Different methods used in waste water treatment (conventional and biological method) summarizes various waste water treatment processes. Conventional methods include preliminary treatment like screens and grit removal, primary treatment using sedimentation, and secondary biological treatment using activated sludge or trickling filters. Biological treatment uses microorganisms to break down organic waste aerobically or anaerobically. Anaerobic processes like anaerobic digestion and UASB reactors produce biogas and reduce sludge. The document provides details on the microbial life and processes involved in waste water treatment.

1. Different methods used in waste water
treatment (conventional and biological
method).
Ritu sheoran
Roll no - 90000304014

2. Contents:-
 Introduction
 Sources
 Characteristics of wastewater
 objective
 Elements present in waste water
 Impact of waste water
 Microbial life in waste water
 Treatment methods-conventional and biological
 Conclusion
 References

3. Introduction:-
What is waste water?
Wastewater is used water from any combination of domestic, industrial ,
commerical or agricultural activities ,surface run off and any sewer inflow or
sewer infiltration.
sources:- disease causing microorganisms
Organic materials,human waste
Toxic substances ( such as heavy metal ions).
Waste water is comprised of liquid and solid waste that is discharged from
 Domestic wastewater from households .
 Municipal wastewater from communities ( also called sewage ).
 Dairy and Industrial establishment- slaughterhouse waste,dairy
waste,tannery wastewater etc.

4. Basic characteristics of wastewater:-

5. Microbial life in waste water
 Biological treatment involves the use of different microorganisms.these
microorganisms present throughout the process. These are:-
 Bacteria,protozoa,fungi,algae,viruses,rotifers,nematodes
 These microorganisms are present in the treatment vats,grows and moves
with sewage water.
 They metabolize the biodegradable organics ,convert them in the carbon
dioxide ,water and energy for their growth and reproduction.
 Biological treatment systems must provide these microorganisms with enough
oxygen , comfortable home , suitable temperatures .
Algae:- causes eutrophication.
Useful in oxidation ponds.
Fungi:-important in decomposing organic matter into simple forms.

6. Harmful bacteria:-
 Various strains of bacteria causes animals diseases through the ingestion of
contaminated food and water.
 Bacteria such as – Escherichia coli,Vibrio cholera and Helicobacter pylori.
 These bacteria are present right from the start of treatment vats due to their arrival
of sewage water.
 E.coli strains are removed after biological treatment by UV radiations ,ozonation and
chlorination while vibrio cholera is eradicated by high doses of UV rays.
Benefical bacteria:- biofilm forming bacteria are present in secondary treatment ,
considered as beneficial in removal of organic materials.
Aerobic bacteria such as Pseudomonas zooglea ,Flavobacterium and anaerobic bacteria
bdellovibrio bacteriovorous.
 Sulphate removing bacteria such as Desulfotomaculum and Desulfotomaculum and
Desulfovibrio.
 These bacteria are removed in the tertiary treatment of the process.
 Nitrogen removing bacteria are known as Nitrifiers and denitrifiers. Nitrifiers include
 Nitrosomonas and nitrobacter .while Denitrifiers include Thiobacillus
denitrificans.

7. Protozoa
 Several types of protozoans are present in sewage water such as Amoeba
,ciliates and flagellates through out the process.
 The importance of protozoans in wastewater treatment is to maintain a slime
layer within the systems.
 They also play a predator role in removing bacteria ,other protozoans and
several small particles .
Virus :-
 Enterovirus and rotavirus are excellent indicators of human fecal
contamination in wastewater.
 These viruses are detrimental to humans,if consumed.
 Life threating diseases such as Polio and Hepatitis A are caused by
Enterovirus.
 Life threatening forms of Diarrhea are caused by Rotavirus .
 Virus are removed from through ozonation ,a process of disinfection .

8. Why to treat wastewater?
 To reuse it.
 To manage water discharged from homes, buisness and industries to reduce
the threat of water pollution.
 To remove pollutants from waste water for its recycling.
 To promote health concern and public health .
 To preserve aquatic life and wildlife habitat.
 Reduce organic content.
 Remove /inactive pathogens
 Reduce inorganic nutrient levels.
 Removal of suspended and floatable material.

9. Chemical and physical pollutant -
contaminants
 Heavy metals including mercury ,lead,and chromium
 Organic particles such as hairs,food,paper fibers,plant material.
 Soluble organic material such as urea,fruit sugar,soluble proteins
 Inorganic particle such as sand ,grit,metal particles,
 Emulsion such as paints , mayonnaise ,emulsified oils.
 Toxins such as pesticides,poisons, herbicides etc.
Biological pollutants:-
Bacteria ( for example :-salmonella,vibrio cholera
,campylobacter.
 Viruses (hepatitis A,rotavirus)
 Parasites such as helminths and their eggs(roundworm ,hookworm.
 It can also contains non pathogenic bacteria and animals such as insects
,arthropods ,small fish

10. Impacts
 Water pollution
 Ecological imbalance
 Biodiversity
 Loss of fisheries
 Climate change
 Caused by bacteria: typhoid fever,Cholera, vomiting.
 Caused by Virus :- Hepatitis A ,polio.
 Excess of nitrogen cause blue baby syndrome.

