2008 Enviro & Sanitation Notes + Tutorial Answers

7/21/2019 2008 Enviro & Sanitation Notes + Tutorial Answers

1/177

ew

zqTA

$t

g

+

f

sfc

Ert

t

lnt

&,fur

nhi

oo

leeaiure

//011

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t

s

Sw

b;rot

ha

s

afptctrt

nale

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rqk

oF

ar)

rofr

E

ntltrcnrnenl-ql

Sor,/ohon

E

t{t/1r J

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2/177

Organic

pollution

i

Curve C

oxygen

profile.

cr

sag

clJrve

=

J

>a

x

(}

:o

&

=

n

.*

C3

Minrmurn

D.O.

\

Curve

A

desxygenaticfi

-\.

-,/

curve B

---ra/

r*"#rrtiJ-

/'/'

t--

-?

\--

Tir*e

or

distance

Figure

4

Generalized

effect of

organic

pollution in

the stream

or

river

(single

point

source

DO

Sag

curve)

Multi-point

sources

DO

sag

curve

Distance

Figure

5

Variation

in DO by

several

point

discharges

18530

ESE Section

l,

Chapter

I W'ater Pollution

l-5


3/177

Tubrql

sl1

l

r

vr

{tou

nk

C0

tn

rnluttrnl

t44ask*ok1

froo

QI

,

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24x

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qre

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yllL

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t/

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0z'20;7

C,

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Ct

r

CIrCu

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=

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W

tr*zc

"

utll

f,4l

th

A0

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hrl

o,lh

notu

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rtuer

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.

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ry/L

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C0


4/177

c)

bo

X

q)

a

ID

Do.

DO-io

0

Saturation

1

Initial

deficit

(Do)

Deficit

@)

{

Critical

point

I

Figure

6

Typical DO sag

curve

for calculation

Initial

DO

deficit

of

the

mixture of

organic

source and

river:

Do"

-

Do,

l,kot:

(.-oo'

- -k.t)

+

D"

e-*"]

(1.1)

'

'kr-kd'

where:DO,

is

saturated

value

of DO

(mg/L)

I(6

:

deoxygenation

constant

(day-t)

Kr:

reaeration

rate

constant

(duy-t)

t

:

the

time

required

for

the waste

to

reach a

given

location

downstream

(day)

The

time

(t")

and distance

downstream

(x.)

at which the oxygen

deficit

is

maximum:

t.=- lni;[l-

r

rr

D"(k,-ko)

-tr-

-*

1

0X"

tc

k,

-ko

Distance

-----t

Time

------+

KoLo

l)

(r.2)

d

Diurnal

variation in DO

Primary

sources

of oxygen in

surface

water

are

photosynthesis

of

aquatic

plants,

algae

and

diffusion of

atmospheric

oxygen

across

the air

water

interface.

The

dissolved oxygen content

of

natural water varies

with

temperature,

photosynthesis

activities

and respiration

of

plants

and animals.

DO

concentration

in a

constant

state

of flux on a daily

basis

(consumption)

48530 ESE Section

I,

Chapter

I

Water

Pollution


5/177

1,

=

,1

,

n

llt

lt

D,

(k, -k"/\

fl

L

k,-ka

(kd

LL-

#J)

Lo:

tnircl

6CI0

p{

#u

wxh.tre

o{

yollurinn

fouru

4

n,rt,

bt

GtUf{t',

0-:

l,

I

*r/J

,

0A*

'

2,,01

f

L,

ar=

&,7^ri/s

&

00r."8,3

ry/L

ftnr{

Ds

=

1,1

ry/L

l,trY"

Ealsn,a

:

0*

D0*

r

0,

00,

=

Q

00,

D

0,

=

CI*

0C"

rQ,00,

3

(l,lvz,o)r(flr

gJ)

,

Z6,J//L

f

"l

rg.Z

7h -

h,t

dtf'ctl

,{

d'rolued or,

Do=?'l-76

'l

fry


6/177

',"

''

'-

pufief

gop

ef

ntyrr,*

6uren

tffi,te:

;

1/w&orq&, fr

ru,er,

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,4^d

U

ti,yiL

(ob/a'r,uil

kr-

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t)''

r@z?

