Biodegradation of Urban Solid Waste

7/25/2019 Biodegradation of Urban Solid Waste

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BIODEGRADATION AND CHARACTERIZATION OF

URBAN SOLID WASTE

BY

ABIOYE, SAMSON OLUWAFEMI

1



TABLE OF CONTENT

List of Tables iv

List of Figures v

Abstract vi

CHAPTER ONE

1.1 Background of Study 1

1.2 Aim and Objectives

1.! Sco"e of Study

1. #ustification of Study

1.$ Outline of ot%er &%a"ters

CHAPTER TWO

2.1 T%e 'aste Stream $

2.1.1 (%ysical com"osition of solid urban )astes *

2.1.2 &%emical com"osition of organic )astes *

2.1.! &%emical c%aracteristics of t%e matured solid urban )aste com"ost +2.2 'aste Treatment 1,

2.! -rban 'aste anagement Strategy 1,

2.!.1 'aste com"osting "rocesses 1!

2.!.2 &o/com"osting 1$

2.!.2.1 O"en co/com"osting 1*

2.!.2.2 O"en )indro) com"osting 10

2.!.2.2.1 O"en )indro) com"osting "rocess 10

2.!.2.2.2 ecom"osition "rocess 10

2.!.2.2.! &ontainer design and use 1+

2.!.2.! n/vessel co/com"osting 13

2.!.! 4merging com"osting "rocesses 13

2. (erformance and "roblems of com"osting 22

2.$ Benefits of &om"osting 22

CHAPTER THREE

!.1 aterials 2!

2



!.2 45ui"ments6 7eagents and A""aratus 2!

!.! 48"erimental (rocedure 2

!.!.1 'aste "re"aration 2

!.!.2 &%aracterisation of )astes used for com"osting 2

!.!.2.1 ry as%ing sam"le "re"aration 2

!.!.2.2 etermination of carbon content 2*

!.!.!.! etermination of nitrogen content 2*

!.!.! &om"osting "rocess 20

!.!. (rocess monitoring and sam"ling 2+

CHAPTER FOUR

.1 7esults 23

.2 iscussion of 7esults !*

CHAPTER FIVE

$.1 &onclusion !+

$.2 7ecommendations !+

7eferences ,

3



List of Tab!s

Tab!s Tit! Pa"!s

2.1 &%emical com"osition of ra) materials used for com"osting 0

2.2 &%emical "ro"erties of t%e matured solid urban )aste com"ost 3

2.! erits and demerits of co/com"osting 21

!.1 &om"osition of t%e t)o )aste mi8tures for t%e com"osting "rocess 2+

.1 &%emical com"osition of )aste materials used for com"osting !,

.2 9utrient values of com"osite )aste before com"osting !,

.! Bio/degradation of mi8ture &1 !1

. Bio/degradation of mi8ture &2 !1

.$ 9utrient values of t%e matured solid urban )aste com"ost !1

4



List of Fi"#$!s

Fi"#$! Tit! Pa"!

.1 &arbon to nitrogen content com"arison of )aste materials used !2

.2 9utrient values of com"osite )aste before com"osting !2

.! Tem"erature:time correlation of sam"le &1 during com"osting "rocess !!

. Tem"erature/time correlation of sam"le &2 during com"osting "rocess !!

.$ ";:time correlation of sam"le &1 during com"osting "rocess !

.* ";:time correlation of sam"le &2 during com"osting "rocess !

.0 9utrient values of t%e matured solid urban )aste com"ost. !$

5



ABSTRACT

7a"id urbani<ation and "o"ulation gro)t% are largely res"onsible for very %ig%

increasing rate of solid )aste in t%e urban areas6 its "ro"er management and recycling is

major "roblems of unici"al &or"oration. T%e study attem"ts to manage "ro"er6

"%ysicoc%emical analysis of -rban Solid 'aste =-S'> and its conversion to enric%ed

com"ost by ecofriendly "rocess.

For t%is study6 turned )indro)s met%od for com"osting of -rban Solid 'aste )as

used follo)ing t%e c%aracteri<ation of t%e various )aste materials and t%e com"osite )aste

material. microbial inoculums )ere added uniformly and tem"erature6 "; and moisture

content )ere maintained t%roug%out t%e com"osting "rocess. T%e c%emical com"osition of

com"ost obtained at t%e end of t%e com"osting "rocess s%o)ed t%e de"endence of o"timal

com"osting "rocess on t%e a""ro"riate &?9 ratio in t%e )aste materials.

T%e initial com"ositions of urban )aste indicated an organic carbon status of 2!.1@

)it% t%e &? 9 ratio of 32. T%e additives used in solid urban )aste com"osting suc% as co)

dung and green manure recorded organic carbon content of 1,.$, and 13.,* and &?9 ratio of

2$.*1 and 3.,!. T%e study s%o)ed t%at t%e %ig%er t%e &?9 ratio t%e lo)er t%e 5uality of t%e

resulting com"ost. T%e &1 com"osite )aste )it% t%e &?9 ratio of 3$.* resulted in a lo)

9itrogen value of t%e final com"ost6 com"ared to t%at of &2 )it% lo)er &?9 ratio as s%o)n inTables .2 and .$. T%e com"osting "rocesses of t%e t)o com"osite sam"les )ere furt%er

com"are using t%e "; and tem"erature "rofiles as s%o)n in Figures .! / .*

T%e results of t%e study clearly indicated t%at t%e recycling of solid urban )aste can

transform garbage or munici"al solid )aste to enric%ed com"osts. T%is is a "ractical

significance if ado"ted by urban farmers as a result of soil %ealt% and in turn t%e "roductivity

of soil can be maintained for furt%er agriculture.

6



CHAPTER ONE

INTRODUCTION

T%e elimination of a )ide range of "ollutants and )astes from t%e environment is an

absolute re5uirement to "romote a sustainable develo"ment of our society )it% lo)

environmental im"act. Biological "rocesses "lay a major role in t%e removal of contaminants

and t%ey take advantage of t%e astonis%ing catabolic versatility of microorganisms to degrade

and convert suc% com"ounds. Biodegradation is t%e term used to describe t%e natural decay

of )astes as a result of t%e action of bacteria. Biodegradation is also defined as t%e c%emical

breakdo)n of materials by a "%ysiological environment. T%e term is often used in relation to

ecology6 )aste management and environmental remediation = bioremediation>. Organic

material can be degraded aerobically )it% o8ygen6 or anaerobically6 )it%out o8ygen.

Biodegradable matter is generally organic material suc% as "lant and animal matter and ot%er

substances originating from living organisms6 or artificial materials t%at are similar enoug% to

"lant and animal matter to be "ut to use by microorganisms. Biodegradation involves t%e

"rocess in )%ic% a "roduct is ca"able of being broken do)n into innocuous sub/"roducts6

like &arbon =iv> o8ide and )ater6 by t%e action of living t%ings =microorganisms>. Banana

"eels )ill biodegrade into biomass6 &arbon =iv> o8ide and )ater. (roducts t%at are susce"tible

to biodegradation are also referred to as bioactive='iki"edia6 2,,3>.

7ecycling involves t%e collection6 "rocessing6 and reuse of materials t%at )ould

ot%er)ise be t%ro)n a)ay. aterials usually solid )astes ranging from "recious metals to

broken glass6 from old ne)s"a"ers to "lastic s"oons6 can be recycled. T%e recycling is also

e8tended to kitc%en )astes6 )eeds and farm yard manure. T%e recycling "rocess reclaims t%e

original material and uses it in ne) "roducts. 7ecycling decreases t%e amount of land needed

for tras% dum"s by reducing t%e volume of discarded )aste t%ereby reducing "ollution

%;eimlic% et al 6 2,,1>.

-rban Solid 'aste is defined as t%e organic and inorganic )aste materials "roduced

from different sources and %ave lost value in t%e eye of t%eir o)ner =As%a et al 6 2,,+>.

&ointreau =2,,*> defined unici"al solid )aste as garbage t%at comes from %omes6

businesses6 and sc%ools. unici"al solid )aste does not include construction )aste6

industrial )aste6 or se)age )aste. unici"al solid )aste can be classified in t)o )ays?

By aterial6 t%at is )%at t%e )aste is made of. 'aste may be "lastic6 "a"er6 metal6

rubber6 food )aste6 or yard )aste. A "lastic toy and a "lastic yogurt carton )ould be

7

http://en.wikipedia.org/wiki/Natural_environment

http://en.wikipedia.org/wiki/Contaminant

http://en.wikipedia.org/wiki/Physiological

http://en.wikipedia.org/wiki/Ecology

http://en.wikipedia.org/wiki/Waste_management


http://en.wikipedia.org/wiki/Environmental_remediation

http://en.wikipedia.org/wiki/Bioremediation

http://en.wikipedia.org/wiki/Aerobic_organism

http://en.wikipedia.org/wiki/Oxygen

http://en.wikipedia.org/wiki/Anaerobic_digestion

http://en.wikipedia.org/wiki/Organic_material


http://en.wikipedia.org/wiki/Contaminant

http://en.wikipedia.org/wiki/Physiological

http://en.wikipedia.org/wiki/Ecology

http://en.wikipedia.org/wiki/Waste_management


http://en.wikipedia.org/wiki/Environmental_remediation

http://en.wikipedia.org/wiki/Bioremediation

http://en.wikipedia.org/wiki/Aerobic_organism

http://en.wikipedia.org/wiki/Oxygen

http://en.wikipedia.org/wiki/Anaerobic_digestion

http://en.wikipedia.org/wiki/Organic_material



in t%e same materials category because t%ey are bot% made of "lastic.

