by Frank Schweizer

Frank Schweizer is an engineer specializing in water resources and waste handling technologyal.

In the Ghanaian capital Accra an attempt is being made to get the waste disposal problem under control with a special infrastructure project, which has been running since 1985. This project is being supported by the Deutsche Gesellschaft für Technische Zusammenarbeit (GTZ) GmbH and the Kreditanstalt fur Wiederaufbau (KfW). A variety of measures are being implemented to achieve this goal, one of them being decentralized smallscale composting of domestic waste.

It was planned to compost the waste at three collection points in lower-income districts of the city. This presupposed the existence in these districts of NGOs which were interested in waste disposal and would actively support the project. As payment for their work they would receive the income from sales of the compost. It was assumed that the compost would sell well, be cause the soils in the vicinity of Accra are very poor in nutrients and food production is correspondingly low.

Small-scale composting was planned not only as a means of reusing the organic matter, but also of reducing the costs of waste disposal.In addition, it was assumed that a decentralized system of this kind would be less susceptible to disruptions caused by shortages of fuel or spare parts, or even strikes, for example.

Problems finding sites

First, to avoid any "false starts", an experimental site was laid out for demonstrating small-scale composting and for training the groups interested in it. As it was not expected at the time that voluntary helpers would be available, personnel from the city's Waste Management Department (WMD) were employed.

At the same time, the project established links with the NGOs in question and a start was made on finding sites for the three collection points. To ensure that the sites would be accepted and that the in habitants would cooperate, opinionleaders in the various districts were approached and talks held with the NGOs.

The most important criterion governing the choice of location was the size of the respective sites. The difficulty here lay in the fact that it was not known how much space would in fact be needed for the waste from a particular district.

At the time of the first site inspections it was still uncertain how long the waste delivered to the sites would stay there, i. e. from the day it was delivered until the day the finished compost was sold.

The experience gathered at the WMD training site and during the search for other sites was taken into account continously when considering where to establish the three planned sites. Even so, the sites which ultimately had to be accepted all had certain shortcomings:

• one was too small;

• one was rather too far away from the neighbourhood it served;

• two of the three sites had public toilets, but these were firmly in the control of the CDRs (Committees for the Defence of the Revolution). These CDRs showed little inclination to look after the waste as well because there was no money to be earned by doing so.

Sorting

At each of the composting sites a "bollerman" supervised the deliveries of household waste from early morning onwards, making sure that the compost heaps were properly stacked. In the course of supervising the work he retrieved re-usable items from the wastebottles, tins, and plantain shells which he could sell as goat fodder.

As a rule the compost heaps were prepared in weekly batches, among other things to facilitate checking of the composting process. When the heap had passed its maximum temperature it was turned over for the first time, principally to aerate the decomposed matter. In doing so, matter that could not be composted was removed with a coarse screen or by hand.

Intensive contact between the organic substances was hindered in particular by plastic foil and milk tins. However, turning the compost heap over also caused it to dry out, which was a disadvantage for the next phase of the decomposition process. The water thus lost was made up by adding waste water from a nearby ditch or from a sanitary sewage disposal truck. Rainfall in the area was scarce, and only enhanced the composting process on a few days per year. In the relatively long dry periods the surfaces of the heaps tended to dry out and catch fire. This severely impaired further decomposition.

The heaps were generally turned over a second time, and more inorganic matter was removed from them when this was done.

The third step was screening. This was done with a fine-mesh sieve or a screening drum. The simple mesh sieves, with wooden frames and wire mesh of various sizes, were made locally. If inorganic matter had already been removed a smaller mesh was used, but under no circumstances was a mesh larger than 5 cm permitted.

The first screening drums were obtained from Bühler-MIAG, of Braunschweig (FRG). They are so simple, however, that they can easily be replicated by local mechanics. Also, very little power is needed to operate them - one manpower is enough! Incidentally, the most popular job in the composting team was that of "drum driver".

The experiments with the screening drum showed that it resulted in a higher compost yield, and that it also improved the quality of the compost.