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,

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h(

k,

{t,

.,i

tl

t*

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tL-

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''(P

'/4

':

I

\

'

l,t(0,

+t

*

i

w(

f*r/

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f

,{4

l"

r t-'I

U//

t,x{

*,

plp

l

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;;-i;tr,,'7

I

tc:

f'"

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..:

'

I'

#st{w*r

Iri d{sn(

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a,+l

-0,7

O,Zx

lo

,7

Xc^

Ux{,

0,3-/t

4

35oox

Z+y Z"L7/ayt=61.it^

r)

t

f-

U

ll

-

*

j

i?-L,kT

k,

=

o

+t

/c/

ha

:

o,z/o/

,0,*)

(

{.: 2,67

dorr

(ob/q,rlil

0

77', .

tn:lqe'o{'

0C

q[a

c/':/,

'

r/o^,1

tt

rry,g-a-ddr,l*o/

*rywyt

o{{fl3}^

^

g,4lx

6rr

/t

.l

.""'

l

^

.

^ ^

t

k.t'{rd.t

I

i4

tF,$,.a"4

r-'Y

-'

'+r.f

j

' -

=

/:b7

/qy:

Dou,{pori

-W'b

"_nr)

r:ffe_b{


7/177

B.

Sources ofnitrogen

and

phosphorus

Major

sources

of

nitrogen

and

phosphorous

are

mainly from:

(i)

agricultural

runoff,

(ii)

municipal wastewater discharges,

(iii)

runoff

from

animal feedlots,

ffid

(iv)

chemical

fertilisers and

nitrogen

deposition from the atmosphere.

The household detergents

used

for

washing clothes contain

large

amount

of

phosphorous,

which

when released

into

water

act

as

stimulant to

algal

growth.

The

major sources that

contribute

to

the N

and P

in

surface waters

are

tabulated

in

Table 4.

Table 4 Sowces

of

nitrogen

G.D

and

phosphorus (P)

Total

phosphorus

is a measure

of the

phosphorus

in mg

of

P per

litre,

which

includes

the

P

bound

to

particulate

matter

and

colloidal

and

soluble

ortho-phosphates.

Total nitrogen

is

the

sum

of organically bound nitrogen,

ammonia"

nitrite

and

nitrate

nitrogen.

Effluent

from

sewage

treatment

plants

increases the nutrient level

significantly in

receiving

water. The

standards

for

discharging

into water

bodies/streams

are:

10 mg/L

as total

nitrogen

and

2.0

mglL

as

ammonia-nitrogen,

and

0.3

mglL

as

total

phosphorus.

Some recent studies

suggest

that

phosphorus

concentrations

in

excess

of

0.015 mg/L

and

nitrogen

concentrations

above

0.3

mg/L

are

sufficient to

cause blooms

of

algae.

C. Effect

of

nutrients

pollution

Nutrient enrichment

can lead

to

blooms of

algae,

which eventually

die

and

decompose. Their

decomposition

removes

oxygen from the

water,

potentially

leading to

levels

of

DO

that are

insuffrcient

to

sustain normal

life forms.

Algae

and decaying organic

matter add

colow,

turbidity, odours

and

objectionable

tastes

to water

that

are difficult

to

remove

and

that

may

greatly

reduce

its

acceptability

as a domestic

water

source.

The

process

of nutrient

enrichment, called

eutrophication, is

an

especially important one

in

iakes.

There

are

many

factors

that control the

rate

of

production

of

algae,

including the availability

of

sunlight

to

power

the

photosynthetic

reactions,

and

the

concentration

of

nutrients

required

for

growth.

While the

list

will

include

all

the nutrients

mentioned in

the introduction,

the

problem

is

greatly

simplified

by

focussing on the

two

that most often

limit

algal

growth:

phosphorous

and

nitrogen, so

that eutrophication

of

surface waters

including rivers,

lakes

and

ponds

can

be

controlled.

