Water pollution

transcript

By-AMIT KUMAR SAHOOII MSc. Bio15151

Water Pollution

2An Offering At Thy Lotus feet

3About 71% of the Earth's surface is water-covered, and the oceans hold about 96.5 percent of all Earth's water.

5Water Pollution

Poorer water quality means water pollution.

Water pollution occurs when harmful substances are released into the water in large quantities which cause damage to people, wildlife, or habitat.

Water Pollution Comes from Point and Nonpoint Sources

Point sources Located at specific places

Easy to identify, monitor, and regulate

Nonpoint sources Broad, diffuse areas

Difficult to identify and control

Expensive to clean up

Agriculture activities: leading cause of water pollution Sediment eroded from the lands Fertilizers and pesticides Bacteria from livestock and food processing

wastes

Industrial facilities

Mining

Other sources of water pollution Parking lots

Human-made materials E.g., plastics

Climate change due to global warming

Point Source of Polluted Water in Gargas, France

Nonpoint Sediment from Unprotected Farmland Flows into Streams

Fig. 20-A, p. 535

Good 8–9

Water Quality DO (ppm) at 20°C

Slightly polluted 6.7–8

Moderately polluted 4.5–6.7

Heavily polluted 4–4.5

Gravely polluted Below 4

Major Water Pollutants and Their Sources

Common Diseases Transmitted to Humans through Contaminated Drinking Water

15Aim of Wastewater

treatment Conversion of waste materials present

in wastewater in stable oxidized end products that can be disposed easily.

To remove contaminants from wastewater.

Protect the public health, recycle and recovery of valuable components.

16Product of wastewater

treatment Waste stream (treated effluents). Solid waste or sludge.

These are suitable to be discharged back to the environment

In a treatment plant the waste is passed through a series of screens, chambers and chemical processes to reduce its bulk and toxicity.

Phases of treatment Primary Secondary Tertiary

Phases of treatment

19Primary treatment

A large percentage of suspended solids and inorganic material is removed from the

sewage.

20Secondary treatment

Involves in reducing organic material form the sewage.

21Tertiary treatment

Necessary if the water is to be reused.

99% of the solid are removed and carious chemical processes are used to ensure the water is as free from impurity as possible.

22Hence the waste water treatment

can be classified as

Physical

Biological

Chemical

23Primary treatment (Physical processes)

This process is based on the physical properties of the contaminants for its removal.

Selectively removal method.

Involves processes like Screening Grinding Grit removal Flocculation Sedimentation Flotation Equalization Coagulation Clarification

24Secondary treatment (biological

Processes) In this process the soluble and

colloidal forms of organic matter is removed.

Involves the use of aerobic as well as anaerobic organisms.

25Two major biotechnological processes

Aerobic processes and systemsOrganic matter + O2+ nutrients CO2+H2O + new cells

Anaerobic processes and systemsOrganic matter + nutrients CH4+ CO2+H2S + new cells

26Aerobic treatment methods

Fungi and bacteria are the most used organisms in this process.

Biological processes reduces the BOD and the toxicity of the industrial effluents.

This method lowers capital cost, improves sludge settling performance, control odor, removes colors and refractory organics.

27Degradation by fungi

Soil fungi – Fusarium sp. Soft rot fungi – Papulospora sp.,

Chaetomium sp. Pseudo-soft rot fungi – Hypoxylem, Xylaria. Little degrading fungi – Collybia, Mycena. White rot fungi – Trametes, Phanerochaete,

Polaria. Brown rot fungi – Gleophyllum, Poria.

Fusarium Chaetomium Xylaria

28Facts about fungi

Able to breakdown variety of environmentally persistent pollutants such as chlorinated aromatic compounds, heterocyclic aromatic hydrocarbons, various dyes and synthetic high polymers.

Degrade modified lignin and other derivatives responsible for color in pulp and paper mill.

29Degradation by Bacteria

Ability to metabolize azo dyes – Pseudomonas strain.

A wide number of bacteria can decompose monomeric lignin substructure models.

During the metabolic attack of lignin a number of simple aromatic compounds are like vanillic acid, p-hydroxy benzoic acid, ferulic and sytingic acids and conferaldehyde are produced.

30Degradation by actinomycetes

Decolourization of crystal violet was first observed in actinomycetes Nocardia coralla and Nocardia

globerula.

Nocardia

31Degradation by Yeasts

Decolourising of dyes – Kluyveromyces marxianus (able to decolorizing 78-98% of remazol black dye), Rhodotorula sp. (biodegrade crystal violet)

Kluyveromyces marxianus

32Mixed culture

Wide variety of habits have also been able to decolorize the diazo-linked chromophore of dye molecules.

