Lecture 3Lecture 3

Water quality and Water quality and constituents in wastewaterconstituents in wastewater

Characteristics of Wastewater Characteristics of Wastewater ContaminantsContaminants

Suspended or dissolvedSuspended or dissolved Inorganic or organicInorganic or organic Biodegradable or persistent (refractory, recalcitrant, Biodegradable or persistent (refractory, recalcitrant,

nonnon--biodegradable)biodegradable) Pathogens (viruses, bacteria, protozoa, Pathogens (viruses, bacteria, protozoa, helminthshelminths)) Oxygen consuming Oxygen consuming –– aggregate constituentsaggregate constituents-- BOD, BOD,

CODCOD Nutrients Nutrients –– N and PN and P Aesthetic factors Aesthetic factors –– floating solids, odorsfloating solids, odors Toxic materials (individual compounds) Toxic materials (individual compounds) –– metals, metals,

organicsorganics

Characteristics of Wastewater Characteristics of Wastewater ContaminantsContaminants

Water quality

Physical Physical parametersparameters

ChemicalChemicalparametersparameters

BiologicalBiologicalparametersparameters

Physical parametersPhysical parameters

SolidsSolidsTurbidityTurbidityTemperatureTemperatureColor, Taste, and OdorColor, Taste, and Odor

Interrelationships of solids found in water and wastewaterInterrelationships of solids found in water and wastewater

Imhoffcone

Settleablesolids sample Evaporation TS

Filter(glass fiber)

Evaporation of filter residue

Evaporation of Filtrate

TSS TDS

Muffle oven Muffle oven

VSS FSS VDS FDS

TVS TFS

TS

SolidsSolids

Definitions for solids found in water and wastewaterDefinitions for solids found in water and wastewater

Total Solids (TS): The residue remaining after a Total Solids (TS): The residue remaining after a wastewater sample has been evaporated and dried at a wastewater sample has been evaporated and dried at a specified temperature (103 to 105 specified temperature (103 to 105 ooCC))

Total volatile solids (TVS): Those solids that can be Total volatile solids (TVS): Those solids that can be volatilized and burned off when the TS are ignited volatilized and burned off when the TS are ignited ( 500( 500±±50 50 ooCC))

Total fixed solids (TFS): The residue that remains after Total fixed solids (TFS): The residue that remains after TS are ignited ( 500TS are ignited ( 500±±50 50 ooCC))

Total suspended solidsTotal suspended solids (TSS): Portion of the TS retained (TSS): Portion of the TS retained on a filter with a specified pore size, measured after on a filter with a specified pore size, measured after being dried at a specified temperature (105 being dried at a specified temperature (105 ooCC). The filter ). The filter used most commonly for the determination of TSS is the used most commonly for the determination of TSS is the WhatmanWhatman glass fiber filter, which has a nominal pore size glass fiber filter, which has a nominal pore size of about 1.58 of about 1.58 μμmm

SolidsSolidsDefinitions for solids found in water and wastewaterDefinitions for solids found in water and wastewater Volatile suspended solidsVolatile suspended solids (VSS): Those solids that (VSS): Those solids that

can be volatilized and burned off when the TSS are can be volatilized and burned off when the TSS are ignited ( 500ignited ( 500±±50 50 ooCC))

Fixed suspended solids (FSS): The residue that Fixed suspended solids (FSS): The residue that remains after TSS are ignited ( 500remains after TSS are ignited ( 500±±50 50 ooCC))

Total dissolved solids (TDS): Those solids that pass Total dissolved solids (TDS): Those solids that pass through the filter, and are then evaporated and dried through the filter, and are then evaporated and dried at specified temperatures. It should be noted that what at specified temperatures. It should be noted that what is measured as TDS is comprised of colloidal and is measured as TDS is comprised of colloidal and dissolved solids. Colloids are typically in the size dissolved solids. Colloids are typically in the size range from 0.001 to 1 range from 0.001 to 1 μμmm

SolidsSolidsDefinitions for solids found in water and wastewaterDefinitions for solids found in water and wastewater

Total volatile dissolved solids (VDS): Those Total volatile dissolved solids (VDS): Those solids that can be volatilized and burned off solids that can be volatilized and burned off when the TDS are ignited ( 500when the TDS are ignited ( 500±±50 50 ooCC))

