waste water treatment
DESCRIPTION
this is a preasentation on water waste treatmentTRANSCRIPT
Wastewater Treatment
By srishti rawat
What is wastewater ?
Water that has been utilized in some capacity that negatively impacts the quality of water.
Sewage is a subset of wastewater that is contaminated with feces or urines.
Where does wastewater come from?
Residences (kitchen, bathroom)
Rainfall, Highway drainage
Industrial institution
Wastewater Constituents
Water (more than 95%) Pathogens (bacteria, viruses and parasitic worms) Non-pathogenic bacteria Organic particles(feces, hair, food, paper fiber, plant
materials) Soluble organic (urea, protein, sugar ,drug) Inorganic particles (sand, grit, metals, ceramics etc.) Soluble inorganic (ammonia, hydrogen sulfide, thiosulfates
etc.) Toxins (pesticides, poisons, herbicides etc.)
Treatment and Disposal of Waste Water in Delhi
Delhi Jal Board is responsible for treatment and disposal of waste water through an efficient network of about 7000 Km of Sewage lines across Delhi.
There are 36 Sewage Treatment plants at 21 locations
S.No. Sewage Treatment plants at Capacity(MGD- Million Gallons per Day)
1 Keshopur Phase I,II,III 72 MGD
2 Okhla Ph I,II,III,IV,V,VI 170 MGD
3 Kondli Ph I,II,III,IV 90 MGD
4 Rithla I,II 80 MGD
5 Yamuna Vihar I,II 20 MGD
6 Vasantkunj I,II 5MGD
7 Coronation Pillar I,II,III 40 MGD
8 Narela 10 MGD
9 Nilothi 40 MGD
10 Najafgargh 5 MGD
11 Papankalan 20 MGD
12 Dr.Sen Nursing Home Nalla 2.2 MGD
13 Delhi Gate Nalla 2.2 MGD
14 Mehrauli 5 MGD
15 Rohini 15 MGD
16 Ghitorni 5MGD
17 Kapashera 5MGD
18 Commonwealth Games Village 1 MGD
19 Bakkarwala 0.66MGD
20 Molarbandh 0.66MGD
21 Timarpur Oxidation Pond 6 MGD
Total 594.72
Delhi Jal Board has provided sewerage facilities in following colonies so far:
S. No Unsewered areas TotalSewerageprovided
1.Unauthorized-Regularized
567 541
2. Urban Village 135 129
3. Resettlement colonies 44 44
4. Rural Villages 189 34
5. Unauthorized colonies 1639 100
What is wastewater treatment?
process of removing contaminants from wastewater, both runoff and domestic and making it suitable to discharge back into the environment.
Municipal wastewater treatment
Industrial wastewater treatment
How can we say water is pure?
Physicallya) Total solid (tested by boiling water)b) Odorsc) Colorsd) Turbidity
Chemicallya. Biological oxygen demand (BOD)b. Chemical oxygen demand (COD)
Methods involved in wastewater treatment
Wastewater Treatment Mechanical (Physical) Treatment
a) Preliminaryb) Primary
Secondary (Biological) Treatment
Tertiary (Chemical) Treatment
Sludge Treatment
Preliminary Treatment
The objective of preliminary treatment is the removal of coarse solids and other large materials often found in raw wastewater.
Removal of these materials is necessary to enhance the operation and maintenance of subsequent treatment unit.
Coarse Screening
Grit Removal
Coarse Screening
Removal of large non biodegradable and floating solids (e.g. rags, clothes, woods, plastics, papers etc.)
Grit Removal
Grit particles which are smaller than the aperture of the coarse screen will pass through and may cause abrasive problems to pipes and pumps.
In grit removal process, velocity is so controlled that grit may settle but most of the organics are retained in suspension.
Grit Removal
Primary Treatment
Objective is the removal of settelable organic and inorganic solids by Sedimentation, and the removal of the material that will float (scum) by skimming.
Around 25-50% of the incoming BODs, 50-70% of the total suspended solids and 65% of oil and grease are removed during primary treatment.
Primary Treatment
Secondary Treatment
Biological Treatment
• Secondary treatment is designed to substantially degrade the biological content of the sewage which are derived from the human waste, food waste, soaps and detergents etc.
• Aerobic bacteria and protozoa consume biodegradable soluble organic contaminants (e.g. sugar, fats, short chain carbon molecules etc.) and binds much of the less soluble fractions into floc.
Continued…
Secondary sedimentation
•Microorganisms must be separated from the treated water by sedimentation to produce clarified secondary effluent.
•Biological floc is settled out in secondary clarifier and the secondary sludge is then sent to sludge treatment unit.
Tertiary Treatment
Purpose is to provide a final treatment stage to further improve the effluent quality before it is discharged to the receiving environment.
Nutrients removal Disinfection• to reduce the number of microorganisms Chlorination Ultraviolet radiation Ozone Odor control
Nutrients Removal
Wastewater may contain high level of nutrients (N or P compounds) which excessive release to environment may cause eutrophication.
Overgrowth of weeds, algae, blue-green algae (cyanobacteria).
DE oxygenation
Toxins produced by some algae may contaminate drinking water supply.
Nitrogen Removal
Nitrification• Biological oxidation of nitrogen from ammonia to nitrate.
I. Ammonia to nitrite using NitrosomonasII. Nitrite to Nitrate using Nitrobacter ssp. DE nitrification (anoxic condition)• Nitrate is converted into nitrogen gas and released into air.
Phosphorus Removal
Biologically• Using Polyphosphate Accumulating Organism (PAOs)• The process is called “Enhanced biological phosphorus
removal”. By chemical precipitation• Using salts of irons (e.g. ferric chloride) or aluminium (e.g.
alum) or lime.
Odor Control
Odor emitted by wastewater treatment are typically an indication of anaerobic or septic condition.
Generally arises due to hydrogen sulfide. Controlled by adding iron salts or hydrogen peroxide or
calcium nitrate.
Sludge Treatment
This process describes the management and disposal of primary and secondary sludge.
processes involved are Anaerobic digestion Composting De watering
Anaerobic Digestion
Anaerobic bacteria acts on sludge and produces large amount of waste solids and biogas ( high concentration of methane).
Methane can be used to generate electricity and run few pumps.
Solid waste (containing water) is sent for composting.
Composting
An aerobic process that involves mixing of wastewater solids with sources of carbons such as sawdust, straw or woodchips.
Aerobic bacteria digests both wastewater solids and carbon source and produce large amount of heat.
Resultant solid is then sent for dewatering.
DeWatering
Water is removed from solid waste for volume reduction. Using drying beds Mechanically filtering often through cloth screens. Centrifugation.
The sludge is now ready to be used off sites as fertilizers.