Sewage

Industries

Land

Groundwater

Urban

runoff

Rain

31.0

1.8

10.6

42.0

5.5

8.5

s8.0

1.0

24.6

2.5

10.0

r.2

48530

ESE Section 1, Chapter

I

lf'ater Pollution l-8


8/177

Tuhntal

1,3

]*u

=

lotL

6taa:

tidii,nl

rnilkttqler

flo*

=

o'L

\Nilonr,

rvtq.rJ

(1nd)

of

,fur/ngen

=

ls)&g//

,

Tontpn[n/pn

ff

niroryn

bnc,

ut

,tasfraq/ar'

7

(Bnw/n/,on"X

ilow=

lod

or

Uq(en/-ra/ron

:

lso

bU

W-'-T

'lsr,b,_b

r

td-,_rM,

uhb

ol

0,{-3

f

dhBOs

tOsL

tU

:

lwtc'

-J

{i tynV

/

q

I

:

/,t7

ry/L

0"8

rT[Qoox

{og

:

lu'lff/o*

lf0

l*ete,6t*xfu

d^'i

r?

:,,i'

hnunhalon

of

nr*agen

n

/lu.

laqspwa/er

ts

Z,l7rq/L

fu

//,u

ti

lou'ur

ilnai

ile,

o/ttcA*y"

h;

="ffi:0;17+d'-t

,'r

SoDrb

=

3t0(l-e-o'ttLls)

=

1f0ryj/L

t


40/177

The

oxidation

of

ammonia is

a

slow

process

and usually

starts only after 6 to

10

days, in

most of

the

cases.

But

if enough

nitrifying

bacteria

are

present,

NBOD

can interfere

with

the results

of

BOD.

Figure

2

illustrates

CBOD and NBOD

Where a

sufficient

number of nitrifying

organisms are

present,

nitrification can

occur as shown by the dotted

curve.

Nitrogenous

biochemical

oxygen

demand, NBOD

Fig.2Illustration

of

NBOD

and

CBOD

G.

Typical

BOD

values

of differentwastewater

J

o)

E

c

(d

E

o

o

c

o

O)

x

o

Unpolluted

natural

water

Polluted natural water

Raw

sewage

Biologically

treated

sewage

Septic

tank

effluent

Storm

run-off

Garbage

tip

leachate

Oil

refinery,

food

industry

10

mg/L

:150

-200mglL

6o

lo

7r

c>

zo_307,

I

-

(f,/q//Jtnl

5s

8op

NAf

fr

ku*

orilo1 fuz

Se*qs(.

rt

kwnge-u

{,//e-nd

flira,tqh

fir,z

Scrcgl ,tb

hke

*t/k;

Surh

as

lapq

Yofrb"

f,N

&

p/athc

*

kaug

yorhpfu

l,he

Sind

(co/lr/fr,/)

:,r/?

lh

ilu

Qrt

ftoinoveC

u,u/

sald

k

Ao/,6^

4

CIlb

^seflh,g

o{

fr,

)J

KUlto

uq

/

80

D

remottql

tcls

U

helt

ulw fqf,an

l-u

f{o*

ft#rc,ryfu

of

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lu


95/177

eDL

:

ffiek

Tarl,Cu

+

e

*-?

+

6r

lhntO,t,el

,7

0,2

M/,/)

Speci{rcgrou/fy

>2,$r

eff

cien

g

of

.b,y1fag

r

a/

J#Jrfu

frcquu|i,

of

cle\nmq

inut

)rrr.all

fr,rt

4,1,

cPt:

fr,il,

,

wnft-

htgl

orr/l

h.

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*,1

rtdud

\rerq ll

Gr,f

uU

rb

unlro/

fiu,

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gn/-cha*fua

tfo

er

o.

b

4

ngc,,hnntCr/

1w114rtJ

,

fiitqd(

k./t'lmq

^

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#


96/177

onsttn/

uelo

ct

hr

honznn,bl

ilow,

6rr/

M

F[o,o'

,eloufu =

o,zS-

fu

0,3f

n/:

(Tq

prtal

uqiile

=

0,3

,/s )

-'

d,ltilt

l

6,

s6[dl'"nflqai

duhb,r/ront

qa,b,4

+

LtK

,f

ftcrcl

wuf

Secfions

qlilw

#lutn/

q4d

+

h

fernou&

q

gn/

7art'rc/u

>c,Z,ua

, A:

;

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rttqn

or'lin6

o^ih"lrt

suspmCp/,p

ftac

fb,u

Le,nril

o/

t

n

cJtanoel

t

yclocir

@n

reeunl

bg

H,e

S:e#l,U

rq/e

fr

fue

rlanber

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c/ranne/r

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of

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la/t

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-

l*lffnffiltila

t

ffitri

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funt

fi-V

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.

