Sources of Pollution -
Physical, Chemical, Organic & Biological properties of Industrial
Wastewater:
I. Physical characteristics of sewage:
1. Temperature:
Ø Temperature of sewage depends upon
season. However temperature is slightly higher than that of ground water.
Ø High temperature of sewage is due to
evolution of heat during decomposition of organic matter in sewage.
2. Color:
Ø Color of sewage indicates its strength
and age.
Ø Fresh domestic sewage is grey in color
but septic sewage is dark in color
Ø When industrial effluent is mixed it
give characteristic color to sewage
3. Odor:
Ø Fresh domestic sewage is almost
odorless.
Ø Septic or stale sewage is putrid in
odor which is due to generation of H2S during anaerobic decomposition of
organic matters.
Ø When industrial effluent is mixed, it
give characteristics odor to sewage
4. Turbidity:
Ø Sewage is highly turbid.
Ø Turbidity of sewage is due to dissolved
substances, colloidal matters, suspended solids and microbial cells.
II. Chemical characteristics of sewage:
1. Organic matter:
In general sewage contains large amount
of organic matters. However amount of organic matter depends on types and
condition of sewage.
Organic matter in sewage may be found
in the form of dissolved substances, colloidal matter, suspended or sedimented
form.
2. Chloride:
Human beings discharge large amount
(8-15gm/day) of chloride in the form of NaCl, especially through urine and
sweat. So domestic sewage from toilet and bathroom contains higher level of
chloride.
Sulfite:
In sewage sulfite in the form of H2S
(hydrogen sulfite) is generated during anaerobic decomposition of organic
matters by anaerobic bacteria. H2S gives putrid odor to sewage.
3. Biological oxygen demand (BOD):
Sewage usually have high BOD due to
presence of large amount of organic matters. Value of BOD ranges from 100mg/ltr
for very dilute sewage to 600mg/ltr or more for concentrated sewage containing
industrial effluent mix.
4. Dissolved oxygen (DO):
Due to high level of microbial cells
and biodegradable organic matters, sewage have very low level of dissolved
oxygen.
In some sewage, DO is completely
absent. Level of DO depends on age and condition of sewage. Low level DO is
also due to lower solubility of oxygen in sewage. Oxygen is only 95% soluble in
sewage than in pure water).
5. pH:
Sewage is slightly alkaline in pH.
6. Nitrogen:
Ø In sewage nitrogen is found in variety
of form like organic nitrogen, ammonia, nitrite, nitrate etc
Ø Fresh sewage mainly contains organic
nitrogen and very little inorganic form of nitrogen. On the other hand organic
septic sewage contains high inorganic nitrogen and low organic nitrogen.
Ø In sewage nitrite never accumulate in
concentration greater than 1mg/ltr because it is intermediate product during
conversion of ammonia into nitrate (NO3).
Ø In sewage treatment plant, NH3
and NO2 are finally converted to NO3.
III. Biological characteristics of
sewage:
1. Bacteria:
Two types of bacteria are found in
sewage.
Intestinal bacteria:
Non-pathogenic intestinal bacteria are
normal flora of gasto intestinal tract of human and animals and enter into
sewage together with stool. Examples; faecal coliform, faecal streptococci,
Clostridium perfingens, etc.
Pathogenic intestinal bacteria such as
Salmonella, Shigella, Vibrio cholera, Yersenia enterocolitica etc enter into
sewage through stool of patients.
Real sewage bacteria
The natural habitat of these bacteria
is sewage.Both aerobic as well as anaerobic are found in sewage. Aerobic
bacteria play important role in oxidation of organic matter during aerobic
process.
Common anaerobic bacteria includes;
Clostridium sporogens
Bifidobacterium
Peptococcus
Methanogenic bacteria like
Methanobacterium, methanosarcina
Common aerobic bacteria includes;
Zeoglea remigera
Noacrdia
Flavobacterium
Achromobacter
Nitrosomonas
2. Algae:
Some algae found in sewage includes
Chlorella phormidum, Ulothrix etc Algae are used in trickling filter in sewage
treatment plant
3. Fungi:
Fungi like Fusarium and Sporotricum are
found in sewage which play important role in trickling filter.
4. Virus:
Some viruses causing human disease such
as Poliovirus, Rotavirus, Hepatitis A and E etc are found in sewage which get
access through stool of patients.
