Sewage treatment with soil-and-plant filters

Report from the Sierra de Cordoba, Argentina by Henning Schiller

In Argentina's Cordoba Province, a pilot programme is currently underway to adapt soil-and-plant filters for sewage treatment in semi-arid climatic zones. On the basis of preliminary results the programme, known as the Sistema Radicular de Depuracion de Aguas Residuales (Root-Zone Sewage Treatment System), looks promising. Environmental NGOs have played a key role in the PR work needed to implement this innovative sewage treatment system.

For a variety of reasons, the Sierras in Cordoba Province, and especially the catchment area of the Lago San Roque lake, as semi-arid hilly region, are subject to competitive utilization. The pleasant climate and the proximity of the city of Cordoba, with its 1.3 million inhabitants, have made the Sierras a popular holiday area. The region is thus characterized by scattered development, with weekend homes, holiday and tourist complexes. The Sierras are Argentina's second-largest tourist centre, receiving more than two million tourists per season.

The Sierras are also the only water reservoir for the city of Cordoba and the 120,000 people who live permanently in the catchment area of the manmade lake. But they are also an extensive pasturage area, where brushfires break out regularly every year, resulting in erosion and degradation of the soil; and an area of uncontrolled deforestation. The re-afforrestation measures being undertaken are either inadequate or inappropriate (conifers or Eucalyptus varieties).

Sewage treatment in this region is either inadequate or non-existent: at present the sewage flows into the lake. Since it has undergone little or no treatment, processing of the raw water from the lake is both an economic and a health problem. Cordoba has to spend some US$ 30,000 a day on flocculants to remove algae from the water. And even though the water is chlorinated, the city cannot guarantee that it is perfectly clean and safe to drink. The water authority recommends boiling the water for ten minutes before drinking it.

The solution so far proposed, for conventinal sewage disposal by means of sewers and a sewage treatment plant, are beset by numerous problems, including insufficient municipal funds due to ineffective taxation systems; construction problems, due to steep gradients and rocky ground; biological limitations on the cleaning capacity of available technolgy as regards the elimination of nutrients, in particular phosphates and nitrates; problems with the maintenance and operation of existing conventional sewage treatment plants due to a shortage of trained personnel;
economic limitations on the length of main sewers in scattered settlements.

In Cordoba, increasing awareness of the constant threat to the drinking water supply has led various NGO's, neighbourhood organizations (gruos vecinales), trade unions and school groups to put pressure on the provincial government via campaigns, press coverage and projects.

Key criteria for any viable alternative to a conventional sewage disposal system would include decentralization, low investment, and minimum maintenance and operation costs. Moreover, it would have to be adapted to the Cordoba region's semi-arid climate.

Experience in Germany

Intensive research on feasible sewage purification systems was carried out in the Federal Republic of Germany in the 1970s and 1980's supported by the BMFT (Federal Ministry for Research and Technology), universities and numerous foundations. As a result, sewage treatment plants were developed which have become internationally known as root-zone systems, solid-and-plant filters, or vegetable sewage treatment systems. They are affordable.

Typical operating costs are low and above all the level of efficiency as regards the third stage of purification, namely elimination of nutrients (phosphates and nitrates) or industrial toxins in receiving waters, is adequate.

figure

The first to accept these sewage treatment systems were NGOs, ecologically-minded individuals and a number of scientists. More than 800 identical or similar systems are already in operation and their popularity is increasing.

Design concept

The design is basically an optimization of the well-know field irrigation systems that were the state of the art a century ago. A few such systems are still in operation. The difference is that the direction of flow has been changed - today it is horizontal instead of vertical - and that plants are used, adapted to soils permanentely affected by contaminated water.

These include, for example, limnophytes such as reed (Phragmites communis), bulrush (Scirpus spp.) and cat's-tail (Thypa spp.).

The role of the soil substrate is also more important today. Our knowledge of soils and the bacteria associated with them is increasing. The rhizasphere effect due to secretion of organic acids by roots is well known, and hydraulic conductivity has been improved by root development. All these things have made it possible to design a fixed-bed reactor with a high level of biological and chemical activity, capable of treating 10 to 50 times more sewage in the same area without contaminating the groundwater.

