sewage treatment 2

8/16/2019 Sewage Treatment 2

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Sludge thickening

• To reduce the volume of sludge• to increase sludge solids at least 4 %

• Gravity thickening and mechanical thickening

• Gravity thickening• Used for primary and tricking lter solids• Without chemical occulants• loading rate: !"#! kg$m% per day

•

&echanical thickening• Used for activated sludge solids• With chemical occulants• dissolved air otation' gravity (elt thickeners' and centrifuge thicke• loading rate: )!"! kg$m% per day *dissolved air otation+' 4!!")!!!

*gravity (elt thickeners+' )-!!"!! ,$m *centrifuge thickening+

• The concentration of pathogens increased during this process



Gravity (elt thickener



.e/atering

• To concentrate sludge (y removing /ater

• 0ressure ltration' centrifugation' andscre/ press

• 0ressure ltration *(elt lter press andplate"and"frame lter+

• Usually /ith polymer occulation

• ,oading rate: 4!"#! gpm$m *hydraulic+ and-!!")!!! l($m$h *solid+

• 1eed solid: )"# %

• 2ake solids: )-"! %



Sludge drying (eds



3elt lter press



Sludge de/atering



Sludge incineration



Septic tanks



Septic tank design

•

Se/age o/• Settling of incoming se/age

• .igestion of settled se/age

• Storage of digested sludge



1orpopulationupto -!



1orpopulationover -!



.isposal of septic tank euent

•

0reliminary data5ature of soil and su(soil condition

Site plan sho/ing the proposed or e6isting(uildings as /ell as reduced ground levels ovsite

.ischarge from the septic tank7

The position and nature of outfall ditches' /tanks or small streams in the vicinity' if any



&ethods

•

Soil a(sorption system• 3iological lters

• Upo/ anaero(ic lters



Soil a(sorption system

•

Seepage pit• .ispersion trench



,85. .9S0S8,

8dvantages:"

)7 8dds manure to land

7 0ollution of natural /ater courses is minimi;ed7

7 9ncrease fertility of land7

47 Gives high caloric value to crops gro/n in se/age farms7

-7 .oes not re<uire any installation of e<uipment involving high i#7 2rops could (e gro/n and hence a return value is al/ays p

o(tain7

=7 &ethod specially suita(le /here large <uantity of river /availa(le at all times of the year7



.isadvantages:")7 .i>cult to get land during rainy and harvest s

7 8dditional land is re<uired for reserve7

7 Sanitary reasons may not permit gro/ing of se/age farms7

47 &ore land area is re<uired if se/age volume issince land capacity is limited7

-7 9f all precautions are not taken' se/age results in se/age sickness to land and health t

2omparison of dilution and land



2omparison of dilution and landdisposal



&?T@. 1 ,85. TA?8T&?5T

Se/age mainly contains /ater /hich can (e uirrigation purposes 7 The fertilising value of semore (ecause it contains n' potash B phosphase/age can (e applied in the follo/ing forms

• 3A8. 9AA9G8T95

• S?W8G? 18A&95G7



3A8. 9AA9G8T95

• 9n this method' se/age is allo/ed to ocultivated lands' from /hich a part of the evaporates' some percolates and the rest escsurface drainage channels7 Se/age /aters the ladds to its fertili;ing value' due to the presnitrogen' phosphorus' potash etc7 These felements of se/age are consumed (y the roots 2rops like cotton' potatoes' sugarcane' grass (e prota(ly gro/th7 This is also called se/age f



S?W8G? 18A&95G

• The process in /hich se/age is used for gro/iis kno/n as se/age farming 7The fertilising elemse/age i7 e nitrates' sulphates' B phosphates a(y the roots of crops7 The nutrients of se/age melds fertile 79t is a prota(le (usiness B a goodcan (e generated (y se/age farming7



&ethods

• 1,.95G &?T@.

• SUA182? 9AA9G8T95 &?T@.

• E9G E8G &?T@.

• ,8G595G &?T@.

• 38S95 &?T@.

• SU3"S9, 9AA9G8T95 &?T@.