,

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t

urQ,

nil

dyr^

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l/,

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g)uer,

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rene

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iltlw

-goru,^ned

$t

*/1,e


97/177

Thus,

when

the

flow varies,

the

depth of flow

varies

changing

the

cross sectional area

of the

chamber

and keeping

the

horizontal

velocity

constant. This

is the main

principle

of

operation

of

horizontal

flow

or

constant

velocity

grit

chamber.

Although

the

grit

chamber

is designed

as

paraboiic,

its

construction

will

be trapezoidal

shape.

Desisn:

The

design

of

the

grit

chambers

is

based

on

the settling

velocity

of

particles

of

critical

size.

Because

of

this

the design follows the

Class

I tlpe of

settling and Stoke's

law

(Section

2,

Chapter

1).

ln

general,

e

Length

of the

channel

in

gnt

chamber

is

governed

by

the depth

required

by the

settling

velocity

and

the

cross sectional

area by

the

rate

of

flow and

the number

of

channels.

.

Velocity

of flow

is controlled

by

special

influent distribution

gates

and use

of special

weir

sections

at

the

effluent

end.

Disadvantages

.

excessive

wear

of

grit-handling

equipment

o

necess0

for

separate

grit

washing equipment

(ii)

Aerated

grit

chambers

.

Overcome

the disadvantages

of

constant velocity

grit

chambers

(e.g.

minimum

wear and

tear

and

no washing

of

grit

is

necessary).

r

A

type

of

a spiral

flow

grit

chamber

o

Designed

to impart a transverse

rolling

motion to the

flow.

.

Air

is

injected

at

a contolled

rate

near the base of

one

longitudinal

wall

of

the

chamber.

ign criteria

for

horizontal

flow

grit

chambers

45-90

0.25 - 0.4

0.9r

-

t.26

0.60

-

0.90

30-40

Detention time,

s

Horizontal

velocityo

m/s

Settling

velocity

for removal of:

0.21mm

material,

m/min

0.15

mm material,

m/min

Headloss

in

a

control

section,

noh

of depth

of channel

48350 ESE Section 3 Chapter

I

Conventional

Domestic

W'astewater Treatmenl

3-5


98/177

.Qef

l=

F,nrd

4.

Q:

2,8f

n%

Srodc(-

t*

tJ

parobolc

4e=+6t]

k

,ata,-w

I

5,3,

l,

l-

{^on

llqrly&

0=

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SMq

)Wk*

u

Taole/,

Q=

solz:

S/4LD

W

nrd

Vt),u t g

furfru.

loadrg

rqrb

SLP:

o,CIozf

*J/ra-(

Stn,t

q:

Lgxt7?

m]//

=

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,

%

Jurhu

araQ:

=

/.{7/o,ooz7'

V?7 nt

ShoK,

0

2,Ya

=ff"=

t=f'63a'

:fin

gintL

l), /"=

7

*,,

llolant.

=

&"x

D,T

'

2,8?r'/sr

6ot.

l73.furJ

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@

5ur{au

?rta,

fi:

LX6:

??7*'

.

cros:J*Sednnal

aretv 4,

=

z/3

@x//)

=

fr

l3*u

SinQ.

lf:

0,17+

,'o

$= 3x

?,63/(2x0,17il'83^

/-:

qq

7/s3

=

lz^

At

t

83n)

fi=

0,llw


99/177

o

Helical

flow

is

permitted

by

the rounded comers

of the chamber cross-section.

o

Grit

collection

and

removal is facilitated by sloping the tank

floor

-

to

allow

grit

to settle.

OUTLgT

CHANNEL

{no

$otml

Axrt

rrigh.nl Et

rlociry

{rn&}

I

I-..


100/177

,1

t&a*/.r

+ tllo

l"asttng

o{,Sfl/

tJ

neZesay,

r

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ua(

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lutq

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raq,ntd

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bJ

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la"il

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6

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127/177

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128/177

5.