Construction

A thorough soil analysis is performed. The site is examined and the relevant sewage-related parameters are recorded. Impermeable basins, made watertight with plastic sheet, concrete etc., and with specially designed drainage systems are then filled with the appropriate substrate (soil), and planted with the marsh plants chosen. The size of the basins is calculated on the basis of anticipated water pollution levels or population equivalences (PEs). As a rule, an area of 2 - 5 m2 is needed per PK. Due to the time the vegetation takes to grow, sewage treatment plants of this type develop slowly. In Europe it takes about three vegetations periods to attain the desired treatment capacity. Sewage plants ranging in size from 5 to 40,000 PEs have laready been built.

Experience with soil-and-plant filters in the temperate climate of Europe, and particularly the Federal Republic of Germany, prompted the government of Cordoba Province to approach Germany with a request for assistant personnnel within the framework of Technical Cooperation. Starting in March 1988, possible sites in the catchment area of the Lago San Roque were inspected. An intensive public relations campaign was also launched, involving several NGO's, municipalities and architects' associations (Colegios de Arquitectos). In the first phase a small test plant was built, to check biological parameters such as choice of vegetation, evaporation rate, vegetation growth rates etc.

figure

· It was found that the plants grew much faster than in Europe, and the evaporations rates were the highest ever recorded. In some arid locations there was no measurable discharge from the pilot plants. This corresponds to 100 per cent purification.
· A further factor requiring adaptation is the different composition of the soils in the Sierras. Almost all the soils here are alluvial, the topsoil consisting of accretions from the degraded mountainsides. The advantage of these soils is that they contain high proportions of organic fractions, sand, loam and a low proportion of clay.
· While these soils are highly permeable to water they tend to deliquesce in the long-term due to their low stability. However, results so far have been encouraging.

To date, a total of nine pilot plants have been built. The sites chosen are individual houses, holiday complexes, administrative buildings and a small urban district. Some of the initial results are documented in the illustrations.

As regards Coli bacteria, the purification capacity was found to be surprisingly good. In the last samples obtained, concentrations were in the order of 1,000/100 ml, meaning that the water was of bathing quality.

The question as to whether the treated sewage can be used to irrigate fruit and vegetable plantations is currently being investigated.

The discussion on drinking water and environmental pollution in Cordoba in recent years has led to the appearance of a new type of socioecologically oriented NGOs. These NGOs are involving the affected sectors of the population in the development of environmentally compatible alternative technologies and promoting environmental consciousness in the communities. They are also collaborating with the various public authorities concerned, which would often be overtaxed on their own.

1) Biological Oxygen demand

Wanted : YOU
es une accion de GATE, Para que tenga exito, lo necesitamos a Ud. y a sus conocimientos sobre la vida local.

¿Conoce Ud. une tecnica local de uso en el trabajo cotidiano, que sea ventajosa y que pueda, a su juicio, ser util tambien pare otras personas, en otras parses del mundo, en su trabajo cotidiano?

Tal vez en la elaboracion de alimentos...
en la fabricacion de utensilios. . .
o un medio de transporte practico. . ..

Describa en forma breve, en la paginas siguentes "COMO FUNCIONA" y envinos les paginas con su trabajo. No olvide indicar su nombre y senas, pues tal vez necesitemos aclarar algun punto; edemas quisieramos expresar nuestro agradecimiento con un pequeno presente a los que nos envien ideas sobre tecnicas interesantes.

Con su participacion en esta accion tal vez se le of rezca la posibilidad de publicar "su" tecnica en el boletin de informaciones de GATE. Tambien por esto: jno olvide darnos sus senas!

Esperamos con mucho interes su respuesta

Atentamente
El "team"del Servicio de Consulta de GATE

Datos del REMITENTE:
Nombre:
Edad:
Profesion:

DESCRIPTION DE LA TECHNICA "que funciona"

AREA DE APLICACION: .
PROCEDIMIENTO:
MATERIALES REQUERIDOS:
FUENTE DE ENERGIA REQUERIDA:
PRODUCTO DE PARTIDA:
PRODUCTO FINAL:
ORIGEN de esta tecnica (pais/region):
¿Utiliza UD. mismo esta tecnica? .
No olvide indicar su NOMBRE y DIRECCION, pare que podemos hacerle Ilegar nuestro agradecimiento:
Nombre:
Calle y N°: .
Casilla de Correo: .. ...
Ciudad:
Pais:
Rogamos devolver, debidamente rellenado a:
GATE ,P.O.B. 5180, D-6236 ESCHBORN 1, Repubica Federal de Alemania

