WASTE TREATMENT Under the - PowerPoint Presentation

Slide1

WASTE TREATMENT

Under the

guidance of: Dr. M.K. Sateesh

Presented by:

Sadhana

ReddySlide2

CONTENT

INTRODUCTIONSOURCES FOR WASTE WATER

TERMSCOMPOSITION OF DOMESTIC WASTE WATEROVER VIEW OF WASTE WATER TREATMENTPrimary TreatmentSecondary Treatment:-Activated sludge , Trickling filter & oxidation pond.Tertiary:-Removal of Nutrients , Heavy metals , PathogensSlide3

INTRODUCTION

The term sewage treatment is now a days is replaced by waste water treatment.Sewage treatment is the process of removal of contaminants from waste water.

The treatment is of chemical, physical and biological processTheir are 2 types of waste water based on the out lets-:1.House and Hotel out let.2.Industrial out letSlide4

SOURCES FOR WASTE WATERSlide5
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TERMSBiochemical Oxygen Demand[BOD]:-

It is the amount of dissolved oxygen [DO] consumed by microorganisms for the biochemical oxidation of organic.Chemical Oxygen Demand [COD]:-

It is the amount of oxygen necessary to oxidize the organic carbon completely to CO2’ H2O, and ammonia.Slide7

TYPES OF BOD

(i) Carbonaceous BOD (CBOD)CBOD is the amount of Oxygen used by a mixed population of heterotrophic microorganisms to oxidize organic compounds

Org comp CO2+H2O+NH4+ Bacterial mass Bacterial bio film

Protozoa biomass +CO2

(ii) Nitrogenous Oxygen demand (NOD)

Autotrophic bacteria such as nitrifying bacteria also require oxygen to oxidize NH

4

+

to nitrate. The oxygen demand exerted by

nitrifiers

is called as NOD and also autotrophic BOD

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COD

Chemical oxygen demand (COD)COD is the amount of oxygen necessary to oxidize the organic carbon completely to CO

2 , water and ammonia.COD is measured via oxidation with potassium dichrome (K2CR2O7) in presence of sulphuric acid & silver is expressed in mg/L.If COD is higher than BOD it means that the amount of organic compounds are high which are not easily bio degraded.

In untreated domestic waste, water COD ranges between 250 to 1000mg/LSlide9

Composition of domestic waste

Domestic waste water is a combination of human and animal excreta (faeces & urine)

and grey water resulting from washing, bathing and cooking. People excrete 100-500g wet weight of faeces & 1& 1.3 L of urine per capita per day.Domestic waste is composed of mainly Proteins 40-60%Carbohydrates 25- 50%Fats & oils 10%Urea derived from urine Slide10

Contd…Even it includes a large number of trace organic compounds that is pesticides , surfactants, phenol & priority pollutants

The latter category comprises non metals (As , SC) metals (Cd, Hg,

Pb) benzene compounds ( benzene , ethyl benzene) & chlorinated compounds Slide11

Overview of waste water treatment

Physical forces as well as chemical & biological process drive the treatment of waste water.

Unit operations :- Treatment methods that rely on physical forces are called unit operations. These includes Screening Sedimentation Filtration or flotation Unit process:- treatment methods that rely on chemical and biological processes are called unit process Slide12

Contd…

Chemical unit consists of 1. Include disinfection

2. adsorption or precipitationBiological unit process involves 1. microbial activity 2. organic matter degradation 3. removal of nutrients Slide13

Contd..Waste water treatment comprises of four steps

Preliminary treatment :- the objective of this operation is to remove debris and coarse materials that may clog equipment's implant.

Primary treatment :- treatment is brought about by physical process such as screening and sedimentation. Slide14

Contd..3

. Secondary treatment:- Biological and chemical are used to treat waste water. Even nutrient removal also generally occurs during secondary treatment.

Biological :- activated sludge, trickling filter, oxidation ponds Chemical :- Disinfection4. Tertiary or advanced treatment:- unit operations and chemical unit process are used to further remove BOD, nutrients, pathogens, parasites and sometimes toxic substancesSlide15
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Activated sludge process

Activated sludge is suspended growth process that began in England at the turn of the century.

