disposal of latrine waste: is biogas technology the answer?

7/29/2019 Disposal of Latrine Waste: is Biogas Technology the Answer?

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Disposal of Latrine Waste: is

Biogas Technology the Answer?

By Daniel Buxton

Loughborough University


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Contents

Disposal issues and solutions Biogas

Benefits and Uses

Possible Digesters

Assessing the technology Past successes

Technological

Social and Cultural issues

Economic Argument Regulation and Management

Conclusions


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Disposal IssuesFSM cycle


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Disposal Options

Onsite Burial

Discharge into:

Sewer

Centralised Treatment Works

Composting

Biogas


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BiogasBenefits and Uses

Benefits

Reduces the amount of wood fuel required

Produces fertilizer

Decreases pathogen content

Uses Cooking, lighting and heating etc

Application 1 cubic metre biogas equivalent

Lighting Equal to 60 100 watt bulb for 6 hours

Cooking Can cook 3 meals for a family of 5 6

Fuel Replacement 0.7kg of petrol

Shaft Power Can run a one horse power motor for 2 hours

Electricity generation Can generate 1.25 kilowatt hours of electricity


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Mixing

tankGas outlet pipe

Plinth level

Outlet tank cover

Displacement Chamber

Outlet

Tank

Slurry

Discharge

Hole

DigesterOutlet gate

Gas storage Area

Inlet Pipe

Foundation

Initial slurr

BiogasPossible digesters


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Assessing the TechnologyPast

Successes Insitu household biogas system

Asia, Latin America and

Southern Africa

Institutional in schools, prisons,

hospitals etcEthiopia, India

Community/parish level (peri-urban)Rwanda


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Assessing the Technology

Technological Benefits of community biogas systems

Economies of Scale

Surplus gas for income generating activities

More efficient operation as the plant usually has a full timeoperator

Equity consideration, people can work in return for gas Barriers -What happens in the pit

Accumulation

Aerobic Degradation

Anaerobic Degradation

Physical mass transfer Leaching/draining

Digestion of macro-invertebrates

The sludge will be partially degraded upon

emptying, decreasing methane yield


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Assessing the TechnologySocial

and Cultural Issues Negative attitudes towards change

Religious issues

Health issues

Lack of real demand


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Economic Argument High initial cost

Increase in frequency of emptying

Scheme should be marketed as win-win


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Regulation and Management Necessary knowledge and skills must be

available at a local level

Policies must be effective and needs

responsiveframeworks to identifywaste as a resource not a burden

Implementation starts at household level

community involvement Government policies should enable not

prescribe


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Conclusions

Cultural and institutional issues often decidingfactor

However, choice of technology and

implementation method have social, economicand policy implications so engineers looking to

pilot such a scheme must be aware of all these

factors effecting success


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Any Questions????

disposal of latrine waste: is biogas technology the answer?

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