econf2_backgroundpaper_drechsel

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Drechsel, Cofie, Vazquez, Danso

Technology development for municipal organic waste recycling for urban and

peri-urban agriculture - A holistic approach

Pay Drechsel, Olufunke Cofie, icardo !"#$ue# and %eorge Danso

UPA Project, International Water Management Institute, Ghana Office,

c/o KNUST Kumasi, Ghana

&ntroduction

One of the challenges of rapid urbanization is how to make sufficient food available on a

sustainable basis for the increasing urban population. According to projection made by United

Nations, Africas population will almost triple by !"#" and this will be primarily in the urban and

peri$urban areas. %n &est Africa, it has been estimated that within !" years, two out of three &est

Africans will live in urban centres supported by rural$urban migration. 'he related increase in

urban food demand is giving way to intensive food production systems in and around cities often

specialized on perishable crops or poultry, and also to e(port$oriented agriculture using the

advantage of urban infrastructure )airports, agro$industry*. 'hese types of agriculture re+uire large

amount of inputs, including plant nutrients. Once the food is consumed or processed in the city,

related market and household refuse as well as human e(creta contribute to urban pollution due to

the common lack of ade+uate sanitation services or end in landfills. %n both cases large amounts of

nutrients are simply wasted )-ig. *. 'his situation calls for an analysis of options for municipal

organic waste recycling for the benefit of agricultural and environmental sustainability in the rural$

urban continuum )Allison et al,//0, 1'231-A ///, 4rechsel and 5unze, !""*.

'ackground

A related international workshop on )peri*$urban agriculture and nutrient recycling was organised

for Africa in /// by -AO and %678A9, where knowledge gaps in waste recycling were analysed

and recommendations developed. 9any scientists, farmers and decision makers emphasized the

need for more information on viable and acceptable options for the recycling of municipal and

agro$industrial waste, especially for farmers in urban and peri$urban areas )4rechsel and 5unze,

!""*. 7ubse+uently, the :anadian donor %48: agreed to co$sponsor a corresponding project in

three agro$ecological zones of &est Africa addressing variations in organic waste generation,

+uality and availability. 'he project is an attempt to develop recycling strategies that should result

in closing the rural$urban nutrient cycle as well as preserving the +uality of the urban environment


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by reducing the )pollution effects of* waste accumulation. %t aims at decision support on viable,

environmental friendly and location$specific composting technologies that fit into the )peri*urban

conte(t and match the re+uirement and ability to pay of different )peri$*urban farming systems and

other potential users. Our understanding of technology development has to go therefore farbeyond the technical part of a compost station and can only be addressed through a more holistic

multidisciplinary situation and stakeholder analysis )977A*. 'he analysis and its different

components are described for the first time in this paper.

-ig . Urban areas as nutrient sinks )4rechsel et al,///; modified*

Approach()ethodology

Although municipal decision$makers are in need of city$specific recommendations, the

methodological approach used for the 977A is generic. %n every city conte(t the 977A involves

municipal authorities, especially the waste management departments, farmers, researchers, private

sector, project staff, market sellers etc. %n total, we are currently collaborating on our project with

about twelve different university departments of three national and two


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'he 977A approach being used involves the application of a close!"loo#concept )-ig. !* to

solve the problem of nutrient mining in food production areas and environmental pollution in

consumption areas. 'his means studying different segments of the loop which are=

. 'he supply of organic waste )+uality, +uantity, availability, etc.*

!. 'he demand for waste compost )who, where, how much, perception, price*

>. 'he process of waste collection and compostingincluding the determination of optimal

number, capacity, and location of compost stations per city and their economic viability

?. @egal, institutional and communal factors affecting the set$up of compost stations.

-ig. !. 7egments of the nutrient recycling loop.

&astecollection,transport and

composting(Process)

&aste re$

use in

production

areas

(Demand)

&aste generation in

consumption areas

(Supply)

@egal, institutional andcommunal settings


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-or each of these segments, we tried to answer pertinent +uestions as summarized in -ig. > and

described below.

*+ The supply of organic waste'he supply studies focus on the various types, amounts, +uality, present and potential uses,

current value and availability of organic municipal waste for composting. Only major sources

)markets, households, agro$industry, abattoirs, timber mills, public toilet systems, etc.* are

considered although minor ones )e.g. bone meal producers* can become important additives.