ROOT TREATMENT (picture)

Sanchez Pilot Plant
B.O.D.1), Overall Efficiency 1989-1991

Recycling by voluntary organisations

by Jon Vogler

Who should recycle? People say: "If only the Government would organise to recycle all the country's waste . . ." But National or State governments are too remote, too slow and too bureaucratic. Recycling is demanding: needs single minded local leadership, awareness of market changes and the flexibility and speed to respond to them. This ist why municipalities are rarely successful, despite their enormous economic advantage: that costs of collecting and processing recyclables can be offset against the savings in garbage collection and disposal which they are obilged by law to perform.

Industry has the kind of command structures needed for flexible management but can only recycle effectively where it controls the source of supply: industrial by-products and wastes such as metal scrap from stamping and machining operations or discarded homogeneous paper and plastic packaging. To recycle post consumer waste (waste which the public has used and discarded) you need an organisation that can motivate people in large numbers: inspire them to take the trouble to tear the paper labels off plastic bottles or wash out margarine cartons. This ist the great strength of voluntary organisations (often known as nongovernment organisations - NGO's) and explains the widespread (if small scale) successes which they have had in recycling projects around the world.

In this article (which I shall illustrate from my own experience of starting and advising on recycling projects, particularly in Third World countries) I shall examine three kinds of NGO recycling acitivites:
creation or improvement of employment,
· fund-raising and the development of public awareness,
· political pressure to improve the environment.

I note, with some sadness, the meagreness of a fourth type of voluntary activity: that of actually cleaning up the environment. Although well meaning NGO's, particularly youth organisations, often organise "litter picks" these tend to be sporadic and small scale. I know of no substantial, permanent organisation devoted to maintaining the purity of any local environment. Possibly people feel that they should do better by paying their local taxes and leaving it to the municipal authorities.

Recycling to create employment

Unemployment, particularly among the young and the unskilled, is one of the major social problems of the age. Voluntary organisations doing youth or social work in a locality often feel that "the devil finds work for idle hands to do" so start a recycling scheme that will employ local people. They believe that neighbouring householders will help by providing the raw materials they want to recycle and that by selling these they can generate the income necessary to pay wages. Usually tines projects need subsidies to succeed. The reason is that the unemployed are often those who lack skills and such people are not able to add much value to a waste material unless they are helped by expensive machinery.

Training youngsters, or even unemployed adults, in necessary skills is not usually a problem. Materials for recycling are common household items, with which people are familiar, and they respond quickly. Controlling the source of supply ist often far mor difficult.
Not all employment projects have to be started from nothing: huge numbers of people in the Third World already make a meagre living from recycling and a few NGOs have grasped the opportunities for helping them with funding, management and technical and marketing expertise. In some cases this means getting deeply involved in the project itself.

Another approach ist for NGOs to remain at arm's length from the actual running of the projects but provide training. I helped Manila Community Services Inc. run a workshop for cummunity leaders, to improve their management of recycling projects. Seminars like this focus on managerial, marketing and commercial matters which, from my experience, are mor frequently a cause of failure than lack of technical competence.

Recycling for fund raising

Recycling has been perceived as a means of fund raising by many NGOs whose objectives do not include recycling per se. Often this results in larger scale programmes than are ever associated with employment schemes. Transportation costs are always the drawback to national recycling schemes, even by organisations with a high profile and national acceptance. Often national NGOs have assets, of which they may be quite unaware, which can be exploited for effective recycling.

Pressure for a Clean
Environment

The emergence of the Green Movement has been one of the most cheering social developments of the last twenty years. The movement has been aware of the danger that its message might seem largely negative, and has embraced recycling as a constructive option so that its supporters can:
· Carry out collective projects that develop community spirit,
· Demonstrate to the public and to polluters, constructive alternatives to careless disposal practices,
· Raise money to finance political lobbying.

One of the problems faced by environmental pressure groups is that of wastes that cannot be recycled. Industries pour these into seas, lakes and rivers or dump them on soil which becomes unusable for thousands of years thereafter. There is a need for far more research into recycling possibilities for such materials and I would like to see the environmental pressure groups challenge not only these industrial firms but also the chemistry departments of universities trough out the world.