By (roduct6 t%at is )%at t%e )aste )as used for originally. T%e )aste may be an old

"otato c%i" bag6 a )orn/out s%oe6 or a broken toy. A "lastic beverage container and an

aluminum beverage container )ould be in t%e same "roduct category because t%ey are

bot% used as containers.

&'& Ba()"$o#*+ of St#+

Solid )aste dis"osal "oses a greater "roblem because it leads to land "ollution if

o"enly dum"ed6 )ater "ollution if dum"ed in lo) lands6 and air "ollution if burnt. 9igeria

and majority of t%e develo"ing countries are facing serious environmental degradation and

"ublic/%ealt% risk due to uncollected dis"osal of )aste on streets and ot%er "ublic areas6

drainage congestion by indiscriminately dum"ed )astes6 and contamination of )ater resources near uncontrolled dum"ing sites =Faisal6 2,,$>.

According to Samant%a =2,,0>6 )%en solid )astes are "oorly managed6 t%ey can

cause considerable t%reats to t%e environment and %uman %ealt% as it decom"oses6 during

incineration6 and t%roug% t%e leac%ing of to8ins. T%e incineration of )aste emits c%emicals

detrimental to %uman %ealt%6 most notably dio8ins6 furans6 and mercury. T%is "oses a t%reat

to %uman %ealt%. An additional concern is t%e large accumulation of met%ane during )aste

decom"osition. According to t%e &%ina &ouncil for nternational &oo"eration on4nvironment =&&&46 2,,0> re"ort6 alarming rate of met%ane e8"losions in )aste "iles and

landfills %as been re"orted over t%e "ast fe) years.

One of t%e major environmental concerns in urban areas today is t%e issue of Solid

'aste anagement. T%e collection6 trans"ortation and dis"osal of solid )aste are normally

done in an unscientific and c%aotic manner. -ncontrolled dum"ing of )astes on outskirts of

to)ns and cities %as created overflo)ing landfills6 )%ic% are not only im"ossible to reclaim

because of t%e %a"%a<ard manner of dum"ing6 but also %ave serious environmental

im"lications in terms of ground )ater "ollution and contribution to global )arming. An

effective system of solid )aste management is t%e need of t%e %our and s%ould be

environmentally and economically sustainable. &om"osting is t%e sim"lest yet best "rocess

for solid )aste management for our condition. t is basically a s"ecial form of 'aste

Stabili<ation t%at re5uires s"ecial conditions of moisture and aeration to "roduce stable

com"ost )%ic% can be used as a lo) grade manure and soil conditioner =eenambal et al 6

2,,!>.

T%e 7e"lenis%ing of t%e soil %ealt% by "roviding t%e muc% needed organic matter6 lest

8



t%e soil become im"overis%ed %as been a major concern. T%e sco"e and "otential for

recycling variety of resources in agriculture is vat by any standards. 'astes recycling can

bring tremendous benefits to agriculture and land management in long run. n addition t%ere

are t%e benefits of a cleaner environment6 a %ealt%ier %abitat and an intelligent use of all

available recyclable resources )it%out condemning t%em as )astes. To)ards t%is end urban

solid )aste com"ost could serve as a valuable organic matter source given t%e s%ortage of

organic nutrient source. efining 5uality standards for organic manures is a very difficult

task given t%e %eterogeneity of residues t%at occur in city )astes and "rocessing met%ods

ado"ted. ntegrated nutrient management combining bot% inorganic and organics resulting in

)%olesome im"rovement of t%e soil. Faced )it% suc% situation utili<ing valuable urban

resources for manure "roduction )ould be viable alternative given t%e ever increasing urban

status resulting in urban )aste "roduction. T%is can be done by ado"ting t%e tec%nology of

com"ostingC. T%e term com"osting refers to a biological "rocess in )%ic% organic urban

solid )aste material is broken do)n by t%e action of micro/organisms. T%e degradation

"rocess takes "lace in t%e "resence of air =aerobic> and results in elevated "rocess

tem"erature and t%e "roduction of &arbon =iv> o8ide6 )ater and stabili<ed organic residue.

T%e key feature of t%e com"osting "rocess is t%e generation of %eat by biological activity

during t%e decom"osition of t%e substrate materials. By forming t%e )aste into large masses

under a""ro"riate conditions6 t%ey )ill reac% %ig% tem"erature6 resulting in ra"id

degradation. ore im"ortantly6 t%ese tem"erature %ave a saniti<ing effect u"on t%e )aste6

reducing t%e numerous of "at%ogenic organism =Dautam et al 2,,3>.

(ractices for collecting6 "rocessing6 and dis"osing of munici"al solid )aste vary

)idely across countries6 generally in accord )it% t%e nature of t%e )aste stream and key

environmental and economic features. T%e least efficient "ractices tend to be found in

develo"ing countries6 creating serious t%reats to local environmental 5uality and "ublic

%ealt%. Suggestions %as been made t%at im"rovements made no) in t%e %andling of

%a<ardous )aste )ill be far less e8"ensive in discounted terms t%an undoing in t%e future t%e

damage being caused by current "ractices. Addressing t%ese issues from a rational societal

"ers"ective )ill become increasingly urgent in t%e future6 es"ecially in t%e develo"ing

countries6 )%ere "rojections %as been made t%at munici"al solid )aste )ill increase at an

annual rate of 2.0 "ercent t%roug% t%e year 2,1, =avid and avid6 2,1,>.

&'- Ai. a*+ Ob/!(ti0!s

T%e aim of t%e "roject )ork is to biodegrade unici"al Solid 'astes.

9



T%e objectives of t%e study areE

c%aracteri<ation of unici"al-rban Solid 'astes

making com"ost from t%e c%aracteri<ed )astes and

c%aracteri<ation of t%e resulting com"ost.

&'1 S(o2! of St#+

T%e study =)aste collection6 com"ost "re"aration and sam"le analyses> is limited

only to solid )astes in Ogbomoso metro"olis.

&'3 4#stifi(atio* of St#+

7a"id urbani<ation and "o"ulation gro)t% are largely res"onsible for very %ig%

increasing rate of solid )aste in t%e urban areas6 its "ro"er management and recycling is

major "roblems of unici"al &or"oration. T%e "ro"osed study attem"ts to manage "ro"erly6

"%ysicoc%emical analysis of -rban Solid 'aste and its conversion to enric%ed com"ost by

ecofriendly "rocess.

&'5 O#ti*! of ot6!$ C6a2t!$s

T%e Literature revie) of t%e "roject )ork revie)s a number of )aste management

strategies. T%e )aste treatment strategies revie)ed areE o"en )indro) com"osting6 in/vesselcom"osting as )ell as vermiculture "rocesses.

T%e t%ird c%a"ter caters for t%e major com"osting activities )%ic% includes collection

of solid )aste6 se"aration of reusable com"onents =recycling> and bioconversion of

biodegradable com"onents into organic fertiliser as )ell as t%e o"timum com"osting

conditions and t%e c%aracteri<ation "rocedures for "ro"er degradation "rocess alongside t%e

"rocess monitoring and t%e sam"ling "rocesses to be ado"ted.

T%e re"ort s%o)s e8tensively t%at t%e biodegradation "rocess largely de"ends on t%e

)aste c%aracteristics. Also6 t%e "; and tem"erature "rofiles during t%e com"osting "rocess

)ere )ell analysed.

T%e last c%a"ter indicated t%at t%e biodegradation of solid urban )astes can transform

garbage to enric%ed com"osts and a number of recommendations for future studies )ere

made

CHAPTER TWO

LITERATURE REVIEW

T%e standards and norms for %andling munici"al solid )astes in industriali<ed

10



countries %ave reduced occu"ational %ealt% and environmental im"acts substantially. About

t%ree decades ago6 %ig%/income countries re5uired o"en dum"s to be covered daily )it% soil

to curtail vector access6 and t%us be u"graded to controlled landfills. Since t%e early 130,Gs6

)%en it became a""arent t%at even controlled landfills may cause significant )ater "ollution6

sanitary landfill tec%nology )as develo"ed to "rovide barriers to "ollutant migration6 as )ell

as to "rovide leac%ate and gas collection and treatment systems.

ost common "ractices of )aste "rocessing are uncontrolled dum"ing )%ic% causes

mainly )ater and soil "ollution. Besides dum"ing or sanitary land filling6 t%e final dis"osal of

solid )aste can be carried out by ot%er met%ods like incineration and com"osting =rec%sel

and Hun<e6 2,,1>.

-'& T6! Wast! St$!a.

Solid )aste comes from various sources. According to 4ncyclo"edia of (ublic ;ealt%

unici"al Solid 'aste =2,1,>6 t%e estimated "ercentages for unici"al Solid 'aste areE

7esidential6 institutional6 commercial6 and industrial? $$ to *, "ercent by )eig%t

&onstruction and demolition )aste? 1$ to 2, "ercent

Se)age sludge? 1 to 2 "ercent

edical )aste =including "otentially infectious material>? 1 to 2 "ercent and

;arbour debris? less t%an 1 "ercent.

redge s"oil can make u" to 1$ to 2, "ercent of t%e )aste in a coastal city )it% a

%arbour. Ot%er forms of )aste t%at can vary by location include agricultural )aste6

mining )aste6 and %a<ardous )aste.

