.6
1.8
TDS
503
612
638
624
620
609
319
328
409
478
340
403
TSS
43
44
78
72
65
63
48
28
49
46
53
22
Hardness
402
368
492
358
423
495
526
518
439
385
369
360
Chloride
64
48
52
73
76
68
40
49
53
32
64
48
DO
4.3
4.2
4.8
5.0
5.23
5.2
5.3
5.0
4.3
4.6
4.9
4.8
BOD
52
47
55
41
48
39
52
52
58
49
43
47
COD
315
409
411
398
363
331
403
394
362
329
299
343
Iron
0.003 0.004 0.004 0.005 0.003 0.002 Nd
Nd
0.002 0.005 0.003 0.006
Lead
0.007 0.008 0.001 0.005 0.009 0.004 0.005 0.015 0.009 0.007 0.004 0.007
Zinc
0.215 0.218 0.260 0.265 0.214 0.322 0.310 0.296 0.263 0.236 0.273 0.282
NH4 -N
35
pH
20
16
19
S5
22
34
40
18
38
26
21
40
All the parameters expressed in mg/lit. except pH and EC (mmhos)
211
Table V-2 :Analysis of sewage waters collected on 15-04-2010
Parameter
pH
S1
S2
S3
S4
S5
S6
S7
S8
7.45
7.50
7.72
7.76
7.49
7.82
7.35
7.75
S9
S10
S11
S12
7.83
7.69
7.60
7.92
Electrical
Conductivity
TDS
1.4
1.9
0.7
1.7
1.5
1.2
1.3
1.7
1.3
1.8
1.9
1.6
562
709
420
532
628.
468
525
576
580
691
632
715
TSS
49.7
58.5
63.9
46.1
58.0
33.9
52.3
42.8
57
34
39
43
Hardness
368
471
340
304
Chloride
74.2
87.5
92
68
96
DO
4.8
4.5
5.0
4.0
4.7
4.2
4.6
4.3
4.6
5.2
5.3
4.8
BOD
54
63
42
48
51
58
74
43
60
52
40
65
COD
262
215
206
178
245
223
228
172
149
193
209
296
21
34
28
39
30
42
22
27
23
44
37
29
Iron
0.002
0.003
0.004 0.002 0.003 0.003 0.004
nd
0.006 0.004 0.002 0.003
Lead
0.007
0.028
0.023 0.015 0.004 0.002 0.008 0.007 0.006 0.004 0.002 0.018
Zinc
0.215
0.310
0.276 0.296 0.238 0.243 0.259 0.244 0.306 0.315 0.320 0.322
NH4 -N
.314.5 220.4 345.1 232.4 382.6 426.2 352.6 289
123.2 116.3
94.0
115.7 134.0 163.5 89
All the parameters expressed in mg/lit. except pH and EC (mmhos)
212
Variation of pH
8
7.5
pH value-march10
7
pH value-April- 10
6.5
S1 S2 S3 S4 S5 S6 S7 S8 S9 S10 S11 S12
Variation of Electrical Conductivity
2
mmhos
1.5
1
Electrical conductivityMarch'10
0.5
Electrical conductivityApril'10
0
S1 S2 S3 S4 S5 S6 S7 S8 S9 S10 S11 S12
Variation of TDS
800
700
600
500
400
300
200
100
0
TDS-mar'10
TDS-April'10
S1
S2
S3
S4
S5
S6
S7
S8
S9 S10 S11 S12
213
Variation of TSS
90
80
70
60
50
40
30
20
10
0
TSS March'10
TSS April'10
S1
S2
S3
S4
S5
S6
S7
S8
S9 S10 S11 S12
Variation of Hardness
600
500
400
300
Hardness March'10
200
Hardness April'10
100
0
S1 S2 S3 S4 S5 S6 S7 S8 S9 S10 S11 S12
Variation of Chloride
180
160
140
120
100
ChlorideMarch'10
80
ChlorideApril'10
60
40
20
0
S1 S2 S3 S4 S5 S6 S7 S8 S9 S10 S11 S12
214
Variation of Dissolved Oxygen
6
5
4
3
DO March'10
2
DO April'10
1
0
S1
S2
S3
S4
S5
S6
S7
S8
S9
S10 S11 S12
Variation of Chemical Oxygen Demand
COD in mg/lt
500
400
300
COD -March'10
200
COD-April'10
100
0
S1
S2
S3
S4
S5
S6
S7
S8
S9 S10 S11 S12
Variation of Biological Oxygen Demand
80
70
60
50
40
BOD -march'10
30
BOD april'10
20
10
0
S1
S2
S3
S4
S5
S6
S7
S8
S9 S10 S11 S12
215
mg/lt
