1. WASTE WATER
MANAGEMENT AND
TREATMENT
JIJEESH V

2. WASTEWATER
 Wastewater is a mixture
of sewage; water from
household use; water
used in commercial and
industrial applications
etc…
 Wastewater contains a
variety of biological and
chemical pollutants which
make it unsafe for
humans and the
environment.

3. WASTEWATER TREATMENT
 The objective of wastewater treatment is to remove
or modify these pollutants, so that it can be safely
discharged into the environment.
 Wastewater treatment uses microbes to
decompose organic matter in sewage.
 If too much untreated sewage or other organic
matter is added to a lake or stream, dissolved
oxygen levels will drop too low to support sensitive
species of fish and other aquatic life.

4.  Wastewater treatment systems are designed to
digest much of the organic matter before the
wastewater is released so that this will not occur.
 Treatment of wastewater typically involves primary,
secondary, and sometimes tertiary steps.
 Secondary treatment is entirely dependent upon
the activity of microbes such as Acidovorax.

5. Wastewater treatment Processes
Wastewater treatment methods
Chemical
Sedimentation Gas
Transfer
FiltrationFlocculation FlotationMixingScreening
Biological
Physical
Aerobic Anaerobic
Precipitation Adsorption Disinfection

6. 1. Primary treatment
 Physically removes large solids using grates, screens,
and settling tanks.
 Large pieces of debris are removed by screening, and
suspended particles are removed from the water
through settling processes.
2. Secondary treatment
 Elimination of organic and inorganic contaminants,
through the effect of microbiological activity upon
wastewater material.

7.  The most widely used and effective methods of
secondary treatment involve activated sludge
treatment.
3. Tertiary treatment
 Removal of further nutrients and pathogens, using
methods such as filtration, passage through
wetlands, or disinfection by treatment with chlorine,
ozone or ultraviolet light.
 Tertiary treatment is not always included in
wastewater treatment systems.

8. PRELIMINARY TREATMENT
 It removes all materials that can be easily collected from
the raw sewage before they damage or clog the pumps
and sewage lines of primary treatment clarifiers.
 Objects that are commonly removed during
pretreatment include trash, tree limbs, leaves, branches,
and other large objects.
 The influent in sewage water passes through a bar
screen to remove all large objects like cans, rags, sticks,
plastic packets etc. carried in the sewage stream.

9.  This is most commonly done with an automated
mechanically raked bar screen in modern plants
serving large populations, while in smaller or less
modern plants, a manually cleaned screen may be
used.
 The raking action of a mechanical bar screen is
typically paced according to the accumulation on
the bar screens and/or flow rate.
 The solids are collected and later disposed in a
landfill, or incinerated.

10.  Bar screens or mesh screens of varying sizes may
be used to optimize solids removal.
 If gross solids are not removed, they become
entrained in pipes and moving parts of the
treatment plant, and can cause substantial damage
and inefficiency in the process

11. 1. PRIMARY TREATMENT( PHYSICAL OR
MECHANICAL)
 Typical materials that are removed during primary
treatment include
 fats, oils, and greases
 sand, gravels and rocks
 larger settleable solids including human waste
 floating materials
 Screening : to remove large objects, that could plug
lines or block tank inlets
 Grit chambers : slows down the flow to allow grit to fall
out. (horizontal, aerated and vortex).

12.  Sedimentation tank ( settling tank or clarifiers) :
Settleable solids settle out & are pumped away,
while oils float to the top & are skimmed off.
Settleable solids are then passed for aeration
in aeration tanks.

13. BAR SCREEN & SEDIMENTATION TANK

14.  Sewage is held in sedimentation tanks for 2-10
hours.
 Greasy material, fats, oils etc..rise to the surface,
forming scum which is skimmed off.
 The organic matter which settle down is called
primary sludge.
 30-40% BOD removal- treatment efficiency.
 Sedimentation is enhanced by the addition of alum
at the treatment plant which produces a sticky
flocculant precipitate.
Settleable solids are then passed for aeration in
aeration tanks

15. AERATION TANKS
 The effluents from primary
treatment are then carried to
aeration tanks.
 Continuously aerated for the
growth of aerobic m.os.
Flocculation occurs.
 These m.os degrade the
organic matter present in the
effluents.