'aste streams differ also in t%e follo)ing attributes?

(%ysical "ro"erties =e.g. com"actibility6 density>

&ombustion "ro"erties =tem"erature6 residual as% "ercentage6 %eat content in BT-s>

c%emical com"ositionE "ercentage of nitrogen6 carbon6 o8ygen6 c%lorine

concentrations of to8ic "olyaromatic %ydrocarbons =(A;s> and metals

"otential for recycling various com"onents and

ease of se"aration.

-'&'& P6si(a (o.2ositio* of soi+ #$ba* 7ast!s

11

http://www.enotes.com/public-health-encyclopedia

http://www.enotes.com/public-health-encyclopedia



unici"al solid )aste com"osition )as observed very demogra"%ically. (rior to

segregation6 t%e solid urban )astes consisted of some reusable material suc% as "lastic6

metals6 glass and "a"er )%ic% totally constituted to about $!@. T%is )as se"arated and

furt%er used in recycling industries. Iegetable matter and ot%er decom"osable is t%e

"redominant constituent )%ic% are "resent to an e8tent of 0@ =Dautam et al, 2009 >.

-'&'- C6!.i(a (o.2ositio* of o$"a*i( 7ast!s

According to Dautam et al =2,,3>6 t%e c%emical com"ositions of various organic

materials used for "re"aring t%e com"ost are given in Table 2.1. -rban )aste is one of t%e

"otential nutrient organic residues6 )%ic% on recycling yield valuable and nutrient ric%

"roduct kno)n as com"ost. T%e urban )aste is found to be slig%tly alkaline in nature =";

0.0*> and )as fairly lo) in 9itrogen6 9 =,.,@>6 (%o"%orous6 ( =,.,,,1+@>6 fairly ric% in

(otassium6 H =,.!$@> and Sodium6 9a =!.@>. T%e organic carbon )as !+@ )it% a &? 9

ratio of 3$,?,.,. Dreen leaves )ere ric% in 9 =,.0$@> and )as used to su""lement 9itrogen

to initially counter t%e nitrogen de"letion. &o) dung used as an additive or inoculum for t%e

com"ost treatments. T%is mainly served as a starter material for com"osting. t also en%ances

t%e decom"osition of cellulosic "lant material and it %ad ,.+$@ 9 )it% a &?9 ratio of !,.11.

Tab! -'&8 C6!.i(a (o.2ositio* of $a7 .at!$ias #s!+ fo$ (o.2osti*"

&%aracteristics -rban )aste &o) dung Dreen leaves

"; 0.0*,, 0.1, 0.!2

12



4& =Js cm/1> 1$.,,,, 1!*!.,, 123*.,,

Organic carbon =@> !+.,,,, 2$.*, !.*,

9itrogen =@> ,.,,, ,.+$ !.,+

(%os"%orus =@> ,.,,1+ ,.20 ,.1

(otassium =@> ,.!$,, ,.!* 1.*$

Sodium =@> !.,,, 2.2* 1.*!

&? 9 ratio 3$,.,,,, !,.11 11.2!

&r =mg kg/1> 22.,,, 12.$, 1+.!,

&d =mg kg/1> ,.2,,, ,., ,.,1

&u =mg kg/1> *$.!*,, 2.$, $.!,

Fe =mg kg/1> 1,*,.,,,, 122$.,, 12$!.,,

Kn =mg kg/1> 0,.,,, +.2, $2.0,

n =mg kg/1> !$*.,,,, 2.,, 20.,,

9i =mg kg/1> !.*,,, 2.!, 22.*,

(b =mg kg/1> 22.2,,, 2.$2 1.$2

So#$(!8 %Ga#ta. et al -99:;

-'&'1 C6!.i(a (6a$a(t!$isti(s of t6! .at#$!+ soi+ #$ba* 7ast! (o.2ost

T%e data on c%emical "ro"erties of t%e matured solid urban )aste com"osts are given

in Table 2.2 =Dautam et al 2,,3>. T%e "; of all t%e com"osts )ere neutral to slig%tly

alkaline. T%is )as described to be due to t%e natural buffering of t%e %umus. ;ig%est "; )as

recorded in &! com"ared to ot%ers. According to Dautam et al =2,,3>6 t%e result concurred

)it% t%e observation of ';O t%at t%e munici"al com"ost )as slig%tly alkaline in nature and

13



%ad a marked buffering ca"acity. T%e "ercent organic carbon varied bet)een %is treatments.

T%e %ig%er t%e 9itrogen content in t%e ra) material used6 t%e %ig%er t%e 9itrogen content in

t%e final com"ost =Dautam et al 2,,3>.

T%e enric%ment of urban )aste )it% rock "%os"%ate yielded com"osts )it% %ig%

(%os"%orous content. T%e enric%ment of com"ost )it% additives increased t%e decom"osition

rate6 )%ic% may be due to availability of essential nutrients for t%e increased biological

activity. According to i et al =2,,3>6 enric%ment of com"ost )it% nutrients like

(%os"%orous in t%e form of rock "%os"%ate resulted in %ig% value com"ost due to %ig%er

degree of decom"osition.

Tab! -'-8 C6!.i(a 2$o2!$ti!s of t6! .at#$!+ soi+ #$ba* 7ast! (o.2ost

&%aracteristics &1 &2 &! & &$ &*

14



"; 0.,2 0.$! 0.$* 0.10 0.1, 0.$

4& =Js cm/1> 1!3.,, 1!*!.,, 11$1.,, 1$.,, 12$.,, 1!3.,,

Organic carbon =@> !+.,, 2+.,, !2.,, !0.,, !!.,, !3.,,

9itrogen =@> ,., ,.,* ,.,* ,.,$ ,.,$ ,.,0

(%os"%orus =@> ,.,,1+ ,.,,2, ,.,,,* ,.,,1* ,.,,22 ,.,,$

(otassium =@> ,.!$ ,.$ ,.!, ,., ,., ,.$

Sodium =@> !., .3, !.+, $.0, $., .!,

&?9 ratio 3$,.,, **.** $!!.!! 0,.,, **,.,, $$0.1

&r =mg kg/1> 22., !!.*, !,., 2+.2, 23.,, 21.,

&d =mg kg/1> ,.2, BL ,.2, BL ,., ,.+,

&u =mg kg/1> *$.!* 1,1.++ 30.1* $.!2 !.0, *.1*

Fe =mg kg/1> 1,*, 1*1+, 131+, 1302, 1+*, 1*,

Kn =mg kg/1> 0,., 3$.,, !.,, *1.*, 0+., *!.,

n =mg kg/1> 2.,, !$*.,, 2+,.,, 20.,, 2$*.,, 2*0.,,

9i =mg kg/1> !.*, $*., 1.,, $0.*, 0.*, 2.*,

(b =mg kg/1> 22.2, 2*.+, 13., 1,.2, 1.+, 12.*,

So#$(!8 %Ga#ta. et al -99:;

-'- Wast! T$!at.!*t

T%ere are more t%an t%irty tec%nological a""roac%es to managing solid )aste. One of

t%e most common is incineration6 )%ic% re5uires a burner and often a su""lemental source of

fuel. T%e tem"erature and t%e residence time of t%e )aste in t%e burner determine t%e

efficiency )it% )%ic% organic matter is converted to carbon. 9on/combustible material6

15



"articularly metals6 accumulate in t%e as% and must be removed eit%er to landfills or for

incor"oration into concrete and ot%er construction "roducts. As organic matter cools in t%e

stack6 un)anted "roducts suc% as dio8ins may also form. &om"osting allo)s organic material

to undergo biodegradation and "%oto degradation6 resulting in sim"le organic molecules t%at

can actually be beneficial to t%e environment =rec%sel and Hun<e 2,,1>.

4art%)orm farming =vermiculture> is anot%er bio/tec%ni5ue for converting t%e solid

organic )aste into com"ost =D%os%6 2,,>. An innovative disci"line of vermiculture

biotec%nology6 t%e breeding and "ro"agation of eart%)orms and t%e use of its castings %as

become an im"ortant tool of )aste recycling all over t%e )orld. 4ssentially6 t%e vermiculture

"rovides for t%e use of eart%)orms as natural bioreactors for cost/effective and

environmentally sound )aste management. 9o) t%ere is an all/round recognition t%at

ado"tion and e8"loitation of vermiculture biotec%nology besides arresting ecological

degradation could go a long )ay to)ards meeting t%e nutrient needs of t%e agricultural sector

in a big )ay=As%a6 2,,+>.

-'1 U$ba* Wast! Ma*a"!.!*t St$at!"

any a""roac%es to )aste management e8ist. Denerally6 solid )aste is managed

t%roug% landfills6 incineration and recycling or reuse. ;o)ever in develo"ing countries6

"ro"erly engineered landfills are not common )%ile t%e cost of modern incineration is too

e8orbitant to bear. ;ence6 t%e most common met%od of )aste dis"osal is some form of

landfill6 including variants suc% as uncontrolled dum"ing in undefined areas6 collection and

dis"osal on unmanaged o"en dum"s6 collectiondis"osal on controlled dum"sites =-94(6

2,,>. t is common to find scavengers moving from door to door or sorting t%roug%

communal bins to "ick dry recyclable materials. ;o)ever6 t%ese "ickers are more interested

in inorganic recyclable materials suc% as "lastics and glass6 but not in organic )astes.