Fixed dissolved solids (FDS): The residue Fixed dissolved solids (FDS): The residue that remains after TDS are ignited ( 500that remains after TDS are ignited ( 500±±50 50 ooCC))

SettleableSettleable solids: Suspended solids, solids: Suspended solids, expressed as milliliters per liter, that will expressed as milliliters per liter, that will settle out of suspension within a specified settle out of suspension within a specified period of timeperiod of time

Interrelationships of solids found in water and wastewaterInterrelationships of solids found in water and wastewater

Imhoffcone

Settleablesolids sample Evaporation TS

Filter(glass fiber)

Evaporation of filter residue

Evaporation of Filtrate

TSS TDS

Muffle oven Muffle oven

VSS FSS VDS FDS

TVS TFS

TS

TurbidityTurbidity（浊度）（浊度） Turbidity, a measure of the lightTurbidity, a measure of the light--transmitting transmitting

properties of water, is another test used to properties of water, is another test used to indicate the quality of waste discharges and indicate the quality of waste discharges and natural waters with respect to natural waters with respect to colloidal and colloidal and residual suspended matterresidual suspended matter..

The measurement of turbidity is based on The measurement of turbidity is based on comparison of the intensity of light scattered by a comparison of the intensity of light scattered by a sample to the light scattered by a reference sample to the light scattered by a reference suspension under the same conditions.suspension under the same conditions.

The results of turbidity measurements are The results of turbidity measurements are reported as reported as nephelometricnephelometric turbidity units (NTU)turbidity units (NTU)

TurbidityTurbidity In general, there is no relationship between turbidity In general, there is no relationship between turbidity

and the concentration of total suspended solids and the concentration of total suspended solids (TSS) in untreated wastewater.(TSS) in untreated wastewater.

There is a reasonable relationship between turbidity There is a reasonable relationship between turbidity and TSS for the settled and and TSS for the settled and filtertedfilterted secondary secondary effluent:effluent:

TSS, mg/TSS, mg/LL≈≈(TSS(TSSff)(T)(T))Where Where TSSTSSff=factor used to convert turbidity =factor used to convert turbidity readings to readings to total suspended solids;total suspended solids;T = turbidity, NTUT = turbidity, NTU

TemperatureTemperature

The temperature of water is a very important The temperature of water is a very important parameter because of its effect on chemical parameter because of its effect on chemical reactions and reaction rates, aquatic life, and reactions and reaction rates, aquatic life, and the suitability of the water for beneficial uses.the suitability of the water for beneficial uses.

Oxygen is less soluble in warm water than in Oxygen is less soluble in warm water than in cold water.cold water.

The increase in rate of biochemical reactions The increase in rate of biochemical reactions that accompanies an increase in temperature.that accompanies an increase in temperature.

TemperatureTemperature Optimum temperatures for bacterial activity Optimum temperatures for bacterial activity

are in the range from 25 to 35 are in the range from 25 to 35 ooCC..

Aerobic digestion and nitrification stops Aerobic digestion and nitrification stops when the temperature rises to 50 when the temperature rises to 50 ooCC..

When t<15 When t<15 ooCC, methane, methane--producing bacteria producing bacteria become quite inactive, and at about 5 become quite inactive, and at about 5 ooCC, the , the autotrophic nitrifying bacteria practically autotrophic nitrifying bacteria practically cease functioning.cease functioning.

At 2 At 2 ooCC, even the , even the chemoheterotrophicchemoheterotrophicbacteria acting on carbonaceous material bacteria acting on carbonaceous material become essentially dormant. become essentially dormant.

Esthetic characteristics Esthetic characteristics –– Color, Taste, and OdorColor, Taste, and Odor

The age of wastewater can be determined The age of wastewater can be determined qualitatively by its color and odor. qualitatively by its color and odor.

Fresh wastewater: light brownishFresh wastewater: light brownish--graygray As the travel time in the collection system As the travel time in the collection system

increases, and more anaerobic conditions increases, and more anaerobic conditions develop, the color of the wastewater changes develop, the color of the wastewater changes sequentially from gray to dark gray, and sequentially from gray to dark gray, and ultimately to black. ultimately to black.

In most cases, the gray, dark gray, and black In most cases, the gray, dark gray, and black color of wastewater is due to the formation of color of wastewater is due to the formation of metallic sulfides.metallic sulfides.

Hydrogen sulfide gas, HHydrogen sulfide gas, H22S, is a common S, is a common cause of odor in water and wastewater.cause of odor in water and wastewater.