This process has since been adopted world wide as a secondary biological treatment for domestic waste water.This process consists essentially of an aerobic treatment that oxidises organic matter to CO2, H2O , NH4 & new cell biomassAir is supplied to this process by diffused or mechanical disposed Slide19

Contd…Effluent from primary treatment is pumped into a tank and mixed with bacteria – rich slurry known as activated sludge

Air or oxygen is supplied to encourage the growth of bacteria.

The material then goes to a secondary setting tank where the water is siphoned off the top of the tank & sludge is removed from the bottom.Slide20

Contd..

Food to Microorganism ratio [F/M] :- A portion of the sludge in the clarifier is recycled back to aeration basin & the remainder is wasted to maintain a proper F/M

F/M ratio indicates the organic load into the activated sludge system & expressed in kilogram BOD per kilogram of MLSS per day. =

Q = flow rate no of sewage in million gallons per day

MLSS= Mixed liquor suspended solids (mg/L)

V= Volume of aeration tank (gallons)

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Activated sludgeSlide22

Major contents of sludge

Bacteria

ZoogleaPseudomonasFlavobacterium AlcaligenesAchromobacterCorynobacterium Acinebacter

Bacillus

Filamentous

Eg

:

Sphaerotilus

Gliding Bacteria

Eg

:-

Beggitoa

Fungi

Geotrichum

Pencillium

Cephalosporium

Cladosporium

Alternaria

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Trickling filter

It is the processing unit which will be circular either rectangular tank containing the filter medium.Depth will be approximately 1.0 to 2.5m this surface area is provided for microbial growth.

The filter media used in trickling filters are stone[crushed limestone & granite], ceramic material, treated wood, hard coal or plastic media.Slide25
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Microorganisms found in trickling

BACTERIA

FUNGIALGAEPROTOZOAZoogleaFusariumUlothrixBodoPseudomonasPenicilliumPhormidiumMonasflavobacteriumAspergillusAnacystisColpidiumAhromobacterc

Mucor

Euglena

Vorticella

Alcaligenes

Geotrichum

Chlorella

Amoeba

FB:Sphaerotilus

.

Yeasts

Arcella

N.

communis

, N.

oligotropha

NitrobacterSlide27

Oxidation pond

Here oxygenation is usually achieved by diffusion and by photosynthetic activity of algaeIn the ditches the microorganisms grow as suspended particles.

The water in pond moves in clock wise direction.Temperature is for about 22 CDuration time is 15 hoursArea is of 15 million gallons Slide28
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Removal of nitrogen

Biological oxidation of nitrogen from ammonia to

nitrate[NITRIFICATION]followed by DENITRIFICATION the reduction of nitrate to nitrogen gas.Nitrosomonas (ammonia oxydizing bacterium or AOB) & Nitrospira ( anitire oxidizing bacteria or NOB)The target region of Nitrosomonas

is

Amo

Agene & 16Sr DNA is target region of

Nitrospira

BABE:- Bio augmentation batch enhanced process can be used to augment nitrification in activated sludge operating at sub optional solid retention times Slide30

Different systems

Single sludge system This system comprise a series of aerobic & anaerobic tanks in lieu of single aeration

tank .Slide31

Multi sludge System

Carbonaceous oxidation, nitrification & de nitrification are carried out in three separate systems Methanol or settled sewage can serve as source of carbon for de nitrifierSlide32

Bardenpho Process

The process consists of 2 aerobic & 2 anoxic tanks followed by sludge

setting tank Slide33

Removal of phosphorus

A/O ( Anaerobic/ oxic

) processA/O process consists of anaerobic zone. During anaerobic phase , inorganic phosphorus is released from the cells as a result of polyphosphate hydrolysis. The energy released is used for up taking of BODBardenpho process: This system remove nitrogen as well as phosphorus. University of cape town process (UCT):In this system train of 3 tanks of anaerobic-anoxic-aerobic followed by clarifier.Slide34

UCTSlide35

BY MICROORGANISMSPolyphosphate accumulating organism [PAOs] are selectively enriched and accumulated large quantities of phosphorous with in the cell.

Up to 20% of their cell. Example for PAOs is Gammaproteo

bacteria of genus Acinetobacter ,Microlunatus phospovorus.Polyphosphate hydrolysis organism[PHA]are hydrolysed P.Example: Betaproteo bacteria, Lampropedia spp. Slide36

PAO”s OrganismSlide37

Heavy metal RemovalHeavy metals are the major toxicants found in industrial waste waters.