T%e general "rinci"le of t%e )aste management %ierarc%y consists of t%e follo)ing ste"s?

inimising )astes

a8imising environmentally sound )aste reuse and recycling

16



(romoting environmentally sound )aste dis"osal and treatment

48tending )aste service coverage

&urrent urban organic )aste recycling "ractices include t%e follo)ing

T%e use of fres% )aste from vegetable markets6 restaurants and %otels6 as )ell as food

"rocessing industries as feed for urban livestock =Allison et al. 133+>

irect a""lication of solid )aste on and into t%e soil

ining of old )aste dum"s for a""lication as fertili<er on farmland =Lardinois and

van de Hlundert6 133!>

A""lication of animal manure suc% as "oultry"ig manure and co) dung

irect a""lication or %uman e8creta or bio/solids to t%e soil =&ofie et al.6 2,,$>

Organised com"osting of solid )astes or co/com"osting of solid )astes )it% animal

manure or %uman e8creta.

'%ic%ever met%od is used6 a "rocess of microbial degradation releases t%e useful

nutrients in organic )aste for soil im"rovement and "lant gro)t%.

Kurbrugg and resc%er =2,,2> re"ort t%at t%e "otential benefits of organic )aste recycling

are "articularly in reducing t%e environmental im"act of dis"osal sites6 in e8tending e8isting

landfill ca"acity6 in re"lenis%ing t%e soil %umus layer and in minimising )aste 5uantity. Ot%er

benefits ada"ted and summarised from ;oorn)eg et al . =1333> )it% "articular reference to

organic )aste com"osting are t%at it?

increases overall )aste diversion from final dis"osal6 es"ecially since as muc% as +,

"ercent of t%e )aste stream in lo)/ and middle/income countries can be com"osted

en%ances recycling and incineration o"erations by removing organic matter from t%e

)aste stream

"roduces a valuable soil amendment integral to sustainable agriculture

17



"romotes environmentally/sound "ractices6 suc% as t%e reduction of met%ane

generation at landfills

en%ances t%e effectiveness of fertili<er a""lication

can reduce )aste trans"ortation re5uirements

is fle8ible for im"lementation at different levels6 from %ouse%old efforts to large/scale

centralised facilities

can be started )it% very little ca"ital and o"erating costs

t%e climate of many develo"ing countries is o"timum for com"osting

addresses significant %ealt% im"acts resulting from organic )aste suc% as reducing

engue Fever

"rovides an e8cellent o""ortunity to im"rove a cityGs overall )aste collection

"rogramme

accommodates seasonal )aste fluctuations suc% as leaf litter and cro" residues

can integrate e8isting informal sectors involved in t%e collection6 se"aration and

recycling of )astes.

&om"osting %as been an attractive o"tion in many res"ects. t is t%e "rocess of

decom"osing or breaking do)n organic )aste materials =by micro/organisms suc% as

bacteria6 "roto<oans6 fungi6 invertebrates> into a valuable resource called com"ost.

&om"osting is done at different scales =large6 medium6 small> by various "eo"le

=munici"alities6 9DOs6 communities6 individuals> and for various "ur"oses =gardening6landsca"ing6 farming> in t%e urban areas =Onibokun6 1333>.

According to ;oorn)eg et al =1333>6 t%e com"osting "rocess is also constrained by t%e

follo)ing factors?

nade5uate attention to t%e biological "rocess re5uirements

18



Over/em"%asis "laced on mec%anised "rocesses rat%er t%an labour/intensive

o"erations

Lack of vision and marketing "lans for t%e final "roduct / com"ost

(oor feed stock )%ic% yields "oor 5uality finis%ed com"ost6 for e8am"le )%en

contaminated by %eavy metals

(oor accounting "ractices )%ic% neglect t%at t%e economics of com"osting rely on

e8ternalities6 suc% as reduced soil erosion6 )ater contamination6 climate c%ange6 and

avoided dis"osal costs

-'1'& Wast! (o.2osti*" 2$o(!ss!s

T%e "rocess of )aste com"osting includes t%e determination of t%e ty"e of facility6

o"timal number6 ca"acity6 and location of com"ost stations "er city. ost critical in t%is

assessment is to include "ossible )ays of com"osting )it% due consideration of )aste su""ly

and com"ost demand. &om"osting is best ac%ieved by "roviding o"timal conditions for t%e

micro/organisms t%roug% t%e best combination of air6 moisture6 tem"erature and organic

materials =Agromisa6 1333>. &om"osting "rocesses can be aerobic =)it% o8ygen> or

anaerobic =)it%out o8ygen> and even alternate bet)een t%e t)o during t%e decom"osition

"rocess. Anaerobic com"osting is a lo)/tem"erature "rocess t%at is not recommended for

urban agriculture due to t%e strong odours and t%e inability to destroy %armful "at%ogens t%at

may be "resent in urban organic )aste. &onversely6 aerobic com"osting is a %ig%/tem"erature

"rocess due to t%e develo"ment of microbes t%at generate %ig%er tem"eratures in t%e com"ost

"ile. T%e key factors affecting t%e biological decom"osition "rocesses andor t%e resulting

com"ost 5uality are?

&arbon to nitrogen ratio

oisture content

O8ygen su""ly6 aeration

(article si<e

";

Tem"erature

19



Turning fre5uency

icro/organisms and invertebrates

&ontrol of "at%ogens

egree of decom"osition

9itrogen conservation

T%e c%oice of a tec%nology for aerobic com"osting )ill de"end on t%e location of t%e

facility6 t%e ca"ital available and t%e amount and ty"e of )aste delivered to t%e site. T%e t)o

main ty"es of systems generally distinguis%ed are?

o"en systems suc% as )indro)s and static "iles and

closed in/vessel systems. T%ese in/vessel or reactor systems can be static or

movable closed structures )%ere aeration and moisture is controlled by mec%anical

means and often re5uires an e8ternal energy su""ly. Suc% systems are usually

investment intensive and also more e8"ensive to o"erate and maintain. O"en

systems are t%e ones most fre5uently used in develo"ing countries. T%ey are classified

according to Akvo"edia =2,1,> as?

Bi* (o.2osti*"? &om"ared to )indro) systems6 bin systems are contained by a constructed

structure on t%ree or all four sides of t%e "ile. T%e advantage %ere is a more efficient use of

s"ace.

T$!*(6 a*+ 2it (o.2osti*"? Trenc% and "it systems are c%aracterised by %ea"s )%ic% are

"artly or fully contained under t%e soil surface. Structuring t%e %ea" )it% bulky material or

turning is usually t%e c%oice for best aeration. &ontrol of leac%ing is difficult in trenc% or "itcom"osting. n some cases6 com"osting materials are com"letely buried in t%e trenc% )%ic%

t%en serves as a "lanting bed. T%e aerobic com"osting "rocess can last from a fe) )eeks to

!/ mont%s6 de"ending on t%e ty"e of com"osting feedstock and t%e met%od of com"osting.

Wi*+$o7, 6!a2 o$ 2i! (o.2osti*"? T%e material is "iled u" in %ea"s or elongated %ea"s

=called )indro)s>.

-'1'- Co<(o.2osti*"

20



&o/&om"osting is t%e controlled aerobic degradation of organics using more t%an one

materials =Faecal sludge and Organic solid )aste>. Faecal sludge %as a %ig% moisture and

nitrogen content )%ile biodegradable solid )aste is %ig% in organic carbon and %as good

bulking "ro"erties =i.e. it allo)s air to flo) and circulate>. By combining t%e t)o6 t%e benefits

of eac% can be used to o"timi<e t%e "rocess and t%e "roduct. For de)atered sludges6 a ratio of

1?2 to 1?! of de)atered sludge to solid )aste s%ould be used. Li5uid sludges s%ould be used

at a ratio of 1?$ to 1?1, of li5uid sludge to solid )aste =Akvo"edia6 2,1,> .

&om"osting can be done eit%er in "its or concrete tanks or )ell rings or in )ooden or

"lastic crates a""ro"riate in a given situation. t is "referable to select a com"osting site under

s%ade6 in t%e u"land or an elevated level6 to "revent )ater stagnation in "its during rains =Ali6

2,,>.

A &o/&om"osting facility is only a""ro"riate )%en t%ere is an available source of )ell/

sorted biodegradable solid )aste. i8ed solid )aste )it% "lastics and garbage must first be

sorted. '%en done carefully6 &o/&om"osting can "roduce a clean6 "leasant6 beneficial

"roduct t%at is safe to touc% and )ork )it%. t is a good )ay to reduce t%e "at%ogen load in

sludge =Bradford 2,,$>.

e"ending on t%e climate =rainfall6 tem"erature and )ind> t%e &o/&om"osting facility

can be built to accommodate t%e conditions. Since moisture "lays an im"ortant role in t%e

com"osting "rocess6 covered facilities are es"ecially recommended )%ere t%ere is %eavy

rainfall. T%e facility s%ould be located close to t%e sources of organic )aste and faecal sludge

=to minimi<e trans"ort> but to minimi<e nuisances6 it s%ould not be too close to %omes and

businesses. A )ell/trained staff is necessary for t%e o"eration and maintenance of t%e

facility=&ofi et al 6 2,,$>.