Tertiary

treatment

5.1

Introduction

The

conventional

sequence

of

primary

treatment

and

biological

secondary treatment

normally

removes

85

-

95%

of

BOD

and

SS.

Although

it

is sometimes

possible

to

achieve effluent

BOD/SS

concentrations

less than

15120

mglL from a

well

designed

and carefully-operated

secondary

treatment

plant,

it

is

usually

necessary

to

provide

tertiary

treatment

if

a

consistently

high

quality effluent

is

required. It should be

noted, however,

that the

aim of tertiary

treatment

is not

to

produce

effluent of

reuse

quality.

The

main objective

of tertiary

treatment

is effluent

polishing

which includes removal

of

fine

suspended

solids.

Because these suspended

solids

are mostly

organic,

their removal

results

in

a

reduction

in

the effluent BOD.

A

second

objective

of tertiary

treatment

is

disinfection,

to reduce

the

concentrations

of

pathogenic and

indicator

bacteria and

other

pathogens

which

could

be a

health hazard to

downstream

users.

Tertiary

treatment

mostly involves

physical

or

physico-chemical

process.

The main treatment

systems

used

for

tertiary

treatment

are:

r

Granular

bed

filtration

o

Disinfection

o

Maturation

ponds

5.2 Granular

bed

filtration

Granular

bed

filtration

is

a

physical

separation

of suspended

solids

from

secondary

effluent.

These filters

range

from slow

sand

filters to rapid

sand and dual media

filters.

The

filters are

made

up

of

a

filter

medium

(e.g.,

sand) and

the operation

of

filtration

involves

the

liquid

passing from

top to

bottom.

Separation of

solids takes

place

within

the surface

layers

of

the

filter and

thus called

in-depth

filtration. Once

the

filter

is

filled

with

particles,

it

needs

to be

cleaned

which is

carried out by backwashing

the filter. Backwashing

is

done

by

using

a

combination

of air

and water

in an

upward

direction

to

normal

flow

under

pressure.

The backwash

wastewater is then

returned

back

to

the

iniet of

the

wastewater

treatment

plant.

After

backwashing,

the filter

is

once

again

clean

to carry

out the

process

of

removing

suspended matter.

48350 ESE Section

3 Chapter

I

Conventional

Domestic

W'astewater Treatment

3-25


129/177

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131/177

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133/177

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134/177

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135/177

7-,,t

/ornl

A,=

,

Q

=

36m

lllt7

=

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*31/

ne&*

rak

'

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=

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=5oor//

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u re,/nc/C

hzzfp,t*

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275

ry

22

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ller:

fiAcilw,ahytq

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6o*/A

fir

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ff

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rn

t*f

lourJ,

fiac,ilw,ahytq

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fir

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ff

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:

50,

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=

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136/177

I/

rs

uted

,,

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qt

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T*o

w0rr1,

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fardrdes

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137/177

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f

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ffi

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138/177

#

Bftqlu

p,or,rti

6ltlpnna/tr,

?

Chltrute

r

/#j

,

l/ilf+

ilz

)

f,

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tr

6;lgrnl

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k^qw

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o'gnrrc

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,

fu

c

a

I /q/i

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lte4tro

fr

oVrlt

{^^(/o,f,?'f[(;,#i1

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nor

econou,,nt

&

dar{;

o{

'f,hoe/i^r#,anb

(ft'rt

l)

frrwnho,

/,/(

fu

(nforue

reuc/irtl

*iil't

t4Ltt-sa/ura/rd

agfanrc

tunVomds

#

#^uoonrq

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l/H,in

rt/llsrilt

frl

tfl'

a&aue

ll P

a

/l

a*^on

lq

talt'

b

eafily

Sfngped

fr

n,lrr

f,rn/

HCc{+

,tlilf *

A"

ill,lrpbaclee,,//,

frosw{rnt

MAr-

rk/l

*,ll

C

A,

/L,/r,{,",

q{uLuJ

uw

Jfuu frer

w{

4

--\w"

content

of

q

solid

woste

somple

with

4

t-Fe composition

given below

Conponent

Moss,

kg

Moisture

?O.9 I

Corbon

34.51

Hydrogen

4.58

Oxygen

30.00

Sulfur

O- 13

Nitrogen

0.43

Ash

4.47


155/177

3+"s

t

x\

oc

$,ab

ull:i."(

3. Estimote the

energy

of

the

woste

KJ

/

Kg

=

337C

+

t4t9H

-

3)

*

93S

*

23N

ssibe.sl

+

t4Le

1t..