16. 2. SECONDARY TREATMENT ( BIOLOGICAL
TREATMENT)
 Typically uses biological treatment processes, in
which microorganisms convert non- settleable solids to
settleable solids. Sedimentation process follows,
allowing the settleable solids to settle out.
 4 methods include :-
1) Activated sludge
2) Trickling filters
3) Oxidation ponds or lagoons
4) Biological contractor system/ Rotating disc

17. 1) ACTIVATED SLUDGE SYSTEM
 . Aerobic sewage
treatment in which
flocculated biological
growth is circulated &
in contact with organic
waste in oxygen
presence is called
activated sludge
process

18.  The activated sludge process is usually
employed following primary sedimentation.
 The wastewater contains some suspended
and colloidal solids and when agitated in the
presence of air, the suspended solids form
nuclei on which biological life develop and
gradually build up to larger solids or gelatinous
masses which are known as activated sludge.

19.  Activated sludge is a brownish floc-like substance
consisting of organic matter obtained from the
wastewater and inhabited by myriads of bacteria
and other forms of biological life.
 Activated sludge with its living organisms has the
property of absorbing or adsorbing colloidal and
dissolved organic matter.
 The biological organisms utilize the absorbed
material as food and convert it to inert insoluble
solids and new bacterial cells.

20.  Much of this conversion is a step-by-step process.
 Some bacteria attack the original complex substances
to produce simpler compounds as their waste products.
 Other bacteria use the waste products to produce still
simpler compounds and the process continues until the
final waste products can no longer be used as food for
bacteria

21.  The generation of activated sludge or floc in
wastewater is a slow process and the amount so
formed from any volume of wastewater during its
period of treatment is small and inadequate for the
rapid and effective treatment of the wastewater
which requires large concentrations of activated
sludge.
 Such concentrations are built up by collecting the
sludge produced from each volume of wastewater
treated and re-using it in the treatment of
subsequent wastewater flows

22.  The sludge so re-used is known as returned
sludge.
 This is a cumulative process so that eventually
more sludge has been produced and is available to
maintain a viable biological population of organisms
to treat the incoming wastes.
 The surplus, or excess activated sludge, is then
permanently removed from the treatment process
and conditioned for ultimate disposal.

23. ACTIVATED SLUDGE ORGANISM
 Particles of the flock inactivated sludge consist of
mixed species of bacteria.
 They embed themselves in a mass of
polysaccharide gum called zooglea.
 Zooglea ramigera
 Z. ramigera & related organisms need complex
nutrient requirement.
 Oxidize sewage rapidly ; active in floc formation
 Other m.os in zooglea are Escherichia, sps of
Pseudomonas, Alkaligens, Bacillus, Sphaerotilus,
several protozoans etc.

24.  Different flora act in antagonism & synergism.
 Bacterial population increases
 Free swimming ciliates & flagellates increases
 Protozoans increases
 Rotifiers & nematodes increases
 End result is mineralization of C,N & P
 Complete mixing, rigorous aeration – efficient
oxidation & reduction
 Fluid part passed- final settling tank
 Part of activated sludge retained – seed to
reinoculate new sewage
 BOD reduction – 80-95%
 Most of settled sludge moved-aeration stopped-
settling stops- bulging process- to anaerobic
sludge digestor.

25. ANAEROBIC SLUDGE DIGESTORS
 These can be used to further treat aerobically treated
sewage or for very highly concentrated sewage.
 Vats have heating, venting, mixing, sludge seeding,
draw-off.
 Protozoa and fungi are insignificant.
 3 step process:
 faculatively or obligately anaerobic.
organic acid and CO2.
 H2, CO2, Acetate
 Methanogens-
Get methane. Products are methane and CO2.
 Opt temp 35-37C and pH 6-8.
 Get a better reduction in volume of sludge.

26. 2. TRICKLING FILTERS
 Sewage is sprayed or
drained over a rock bed
or molten plastic.
 Rocks large- air
penetrates
 Small- increased
surface area for
microbial activity
 No filtration action
 Slimy gelatinuous film of
aerobes (zoogleal slime,
a biofilm) grow on bed
 Envelop- Exopolysacc.-
gum

27.  M.os oxidizes organic matters trickling over the surfaces
to CO2 & water.
 As the biofilm layer thickens, it eventually sloughs off
into the treated effluent and subsequently forms part of
the secondary sludge.
 Typically, a trickling filter is followed by a clarifier or
sedimentation tank for the separation and removal of the
sloughing
 80-85 % BOD removal.
 The underdrain system in trickling filters serves two
purposes:
(a) to carry the wastewater passing through the filter and
the sloughed solids from the filter to the final clarification
process, and
(b) to provide for ventilation of the filter to maintain
aerobic conditions.