Adding e8creta6 es"ecially urine6 to %ouse%old organics "roduces com"ost )it% a %ig%er

nutrient value =9/(/H> t%an com"ost "roduced only from kitc%en and garden )astes. &o/

com"osting integrates e8creta and solid )aste management6 o"timi<ing efficiency.

&om"ost can be a""lied in a range of end uses6 )it%in gardens6 on Bro)nfield sites6

landsca"ing and full scale agriculture. T%e screening grades t%e "roducts to bet)een !,mm

and ,mm "articles )%ic%6 de"endent on grade6 can t%en be used as soil im"rover6 mulc%6

to"soil constituent6 turf dressing6 and gro)ing medium.

T%e t)o ty"es of &o/&om"osting designs according to Akvo"edia =2,1,> are?

21



o"en designs and

in/vessel designs.

-'1'-'& O2!* (o<(o.2osti*"

n o"en com"osting6 t%e mi8ed material =sludge and solid )aste> is "iled into long %ea"s

called )indro)s and left to decom"ose. 'indro) "iles are turned "eriodically to "rovide

o8ygen and ensure t%at all "arts of t%e "ile are subjected to t%e same %eat treatment. 'indro)

"iles s%ould be at least 1m %ig%6 and s%ould be insulated )it% com"ost or soil to "romote an

even distribution of %eat inside t%e "ile. e"ending on t%e climate and available s"ace6 t%e

facility may be covered to "revent e8cess eva"oration and "rotection from rain.

To ade5uately treat e8creta toget%er )it% ot%er organic materials in )indro)s6 t%e ';O

=13+3> recommends active )indro) co/com"osting )it% ot%er organic materials for one

mont% at $$/*,M&6 follo)ed by t)o to four mont%s curing to stabilise t%e com"ost. T%is

ac%ieves an acce"table level of "at%ogen kill for targeted %ealt% values.

'indro) &om"osting cannot be used to "rocess organic materials )%ic% include catering

and animal )astes as t%ese %ave to be "rocessed via n/vessel &om"osting or Anaerobic

igestion due to t%eir Animal By/(roducts 7egulations categorisation.

T%e "rocess of )indro) com"osting is relatively sim"le. T%e feedstocks are s%redded6

mi8ed and "laced into )indro)s along a non "ermeable surface. T%e )indro)s are turned on

a regular basis to im"rove o8ygen content6 distribute %eat to regulate tem"erature and to

distribute moisture. T%e )indro)s are turned multi"le times during t%e com"osting "rocess6

)%ic% takes on average si8teen )eeks6 de"ending on maturity re5uirements. T%e last "art of

t%e "rocess involves screening t%e com"ost to remove contaminants suc% as "lastics and

metals6 and to also grade t%e com"ost for various end uses. Oversi<ed materials are also

removed and can be "ut back t%roug% t%e )%ole "rocess until t%ey %ave com"osted do)n

sufficiently.

-'1'-'- O2!* 7i*+$o7 (o.2osti*"

22



'indro) com"osting is used for "rocessing garden )aste6 suc% as grass cuttings6 "runing

and leaves in eit%er an o"en air environment or )it%in large covered areas )%ere t%e material

can break do)n in t%e "resence of o8ygen.

According to Scottis% 4nvironmental (rotection Agency =S4(A> =2,1,>6 o"en )indro)

com"osting is a managed biological "rocess in )%ic% biodegradable )aste is broken do)n by

naturally occurring micro/organisms to "roduce a stabilised residue. O"en )indro)

com"osting can be combined )it% a range of ot%er )aste treatment tec%nologies.

Only meat e8cluded food )astes can be treated6 as sti"ulated by t%e Animal By/ (roducts

=Scotland> =SS 2,,!11> 7egulations. deally t%is "rocess s%ould treat only segregated

biodegradable )aste. i8ed )aste can be treated by anaerobic digestionE %o)ever t%is may

result in contamination of t%e li5uid and solid fractions )%ic% can make t%em less suitable as

soil conditioners or fertili<ers.

-'1'-'-'& O2!* 7i*+$o7 (o.2osti*" 2$o(!ss

'aste is collected and broug%t to t%e site )%ere it is c%ecked to ensure it is of sufficient

5uality. t is t%en s%redded and "iled into )indro)s6 )%ic% are elongated "iles s%a"ed for

ideal com"osting. Aeration is encouraged by suitable mi8ing of t%e initial material and

regular mec%anical agitation =turning>. ecom"osition is allo)ed to continue until t%e )aste

%as been stabilised and matured. Before use6 t%e com"ost is c%ecked for contaminants to

ensure t%at it fulfils t%e "%ysical6 c%emical and biological re5uirements for commercial

com"ost=S4(A6 2,1,>.

-'1'-'-'- D!(o.2ositio* 2$o(!ss

&om"ost containers can be used to easily obtain t%e o"timal decom"osition conditions for

organic )aste by regulating t%e air6 %umidity and tem"erature during t%e com"osting "rocess

and t%us create t%e ideal environment for micro/organism develo"ment =bacteria6 "roto<oans6

fungi6 invertebrates>. Dood %andling of t%e com"ost "ile accelerates t%e decom"osition rate

)%ile also minimising t%e nutrient loss. Dood "ractices include cutting u" and s%redding t%e

organic )aste6 turning t%e "ile to increase aeration6 s"rinkling )ater on t%e "ile if it becomes

too dry =dusty )it% ants>6 and kee"ing t%e container closed during %eavy rains to "revent t%e

"ile from )ater logging =(rakas% et al 6 2,,0>.

23



aintaining t%e o"timal &9 ratio of 2$/!, may re5uire careful monitoring and

a""ro"riate %andling6 as nitrogen levels are often 5uite %ig% )%en com"osting domestic

organic )aste in containers due to t%e concentration of nitrogen/ric% matter and limited

aeration. -nder suc% conditions t%e com"ost becomes "utrid6 acidic and com"acts6 and its

5uality deteriorates. T%is t%en leads to %ig% odour emissions and t%e "revalence of anaerobic

conditions. Turning t%e "ile and adding dry "orous materials =carbon ric%>6 suc% as leaves6

sa)dust6 or stra)6 can easily rectify t%is "roblem. t s%ould be noted t%at if anaerobic

conditions "revail6 t%ermo"%ilic microbes may not develo"6 and conse5uently6 t%ermo"%ilic

tem"eratures may not be ac%ieved. ;o)ever6 in container com"osting t%is is not so crucial as

only domestic organic )aste is used6 rat%er t%an )aste from unkno)n sources t%at may

contain un)anted =i.e. %uman> "at%ogens andor agricultural residues t%at may contain cro"

diseases andor )eed seeds ='ong and Lin6 2,,2>.

-'1'-'-'1 Co*tai*!$ +!si"* a*+ #s!

&ontainers can be "ur"ose built =e.g. from bricks6 blocks6 "lastic barrels6 )icker baskets>

or constructed from recycled materials =e.g. oil drums6 "lastic barrels6 building materials>.

T%e s"ace re5uired for a com"osting site is a""ro8imately 1.$/2 m 2 "er %ouse%old. T%is

allocated area allo)s enoug% s"ace to "lace t)o containers side by side6 or to build t)o

c%ambers if using bricks or blocks =%eig%t 1m>E sufficient )orking s"ace s%ould be

maintained around t%e front of t%e containers. T%e c%ambers are filled se5uentially6 so t%at

)%en t%e second c%amber is full t%e com"ost in t%e first c%amber can be em"tied and t%e

mature com"ost stored until ready for use. n designing containers6 consideration %as to be

made for aeration vents6 drainage6 ground soil contact and over%ead "rotection.

&ement )as used in t%e construction of t%e double/c%amber bins alt%oug% ga"s )ere left

bet)een t%e blocks in t%e bottom to facilitate aeration =left )it%out mortar for tem"orary use>6

and t%en eac% c%amber )as covered )it% a )ooden lid. n some locations and in si8 sc%ools

larger versions consisting of t%ree %ig%/ca"acity c%ambers )ere also built and demonstrated.

But regardless of t%e ty"e of container selected6 some fundamental design "rinci"les need to

be considered including?

(ile com"ost directly on ground soil t%us ensuring drainage and allo)ing contact )it%

soil micro/organisms =in sealed containers "rovide drainage %oles and add fres%com"ost in eac% cycle to ensure micro/organisms are "resent>.

24



(rovide means of aeration in container )alls =%oles in drums or ga"s bet)een blocks>.

-se covers to close containers at nig%t and regulate com"ost "ile during day.

=rec%sel and Hun<e6 2,,1>.

-'1'-'1 I*<0!ss! (o<(o.2osti*"

n/vessel com"osting re5uires controlled moisture and air su""ly6 as )ell as mec%anical

mi8ing. T%erefore6 it is not generally a""ro"riate for decentrali<ed facilities. Alt%oug% t%e

com"osting "rocess seems like a sim"le6 "assive tec%nology6 a )ell/)orking facility re5uires

careful "lanning and design to avoid failure. n/vessel non flo) aerobic com"osting systems

t%at use reactors are "o"ularly termed mec%anicalC enclosedC or in/vesselC6 )%ile t%ose

t%at do not are often termed o"en systemsC. 7eactor Systems of n/ Iessel ty"e are t%ose in

)%ic% com"osting material is "laced for t%e "rocess. Denerally n:Iessel systems "rove

advantageous because of t%e follo)ing reasons

ra"id rate of decom"osition

"recise control of moisture6 aeration and tem"erature

5uicker odour removal

lesser area re5uirements

lesser "ersonnel re5uirements and

"est control.