5. Protozoa:
Some protozoa that cause disease of
intestinal tract enter into sewage together with stool of patient.
Examples: Entamoeba histolytica,
Giardia, Balantidium coli etc are pathogenic protozoa Few protozoa such as
Vorticella and Opercularia are found in trickling filter.
Difference between industrial;
municipal waste waters:
|
Industrial
waste water |
Municipal
Waste water |
|
Industrial wastewater consists of
wastes originating from the industrial processes of various industries such
as paper manufacture, textile, sugar, brewing, dyeing etc.
|
Municipal waste water consists of
liquid waste originating from bathrooms, water closets, kitchen sinks, wash
basins etc of residential, commercial or institutions buildings. For examples apartments, hotels,
hospitals, shopping mall etc |
|
The quality of industrial wastewater
depends largely upon the type of industry & the chemicals used in their
process water |
Municipal water contains same type of
pollutants. |
|
Contains several chemical pollutants
& toxic substances in too large proportions. |
Do not contain very toxic chemicals. |
Effects of industrial effluents on Natural
water Bodies.
Chemical
Contamination: Industrial effluents may contain toxic chemicals such as
ammonia, nitrates, phosphates, and other hazardous substances like pesticides
and hydrocarbons. These can lead to the poisoning of aquatic ecosystems,
harming fish, plants, and other organisms.
Heavy Metals:
Metals like mercury, lead, and cadmium are commonly found in industrial waste.
These accumulate in water bodies and in the tissues of aquatic organisms,
leading to bioaccumulation and biomagnification, affecting the entire food
chain.
pH
Alterations: Effluents can alter the pH of water bodies, making them either
too acidic or too alkaline for the survival of aquatic species. Extreme pH
changes can kill fish and other marine life, destroy coral reefs, and reduce
biodiversity.
Eutrophication
Industrial effluents containing high
levels of nutrients like nitrogen and phosphorus can lead to eutrophication,
which causes excessive algae growth in water bodies. When algae die and
decompose, it depletes oxygen levels in the water, creating hypoxic conditions
or dead zones where most aquatic life cannot survive.
Thermal Pollution
Some industries release heated water
into natural water bodies. This thermal pollution can disrupt the local
ecosystem by altering the temperature of the water, affecting species that are
sensitive to temperature changes. Warmer waters hold less dissolved oxygen,
further stressing aquatic organisms and reducing biodiversity.
Impact on Human Health
Contaminated water sources may enter
human food chains through fish and seafood consumption, posing serious health
risks, including cancer, neurological damage, and other chronic illnesses.
Industrial effluents that pollute
drinking water sources can lead to diseases such as gastrointestinal issues,
liver and kidney damage, and other waterborne diseases.
Effect of sewage on Natural water
bodies:
Methane and Greenhouse Gas Emissions
The decomposition of organic matter
from sewage under anaerobic (oxygen-limited) conditions produces methane, a
potent greenhouse gas. Methane emissions from sewage-contaminated water bodies
contribute to climate change and exacerbate environmental problems.
Impact on Drinking Water Sources
Sewage contamination of rivers, lakes,
and groundwater can affect drinking water supplies. Even small amounts of
untreated sewage can make water unsafe for human consumption, leading to
serious public health risks. This is especially dangerous for communities that
rely on untreated or minimally treated water sources.
Toxicity from Heavy Metals and
Chemicals
Some sewage contains heavy metals like
mercury, lead, and cadmium from household waste, industries, and stormwater
runoff. These metals can accumulate in the tissues of aquatic organisms,
leading to bioaccumulation and biomagnification throughout the food chain,
affecting fish, birds, and even humans.
Pharmaceuticals and personal care
products from sewage can interfere with the hormonal and reproductive systems
of aquatic organisms.
Pathogen Contamination
Untreated or partially treated sewage
contains pathogens such as bacteria, viruses, and parasites (e.g., E. coli,
cholera, giardia, and cryptosporidium). These pathogens can contaminate water
bodies, posing risks to both aquatic life and human health.
Water contaminated with pathogens can
spread waterborne diseases such as cholera, dysentery, and hepatitis among
people who use the water for drinking, bathing, or recreational purposes.
Water treatment and analysis Part-I
Water treatment and analysis Part-II
Water treatment and analysis Part-III
 B.Sc. Undergraduate course as per New education policy (NEP) Part -III){kind=link}