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Sawdust utilization; experiences in Mutare, Zimbabwe


Table of Contents

Boiling Point
Front cover of Boiling Point issue 39
Issue 39 (1997) Using biomass residues for energy
ArticleSawdust utilization; experiences in Mutare, Zimbabwe
AuthorMr Chinyowa


Expériences d'utilisation de déchets de scierie a Mutare, Zimbabwe.

Le développement de l'industrie du bois dans cette région a engendré des problèmes en matière de gestion de déchets tant pour les municipalités que pour les industriels. L'auteur examine les avantages et les problèmes du projet de production de briquettes à partir des déchets de scieries. L'information recueillie semble indiquer que le produit est accueilli favorablement et la demande peut augmenter si des prix compétitifs sont offerts. Cependant un des problèmes majeurs réside dans l'absence de coordination entre les différents acteurs notamment les industriels, ONG, usagers et municipalité.

[top] [end]Introduction

Mutare is predominantly a timber-based industrial town, catering for all the timber plantations in the eastern Highlands of Zimbabwe. It is estimated that the timber industry accounts for over 80% of all Mutare's industrial activities. Over the past three to four years there has been a boom in the timber industry with some companies recording growth close to 400%. The expansion within the timber industry was not matched by the corresponding waste management plan. Industry found itself with large stockpiles of sawdust, shavings, offcuts and bark, which were either awaiting incineration or transportation.

[top] [end]Problems with wood waste

  • Dust nuisance
  • Accumulation on premises because of poor housekeeping
  • Transportation
  • Increased smoke complaints caused by overloading of incinerators
  • Land-fill problems; wastes too bulky, resulting in rapid filling of dumps
  • Fire hazards

[top] [end]Mutare City Council's position

Council officials reacted by encouraging industry to cart all their waste to the municipal dump. Having originally accepted responsibility, councils were faced with a waste problem. In an attempt to get rid of this problem, the council attempted to be highhanded, imposing a blanket ban on the dumping of all wood-related waste at the municipal refuse dump. The response from industry was obvious. Alternative dump sites outside the municipal areas were found in outlying areas, and the wood waste started to find its way to destinations as far as 15 km from the source. Financial costs and negative publicity made companies start to look for new options. Industry needed to look at wood waste as a potential raw material for energy rather than as a liability.

[top] [end]Briquetting

The Biomass Users Network (BUN), the Forestry Commission (FC) and Intermediate Technology Development Group (ITDG) are involved in a sawdust briquetting pilot project. The project was set up as follows:

The target groups were institutions and small-scale entrepreneurs currently depending on wood fuel, charcoal and coal for energy. Trials have been mainly conducted by public institutions such as the army, prison service, police and schools. About seven and a half tonnes of sawdust briquettes were delivered or collected by users, primarily for cooking purposes.

[top] [end]Feedback from users

[top] [end]Advantages

  • Compatibility with wood and charcoal stoves, hence no need to invest in another stove
  • User friendly i.e. clean to handle
  • Product resembles wood and so it is acceptable culturally and socially

[top] [end]Problems

  • Storage at both production and users' sites; product collapses when wet
  • Transporting briquettes for distribution; tendency to disintegrate during transportation
  • Difficulty of igniting the briquettes initially
  • High quantity of ash
  • Briquettes burn faster than wood, so more need to be used
  • Use of briquettes still not considered the norm; if the person in charge is off-duty, personnel tend to revert to using firewood or coal
  • Briquetting machine is not yet working at full capacity, resulting in a shortage of the product

[top] [end]Factors being addressed at present

  • Plant and/or equipment modifications
  • Product shelf life
  • Supply guarantee
  • Price competitiveness

[top] [end]Conclusions

As a way forward, it is important to bring all players, e.g. the timber industry, local authorities, NGOs to look closely at the problems and come up with solutions associated with wood waste.

Preliminary information suggests that the product is usable and people may buy it if it is competitively priced. Producers should invest in market research and development in order to commercialize the project. There might be need to invest in driers to enable continuous production. A model to demonstrate the use of briquettes might help to motivate prospective customers.

[top] [end]Contents: Boiling Point 39: Using biomass residues for energy

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Using biomass residues for energy - Briquetting agricultural residues - Briquetting of biomass residues in India using a Beehive Pyrolyser and briquetting machine - Briquettes in Sudan - An introduction to the reality of household fuel needs in Bangladesh - Sawdust utilization - experiences in Mutare, Zimbabwe - Biomass resources use in tea plantations in Sri Lanka - Development of cooking-cum-heating stoves in the upland of North Vietnam - Fuelwood as a source of urban household energy in Ethiopia - A supply perspective - Community-managed micro-hydro projects in Northern Pakistan - The low wattage cooker - the Nepal experience - Routes for commercialization of rural stoves - Thermally efficient improved wood-burning metal cooking stove - The Women and Energy Project for stove dissemination in Kenya - crossing the sustainability bridge

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