Chemical parametersChemical parameters

Dissolved oxygenDissolved oxygen Aggregate organic constituentsAggregate organic constituents Individual organic compoundsIndividual organic compounds Inorganic nonmetallic constituentsInorganic nonmetallic constituentsMetallic constituentsMetallic constituents

Dissolved oxygen (DO)Dissolved oxygen (DO) Oxygen is slightly soluble in water. The Oxygen is slightly soluble in water. The

saturation concentration at 20 saturation concentration at 20 ooCC is about 9 is about 9 mg/L.mg/L.

DO is one of the most important parameters DO is one of the most important parameters of water quality in streams, rivers, and lakes.of water quality in streams, rivers, and lakes.

If there is much organic material in the water, If there is much organic material in the water, bacteria will use up the DO very rapidly. bacteria will use up the DO very rapidly. Consequently, fishes will be dead as a result Consequently, fishes will be dead as a result of lack of DO.of lack of DO.

DO plays important role in biological DO plays important role in biological wastewater treatment facilities. wastewater treatment facilities.

Aggregate organic constituentsAggregate organic constituents

Chemical oxygen demand (COD)Chemical oxygen demand (COD) Biochemical oxygen demand (BOD)Biochemical oxygen demand (BOD) Total organic carbon (TOC)Total organic carbon (TOC) Theoretical oxygen demand (Theoretical oxygen demand (ThODThOD))Oil and greaseOil and grease SurfactantsSurfactants

Chemical oxygen demand (COD)Chemical oxygen demand (COD)

Theory : computed from formulaTheory : computed from formulaOrganic+OOrganic+O22 COCO22+NH+NH44

+++H+H22OO

Measurement (Measurement (CODCODcrcr): computed from ): computed from dichromate (Crdichromate (Cr22OO77

22--) consumed) consumed

COD measures all organics, includingCOD measures all organics, includingthe the nonbiodegradablenonbiodegradable substances.substances.

Organic electron donor

O2

e-

Organic electron donor

Cr2O72-

e-

Chemical oxygen demand (COD)Chemical oxygen demand (COD)The COD test is used to measure the oxygen equivalent of the The COD test is used to measure the oxygen equivalent of the

organic material in wastewater that can be oxidized organic material in wastewater that can be oxidized chemically using potassium dichromate in an acid solution.chemically using potassium dichromate in an acid solution.

Oxidize with excess CrOxidize with excess Cr22OO7722--

Measure CrMeasure Cr22OO7722-- remainingremaining

Convert CrConvert Cr22OO7722-- consumed to Oconsumed to O22 equivalent equivalent

CrCr22OO7722-- +14H+14H+++6e+6e--=2Cr=2Cr3+3++7H+7H22OO

OO22+4H+4H+++4e+4e--=2H=2H22OO

Dichromate equivalent mass=(1/6)216=36gDichromate equivalent mass=(1/6)216=36goxygen equivalent mass= (1/4)32=8goxygen equivalent mass= (1/4)32=8goxygen equivalent conversion factor for oxygen equivalent conversion factor for

dichromate=8/36=0.222dichromate=8/36=0.222So 1 g CrSo 1 g Cr22OO77

22-- is equivalent in its oxidizing power to 0.222g Ois equivalent in its oxidizing power to 0.222g O22

Biochemical oxygen demand (BOD)Biochemical oxygen demand (BOD)

BOD is an indirect measure of the total amount BOD is an indirect measure of the total amount of biodegradable organics in the water. of biodegradable organics in the water.

The more organic material there is in the water, The more organic material there is in the water, the higher the BOD exerted by the microbes will the higher the BOD exerted by the microbes will be.be.

The complete decomposition of organic material The complete decomposition of organic material by microorganisms takes time, usually 20d or by microorganisms takes time, usually 20d or more under ordinary circumstances.more under ordinary circumstances.

Biochemical oxygen demand (BOD)Biochemical oxygen demand (BOD)

The amount of oxygen used to completely The amount of oxygen used to completely decompose or stabilize all the biodegradable decompose or stabilize all the biodegradable organics in a given volume of water is called the organics in a given volume of water is called the ultimate BOD, or BODultimate BOD, or BODLL..