'he key +uestion which has to be addressed in the waste supplyconte(t is= Wherewithin the

rural$urban zone is whichamount of waste of whatkind of +uality when de facto availale for

composting )cf. -ig.>*. 'his information we mostly ac+uire via=

Secondary data on the amount, location and disposal of municipal waste from the waste

management departments, N1Os or projects, and if available on its +uality.

!uestionnaire surveysamong organic waste producers using randomly selected sources

from a stratified total per product. &e address breweries, wood3food3 fruit processing

industries, poultry farms, etc. to +uantify the amount, kind and fate of waste generated in

different periods of the year.

"aoratory analysisof the amount of nutrients in the waste as well as of potential

contaminants including heavy metals and


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.upply Demand

Processing

&nstitutional, legal and

communal framework

&hat organic wastes are produced

&here are they produced3disposed

%s the waste treated Bow

&hat are the current disposal costs and3orenvironmental3social e(ternalities

&hat is the +uality )potential soil fertilityvalue* of the material and is the material

contaminated or phytoto(ic

Are there seasonal variations in itsavailability or +uality

&ho owns the waste

&hat is the current use of the waste)Are there competing uses in comparison with

composting, for e(ample= as untreatedfertilizer, livestock feed, fuel, or recycled for

other manufacture or use*&hat is the related market demand and

economic waste value

Bow much3which waste is unused and defacto available for composting

Are there waste use3collection constraintsrelated to health, handling, safety and

environment which could be addressed

Are there constraints3support related to officialplans, programmes, regulations, by$laws

or policies and how could we make

best use of them

Are there constraints to the set$up of compoststations related to land availability

&hat are the official attitudes andrecommendations e.g. at institutional3

municipal3communal level

:ould inter3intra$sectoral cooperations beimproved )platform building*

Bow can local key groups3stakeholders become

involved )community based stations*

&hat are the implication of composting for thesegroups and what kind of commitment3input

would be necessary from them

&hat management settings and instruments)9C. Duestions to be answered in the 977A for an appropriate establishment of municipal compost

stations for )peri*urban agriculture and other uses )modified from Barris et al., !""*

%s composting the most appropriate method totreat the waste for soil improvement

&hat should be the capacity of the compostproduction )comparing supply and

demand*

&hich technologies appear appropriate)which technologies have been applied

successfully in the subregion*

Are these technologies locally available

%s appropriate maintenance of thesetechnologies likely3possible

Are there technical waste$use constraintsrelated to separation3collection3transport

and how could we address them

&hat is the transport capacity of the waste

collectors

&hat is the public perception towards sourceseparation or composting

&hat is the location of the waste sources and

of the potential compost users

Bow many compost stations are needed to

keep transport costs low

&hat would be the total establishment and

running costs

&hich )economic* benefits for the society atlarge are possible

:an these justify municipal subsidies

&hat is the best mi(ture of waste fromdifferent sources

Bow to realize co$composting


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/+ The demand for 0waste1 compost

'he demand assessment involves first of all the characterization of all potential clients under

consideration of increasing compost transport costs with increasing distance from the compost

stations. 'his part of the 977A has to go beyond agricultural production. A major andfinancially powerful demand, especially in rapidly e(panding cities, comes from landscape

design )horticulturists, parks and gardens* or real estate developers in general!. 'he demand

analysis has to consider socio$cultural aspects, production economics, attitudes3perception of

the use of waste compost )with or without nightsoilE*, actual demand and its likely

development, as well as clients ability and willingness to pay. %t also should include the

analysis of consumers market for food produced from compost. 5ey +uestions are again

summarized in -ig. >. 9ethods used to answer these include=

#dentificationof the different UFA farming systems, estate developers, garden operators,

landscape designers, if possible with and without compost e(perience.

'his is followed by stratification)in terms of company or farm size, crops grown, etc* of

the various potential compost buyers for randomly selected individuals as representative

samples for each group.

Structured questionnairesconsisting of both open$ended and closed +uestions are used.

'he open +uestions give the farmers3real estate developers etc. chance to e(press theirviews about the use of compost and other factors that will affect their willingness to pay

for it )e.g. fertilizer availability and costs, tenure arrangements etc.*. 8epeated pre$testing

of +uestionnaires reveals faults and allow for improvement in preparation for the actual

survey.