Degradation of xenobiotics.

33Factors that play an important role in

aerobic treatment

Oxygen

Temperature

Concentration of pollutants

Structure of compounds

34Activated sludge

35Trickling Filters

37Fixed film Bioreactor

38Anaerobic Processes

Involves wide variety of symbiotic microorganisms.

Three major groups of bacteria involved in this process Hydrolytic (converts polymers into

simpler monomers) Acidogenic (converts simple monomers to

volatile fatty acids) Methanogenic (conversion of acetates into

methane and carbon dioxide)

Facultative lagoonsFacultative lagoons or stabilization ponds use only natural phenomena and almost no mechanical action. Oxygenation for bacterial oxidation of organics comes from photosynthesis by algae and a bit from wind. CO2 released by bacteria is used by the algae. Excess biomass and other settleables are treated by anaerobic bacteria at the bottom.

Facultative lagoon interactions

http://www2.bren.ucsb.edu/~keller/courses/esm223/esm223_15.pdf

41Advantages of anaerobic to aerobic system

Less amount of sludge produced.

10% of the cost required for the disposal of the sludge produced in a aerobic system.

5-20% less nutrients required.

No energy for aeriation.

42Up flow anaerobic sludge blanker

reaction (UASB)

UASB REACTOR

44Anaerobic contact

reactor

45Expanded bed reactor

46Expanded Bed retractor

47Tertiary treatment

Thermal pre-treatment Wet air oxidation Concentration incineration Anaerobic treatment

All these above are supplemented by the following processes. Chemical precipitation Absorption Activated carbon Peat Wood chips Silica gel Membrane filtration Ion exchange Irradiation

48Anaerobic

Treatment

Thermal Pretreatment plant

Wet air oxidation Plant

Chemical Precipitation/Precipitate softening: used to remove or reduce the hardness in potable waters due to excess of salt of calcium and magnesium. Precipitate softening converts the soluble salts into insoluble ones, removed by flocculation and sedimentation.

Adsorption: Physical process where soluble molecules are removed by attachment to the surface of a solid substrate (absorbent).

Activated carbon: used in dye removal by adsorption. Its well suited for only some particular waste system types

Powdered activated carbon (PAC): can be added to process water in various stages of treatment process.

Granular activated carbon (GAC): easier to handle than PAC. Is used for continuous applications in either a packed or expanded bed.

Peat: the cellular structure of peat makes it an ideal choice as an adsorbent. Has an ability of adsorbing transition metals and polar organic compounds.

Wood chips: They show a good adsorption capacity for acid dyes. Drawbacks: not as effective as the other sorbents available and takes a longer contact time.

Silica gel: effective material for removing dyes.

Membrane filtration: involves primary polymeric membranes to physically filter out minutes particles including viruses and some ions of solution under pressure.

Ion Exchange: involves reversible interchange of ions of the same charge between a solid ion-exchange medium and a solution. Used in softening of water by the exchange of Ca2+

and Mg2+ with Na+ and Na2R.

Irradiation: sufficient amount of oxygen is dissolved to break down organic substances effectively by radiation.

Boomerang effect: Whatever goes comes back around.

Prevention of Water Pollution

Dealing with water pollution is something that everyone (including governments and local councils) needs to get involved with. Here are a few things you can do to help:

Never throw rubbish away anyhow. Always look for the correct waste bin. If there is none around, please take it home and put it in your trash can. This includes places like the beach, riverside and water bodies.

Use water wisely. Do not keep the tap running when not in use. Also, you can reduce the amount of water you use in washing and bathing. If we all do this, we can significantly prevent water shortages and reduce the amount of dirty water that needs treatment.

Do not throw chemicals, oils, paints and medicines down the sink drain, or the toilet. In many cities, your local environment office can help with the disposal of medicines and chemicals. Check with your local authorities if there is a chemical disposal plan for local residents.

Buy more environmentally safe cleaning liquids for use at home and other public places. They are less dangerous to the environment.

If you use chemicals and pesticides for your gardens and farms, be mindful not to overuse pesticides and fertilizers. This will reduce runoffs of the chemical into nearby water sources. Start looking at options of composting and using organic manure instead.

If you live close to a water body, try to plant lots of trees and flowers around your home, so that when it rains, chemicals from your home does not easily drain into the water.

Participate in a clean up

67References

Environmental Biotechnology – Indu Shekhar Thakur

Wikipedia

Professor M. Siva Kumar Slides

Water pollution

Science