T%e "rinci"le be%ind t%ese non flo) tec%ni5ues is to use batc% o"erated com"ost bo8es

t%at are no) available in t%e market. n t%e "rocess6 t%e )astes are loaded at t%e start of t%e

cycle and ty"ically remain in t%e bo8 reactor for 0 to 1 days. Aeration is usually controlled.

&uring is conducted in )indro)s for several mont%s. T%e above tec%ni5ue is t%e best solution

for laboratory scale studies = eenambal6 2,,!>.

-'1'1 E.!$"i*" (o.2osti*" 2$o(!ss!s

4merging trends include t%e "ractice of vermiculture and t%e use of effective micro/

organisms to accelerate t%e com"osting "rocess. Iermiculture is t%e use of )orms to digest

organic )aste into ric% %umus6 similar to com"ost6 t%at can t%en be a""lied in urban

agriculture. Local varieties of bot% surface and burro)ing eart%)orms can be used6 alt%oug%t%e latter are "articularly suited as t%ey not only digest organic matter but also modify t%e soil

25



structure. Iermiculture is "articularly suited to urban agriculture because it can be a""lied in

a variety of settings and at different scales. T%e "ractice is also used very often as "art of

integrated gardening in community building urban agriculture. ndeed6 broad/scale

vermiculture is )ides"read in ndia6 ndonesia and t%e (%ili""ines =DFA/-m)elt6 1333>6

)%ile t%e "ractice %as recently been gaining ground in &uba and Argentina =ubbeling and

Santandreu6 2,,!E Iiljoen and ;o)e6 2,,$>. n broad/scale vermiculture6 t%e eart%)orms are

introduced to organic )aste "iled in elongated ro)s t%at are covered )it% some form of

vegetative "rotection to "revent )ater logging =smail6 1330>

26



Tab! -'18 M!$its a*+ +!.!$its of (o<(o.2osti*"

A+0a*ta"!s Disa+0a*ta"!s=i.itatio*s

/ T%roug% co/com"osting6 a useful and safe

end "roduct is generated t%at combines

nutrients and organic material.

/ 4asy to set u" and maintain )it%

a""ro"riate training

/ (rovides a valuable resource t%at can

im"rove local agriculture and food "roduction

/ &an be built and re"aired )it% locally

available materials

/ Toilet "a"er is decom"osed

/ Lo) ca"ital costE lo) o"erating cost

/ (otential for local job creation and income

generation

/ 9o electrical energy re5uired

/ Long storage times

/ 7e5uires e8"ert design and o"eration

/ Limited control of vectors and "est

attraction

/ Labour intensive

/ Lo)er cost variants re5uires a large land

area =)%ic% is )ell located>

So#$(!8 %A)0o2!+ia, -9&9;

-'3 P!$fo$.a*(! a*+ 2$ob!.s of (o.2osti*"

&ontainer com"osting "roved to be %ig%ly effective for decom"osing organic )aste6

"articularly )%en good com"osting "ractices )ere follo)ed6 s"ecifically )%ere organic

materials )ere s%redded and t%e com"ost "ile fre5uently aerated. (roblems encountered

27



included com"ost com"action and "utrefaction6 lo) "artici"ant motivation and loss of t%e

actual com"osting site. uring t%e earlier "%ases6 some "roject "artici"ants eager to fill t%eir

containers )it% organic )aste invited t%eir neig%bours and friends to also use t%em. As t%e

containers )ere designed for individual %ouse%old use t%ey )ere ra"idly filled6 )%ic%

resulted in com"ost com"action and "utrefaction. 7emoving t%e to" layers and increasing

aeration of t%e remaining com"ost "ile remedied t%is. n "laces )%ere t%e larger ca"acity

tri"le/c%amber containers )ere used t%is "roblem did not occur =Akvo"edia6 2,1,>.

-'5 B!*!fits of Co.2osti*"

T%e recycling of urban organic )aste brings several ecological advantages t%at can

en%ance energy efficiency t%roug% carbon6 nutrient and )ater conservation in urbanlandsca"es =;olmgren6 2,,2>. T%ese advantages can be categorised as t%e micro/environment

benefits as t%ey relate directly to soil amelioration measures6 but in addition6 energy

efficiency s%ould also be considered in t%e broader sense to enca"sulate t%e )ider advantages

t%at can be accrued at national6 regional and international scales. For e8am"le6 recycling

organic )aste t%roug% com"osting in urban agriculture reduces t%e need to im"ort c%emical

fertili<ers and food stuffs. Furt%ermore6 )%en urban organic )aste recycling is decentralised

t%ere is reduced need for e8ternal in"uts suc% as e5ui"ment6 fuel and trans"ortation.

any urban areas are vast nutrient sinks as t%e recyclable nutrient "otential from organic

)aste is seldom e8"loited and t%us lost. T%is is com"ounded by t%e combination of soil

nutrient mining in rural and urban "roduction areas and t%e accumulation of urban organic

)aste in t%e dis"osal sites. n t%ese sites t%e mined nutrients accumulate in t%e urban areas6

largely t%roug% informal )aste dis"osal due to t%e inefficiency of formal )aste dis"osal

structures =rec%sel and Hun<e6 2,,1E &ofie6 2,,2>.

CHAPTER THREE

RESEARCH METHODOLOGY

T%e c%a"ter discusses e8tensively6 t%e met%odological "rocedure undergone in t%e

course of t%is researc% )ork. T%e researc% materials6 e5ui"ments and a""aratus for t%e study

28



"ur"ose )ere %ig%lig%ted. T%e )aste collection6 com"ost "re"aration "rocess and t%e "re/

c%aracteri<ation and "ost/c%aracteri<ation of t%e com"ost ra) material and t%e matured

com"ost are e8"lained in details.

1'& Mat!$ias

T%e main ra) materials used for "re"aration of com"ost are as listed belo)?

-rban )astes

Farm )astes and )eeds.

Additives suc% as green leaves6 co) dung6 urea6 matured com"ost or ric% loamy soil

)%ic% all serve as inoculums.

1'- E>#i2.!*ts, R!a"!*ts a*+ A22a$at#s

T%e e5ui"mentsa""aratus used in t%e "re"aration and c%aracteri<ation of com"ost are

?

&om"ost bin ='ell aerated containers>

Turner

"; metre

T%ermometer

Atomic Absor"tion S"ectrosco"y =AAS>.

rying oven

Furnace

;ot "late

Silica crucible

'atc% glass

Scrubber tubes

eioni<ed )ater

&oncentrated nitric acid =;9O!>6 0,@

&oncentrated %ydroc%loric acid =;&l>6 !0@

iluted ;&l

Tetrao8osul"%ate=vi>acid

Tetrao8o"%os"%ate=v>acid

Sodium %ydro8ide

;ydrogen (ero8ide =;2O2>

"olyvinyl alco%ol solution

9esslerNs reagent.

1'1 E?2!$i.!*ta P$o(!+#$!

T%e e8"erimental "rocedure involvesE )aste "re"aration="re/c%aracteri<ation>6

com"ost "re"aration and "rocess monitoring and sam"ling ="ost/c%aracteri<ation> of t%e finalcom"ost.

29



1'1'& Wast! 2$!2a$atio*

T%e first ste" in t%e e8"erimental study )as t%e collection of t%e )astes from different

sources. 7otten fruits )ere also included in t%e collection. Before "re"aration of t%e

com"osite sam"le6 %and sorting )as done to segregate un)anted materials like stra)6 "lastic

covers6 "ackaging materials etc. T%en a com"osite sam"le )as "re"ared and allo)ed to dry

for fe) days to adjust t%e moisture content to t%e desired levels. T%e dried sam"les )ere

s%redded manually into "ieces bet)een si<es 2 and ! cm. T%e "ur"ose of )%ic% is to %ave

good uniformity in %eating and to "rovide greater surface area for microbial attack. T%e

s%redded sam"le )as t%en analy<ed for various "%ysical6 c%emical and biological

c%aracteristics to get a roug% idea about t%e biodegradability of t%e sam"le.

1'1'- C6a$a(t!$isatio* of 7ast!s #s!+ fo$ (o.2osti*"

T%e c%aracteri<ation follo)s t%e dry as%ing tec%ni5ue for t%e detection of various elements

"resent in t%e sam"le. t describes t%e "rocedure for as%ing a variety of materials for subse5uent

determination of mineral nutrients by flame atomic absor"tion s"ectrosco"y.

1'1'-'& D$ as6i*" sa.2! 2$!2a$atio*

T%e met%od is a""licable to sam"les for t%e determination of various mineral nutrients

=(6 Fe6 Kn6 and n etc>. T%e sam"le "re"aration met%od and subse5uent analysis )ere

evaluated. T%e sam"les consisted of t%ree com"osite ra) material grou"s?

-rban )aste

&o) dung

Dreen leaves

T%e met%od consists of "re"aring an as% by using %eat and nitric acid to decom"ose t%e

organic matter6 and dissolving t%e inorganic residue in an a""ro"riate volume of dilute

%ydroc%loric acid.

P$o(!+#$!8

30



1. T%e amount of sam"les re5uired =about $ g of dry matter> )ere )eig%ed into a

crucible. crucible )eig%t6 and crucible "lus sam"le )eig%t )ere noted.