BOD is a function of time.BOD is a function of time. BODBODtt=BOD=BODLL∙∙(1(1--1010--ktkt))Where Where BODBODtt= BOD at any time t, mg/L= BOD at any time t, mg/Lk= a constant representing the rate of the BOD k= a constant representing the rate of the BOD

reactionreactionT=time, d T=time, d

BOD increase over time until all the organic pollutants BOD increase over time until all the organic pollutants are stabilized. The value of BOD after 5 d, or BODare stabilized. The value of BOD after 5 d, or BOD55, is , is

used for routine measurement and analysisused for routine measurement and analysis

0 1 2 3 4 5 6 7 8 9 10 11 12 13

BO

D, m

g/L

BODL

BOD5

Time, d

•Organic+O2 CO2+NH4++H2O＋cells

Nitrogenous biochemical oxygen demand Nitrogenous biochemical oxygen demand （（NBODNBOD））

NoncarbonaceousNoncarbonaceous matter, such as ammonia, is matter, such as ammonia, is produced during the hydrolysis of proteins.produced during the hydrolysis of proteins.

A number of bacteria are capable of oxidizing A number of bacteria are capable of oxidizing ammonia to nitrate. These are called nitrifying ammonia to nitrate. These are called nitrifying bacteria.bacteria.

The oxygen demand associated with the The oxygen demand associated with the oxidation of ammonia to nitrate is called the oxidation of ammonia to nitrate is called the nitrogenous biochemical oxygen demand nitrogenous biochemical oxygen demand （（NBODNBOD））

Nitrogenous biochemical oxygen Nitrogenous biochemical oxygen demand demand （（NBODNBOD））

e-

O2

Cells

Ammonium

NH3+O2＋ CO2 HNO3+H2O＋cellsNitrification

mg/L O2demand

BODL

NBOD

Combined carbon and nitrogenous BOD

Nitrification is usually observed to occur from 5 to 8 days after the start of the BOD incubation period

time

Limitation in the BOD testLimitation in the BOD test

A high concentration of active, A high concentration of active, acclimated seed bacteria is requiredacclimated seed bacteria is required

Pretreatment is needed when dealing Pretreatment is needed when dealing with toxic wastes, and the effects of with toxic wastes, and the effects of nitrifying organisms must be reducednitrifying organisms must be reduced

Only the biodegradable organics are Only the biodegradable organics are measuredmeasured

The relatively long period of time The relatively long period of time required to obtain test resultsrequired to obtain test results

Total organic carbon (TOC)Total organic carbon (TOC) The TOC test, done instrumentally, is used to The TOC test, done instrumentally, is used to

determine the total organic carbon in an determine the total organic carbon in an aqueous sample.aqueous sample.

The TOC of a wastewater can be used as a The TOC of a wastewater can be used as a measure of its measure of its pollutionalpollutional characteristics, and in characteristics, and in some cases it has been possible to relate TOC some cases it has been possible to relate TOC to BOD and COD values.to BOD and COD values.

The TOC test takes only 5 to 10 min to complete.The TOC test takes only 5 to 10 min to complete.

Theoretical oxygen demand (Theoretical oxygen demand (ThODThOD))

ThODThOD=COD=COD’’+NBOD+NBOD’’

mg/L O2demand

CODCOD’

NBOD’

NBODb

BODL～CODb

5 days time

persistent

BOD5

Example: What are CODExample: What are COD’’, , NBODNBOD’’andandThODThOD for 100 mg/L of for 100 mg/L of alaninealanine((丙胺酸）丙胺酸）

AlanineAlanine: CH: CH33CHCOOH or CCHCOOH or C33HH77OO22NN NHNH2 2

MW=3(12)+7+2(16)+14=89MW=3(12)+7+2(16)+14=89 CC33HH77OO22N + 3ON + 3O22 =3CO=3CO22 + NH+ NH33 +2H+2H22OO NHNH33+2O+2O22 =HNO=HNO33 +H+H22OO CODCOD’’=3(32)/89(100)=108 mg/L=3(32)/89(100)=108 mg/L NHNH33 released by released by alaninealanine oxidation (as N) oxidation (as N)

=14/89(100)=15.73 mg/L=14/89(100)=15.73 mg/L NBODNBOD’’= 15.73(2(32)/14)=72 mg/L= 15.73(2(32)/14)=72 mg/L ThODThOD=COD=COD’’+NBOD+NBOD’’=180 mg/L=180 mg/L