Variation of NH4-N
50
40
30
20
10
0
NH4 -N -March'10
NH4 -N April'10
S1 S2 S3 S4 S5 S6 S7 S8 S9 S10 S11 S12
mg/lt
Variation of Iron
0.008
0.006
0.004
0.002
0
Iron March'10
Iron April'10
S1 S2 S3 S4 S5 S6 S7 S8 S9 S10 S11 S12
mg/lt
Variation of Lead
0.03
0.025
0.02
0.015
0.01
0.005
0
Lead March'10
Lead April'10
S1 S2 S3 S4 S5 S6 S7 S8 S9 S10 S11 S12
mg/lt
Variation of Zinc
0.35
0.3
0.25
0.2
0.15
0.1
0.05
0
Zinc March'10
Zinc April'10
S1 S2 S3 S4 S5 S6 S7 S8 S9 S10 S11 S12
216
On the state of the environments knowing the quality of water
would enable us determine whether or not the medium is fit for its
intend use. Eventually it also provides an estimate of the degree of
fitness of water.
In the present study it is observed that the concentration of major
ions in well and bore – well samples exceed the maximum permissible
limits prescribed by Indian standards for drinking purpose.
The results indicate that the water is excessively hard and the
reason might be due to the suspected sewage pollution through a sandy
aquifer. However, it is likely to be influenced by sewage intrusion and
salt water contamination.
217
References
1) Masters, M.Gilbert. Introduction to Environmental Engineering
and Sciences, Prentice Hall of India (p) Ltd, New Delhi (1994).
2) Train, R.E, Quality Criteria for water, USEPA, Washington DC,
(1979).
3) Standard Methods for the examination of water and waste water
(20th ed.).APHA.AWWA, WEF, New York (1998).
4) Maiti, S.K. Handbook of methods in Environmental studies (Vol
1).ABD Publishers, Jaipur (2001).
5) Siddiqui, H.R.Characterstics of domestic and municipal sewage in
India, Indian J.Env. Health 55:85-88(1975).
6) Arceivala S.J. Wastewater treatment for pollution control. (2nd
ed).TMH. New Delhi. (1998).
7) Rao, P.L.K.M.P.L Smedley and K.S.Devi. 1998. Incidence of iron
in ground water in Delong Block in Coastal Orissa. J. Poll.Res.,
11(3):293-294. (1989).
8) Council of the European Communities. Directive concerning
urban wastewater treatment (91/271/EEC) 1991.
9) Foundation for Water Research. Review of Current Knowledge:
Sewage Sludge. Foundation for Water Research, Marlow SL7 1FD.
2002.
10) Council of the European Communities. Directive on the
protection of the environment, and in particular the soil, when
sewage sludge is used in agriculture. (86/278/EEC). Official
Journal of the European Communities. No.181/6. 4 July 1986.
11)
The Safe Sludge Matrix - Guidelines for the Application of Sewage
Sludge to Agricultural Land, 3rd Edition, April 2001. Guidance on
the agreement made between Water UK representing the UK Water
and Sewage Operators and the British Retail Consortium (BRC)
representing the major retailers. This agreement affects all
applications of sewage sludge to agricultural land and came into
force on
31
December1998.
218