• A9.G? 85. 1?AAW 9AA9G8T95 &[email protected]



• 1,.95G:" The area to (e irrigated is dividvarious parts surrounded (y dykes7 The se/agelike small ponds in (et/een the dykes7 The ddose varies from 7! cms7 To -7! cms7 .ependinirrigation re<uirements



• ;ig;ag run method: 9n this method the ridarranged in a ;ag";ag method /ith corresfurro/s (y their side7



• ,8G595G": These are used cheaply for disposal7 9n this method the se/age is allo/ednatural depression availa(le or articial contanks7 .etention period is a(out a month7 .uperiod the sludge is sta(ili;ed and dried7 The euent passes /ay from an outlet placed at tend7 ,agoons should (e shallo/ and mconstructed a/ay from the to/n7

•

38S95 &?T@.: 9n this method (ig trees are plan isolated manner' (asins are formed aroutree7 These (asins are lled /ith se/age7 This msuita(le for fruit gardens7

• SU3 SUA182? 9AA9G8T95: @ere se/age is a



SU3 SUA182? 9AA9G8T95: @ere se/age is athe roots of plants' through the open Fointed agdrain"pipes7 These pipes are laid a(out )7! m (ground level7 The se/age rises up due to

action7 @ere soil takes less load (ut theconomical method7

A9.G? 85. 1?AAW 9AA9G8T95 &?T@.



• A9.G? 85. 1?AAW 9AA9G8T95 &?T@.

9n this method ' se/age is supplied in furro/s crop ro/s7 Se/age spreads laterally irrigating t

(et/een t/o furro/s7 The /idth of furro/ var)!")-! cm and the depth from -"-! cm7 The the ridge varies from )-"-! cm and length from7 The percolated euent is collected in undedrains o/s to/ards natural drainage for disposa

SEWAGE SICKNESS



SEWAGE SICKNESS

The phenomenon (y /hich the soil looses its careceiving the se/age load is kno/n as se/age sickness

0A??5T95 1 S?W8G? S92H5?SS:"

• 0rimary treatment like screening B sedimentation sgiven to se/age (efore its application to land suspended solids are removed B the pores of soil /clogged7

• The se/age should (e applied intermittently on lagiving rest to the land for sometime 7The land sploughed during non supply period of se/age so thataerated7



• Heeping some portion of land reserved in ordethe same in resting period 7?nough area /ill (e for this purpose7

• 3y planting diIerent crops on the same land (ysystem of crops 7The soil /ill (e aerated B /

the fertili;ing elements of se/age 7• 3y providing su>cient under drainage system t

the e6cessive se/age <uantity7

• 3y fre<uent ploughing B rotation of soil7

• 3y not applying the se/age in e6cess <uantity 7



6idation ponds$ sta(ili;ation p

• The oldest /aste/ater treatment systems• Ae<uires a minimum of technology

• Aelatively lo/ in cost

• Used for ra/ se/age as /ell as primaryJ orsecondaryJtreated euents7

•

1acultative ponds and aerated lagoons



1acultative ponds

• ;ones: upper photic *aero(ic+ ;one fa



• ;ones: upper photic *aero(ic+ ;one' fa*aero(ic and anaero(ic+ ;one and lo/er anaero

• Upper aero(ic ;one: algae use 2' sun

inorganic nutrients *photosynthesis+ to o6ygen and algal (iomass7• 1acultative ;one: (acteria and other hetconvert organic matter to car(on dio6ide' nutrients' /ater and micro(ial (iomass7

• ,o/er anaero(ic ;one: anaero(ic (acteria

the (iomass from upper ;ones• 9nuence (y many factors

• Sunlight• Temperature• p@•

3iological activities



8erated ,agoons



8erated ,agoons

2hl i ti



2hlorination

• .isinfection of se/age euent

• 2ontrolling the odour produced

• 1or the formation of oc in coagulation procom(ination /ith other chemicals

• 1or the removal of grease' oils in skimming tank

• 1or prevention of sludge (ulking in activatedplants

• 1or overcoming ponding due to clogging in lters

• Aeduction of 3. of ra/ se/a e treated se/

sewage treatment 2

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