Oil and greaseOil and grease Include fats, oils, waxes, and other related Include fats, oils, waxes, and other related

constituents found in wastewater.constituents found in wastewater. They are compounds (esters) of alcohol or They are compounds (esters) of alcohol or

glycerol (glycerin) with fatty acids. glycerol (glycerin) with fatty acids. The The glyceridesglycerides of fatty acids that are liquid of fatty acids that are liquid

at ordinary temperatures are called oils, and at ordinary temperatures are called oils, and those that are solids are called grease (or those that are solids are called grease (or fats)fats)

If grease is not removed before discharge of If grease is not removed before discharge of treated wastewater, it can interfere with the treated wastewater, it can interfere with the biological life in the surface waters and biological life in the surface waters and create unsightly film.create unsightly film.

SurfactantsSurfactants Surfactants are large organic molecules that are slightly Surfactants are large organic molecules that are slightly

soluble in water and cause foaming in wastewater soluble in water and cause foaming in wastewater treatment plants and in the surface water into which the treatment plants and in the surface water into which the waste effluent is discharged.waste effluent is discharged.

Surfactants are most commonly composed of a strongly Surfactants are most commonly composed of a strongly hydrophobic group combined with a strongly hydrophilic hydrophobic group combined with a strongly hydrophilic group.group.

Types: Types: Anionic surfactants are negatively charged [e.g., Anionic surfactants are negatively charged [e.g.,

(RSO(RSO33N)N)--NaNa++];]; Cationic surfactants are positively charged [e.g., Cationic surfactants are positively charged [e.g.,

(RMe(RMe33N)N)++ClCl--];]; NonionizingNonionizing (nonionic) surfactants commonly contain a (nonionic) surfactants commonly contain a

polyoxyethylenepolyoxyethylene hydrophilic grouphydrophilic group

SurfactantsSurfactants

20052005--20102010年中国合成洗涤剂产量趋势图年中国合成洗涤剂产量趋势图

SurfactantsSurfactants Surfactants tend to collect at the airSurfactants tend to collect at the air--water interface water interface

with the hydrophilic in the water and the hydrophobic with the hydrophilic in the water and the hydrophobic group in the air.group in the air.

During aeration of wastewater, surfactants collect on During aeration of wastewater, surfactants collect on the surface of the air bubbles and thus create a very the surface of the air bubbles and thus create a very stable foam.stable foam.

ABS (alkylABS (alkyl--benzenebenzene--sulfonatesulfonate): resists biological ): resists biological degradation, causing foaming problems. degradation, causing foaming problems.

S

CCH2CHCH2(CHCH2)xCH3

CH3

CH3

CH3 CH3

OO

O

S

CHCH2CH2(CH2)xCH3CH3

OO

O

ABS LAS

LAS (linearLAS (linear--alkylalkyl--sulfonatesulfonate): biodegradable. ): biodegradable. The foaming problem has The foaming problem has been greatly reduced.been greatly reduced.

Inorganic nonmetallic constituentsInorganic nonmetallic constituents

pHpH ChloridesChlorides AlkalinityAlkalinity NitrogenNitrogen PhosphorusPhosphorus SulfurSulfur

pHpH The hydrogenThe hydrogen--ion concentration is an important ion concentration is an important

quality parameter of both natural waters and quality parameter of both natural waters and wastewaters.wastewaters.

pH=pH=--loglog1010[H[H＋＋]] The concentration range suitable for the The concentration range suitable for the

existence of most biological life is quite narrow existence of most biological life is quite narrow and critical (6~9)and critical (6~9)

For treated effluents discharged to the For treated effluents discharged to the environment the allowable pH range usually environment the allowable pH range usually varies from 6.5 to 8.5. varies from 6.5 to 8.5.

ChloridesChlorides Chloride ions, Chloride ions, ClCl--, in drinking water do not , in drinking water do not

cause any harmful effects on public health, cause any harmful effects on public health, but high concentrations can cause a salty but high concentrations can cause a salty taste that most people find objectionable. taste that most people find objectionable.

Chloride is a constituent of concern in Chloride is a constituent of concern in wastewater as it can impact the final reuse wastewater as it can impact the final reuse applications of treated wastewater.applications of treated wastewater.

Chlorides in natural water result from the Chlorides in natural water result from the leaching of chlorideleaching of chloride--containing rocks and containing rocks and soils with which the water comes in contact, soils with which the water comes in contact, and in coastal areas from saltwater intrusion.and in coastal areas from saltwater intrusion.