28. 3. BIOLOGICAL CONTRACTOR SYSTEM/
ROTATING DISC
 A biofilm – based design.
 Series of disc of several
diameters are mounted
on a shaft.
 Disc rotates slowly ; their
lower part(40%)
submerged in waste
water.
 Aeration provided.
 Rotation causes
accumulated biofilm to
slough off when thick
 Equivalent to floc
accumulation.

29. 4. OXIDATION PONDS OR LAGOONS
 Sewage pond is deep-
entirely anaerobic.
 2 stages:
 Sludge settles out
 Effluent pumped to an
adjoining pond or system
of shallow ponds enough
to aerated by wave action
 Algal growth is
encouraged ; since
difficult to manage aerobic
condition.

30.  Bacterial action – decomposing organic matter &
generate CO2
 Algae use CO2- photosynthesis- produce O2-inturn
encourage aerobial activity in the sewage.
 Considerable amount of organic matter in the algal
form accumulates ; not a problem ; since pond is
nutrient-rich.

31. MICROBIAL PROCESSES IN WASTEWATER
TREATMENT
 Many microbial activities are observed.
 Microorganisms associated, do not persist long
(fragile).
Secondary treatment is entirely
dependent upon the activity of microbes.
Eg: Biofilters (Trickling filters) , Activated sludge etc..

32.  Microbes frequently present in activated
sludge:
Achromobacter, Flavobacterium,
Nitrosomonas, Beggiatoa, Thiothrix, Nocardia,
Mycobacterium, Geotrichum, Nitrobacter.
 Biofilters hosts :
Nematodes, insect larvae, microfungi, algae,
small worms and freshwater leech.

33. MICROORGANISMS
 Microorganisms are present in sewage water
treatment vats well throughout the entire process.
 Microorganisms encompassing: bacteria,
protozoa, and viruses, in the treatment vats, exist
and grow in the sewage water and are transferred
throughout the vats with the movement of sewage
water.
 Some microorganisms are used during the
secondary treatment to remove pollutants.
 However, most microorganisms will be removed
from the wastewater during the disinfection stage of
the treatment.

34.  There are some microorganisms that continue on to
the tertiary treatment to utilize removal of other
pollutants like nitrogen, but will later be disinfected
and killed.
BACTERIA
 Wastewater treatment vats are inhabited by varied
and broad strains of bacteria like Escherichia coli
, Vibrio cholerae ,Helicobacter pylori etc ..

35. BENEFICIAL BACTERIA
1) Biofilm forming bacteria
Are present in the
trickling filter phase of the
secondary treatment process,
considered to be beneficial in
the removal of organic
materials.
Pseudomonas, Zooglea,
Chromobacter, and , namely
a few of whom are aerobic
heterotrophic organisms.
Flavobacterium Such bacteria
are exposed to oxygen during
the treatment to break down
the organic molecules.

36. 2.NITROGEN REMOVING BACTERIA
 Nitrogen removing bacteria (nitrifiers and
denitrifiers) -
Nitrifiers include strains Nitrosomonas
europaea as well as Nitrobacter hamburgensis.
Denitrifiers include strains Thiobacillus
denitrificans.

37. BDELLOVIBRIO BACTERIOVORUS
 Traces of Gram-negative bacteria
can also be found in the
wastewater treatment vats, such
as Bdellovibrio bacteriovorus,
which penetrate and lyses other
gram-negative bacteria within
sewage water.
 obligate aerobic, parasitic
bacterium
 able to replicate on the aerobic
filter film but is unable to live in
anaerobic sludge.
 main function of this bacterium is
to purify waste water by reducing
gram-negative bacteria with the
ability to survive within sewage.
 penetrate a host, replicate, and
finally lyses the host’s cell.

38. BROCADIA ANAMMOXIDANS
 anaerobic
chemolithoautotrophic
bacteria and is one of several
oxidizers of ammonia.
 Take in ammonia from the
sewage water, by the
release hydrazine (rocket
fuel) via an enzyme called
hydroxylamine
oxidoreductase.
 clarifying wastewater of
forms of ammonia.

39.  Nitrogen removal from wastewater is carried out
through the: oxidation of ammonia to nitrite, the
oxidation of nitrite to nitrate, and finally, the
conversion of nitrate to nitrogen gas.
 There are several other bacteria, in addition to
Brocadia anammoxidans, used during nitrification
and denitrification processes.