Conclusion
The examples given show the rich variety of recycling activities practised by voluntary organisations in all parts of the world. They have had an important impact, in encouraging governments and municipalities to adopt enlightened environmental policies, but there ist still much to be done. It is to be hoped that Eastern Europe will produce comparable NGOs, to put pressure on the new governments to attack some of the dreadful pollution that was caused during the communist era.

The United Nations has an Environmental Programme (UNEP) which has, in the past, had a poor reputation for constructive activity. Its staff should abandon their comfortable offices in a lovely suburb of Nairobi and start to tackle some of these dirty, unattractive waste recovery and disposal problems. In Eastern Europe, as in much of the Third World, the need of people to obtain a livelihood will, inevitably, take priority over environmental considerations. However recycling can provide a constructive solution to both. NGOs are pointing the way; it is time for industry, municipalities, governments and international bueraucracies to follow.

References

Jon Vogler, Jobs from Junks. 66 pp.
1983. Intermediate Technology
Publications Ltd, £ 5.95.
Jon Vogler, Small Scale Plastics
Recycling. 104 pp. 1984 same publisher, £ 10.95.

Order from:
IT Publications, 103-105 Southbampton Row, London WC1B 4 HH, UK.

Case Studies: Recycling in Kenya, Jamaica, Egypt, United Kingdom
· In Nairobi I worked with the Undugu-Society of Kenya to try andprovide employment for the Parking Boys: youths who normally roam the streets demanding protection money from motorists who park their cars. The project involved recovering the scrap metal from wrecked cars (which litter the streets of the city) and selling it to the local steel mills, who melt it to make reinforcing bars for the construction industry. The project involved training selected youths to dismantle wrecks, using only hand tools, into pieces of small- enough size to transport economically to the steel mill and load into the "charge baskets " that feed the fumaces. The project was technically successful but did not proceed because the Nairobi City Council/ would not take the necessary legislative and administrative steps to authorize the project to deal with the huge numbers of rusting cars which disfigure their city.
· In a tough, poor area of downtown Kingston, Jamaica / worked with Coke Methodist Church to develop a recycling scheme to create employment for local women. They received a one week training course in identification of the main different kinds of plastics and rapidly became proficient at separating polymers, to the satisfaction of a local manufacturer of agricultural irrigation pipes. Initially it proved difficult to obtain sufficient supplies of waste plastic and the project was threatened, but contacts were made with scavengers on the local municipal garbage dump, who willingly undertook to collect plastics materials and from then on obtaining sufficient supplies proved no difficulty. The success of the project was further enhanced by purchase of a granulating machine which both added value to the end product and reduced its transportation costs. The project proved successful and enduring.
· An attempt to replicate the successful Jamaican plastics recycling project in Nairobi, Kenya failed. Good progress was made in obtaining reliable supplies, training work people and negotiating lucrative sales contracts. The market for recycled materials, in economies such as the Kenyan, which suffer from balance of payments problems and heavy input tariffs, can make such projects very attractive. The problem was that the senior project management, the Salvation Army, failed to resolve problems (such as the supply of electricity to run the granulating machine). The message is that single minded local management, with commitment and authority, is essential.
· I worked with Oxfam and Environmental Quality Intemational, management consultants of Cairo, to help the Zabaline garbage collectors improve their sorting and processing techniques, add value to recyclables and sell them into better markets. This was but one part of a programme, funded by Oxfam and encouraged by the local Coptic Priest, to develop an aspects of the Muqattam community. The most important contribution was to strengthen the Zabaline's own local community association. For example, instead of Oxfam funding individual recycling projects, they enabled the association to set up a rotating fund which would make loans to its members. Repayments of these loans there after provided financial inputs from which more loans could be made This "rotating loan scheme" thus had a dual effect: facilitating recycling schemes and strengthening the association.
· When I set up Oxfam's Waste saver Centre in Huddersfield, UK, near/y twenty years ago, we started making local collections of recyclables. These proved uneconomic and soon had to be discontinued. However we discovered that the charity's national network, of six hundred retail gift shops, suffered from a problem: disposing of second-hand clothes, donated by the public, which were not of a sufficiently high standard to resell. The problem of getting these to our single, central recycling centre, often two hundred miles away from some shops, was solved by negotiating a contract with National Carriers Ltd, a nationwide transportation company.