Chlorine residualChlorine residual Chlorine, ClChlorine, Cl22, is one of the most common , is one of the most common

chemicals added to water and wastewater, chemicals added to water and wastewater, primarily for disinfection. primarily for disinfection.

As a disinfectant, residual concentration of ClAs a disinfectant, residual concentration of Cl22 is is usually maintained in the water distribution usually maintained in the water distribution system, ensuring good sanitary quality of water. system, ensuring good sanitary quality of water. In drinking water, a residual of about 0.2 mg/L is In drinking water, a residual of about 0.2 mg/L is optimal. optimal.

Problem: The chlorine can react with organics in Problem: The chlorine can react with organics in the water, forming toxic compounds. e.g., the water, forming toxic compounds. e.g., trihalomethanestrihalomethanes ((THMsTHMs) has been identified as ) has been identified as potential carcinogens.potential carcinogens.

AlkalinityAlkalinity Alkalinity in water and wastewater results from Alkalinity in water and wastewater results from

the presence of the hydroxides [OHthe presence of the hydroxides [OH--], ], carbonates [COcarbonates [CO33

22--], and bicarbonates [HCO], and bicarbonates [HCO33--] of ] of

elements such as calcium, magnesium, sodium, elements such as calcium, magnesium, sodium, potassium, and ammonia.potassium, and ammonia.

The alkalinity in wastewater helps to resist The alkalinity in wastewater helps to resist changes in pH caused by the addition of acids.changes in pH caused by the addition of acids.

Wastewater is normally alkaline, receiving its Wastewater is normally alkaline, receiving its alkalinity from the water supply, the groundwater, alkalinity from the water supply, the groundwater, and the materials added during domestic use.and the materials added during domestic use.

AlkalinityAlkalinity

Alkalinity is determined by titrating against Alkalinity is determined by titrating against a standard acid; the results are expressed a standard acid; the results are expressed in terms of calcium carbonate, mg/L as in terms of calcium carbonate, mg/L as CaCOCaCO33..

Alkalinity=Alkalinity=--(H(H++)+(HCO)+(HCO33--)+2(CO)+2(CO33

22--) ) +(NH+(NH33)+(HS)+(HS--)+(OH)+(OH--)+other species that )+other species that can take up and hold onto a protoncan take up and hold onto a proton

AcidityAcidity

Acidity: the cumulative hydroxide Acidity: the cumulative hydroxide concentration taken up by acidic species concentration taken up by acidic species when a solution is titrated to the COwhen a solution is titrated to the CO33

22--

equivalent point.equivalent point.

Acidity=(HAcidity=(H++))+(HCO+(HCO33--)+2(H)+2(H22COCO33

**) +(NH) +(NH44++))--(OH(OH--))

AcidityAcidity

The major sources of acidity in biological systems are:The major sources of acidity in biological systems are: HH22COCO33

**（（Carbonic acid, from oxidation of organics)Carbonic acid, from oxidation of organics) HH+ + (from oxidation of reduced (from oxidation of reduced inorganicsinorganics HH22S S

(hydrogen sulfide), NH(hydrogen sulfide), NH33, etc.) and HCO, etc.) and HCO33--

HCOHCO33--

In covered reactors, COIn covered reactors, CO2 2 accumulates in the gas accumulates in the gas phase, Hphase, H22COCO33

* * increases, and pH decreases.increases, and pH decreases. In aerated benchIn aerated bench--scale reactors open to the scale reactors open to the

atmosphere, COatmosphere, CO2 2 equilibrates with atmospheric COequilibrates with atmospheric CO22, , so (Hso (H22COCO33

**)~10)~10--55M, and pH~8.1M, and pH~8.1

NitrogenNitrogenSources of nitrogenSources of nitrogen The nitrogenous compounds of plant The nitrogenous compounds of plant

and animal origin. e.g., ammonia and animal origin. e.g., ammonia derived from the distillation of derived from the distillation of bituminous coal.bituminous coal.