-or the assessment of the attitude and perception of farmers on the use of composted

organic waste, we use individual interviewsfollowed byfocus $roup discussion)-14*.

'he latter comprises groups of G$" farmers )usually differentiated according to gender*,

which still allows in$depth interviews and personal feedback in comparison with village

meetings )common in our region*. 'he -14 usually e(clude community opinion leaders

that could prevent other members to come out with their own ideas, problems and

suggestions. 'he -14 is an informal F8A tool. Another F8A tool used in our studies is

matri rankingto compare advantages and disadvantages of different )demonstrated*

nutrient sources )cf. 4rechsel et al,!""* 8eal estate developers are only interviewed

individually.

!%n Accra, for e(ample, real estate developers show strong interest in large$scale and regular compost production.


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-or the willingness to pay )&'F* for compost, contin$ent valuationmethod is used. 'his

involves direct +uestioning of individuals in a survey to determine if and how much they

are willing to pay for waste compost. 'his results in a bidding game, which helps to

determine the ma(imum amount the consumers are willing to pay for the compost. )Nunanet al, !"""*. %t is assumed that certain variable like wealth, age, se(, e(perience

with3without compost, level of education etc. will have influence on the individual

willingness to pay. 'herefore, the multivariate probit modelis used to analyse the impact

of these variables on the &'F, as compared to a regression analysis.

'o give the &'F analysis a reality check, the different UFA farming systems are analysed

for their farm finances and de facto ability$to$pay for further inputs.

2+ The process of waste collection and composting

'his part of the 977A compares supply and demand to estimate the re+uired3possible capacity of

the compost production to decide about an appropriate technical approach and depending on the

locations of supply and demand on the number of compost stations under consideration of

transport costs. 'he methods used include=

'he development of different scenarios using conservative vs. optimistic )supply,

demand* estimates, by using for e(ample the software tool on the economicfeasibility of compost stationsdeveloped by 1'231-A )///*. 7cenarios have to

address different levels of technical sophistication and the actual and potential )but

realistic* transport capacity of the city$specific waste collection system. Not all waste

can be collected. A conservative scenario would build on the actual collection pattern

and transport capacity and only re+uire different disposal sites )H the compost

station)s** which might even be located at the landfill to minimize e(tra transport costs.

!isitto related compost plants within the country and in neighbouring countries to

observe, study, e(change and obtain information on the technical3operational and

economic aspects of composting )cf. -ig > process part for typical +uestions*. %n this

regard, we studied different composting plants which differ in scale and level of

sophistication to allow us determine and recommend the most appropriate technology

of composting facility for each city minimizing system cost and maintenance

re+uirements as much as possible.

3ield testingof different options and combinations of organic waste composting and

co$composting with nightsoil to give a safe )assured through laboratory tests* and rich


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)assured through fertilization trials* product that is acceptable and safe for the farmer

and consumer.

%n case of high compost demand the possibility of organic waste separation at the

household level )source separation* should be e(plored. &e did so throughhousehold surveyswith +uestionnaire distributed to !#"" urban families in

collaboration with about ># junior secondary schools )I77* covering all parts of our

cities. &e e(plained advantages of waste composting and asked the households for

their perception of waste separation as well as on the incentives necessary to get source

separation realized. 'he obtained information will provide a basis for further awareness

campaigns and any pilot project.

'o / Consumption analysis

'he above mentioned +uestionnaire surveys in !#"" households was also used to study over

one week food purchases and consumption in our cities as contribution to the 9aterial -lu(

Analysis mentioned in 6o( . 'he household information was used as comparison to the data

provided through our market surveys. 6oth surveys addressed all major crops and food items

and were carried out in two different seasons reflecting contrasting variation in food

availability within a year. 'here was also a supplementary survey on street food consumption.

A range of information has been collected from the households allowing us to differentiate

consumption patters between cities, gender, age, income level, religion and e.g. cultural3tribal

background.

4+ Analysis of legal, institutional and communal settings

'his part of the 977A targets the legal, institutional and administrative conte(t within which

composting and use of compost could be feasible. %t involves an assessment of environmental and

sanitation by$laws and policies as well as public awareness and the perception of authorities and

other interest groups, especially :6Os and N1Os to work with or support organic waste

recycling.