We obtained low tariffs by exploiting the fact that timing of our shipments was unimportant. National Carriers often had to transport urgent cargo without having enough to make up a full load. Under the scheme they could collect sacks of second-hand garments when collection work was slack, hold it in their warehouses and use it to top-up any partially loaded vehicle Because it was a national contract, for which we paid solely by the number of full truckloads delivered to our Huddersfield factory, the entire scheme ran with absolutely minimal paperwork.

The shop manageress in a remote town simply telephoned her local National Carriers depot when she had ten bags ready for collection. She paid nothing, received no receipt and no paperwork had to be handled. The project has endured and prospered, largely due to the expert marketing of Mr. John Secker, a former textile reclaimer. It now makes Oxfam nearly half a million pounds profit a year.
In Britain, Friends of the Earth campaigned against the use of disposable bottles by soft drinks manufacturers. They dumped a truckload of discards on the prestigious head office doorstep of the Schweppes company (soft drinks manufacturers) and fumed that company's own publicity campaign against it by adopting the slogan "Who is Schwitting on Britain?" The result of this and similar campaigns was to force all the glass manufacturers and users to associate, in a nationwide scheme for recycling beverage containers, through bottle banks at supermarkets and public car parks.

Many environmentalists regard this scheme as unsatisfactory. They believe bottles should be reused, for multiple trips (with savings to the beverage purchaser) rather than smashed, melted down and remanufactured (with profit to the glass bottle manufacturer). However the public at large has embraced the scheme with enthusiasm.

Mechanization and organic agriculture

by Klaus Lengefeld.

In developing countries, animal traction is still by far the most important energy source for farmers. An estimated 53 % of the cultivated land is prepared with oxen or donkeys, horses or sometimes camels. Even manual labour, which accounts for 26 % of field cultivation, is still more important than tractor power, at only 21 %. But the Third World's farmers have not retained animal traction and manual labour because they consider it ecologically more appropriate - they just can't afford tractor power.

As long es the only drawback of a tractor seems to be its price, it will be extremely difficult to improve the image of non-motorized techniques and upgrade them from their position as a "second-best solution". On the other hand it will be equally difficult to determine under which circumstances a tractor or other high-tech solutions could be appropriate for agriculture in developing countries.

Basic principles and problems

Faced today with the necessity of feeding more than 5 billion people, and with the world population still growing at a rapid rate, it is not very helpful to gear all agriculture towards the former symbiosis of man and nature. On the other hand, the food problem cannot be solved by introducing world-wide agriculture with the level of mechanization of the North American farmer of today - this would absorb nearly all the energy consumed at present throughout the world.

Between these two extremes, there is plenty of scope for appropriate solutions, and the way to develop them should not be ideologically biased.

Mechanization in organic agriculture does not necessarily preclude machinery of one type, nor can equipment of a particular sort be branded a 'tool for organic farming'. Even the hand hoe contributes to soil destruction when used in inappropriate systems of shifting cultivation - it was not Caterpillars that destroyed the forests of North Africa.

Like organic agriculture as a whole, the implements used for it should not impact in a way that endangers the ecological balance or helps to convert it to an artificial one, based on biotechnologically mutated varieties and chemical inputs. But unlike these constituents of conventional agriculture, the tractor will not necessarily have to disappear in organic farming, although hand- or animal-operated implements disturb the environment far less than motorized operations. Nevertheless, even tractor-operated ploughing with its heavy impact on soil can be in line with the tenets of organic farming - otherwise the overwhelming majority of IFOAM and other organic farmers in industrialized countries would be unable to continue operations.

The fundamental problems involved in integrating the tractor into organic farming systems are its requirements for quite unnatural field conditions and its limited capacity for selective operations.

Big rectangles, treeless and stone free plains are the ideal areas for working with a tractor, and yet the land clearing action this entails is a high price to pay for motorization in organic agriculture. Obviously this initial devastation of the pre-farming ecosphere can by no means be completely repaired, not even with the most sophisticated agroforestry system.