The affinity of biological solids for heavy metals was found to follow the order:Pb>Cd>Hg>Cr3+>Cr6+>Zn>Ni.

It was reported that biofilm microorganisms were 2 to 600 times resistant to metals than planktonic. Slide38
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Disinfection

Temperature.Effect of pH.

Chlorine It help in inactivation of microorganisms by cell injury.Disruption of cell permeability.Expose to chlorine leads to leakage of proteins,RNA and DNA.Interrupts nutrient transportation, inhibits cell respiration, damages iron sulfur center.Arest enzyme action by accumulation of hydrogen peroxide.Slide40

DisadvantagesChlorination of drinking water is risk for bladder, kidney and colorectal cancers.

The disinfection by products [DBPs] are mutagens or carcinogens and teratogens.Cardiovascular diseases.

Examples of microorganisms- E. coil, Poliovirus,Campylobacter jejuni.Slide41

Chloramination

NH3 + HOCl

NH2Cl + H2O (Monochloramine, pH 8.5)NH2Cl + HOCl NHCl2 + H2O (Dichloroamine, pH 4.5) NHCl2 + HOCl

NCl

3

+ H

2

O

(

Trichloroamine

, pH <4.5)

Examples:-

Bacteria-

E.coil

, Coli forms, Mycobacterium fortuitism,

M.avium

, M. Intracellular , S. tphimurium,

Shigella sonnei

.Viruses- Polio I, Hepatitis A , Coli phage MS2, Rotavirus SA11.

Protozoan

: Cysts-Giardia

muris

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Chlorine dioxideDestruction of cysts pathogenic protozoa such as

Naegleria gruberi.At pH 9.0 bacteriophage F2 is inactivated by acting up on protein coat

It disturb the protein synthesis in bacterial cell.Examples-Bacillus subtilis spores, K. pneumonia.Slide43

Chlorine dioxideSlide44

OZONE

By passing dried air between electrodes separated by air gap and applying alternating current.The volts used here is from 8000 to 20,000V.

Standard oxidation potential is 2.07eV but for in activation of bacteria it needs 0.10g/L.Example-E. coli-0.001 to 0.2Enteric viruses-0.04 to 0.42.Mycobacterium > Polio virus 1 > Candida parapsilosis > E.coi > Salmonella typhimurium.Slide45
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Process

Free radicals are produced to aqueous media that inactivates microorganisms.DISADVANTAGES

Mutagenic by product is bromate (BrO3 ) carcinogenMore electricity, costly It don’t cause damage to bacterial spore DNA Slide47

U.V LIGHT

@ wavelength of 253.7nm

It damages micro organisms DNA It causes thymine & cytosine dimer which block DNA replication For viruses it damages viral genome, or virus coat Protozoan cysts >bacterial spores>viruses> vegetative bacteria. Slide48

DISADVANTAGES

Difficulty in

determining U.V doseFormation of biofilms on lamp surfaceElectrical problem Slide49

PHOTO INACTIVATION

Solar radiation

Solar radiation @ ≥ 600w/m2 for 5 hours to reduce pathogens Ex:- vibrio cholerae, salomenella. Water in plastic bottle is exposed to sunshine for 7 h to 550C

PhoTODYNAMIC

inactivation

It is also called as photochemical disinfection

It consists of visible or sunlight as energy source, O2 & sensitizer dye such as methyl blue, rose Bengal or eosin

It reduce the poliovirus I for 1.8 log

Here flow will be 50m

3

/h

35min in reduce 4-5 log of microorganisms Slide50

PHOTODYNAMIC INACTIVATERSlide51

PHOTO CATALYTICTitanium dioxide [Tio

2]+Fluorescent or sunlight=photo catalytic. Even it degrades the endotoxin which are released from the cells.Slide52
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REFERENCEShttp:⁄⁄ www.scitrav.com ⁄ wwater

53⁄ water lnk.htm[collection of web pages on activated sludge]

http:⁄⁄ www.epa.gov ⁄enviro ⁄ html⁄icr⁄dbp.htm1[disinfection byproducts from U.S.EPA]http :⁄⁄ www.epa.gov ⁄owm⁄ mtb⁄ U.V.pdf[U.V disinfection]Waste water Microbiology[3rd edition] by GABRIEL BITTON.Environmental Biology for Engineers and Scientists by David A.Vaccari, Peeter F. Strom,Jaes E.AllemanSlide54

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