As an experiment, the screening drums were also used to sort the domestic waste as soon as it was delivered. Following this preliminary separation the fine waste was then composted separately from the coarse waste, which facilitated further processing.

Jobs for the jobless

It turned out that NGOs were not in a position to provide labour reliably, so the workers were paid regular wages out of project funds instead.

Even the workers delegated by the WMD expected extra wages for the dirty and often dusty work they did. A number of "food for work" solutions were also tried out.

However, employing jobless people proved to be the most economical solution. They were assigned a certain work quota and a meal allowance, which was paid as soon as the quota was fulfilled. At the end of the month they received a wage equivalent to the statutory minimum. On these terms satisfactory work could be expected. After all, the income was regular and assured, and since the job only took up the mornings it was still possible for the workers to do other casual jobs in the afternoons.

Compost utilization

Although the soils in Accra are low in nutrients and humus, it proved difficult to sell compost to the target group, the low- and medium-income groups, because the indigenous population are traditionally fishermen. Kitchen gardens are practically unknown.

The benefits of the compost as a means of improving the soil was repeatedly stressed in the media. Most of the compost was sold to farmers, who ordered it by the containerload. It was also bought by local and foreign garden-lovers (usually in 7 m³containers). And the repeated pilfering of the compost was, in the final analysis, also a positive sign.

Concern regarding the hygienic aspect of compost production was voiced in particular by people living next to the composting sites. They also found the smell a nuisance, though in fact the latrines were to some extent responsible for this. The compost heaps only caused an odour nuisance when the heaps were turned over and anaerobic zones were exposed. However, this was more a sign of a "malfunction", which should not in fact occur.

Compost hygiene was assured by constantly checking the temperature of the heap, which reached a maximum of 70-75°C. All users of the compost were informed that it was hygienic. In any event, as compared to the faecal matter, which was disposed of poorly and constituted a serious health hazard, the compost could certainly be described as harmless.

Further reading

A project in the Kathmandu valley in Nepal provides an example of successful waste management with involvement of the population. GTZ has now published the experience gathered on this project in its series of special publications: SP231-Abfallwirtschaft mit Bevolkerungsbeteiligung. Ein Beispiel aus Nepal/Solid Waste Management with People's Participation. An Example in Nepal (ISBN 3-88085389-4). The bilingual publication (German and English) is 82 pages long and costs DM 32.00. It may be ordered from TZ-Verlagsgesellschaft mbH, Postfach 1 164, 6101 Roßdorf, FRG.

Abstract

In Accra, the capital of Ghana, decentralized, small-scale composting of domestic waste has been introduced to help ease the waste situation. The project has been running since 1985, with three collection points in low-income districts. As soon as it arrives at the collection points the waste is pre-sorted-immediately re-usable material is separated from organic waste. More solid waste is removed after the compost heap has been turned over for the first time. The waste is sorted a further two times during the composting process. The compost is used mainly by farmers.

Résumé

Le compostage á petite échelle et décentralisé des ordures ménagères doit contribuer a réduire le problème des ordures dans la capitale du Ghana, Accra. Ce projet est en place depuis 1985 a trots endroits des quartiers populeux. Des leur arrivée aux points de collecte, les ordures vent immédiatement triées, d'une part /es matières recyclables, d'autre part les matières organiques. Apres la première réalisation des frais on effectue un deuxième triage. Puis une troisième et une quatrième fois au cours du processus de compostage. Le compost ainsi obtenu est utilise essentiellement dans l'agriculture.

Extracto

El compostage descentralizado en peque a escala de las basuras domiciliarias debe contribuir a paliar la grave situación de su eliminación en la capital de Ghana, Accra. Este proyecto se lleva a cabo desde 1985 en tres puntos de recogida en los barrios mas pobres de la ciudad. Ya en el momento de la descarga en los puntos de recogida tiene lugar una primera clasificación aproximada en materiales aprovechables inmediatamente y componentes orgánicos. Después del primer trasvase del siloparva de compostage se rea/iza una segunda clasifcación. Durante las siguientes operaciones del proceso de compostage se realizan otras dos clasificaciones. El compost elaborado se utiliza rincipalmente en la agricultura.