2. T%e sam"les )ere dried in an oven for about 1* %ours =overnig%t> at 1,$o&. crucible

"lus dry sam"le )eig%t )as noted.

!. T%e sam"les )ere "laced in t%e furnace set to 2,,o& )it% allo)ance for t%e smoke to

esca"e.

. As t%e smoking )as reducing6 t%e furnace tem"erature )as raised by $,o increment

$. Ste" )as re"eated until t%e tem"erature reac%ed !$,o&6 t%en furnace door )as t%en

closed and t%e tem"erature set to $,o&6 and as% for anot%er 1* %ours =overnig%t>.

*. T%e sam"les from t%e furnace )ere allo)ed to cool6 'etted )it% )ater =;2O> and

sufficient ;9O! added to cover t%e as% =ty"ically 2/ ml>. T%is )as t%en covered )it%

a )atc% glass and reflu8 on a %ot "late for about 1 %our6 t%e )atc% glass )as t%en

removed

0. Ste" * )as re"eated until a )%ite as% is obtained.

+. 2/$ ml diluted ;&l )as added and t%e as% dissolved by gently boiling t%e solution6cooled and made u" to t%e a""ro"riate volume )it% ;2O.

3. T%e various elements )ere analysed by flame atomic absor"tion s"ectro"%otometry.

1'1'-'- D!t!$.i*atio* of (a$bo* (o*t!*t

T%e analysis of &arbon content in t%e )aste materials follo)s t%e "rocedure described

belo)

2 g of t%e )aste sam"le )as )eig%ed and mi8ed )it% a tetrao8osul"%ate=vi>acid and

tetrao8o"%os"%ate=v>acid

T%e "re"ared sam"le )as t%en combusted in a furnace at 1!$,o& in an O8ygen/ric%

atmos"%ere )%ere all t%e &arbon content )as converted to &arbon=iv>o8ide =&O2>

31



T%is )as t%en "assed t%roug% scrubber tubes to remove interferences suc% as &%lorine

gas and )ater va"our

T%e &arbon=iv>o8ide "roduced )as t%en collected in Sodium %ydro8ide =9aO;>

solution t%roug% )%ic% its gravimetric analysis )as "erformed.

G$a0i.!t$i( A*asis

1'1'1'1 D!t!$.i*atio* of *it$o"!* (o*t!*t

T%e analysis of 9itrogen content in t%e )aste materials follo)s t%e "rocedure

described belo)

$ g of t%e )aste sam"le )as )eig%ed into a digestion flask

ml of tetrao8osul"%ate=vi>acid )as added and t%e mi8ture )as %eated at !,o& for $

minutes

1$ ml of !,@ %ydrogen (ero8ide solution =; 2O2> )as added t%roug% t%e ca"illary

funnel6 maintaining t%e tem"erature

After 1, minutes6 t%e digestion is com"leted and t%e mi8ture )as carefully )as%ed

)it% distilled )ater

T%e mi8ture )as left to cool before being made u" to 1,, ml by distilled )ater.

,.$ ml ali5uot of t%e digest )as )it%dra)n and mi8ed )it% 2.$ ml of ,.1 gl

"olyvinyl alco%ol solution and 1.,,ml of 9esslerNs reagent.

T%is solution )as t%en analysed under t%e Atomic Absor"tion S"ectrometer

T%e absorbance obtained )as converted into concentration by means of a linear

calibration curve.

1'1'1 Co.2osti*" 2$o(!ss

32



T%e "re"aration of com"ost follo)ed t%e Turned 'indro)s met%od. A )ooden

com"ost bin constructed for good aeration )as "ut in "lace. T%e urban )aste )as manually

se"arated and t%en "iles of mi8ed solid )aste )as used and t%e re5uired o"erating condition

of moisture =,/*,@ ))>6 tem"erature =!2/*,o&> and air )as maintained t%roug%out t%e

com"osting "eriod.

&ollected )aste )as broug%t to t%e laboratory )%ere it )as c%ecked to ensure it is of

sufficient 5uality. t )as t%en be s%redded and "iled into )indro)s6 )%ic% are elongated "iles

s%a"ed for ideal com"osting. (ro"er aeration )as also ensured by suitable mi8ing of t%e

initial material and regular agitation =turning>. ecom"osition continued until t%e )aste %as

been stabili<ed and matured. After )%ic%6 t%e com"ost )as c%ecked for contaminants to

ensure t%at it fulfills t%e "%ysical6 c%emical and biological re5uirements for commercial

com"ost =S4(A6 2,1,>. T%e tem"erature is an im"ortant indicator for identifying t%e "rocess

stage during com"osting. Ty"ically6 t%e tem"erature of com"osting material rises during t%e

initial days and stays at an elevated tem"erature for some days =T%ermo"%ilic conditions i.e.

above $o&> before dro""ing gradually. &onstant turning )as t%erefore ensured to maintain

an o"timum o"erating tem"erature.

Tab! 1'&8 Co.2ositio* of t6! t7o +iff!$!*t 7ast! .i?t#$!s fo$ t6! (o.2osti*" 2$o(!ss

MI@TURE= C& C-

CONSTITUENT

-rban 'aste =kg> 1.$, 2.,,

&o) ung =kg> ,.!, ,.,

Dreen Leaves =kg> 1.$ 1.1

33



1'1'3 P$o(!ss .o*ito$i*" a*+ sa.2i*"

T%e "rocess of com"osting )as monitored )it% great attention. T%e com"ost )as

turned as and )%en re5uired to ensure uniform mi8ing and "ro"er aeration. T%e "; and

tem"erature sam"ling )as done once in every four days. T%e final com"ost sam"le )as

analy<ed for nutrient values6 "%ysical6 c%emical and biological c%aracteristics. T%e collected

sam"les )ere oven dried6 grinded6 fine sieved before analysis. T%e analyses )ere done for a

score of "%ysical and c%emical "arameters like ";6 &9 7atio6 %eavy metals6 4lectrical

conductivity etc =eenambal et al 6 2,,!>.

CHAPTER FOUR

RESULTS AND DISCUSSION

3'& R!s#ts

T%e results obtained in t%e course of t%e researc% )ork ranging from t%e )aste

"re"aration stage6 to t%e "re/c%aracteri<ation of t%e )aste6 t%roug% to t%e com"osting "rocess

alongside "rocess monitoring and sam"ling and finally to t%e "ost/c%aracteri<ation "rocess of

t%e matured com"ost )ere as s%o)n in Tables .1 / .$ and gra"%ically re"resented in

Figures .1 / .0 res"ectively.

34



Table .1 s%o)s t%e c%emical com"osition of t%e )aste materials used for

com"osting6 Table .2 s%o)s t%e nutrient values of com"osite )aste materials before

&om"osting6 Tables .! and . describes t%e (%ysical "ro"erties of t)o different com"ost

materials during t%e com"osting "rocess6 )%ile Table .$ s%o)s t%e nutrient value of t%e final

com"ost. T%e com"arison bet)een t%e &arbon to 9itrogen content of eac% of t%e )aste

material used )ere as re"resented in Figure .16 Figure .2 s%o)s t%e nutrient values of

com"osite )aste before com"osting )%ile t%at for t%e com"ost sam"les is s%o)n in Figure .0.

T%e correlation bet)een t%e Tem"erature6 "; of t%e t)o com"osting materials )it%

time )ere as re"resented in Figures .! and . and Figures .$ and .* res"ectively.

Tab! 3'&8 C6!.i(a (o.2ositio* of 7ast! .at!$ias #s!+ fo$ (o.2osti*"

&%aracteristics -rban )aste &o) dung Dreen leaves

"; *.10 0.23 0.,1

4& =Js cm/1> 12+ !2+ *1

Organic carbon =@> 2!.1, 1,.$, 13.,*

9itrogen =@> ,.,2$ ,.1 2.11

(%os"%orus =@> 1.$2 ,.2, ,.,0

35



(otassium =@> ,.!$ ,.!* 1.*$

&? 9 ratio 32.,, 2$.*1 3.,!