Sodium nitrate (in mineral deposits and Sodium nitrate (in mineral deposits and in the manure found in seabird in the manure found in seabird rookeries)rookeries)

Atmospheric nitrogenAtmospheric nitrogen

NitrogenNitrogenForms of nitrogen:Forms of nitrogen:--III 0 I II III IV VIII 0 I II III IV VNHNH33 –– NN22 –– NN22O O –– NO NO –– NN22OO33 –– NONO22 –– NN22OO55

The most common and important forms of nitrogen in The most common and important forms of nitrogen in wastewater and their corresponding oxidation state wastewater and their corresponding oxidation state in the water/soil environment are: in the water/soil environment are:

ammonia (NHammonia (NH33, , --III), ammonium(NHIII), ammonium(NH44++, , --III), nitrogen III), nitrogen

gas(Ngas(N22, 0), nitrite ion (NO, 0), nitrite ion (NO22--, +III), and nitrate ion (NO, +III), and nitrate ion (NO33

--, , +V).+V).

The oxidation state of nitrogen in most organic The oxidation state of nitrogen in most organic compounds is compounds is ––III. III.

Definition of the various terms used to Definition of the various terms used to define various nitrogen speciesdefine various nitrogen species

Form of nitrogenForm of nitrogen Abbrev. Abbrev. DefinitionDefinition

Ammonia gasAmmonia gas NHNH33 NHNH33

Ammonium ionAmmonium ion NHNH44++ NHNH44

++

Total ammonia nitrogenTotal ammonia nitrogen TANTAN NHNH33+NH+NH44++

NitriteNitrite NONO22-- NONO22

--

NitrateNitrate NONO33-- NONO33

--

Total inorganic nitrogenTotal inorganic nitrogen TINTIN NHNH33+NH+NH44+++NO+NO22

--++ NONO33--

Total Total KjeldahlKjeldahl nitrogennitrogen TKNTKN Organic N+NHOrganic N+NH33+NH+NH44++

Organic nitrogenOrganic nitrogen Organic NOrganic N TKNTKN-- (NH(NH33+NH+NH44++))

Total nitrogenTotal nitrogen TNTN Organic N + Organic N + NHNH33+NH+NH44

+++NO+NO22--++ NONO33

--

PhosphorusPhosphorus

P is an essential nutrient that contributes to the P is an essential nutrient that contributes to the growth of algae and the growth of algae and the eutrophicationeutrophication of lakes.of lakes.

Municipal wastewater may contain 4Municipal wastewater may contain 4--16 mg/L of 16 mg/L of PP

PhosphorusPhosphorusThe usual form of phosphorus that are found in aqueous The usual form of phosphorus that are found in aqueous

solutions :solutions : Orthophosphate: POOrthophosphate: PO44

33--, HPO, HPO4422--, H, H22POPO44

--, H, H33POPO4 4 are are available for biological metabolism without further available for biological metabolism without further breakdown.breakdown.

Polyphosphate: include those molecules with two or Polyphosphate: include those molecules with two or more phosphorus atoms, oxygen atoms, and, in some more phosphorus atoms, oxygen atoms, and, in some cases, hydrogen atoms combined in a complex cases, hydrogen atoms combined in a complex molecules.molecules.

Organic phosphate: It is of minor importance in most Organic phosphate: It is of minor importance in most domestic wastewater, but it can be an important domestic wastewater, but it can be an important constituent of industrial wastes and wastewater sludge.constituent of industrial wastes and wastewater sludge.

sulfursulfur

The The sulphatesulphate ion occurs naturally in most ion occurs naturally in most water supplies and is present in water supplies and is present in wastewater as well.wastewater as well.

Sulfur is required in the synthesis of Sulfur is required in the synthesis of proteins and is released in their proteins and is released in their degradation.degradation.

sulfursulfur Under anaerobic conditions:Under anaerobic conditions:

bacteriabacteriaOrganic matter + SOOrganic matter + SO44

22-- SS22--+H+H22O+COO+CO22

SS22--+2H+2H++ HH22SS

e.g.e.g.2CH2CH33CH(OH)COOH + SOCH(OH)COOH + SO44

22-- 2CH2CH33COOH+SCOOH+S22--+2H+2H22O+2COO+2CO22

( lactic acid,( lactic acid,乳酸乳酸) ) sulphatesulphate （（acetateacetate）） sulfidesulfide

HH22S can be oxidized biologically to sulfuric acid, which is S can be oxidized biologically to sulfuric acid, which is corrosive to concrete sewer pipes, known as corrosive to concrete sewer pipes, known as ““crown rotcrown rot””..

Biological parametersBiological parameters

The biological characteristics of wastewater are The biological characteristics of wastewater are of fundamental importance in the control of of fundamental importance in the control of diseases caused by pathogenic organisms of diseases caused by pathogenic organisms of human origin.human origin.