11. fig:-Waste water treatment process-

12. Waste water treatment
 Preliminary treatment-
 Screens:- are used to removing floating material , floating material are
paper, tree branches, dead animals etc.
 Grit removal:- grit chamber used to removing grit, heavy settlable inorganic
material also called grit like sand and silt etc.
 Skimming tank:- also removes fat ,oil and grease.
 Removal of such waste water constituents that causes maintenance or
operational problem in treatment operation.it consists tree branches , dead
animals, wood.BOD reduction 15-35%.
Primary treatment or Mechanical Treatment-solids are separated ,removal of
physical stuff.
 Secondary treatment or Biological treatment-95% suspended solids are
removed.
 Dissolved biological organic Is converted into solid mass By using water borne
Bacteria.
 Tertiary treatment or Advance Biological or chemical treatment
Sludge disposal

13. Conventional waste water treatment

14. Methods used in Primary treatment
 In primary treatment suspended solid and floating material is removed .
 Fatty and oily substance can be removed by floatation method.
 Centrifugal separator is a instrument used to trap fatty and oily substance
,fatty substance are reached to outside and clean water remain in the centre
of cyclone.
 The water is passed In settling tank in which water remain for a long time in
which suspended particles are settled down and this process known as
sedimentation.
 Some small particles may be separated by Floatation method.
 Colloidal particles can be removed by Flocculation and precipitation.

15. coagulation
This process involves adding iron, aluminum salts such as ferric chloride or ferric
sulphate.
 These chemicals are called coagulants they carry positive charge neutralize
negative charge of dissolved solids in water in this reaction particles bind
together sometimes called flocculation.
 Disadvantages :- chemical used in coagulation react with sewage and they
destroy microorganisms which are helpful in digestion of activated sludge.
 Produces large quantities of sludge this make a problem in sludge disposal ,
requires skilled supervision.
 Advantage:-
 Coagulation also removes phosphates from sewage which is help in controlling
eutrophication.
 Effluent release have more better effluent with lesser amount of BOD and
suspended solids.
 It also removes suspended particles such as iron.

16. Flocculation
 Now the patricles have a neutral charge.
 Can stick together
 The water flows into a tank with paddles that provide slow mixing.
 Bring the small particles together to form larger particles called flocs.
 Mixing is done quite slowly and mixing gently in the flocculation step .
 If the mixing is too fast, the flocs will break apart into small particles that are
difficult to remove by sedimentation or filtration.

 Sedimentation:-settling down of suspended particles at the bottom of water
is called sedimentation. This process is also known as clarification.
 In this process water is collected into a big pond ,slowly –slowly impurities are
settled down by gravitation .The process can be accelerated by adding alum.
 Main principle of sedimentation is to allow water to rest or flow at a very slow
velocity.So that heavier particles settle down due to gravity .This
sedimentation tank are designed to remove a part of organic matter from
sewage effluent coming out from grit chamber.

17. Filtration:-
 This treatment is used for liquid – solid separation.variables size of filter
media are used
 Liquid passes through a porous media that traps the solids.
 Two types of sand filtration are used slow sand filtration – this is biological
process it uses bacteria ro treat water.baceria start a community on top layer
of sand nd clean the water as it passes through by digesting contaminants in
the water.
 Slow sand filtration removes bacteria, protozoa,viruses and produces clean
water.
 Rapid sand filtration used to remove suspended solids from water.it is a
physical process.
 High flow rates and require Little space to operate In rapid sand filtration.
 Flow rate is 20 metres per hour.The filters are generally cleaned twice Per
day.