Fe =mgL> 0.33 0.,2 1!.12

Kn =mg kg/1> 2.3! ,.202 ,.1*+

&u =mg kg/1> ,.!$0 ,.2* ,.!,

Tab! 3'-8 N#t$i!*t 0a#!s of (o.2osit! 7ast! b!fo$! (o.2osti*"

Mi?t#$! Ca$bo* Nit$o"!* P6os26o$o#s C=N Ratio

C& 2+.*+ ,.!, ,.1! 3$.*

C- 2*.$, ,.!+ ,.!+ *3.0

Tab! 3'18 Bio<+!"$a+atio* of .i?t#$! C&

Da=

Pa$a.!t!$ & &9 &3 & -- -

A.bi!*t T!.2!$at#$! %o&> !,.,, 20.,, 20.,, 20.,, 2+.,, 2+ .,, 2$.,,

Co.2ost T!.2!$at#$! %o&> 20 .,, .,, !$.,, 2+.,, 2+.,, 2+ .,, 20.,,

2H $.0 *.+3 0.2, 0.* 0.0, 0.+1 0.3,

36



Tota Soi+s %@> $2.,, $,.,, $.,, $1.,, $!.0, $*.,, $3.,,

Tab! 3'38 Bio<+!"$a+atio* of .i?t#$! C-

Da=

Pa$a.!t!$ & &9 &3 & -- -

A.bi!*t T!.2!$at#$! %o&> !,.,, 20.,, 20.,, 20.,, 2+.,, 2+ .,, 2$.,,

Co.2ost T!.2!$at#$! % o&> 2* .,, +.,, !*.,, !,.,, 23.,, 2+ .,, 20.,,

2H $.+ *.03 0.21 0.!, 0.!$ 0.* 0.*$

Tota Soi+s %@> $$.,, +.,, .,, $,.,, $2.,, $*.,, *,.,,

Tab! 3'58 N#t$i!*t 0a#!s of t6! .at#$!+ soi+ #$ba* 7ast! (o.2ost'

Mi?t#$! Ca$bo* Nit$o"!* P6os26o$o#s Potassi#. C=N Ratio 2H Co*+#(ti0it

%s (.<&;

C& 2!. ,.*! ,.1 ,.!$ !0.1 0.3, 13$,

C- 2!.1* ,.0$ ,.!+ ,.$ !,.++ 0.*$ 220,

37



Fi"#$! 3'&8 Ca$bo* to *it$o"!* (o*t!*t (o.2a$iso* of 7ast! .at!$ias #s!+

Fi"#$! 3'-8 N#t$i!*t 0a#!s of (o.2osit! 7ast! b!fo$! (o.2osti*"

38



9 5 &9 &5 -99

5

&9

&5

-9

-5

19

15

39

Time (Days)

T e m p e r a t u r e ( o C )

39



Fi"#$! 3'18 T!.2!$at#$! ti.! (o$$!atio* of sa.2! (& +#$i*" (o.2osti*" 2$o(!ss

9 5 &9 &5 -99

5

&9

&5

-9

-5

19

15

39

35

59

Time (Days)

T e m p e r a t u r e ( o C )

Fi"#$! 3'38 T!.2!$at#$! ti.! (o$$!atio* of sa.2! C- +#$i*" (o.2osti*" 2$o(!ss

40



, $ 1, 1$ 2,,

1

2

!

$

*

0

+

Time (Days)

p H

Fi"#$! 3'58 2H ti.! (o$$!atio* of sa.2! C& +#$i*" (o.2osti*" 2$o(!ss

41



, $ 1, 1$ 2,,

1

2

!

$

*

0

Time Days)

p H

Fi"#$! 3'8 2H ti.! (o$$!atio* of sa.2! C- +#$i*" (o.2osti*" 2$o(!ss

42



Fi"#$! 3'8 N#t$i!*t 0a#!s of t6! .at#$!+ soi+ #$ba* 7ast! (o.2ost'

3'- Dis(#ssio* of R!s#ts

T%e c%emical com"ositions of various organic materials used for "re"aring t%e

com"ost as given in Table .1 describes t%e urban )aste as being slig%tly acidic in nature =";*.10> and )as fairly lo) in 9itrogen =9> =,.,2$@>6 )it% (%os"%orous =(> and (otassium =H>

43



%aving 1.2$@ and ,.!$@ res"ectively. T%e organic carbon =&> )as 2!.1@ )it% a &? 9 ratio

of 32.,,. Dreen leaves )ere ric% in 9 =2.11@> and )as used to su""lement 9itrogen to

initially counter t%e nitrogen de"letion during t%e )aste "re"aration stage. &o) dung )as

used as an additive or inoculum for t%e com"ost treatments. t served mainly as a starter

material for com"osting. t also en%ances t%e decom"osition of cellulosic "lant material and it

%ad ,.1@ 9 )it% a &?9 ratio of 2$.*1

T%e data on t%e nutrient values of t%e matured solid urban )aste com"ost are as given in

Table .$. T%e "; of t%e t)o com"osts =&1 and &2> )ere slig%tly alkaline6 )it% %ig%est ";

being recorded in &1 =0.3,>. T%e results of study concurred )it% t%e observation of

=T%om"son and Troe%6 130+> )%o re"orted t%at t%e munici"al com"ost )as slig%tly alkaline

in nature. T%e 9itrogen content )as %ig%er in &2 =,.0$> due to %ig% 9itrogen content in t%e

initial )aste materials.

T%e com"arison of Tables .2 and .$ s%o)ed t%at t%e %ig%er t%e &arbon6 & content in

t%e com"osting material6 t%e lo)er t%e com"ost 5uality )%ic% is determined by t%e &9

content. 4ffective com"osting t%erefore %as to do )it% t%e a""ro"riate &9 "ro"ortion from

t%e )aste "re"aration stage.

According to ';O =13+3>6 t )as revie)ed t%at effective com"osting takes "lace by

maintaining a tem"erature range of !2/*,o&. T%e rig%t &9 dosage %el"s in attaining t%is

o"timal tem"erature6 t%is could be seen in Tables .! and .. T%e & 1 sam"le )it% an initial

%ig%er &9 content =3$.*> attained a ma8imum com"osting tem"erature of o& )%ile

Sam"le &2 )it% fairly lo) &9 content =*3.0> attained a slig%tly %ig%er com"osting

tem"erature of +o&. T%e Table also s%o)ed increased tendency of a slig%t alkalinity )%ic% is

t%e c%aracteristic "ro"erty of a good com"ost as t%e &9 content reduces. T%e %ig%er

9itrogen content com"osite )aste material &1 s%o)ed a muc% %ig%er com"osting tem"erature

range of 22o& =2*/+o&> com"ared to 10o& =20/o&> of t%e lo)er 9itrogen content

com"osite )aste material &2 =Tables .! and .$>

T%e figures furt%er e8"lained t%e conce"t be%ind t%e com"osting "rocess. Figure .1

s%o)ed t%at t%e 9itrogen deficiency of t%e urban )aste )%ic% is majorly &arbon constituted

could be made u" for by t%e addition of Dreen leaves )%ic% are 9itrogen/ric%6 t%us ensuring

ade5uate 9itrogen nutrient value in t%e com"osite )aste before com"osting as s%o)n in

Figure .2. Figure .! and . s%o)s t%e tem"erature = o&> variation )it% time =ays>. Figure

.! s%o)s t%e stee" decrease in com"osting tem"erature of sam"le &16 )%ic% is 9itrogen

deficient com"ared to a gradual decrease observed in sam"le & 2 of %ig%er initial 9itrogen

44



content as s%o)n in Figure .. A gradual tem"erature decrease is a "rere5uisite to an

effective com"osting "rocess6 as t%e )aste materials are being decom"osed at a muc%

elevated tem"erature for a longer duration of time.

&onclusively6 t%e enric%ment of com"ost )it% additives increased t%e decom"osition

rate6 )%ic% may be due to availability of essential nutrients for t%e increased biological

activity. From t%is investigation it can be stated t%at enric%ment of urban )aste )it% co)

dung6 organic nitrogen6 microbial culture and micronutrients resulted in value added com"ost.

CHAPTER FIVE

CONCLUSION AND RECOMMENDATIONS

5'& Co*(#sio*

45



T%e 48"erimental study of biodegradation of -rban Solid 'astes %as establis%ed t%e

follo)ing significant details.

T%e "rocess of com"osting is significantly affected by constituents like &9 ratio6

moisture content6 ";6 electrical conductivity6 total solids and tem"erature. From t%e analysis of &9 ratio6 t%ere is a noticeable reduction bet)een t%e t)o

com"ost sam"les &1 =;ig% &arbon content> and &2 =Lo) &arbon content>6 )%ic%

im"lies t%at addition of e8cessive carbon content6 is not encouraged.

T%e results of t%e study clearly indicated t%at t%e Biodegradation of solid urban

)astes can transform garbage to enric%ed com"osts. T%is is an im"ortant message of "ractical

significance if ado"ted by urban farmers. T%ereby t%e soil %ealt% and in turn t%e "roductivity

of soil can be maintained for future agriculture. T%is "oint gains im"ortance given t%e fact

t%at t%e 5uantum of cultivable land is fast d)indling es"ecially in t%e develo"ing countries.

T%erefore t%e essence of t%e "resent study is t%at t%e urban farmers s%ould be motivated to

"ractice urban )aste recycling t%roug% bioremedial measures.

5'- R!(o..!*+atio*s

As a result of %a"%a<ard manner of dum"ing of refuse )%ic% is "osing a serious

environmental t%reat to t%e environment6 an effective system of solid )aste management is

t%e need of t%e %our and s%ould be environmentally and economically sustainable.

&om"osting )%ic% is t%e sim"lest yet best "rocess for solid )aste management %as gone a

long )ay in ma8imising environmentally sound )aste reuse and recycling

;o)ever6 t%e follo)ing recommendations )ere t%ereby made to)ards )aste

minimi<ation6 ma8imising environmentally sound )aste reuse and recycling as )ell as

"romoting environmentally sound )aste dis"osal?

uc% attention s%ould be "laced on biological "rocess re5uirements during

com"osting "rocesses

T%ere s%ould be furt%er investigation on t%e emerging com"osting "rocesses suc% as

t%e vermiculture and t%e use of effective micro/organisms to accelerate t%e

com"osting "rocess

T%e standards and norms for %andling munici"al solid )astes )%ic% %ad reduced

occu"ational %ealt% and environmental im"acts substantially in industriali<ed

countries s%ould be ado"ted by t%e develo"ing countries to tackle bot% t%e

environmental and t%e agricultural "roblems

46



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Association6 &oventry6 -H.

47



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Biodegradation of Urban Solid Waste