-

ffl

*

e3

(0.1)

+

23

(0.5)

=

72/33.t+.1,294.8

*

9.3

*

11.5

=

3,548.7

Computotions

such as

the obove ore

especiolly

-

importont where

the

tecovety

of eneegy

froffi


156/177

i*

;.1*::;;':ri*iiiiig1::tifi:i7ii

i:=,?1i.];;ir


157/177

Bosed on

the

operotion mode, collection

systems

ore

clossified

info

fuo

cotegories:

*

Hauled

c^q+ainee.eisnns,(H):

The

confainers

used

for

the

storoge

of

wostes

ore

houled

to

the

proeessing,

tronsfer,

or

disposol

site.

empfied,

cnd

returned

to

either

fheir

originol

locofion

or some

ofher

locotion-

:*i

Stqtionary

sqltoiner

svstems.(SCQ):

The

A;Toiners

usea-forlhe

storoge

of

wostas

i".oin

ot

the

point oi "n".oiion,

excePtdf,A

they ore movei

to

the

curb

or

ofher

locoqfn

y*

be

emptied.

"-

Hauled

contoiner

systems

(HCS)

Tilck

b

dispdtuh

lhtioh

-

.nd

of

doily

Mi,

t2

solid wosies

Piclop

loodcd

ontoincr

Trcnifcr stqiiot

disposol

situ

(

I

I

I

j

i

i

t

l

I

t

tl

i

]L

ri

i

Stotionsry

container

systems

(SCS)

L6d

dnbnts fM

contuin"r{s)

ot

Piclop

locotion

solid

w#

inb

collcdion

vehiclc

piclop

leaiion

Driva

to

neat

@niqincr

Etr?iy

@llection

vchicle

fm

dispolch

siolion

_

beginning

of

doily

Mto

(s)"

tr

loodcd

Orive

.frPfy

collestion

vehiclc

b

b.ginBing

of nf

colleclion

dle

or

retun

to

di+dtch

siotion

- end of

mtB

/

collecnoavzhiclc

,/

h

lodtion

whcru

-/

con*nts

of

vahiclc

/

will

b9z@(

/tr

t\

Tmnsf.r shfion- {eHtd;- l

or

di+6cl

sit

Y__y

:

resideniiol

wostes

by council/confroctors


158/177

ift$N:ltFe'Ef'

Tronsfer

and

tronsport

operotions become

o

necessity

when

Houl

distonces

to

ovoiloble

processing

centers or

disposol

sites

increose

so thot direct houling

is

no longer economicolly

feosible

)

The

use of small-copocity

collection

vehicles

(generolly

under

15

rn3)

F The

existence

of

low-density

residenfiol

service

)

The

use

of

o

houled

contoiner system

*td

relotively

smoll contoiners

for

the collection\f


159/177

F

i;

is

to

be

on

the

houling

route

A

=

Cosl

of

smoll

vehicles, $/m3'km

g

=

O

&

M,

depreciotion'

iooding

&

unlooding

ot

T5'

$/rn3

Z

=

iott

of

houling

lcrge

vehicles' $/m3'km

;

=

;;";""

i"i""nlollection

oreo

ond

rs'

krn

V

=

Oi"ron""

belweenT5

&

disposol

site

(DS)'

km^-

I'l;ffi

ffi

;l1,'u:c,fltu-,9,'ur,.f

,lft,

i

-

ili"*r

disfonce

between

collection

oreo

&

D5

Cost

with

o

transfer

sfotion'

T=zAX+B+ZC:t

Cost

wifhout

a

tronsfer

station'

Tr=ZA(X+Y)

If

T


160/177

\

1.

Pr.epor.e

o

plot

of cost versus

haul

time

in

minutes ond

determine

break-even fine-

60 E0

100

Time (minues)

n

lfre

h

'

i,t

colterh*

Puutti

pnr'tle/

&

fuq.

t{w

Documents

2008 Enviro & Sanitation Notes + Tutorial Answers