Microorganisms play fundamental role in the Microorganisms play fundamental role in the decomposition and stabilization of organic decomposition and stabilization of organic matter in nature and in wastewater treatment matter in nature and in wastewater treatment plantplant

Microorganisms found in surface Microorganisms found in surface waters and wastewaterwaters and wastewater

Bacteria:Bacteria: singlesingle--cell prokaryotic cell prokaryotic （原核的）（原核的）organisms. The interior of the cell contains organisms. The interior of the cell contains a colloidal suspension of proteins, a colloidal suspension of proteins, carbohydrates, and other complex organic carbohydrates, and other complex organic compounds, called the cytoplasmcompounds, called the cytoplasm（细胞（细胞质）质）. .

Bacteria are very small (2 Bacteria are very small (2 μμm) and can m) and can be seen only with the aid of a microscope.be seen only with the aid of a microscope.

Campylobater coli

Salmnel（肠沙门氏菌)

E. coli

Fungi/yeastFungi/yeast

Fungi Fungi are are multicellularmulticellular, , nonphotosyntheticnonphotosynthetic, , heterotrophic eukaryotesheterotrophic eukaryotes（真核细胞）（真核细胞）. Most . Most fungi are either strict or facultative aerobes fungi are either strict or facultative aerobes which reproduce sexually or asexually.which reproduce sexually or asexually.

Yeast Yeast are fungi that cannot form a myceliumare fungi that cannot form a mycelium（菌丝体）（菌丝体） and are therefore unicellular.and are therefore unicellular.

Fungi have the ability to grow under lowFungi have the ability to grow under low--moisture, lowmoisture, low--nitrogen conditions and can nitrogen conditions and can tolerate an environment with a relatively low pH.tolerate an environment with a relatively low pH.

红酵母

青霉菌

脚气真菌

啤酒酵母

ProtozoaProtozoa

Protozoa are motile, microscopic Protozoa are motile, microscopic eukaryotes that are usually single cells. eukaryotes that are usually single cells. They are generally an order of magnitude They are generally an order of magnitude larger than bacteria and often consume larger than bacteria and often consume bacteria as an energy source.bacteria as an energy source.

Amoeba阿米巴

游泳形线毛虫钟形虫

太阳虫

AlgaeAlgae

AlgeaAlgea are unicellular or are unicellular or multicellularmulticellular, , autotrophic, photosynthetic eukaryotes autotrophic, photosynthetic eukaryotes （真核细胞）（真核细胞）..

In wastewaterIn wastewater--treatment lagoons, the treatment lagoons, the ability of algae to produce oxygen by ability of algae to produce oxygen by photosynthesis is vital to the ecology of photosynthesis is vital to the ecology of the water environmental.the water environmental.

蓝绿藻

绿藻

蓝藻细菌

VirusesViruses Viruses are composed of a nucleic acid core (either DNA Viruses are composed of a nucleic acid core (either DNA

or RNA) surrounded by an outer shell of protein called a or RNA) surrounded by an outer shell of protein called a capsidcapsid （衣壳）（衣壳）..

Viruses are obligate intracellular parasites that multiply Viruses are obligate intracellular parasites that multiply only within a host cell, where they redirect the cellonly within a host cell, where they redirect the cell’’s s biochemical system to reproduce themselves.biochemical system to reproduce themselves.

Indicator organismsIndicator organisms

ColiformColiform: A very important biological : A very important biological indicator of water quality and pollution.indicator of water quality and pollution.

Not pathogenic, but always present in the Not pathogenic, but always present in the intestinal tract of humans, and million are intestinal tract of humans, and million are excreted with body wastes.excreted with body wastes.

Water that has been recently Water that has been recently contaminated with sewage will always contaminated with sewage will always contain contain coliformscoliforms..

E. coli.E. coli.

A particular species of A particular species of coliformscoliforms found in domestic sewage.found in domestic sewage. There are roughly 3 million There are roughly 3 million E. coliE. coli bacteria bacteria

in a 100 in a 100 mLmL untreated sewage.untreated sewage.Most strains of Most strains of E. coliE. coli are generally are generally

harmless, but infected individuals also harmless, but infected individuals also excrete pathogens along with the excrete pathogens along with the coliformcoliform..

No No coliformcoliform no sewage no pathogensno sewage no pathogens