9ethods used include

7tudy of the legal framework, sanitation policies, medium term plans, project plans and

other documents )literature reviewand interview of key persons*


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5uestionnairesfor surveying perceptions and anticipated problems of different

stakeholders and related openinterviews with municipal authorities, interest groups

)N1Os, :6Os, projects, &orld 6ank, etc.* and private investors.

3ocus group discussionswith community leaders and community members on

environmental issues, waste management, and organic waste recycling discussing possible

scenarios of community$based compost station )perception, options, by$laws, realization

potential, etc.*.

6pected esults

. :omprehensive decision support for municipal authorities on realistic options for organic

waste recycling in their city$conte(t.

!. Faving the way for the production of alternative fertilizer )soil ameliorant* for the use of urban

and peri$urban farmers.

>. :apacity building at different levels, e.g. through the involvement of currently G" students.

?. 8esults on rural$urban food flows, consumption patterns, waste generation, compost demand ,

recycling options etc. from cities in different agro$ecological zones in &est Africa allowing

data e(trapolation to other cities.

esources re$uired for the study

7uman resourcesAll described surveys etc. are being carried out through students in the

frame of their 6.7c. and 9.7c. dissertations. 'his keeps personal costs low. Bowever, a major

re+uirement is the availability of students3supervisors from various disciplines )planning, agro$

economics, geography, environment, etc.*.

Operational costsAll described surveys etc. are being carried out through local students.

'his kept operational costs low. @ocal supervision was facilitated through the employment of

project assistants located in each of the project cities.

6$uipment costsNo special e+uipment re+uired as the 977A is only providing decision

support not actually setting up the compost stations. -or e(cellent communication between the

cities and our coordination office, we supported local email access. 'o facilitate data

processing, we supported the universities with personal computers.

.oftware re$uirements-or data analysis 6cel and .P..are being used. -or the 9-A

S#%&'(

was introduced by our 7wiss partners


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7%96OJ considers flows of food, fodder and wood and allows to assess the amount of

nutrients that could be reintroduced into the nutrient cycle via solid waste and e(creta co$

composting. &ith the help of 9-A, major nutrient flu(es between urban, peri$urban and rural

agriculture can be +uantified )-ig. ?*. -inally, 1%7 software )Arc!iew* is being used tovisualized on city maps e.g. the location of major waste sources as well as of different clients

)e.g. urban farming systems* to illustrate distances and to suggest possible locations of

compost stations.

Time re$uirements4epending on number of cities and +uantity and +uality of students and

coordination, the whole study can be carried out in ! years )for three cities*, especially if the

9-A is e(cluded.

eferences

Adam, 9.1. !"". 4efinition and boundaries of the peri$urban interface $ patterns in the

patchwork. %n= 4rechsel, F. and 4. 5unze )eds.* &aste :omposting for Urban and Feri$

urban Agriculture $ :losing the rural$urban nutrient cycle in sub$7aharan Africa.

%&9%3-AO3:A6%= &allingford )in press*

Allison, 9., Barris, F.I.:., Bofny$:ollins, A.B. and 7tephens, &. //0. A review of the use of

urban waste in peri$urban interface production systems. 'he Benry 4oubleday 8esearch

Association, :oventry, U5. >?p.

6elevi, B., @eitzinger, :., 6inder, :., 9ontangero, A., 7trauss, 9. and :. 2urbrKgg. !""".

9aterial -low Analysis. A Flanning 'ool for Organic &aste 9anagement in 5umasi,

1hana. Bealthy :ities :onference, to be held in Accra, 1hana, in !"" )submitted*.

4rechsel, F. and 4. 5unze )


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4rechsel, F., Duansah, :. and 7. Asante$9ensah. !"". 'ools for the assessment of farmers

perception of organic wastes as nutrient source. %n= 4rechsel, F. and 4. 5unze )eds.* &aste

:omposting for Urban and Feri$urban Agriculture $ :losing the rural$urban nutrient cycle in

sub$7aharan Africa. %&9%3-AO3:A6%= &allingford )in press*

1'231-A ///. Utilization of organic waste in )peri$*urban centres. 7upraregional 7ectoral

Froject. 1'2,

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