40. NITROSOMONAS EUROPAEA (NITRIFIER)
 a Gram-negative
chemolithoautotroph ammonia-
oxidizing bacterium
 catalyzes the foremost phase in
the oxidation of toxic ammonia
to nitrite.
 optimum temp 20-30 C and pH
6.0- 9.0
 derives energy from burning
ammonia together with oxygen

41. NITROBACTER HAMBURGENSIS (NITRIFIER)
 Nitrobacter hamburgensis is a
gram negative, obligate
chemolithotroph which exhibit
an aerobic lifestyle, dependent
on oxygen.
 a nitrifying organism and is vital
during the process of sewage
water treatment due to the fact
that it is capable of catalyzing
the oxidation of nitrite to
nitrate, the second phase of
nitrification.

42. THIOBACILLUS DENITRIFICANS
 Are implicated for the duration
of the third phase of the
nitrogen removal cycle.
 This organism denitrifies
nitrate to nitrogen gas,
which is then released into
the atmosphere.
 T. denitrificans use inorganic
sulfur compounds as an
energy source.
 Their optimal conditions vary
between 30C and pH 7.5 -
8.0.

43. SULFATE REDUCING BACTERIA
 Lastly, sulfate reducing
bacteria which such as
Desulfotomaculum and
Desulfovibrio, whom reduce
sulfate to hydrogen sulfide
(H2S).
 These sulfate reducing
microbes prefer
environments with an
approximate pH 7 and are
inhibited below pH value of
5.5 and above 9.
 Optimum temperature
ranges between 28 - 32C.

44. PHOSPHORUS REMOVAL
 Phosphorus is a nutrient which makes the growth of
algae possible.
 Chemicals including: ferric chloride, alum, or lime
are added to the wastewater, which allow the
smaller particles including phosphorus to group into
larger masses.
 Then are removed through the sedimentation
tanks.

45. PROTOZOA
 Amoebae, ciliates, and flagellates are found present for
sewage treatment.
 Importance of protozoa in wastewater treatment is to
maintain a slime layer within trickling filter systems.
 Play a predatory role in removing bacteria, other
protozoa, and several small particles.
 have multiple feeding mechanisms: filter and raptorial
feeding.
 Filter feeders consume during the trickling filter phase
when water is passed through the filter.
 Raptorial feeders, such as flagellates and amoebae,
feed on different types of bacteria. Larger forms of
amoebae eat ciliates and flagellates as well as smaller
amoebae feed primarily on bacteria.

46. VIRUS
 Enterovirus and rotavirus, amongst a handful of
viruses are excellent indicators of human fecal
contamination in wastewater .
 These viruses must be maintained at temperatures
below 10 C and a pH 3.5- 4.
 Two enteroviruses present in sewage water
treatment involve Hepatitis A and Polio myelitis.
 Viruses are removed from water through ozonation,
a process of disinfection.

47. 3. TERTIARY TREATMENT (CHEMICAL TREATMENT)
 Removes disease-causing organisms from
wastewater .
 3 different disinfection process are :
 Chlorination
 UV light radiation (a physical treatment)
 Ozonation

48. CHLORINATION
 Chlorine is used in 2 forms – Cl2 gas form or
hypochlorite tablets
 Cl react with water to form HOCl, which rapidly
dissociate to form hypochlorite ion.
 Cl is effective against enteric bacteria.
 Most common
 Advantages: low cost & effective
 Disadvantages: chlorine residue could be harmful
to environment.
 Dechlorination done.

49. OZONATION
 Disinfection achieved by formation of free radicals
as oxidizing agents.
 More effective against viruses & bacteria than
chlorination.
 Advantages: safer than chlorination
fewer disinfection by-product
 Disadvantage: high cost
low solubility of ozone in water

50. UV RADIATION
 Damage the genetic
structure of bacteria,
viruses and other
pathogens.
 Advantages:
 no chemicals are used
 More rapid
 water taste more natural
 No by-products formed
 Disadvantages: high
maintenance of the UV-
lamp

51. MEMBRANE FILTRATION
 Membrane technologies disinfect treated
wastewater by physically filtering out m.os.
 Does not require addition of reactive chemicals
 No toxic by-products are produced.
 Membrane technologies include: reverse osmosis,
ultrafiltration, microfiltration, nanofiltration.

52. THANK YOU……….