18. Biological treatment:-
 It uses microbes to decompose organic waste.
 Biological method consist aerobic and anaerobic process that removed 90%
BOD from sewage waste water.
 Aerobic waste water treatment :- takes place in presence of oxygen and
influence the growth of aerobic microorganism.
 Microorganism present in aeration tank it utilize the organic matter in the
waste water for their growth and maintenance.
 Aerobic treatment utilizes oxygen and bacterial biomass to assimilate organic
matter and other pollutants like nitrogen and phosphorus into carbondioxide,
water and other biomass.
 Reduced odor and better nutrient removal efficacy.
 Methods used- trickling filter
activated sludge process
oxidation ponds

19. Fixed film system
 Microorganism grow on substrate Such as rocks ,sand and plastic.
 Wastewater is spread over surface.
 Example :- trickling filter.
Trickling filter :- after primary treatment Of the effluent is passed through
the bed and the filter medium which is consisting bed of stone in which
microorganisms are present.orgqnic Material in waste water is adsorbed by
microorganisms . Maintenance and operation are necessary requirement.
 Skilled labor is essential to preserve trickling filter without any trouble like
prevent clogging.
 This method is appropriate for treatment of grey water.
 Low pathogen removal-Bacteria -20-90%,viruses-50-90%.
fig:trickling filter

20. Activated sludge
 Mixed community of microorganisms .
 In aeration stage ,where aerobic bacteria digest biological wastes
 Settling stage allows undigested solids to settle , forms a sludge that must be
periodically removed from system.
 Primary wastewater mixed with bacteria rich activated sludge and air or
oxygen is pumped into the mixture.
 Both aerobic and anaerobic bacteria may exist.
 Promotes bacterial growth and decomposition of organic matter.
 BOD removal is approximately 85%.
 Microbial removal by activated sludge- 80-99% removal of bacteria and 90-
99%removal of viruses.

22. Fig : activated sludge

23. Oxidation ponds
 Oxidation ponds are a few meters deep ,they
are low cost, odour and mosquitoes can be a
problem.
 New biological method have been introduced
nowdays for wastewater treatment.oxidation
pond is shallow pond where waste water is
purified by action of algae and aerobic
bacteria.
 Organic matter decompsed by bacteria and
consumed by algae .
 Aerobic bacteria get oxygen from atmosphere
and convert organic matter in sewage and
relaease CO2 which is again taken by algae
during photosynthesis.
 Pathogen removal – Bacteria-90-99%
 Virus-90-99%
 Protozoa-67-99%
 These are preferred in developing countries due
to low cost ,low maintenance.this is balanced
by larger land requirement.

24. Anaerobic treatment:-
 Takes place in absence of air these microorganisms are called anaerobes .these
microorganisms do not require air to assimilate organic impurities.
 Final product of organic assimilation in anaerobic treatment is methane and CO2
gas and biomass.
 Energy efficient process.
Treatment methods-
anaerobic digestion:- used to treat biodegradable waste ,sewage in absence of
oxygen 4 satge :-Hydrolysis- hydrolysis of complex material into simple dissolved
Material sugars, amino acids. Because the microorganisms are not capable of
assimilating particulate organic material.
Acetogenesis- product generated acetic acid , hydrogen and CO2.
Methanogenesis – methane and CO2 is produced by arcahebacteria.
Advantage-sludge less volume,lower operating costs, biogas production
Disadvantage- accumulation of heavy metals and contaminants in sludge.

25. Anaerobic filter
 These filter run up in up flow mode ,this is a fixed bed biological reactor with
one or more filtration chamber is needed .
 As waste water Flows through the filter ,particles are trapped and organic
matter are degraded by active biomass that is attached to surface of filter
material.
 Advantages – high reduction of BOD .
 Low sludge production, no need of electricity, maintenance and management
are easy.
 Disadvantages- channel formation ,risk of clogging ,low reduction of
pathogens.

26. UASB (Up flow anaerobic sludge blanket
reactor)
 Anaerobic reactor used to treat several industrial
wastewater such as petroleum ,distillery heavy metals
,tannery .
 Bacteria remain in sludge and breakdown organic matter by
anaerobic digestion and transform it into biogas.So it is
called methanogenic.
 Methane gas is produced with high concentration and can
be used as energy sources.
 Process:-Screening
 Grit removal
 Pumping
 Main UASB reactor
 Gas collection system
 Sludge drying bed.
 fig:-UASB reactor

28. When the treatment is done
 Effluent back to stream after
a final carbon filtration And
Chlorination and dechlorination
Sludge – very nutrient rich
Applied directly to land as fertiliser
Incinerated ( good fuel after drying.

29. Conclusion
 Water is one of the most important Source on earth.
 It is known as universal solvent.we must not the waste the water.
 The waste water that we obtain from our daily purposes and from industries
must be treated in treatment system inorder to reduce pollution.
 Our government must provide facilities and infrastructure to avoid water
pollution and manage waste water.
 UASB reactor showed that high biogas production used in power generation
and COD removal efficiency are high . Effluent remaining from UASB reactor
used in irrigation,sometimes UASB reactor removes nitrogen from waste.
 Low sludge production and less energy is applied and high energy is generated
,cost of operations and maintenance low as compare to conventional
treatment.
 Conventional method are not competent in decreasing the heavy metals
,toxic , phosphorus ,nitrogen.

30. References
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