But agriculture and machinery use within it can proceed in a way that avoids secondary destruction such as soil degradation or the extinction of the remaining ecological variety. Tractor-driven equipment can help with terracing, levelling and stabilizing the land, the rapid motorized soil preparation and sowing can shorten the period when the fields are uncovered, and tractors can facilitate the preparation of mulch with the double effect of soil protection and fertilization.

Nevertheless it is obvious that the diversified cultivation systems of organic farming like mixed-, inter- or alley-cropping present major constraints for the use of conventional farm equipment, which has been developed for one dimensional tasks in one-crop fields. This kind of technology normally is not suitable for selective treatment of the various species which, in addition, are in different phases of growth.

Mechanization and organic farming

In developing countries, the scenario for considering mechanization in organic farming in general, and particularly the role of the tractor, is much more polarized. In general terms, this is the result of the much more extreme conditions under which machines have to be used on these continents with tropical and subtropical climates and a highly unjust distribution of resources, wealth and political power.

Climatic factors such as high wind or rainfall, intensive solar radiation, extreme temperature fluctuations or the lack of a cold period for soil recovery and pest decimation can multiply the impact of any agricultural intervention and particularly that of machinery use. Under these conditions, land clearing for tractor use as well as the regular tractor operations can endanger the natural resources far more than in temperate climates, where the ecological balance is normally less fragile. A single tropical thunderstorm can carry away most of the fertile soil from a freshly prepared field. If the work is performed by tractors, this could affect a larger area and a greater portion of the fertile soil horizon, in comparison with land worked by animal traction or hand labour.

On the other hand, the climatic situation in many developing countries can also be favourable for the use of motorized machinery in tropical ecologically sound agriculture. In rainfed agriculture with a shorter production cycle, the periods with appropriate climatic and soil conditions for the various stages in plant production are much more limited than in temperate climates. Soil preparation in particular can often be performed only on a few days a year without major risks of erosion or soil degradation.

The preparation of 1 ha with a hand hoe is a job involving 15-20 days work for the average 2-3 adult person work force (working full time) of a peasant family in developing countries. With animal power it can be achieved in an average of 7-10 days, and even a small 40 kW-tractor will do the same job in just one day. Thus the non-motorized farmers will have to start soil preparation much earlier and to expose their fields to the inclemency of the weather, although little by little, for a longer period than tractor users.

Socio-economic assessment

Organic farming is often misunderstood as agriculture in harmony with nature, and the farmer's needs are largely ignored. People who have never experienced hard farm labour such as manual weeding in particular expect that farmers, as penance for having mutilated ecosystems for the sake of their agricultural profits, should now subordinate their needs to the great task in hand of restoring the lost environmental balance in rural areas. But organic farming must be in harmony with nature and men, which means with the social and economic needs of the farmer and with society's needs for food and other essential agricultural products.

Even in a small country like Nicaragua with one Mio. ha of cultivated land, about half of it's 3.8 Mio people, that means the complete adult population would have to work one month with the hand hoe only for soil preparation. This model, borrowed from Cambodian Stone-Age communism, is anything but acceptable.

The same work could be done with an estimated 300.000 ox-pairs, a population of oxen that can never be fed on the available forage base. Even for the by far smaller existing herd the supply of sufficient fodder is increasingly difficult, particularly at the end of the dry season when field cultivation is required.

The small farmers' view of mechanization in developing countries is fairly ambivalent. On the one hand, they have all too often been the losers in mechanization programmes in agriculture, which normally give preference to medium-sized or big farmers and can be the pretext for their expulsion. (Tractor use is considered as not possible or profitable in small scale agriculture.) On the other hand, even small farmers with only 2 or 3 hectares up cultivation experience labour shortages for certain tasks at certain times of year, e.g. for soil preparation, weeding or harvesting. These labour peaks would very well justify the use of more efficient equipment including tractors, even for small farmers.

Organic farming is in general not labour-saving. It tends rather to add new operations to the farmer's everyday burden. Manuring for example is quite a complicated process that can include the collection, composting of the excrements and the spreading of this heavy stuff, or even the cultivation, cutting and incorporation of an extra crop between the rows or on a fallow field for green manure. Anyone who has ever stood in front of an intensive fallow plot in tropical regions, that can easily grow within three years to vegetation measuring over three metres in height and impenetrably dense, and who has seen the farmers'poor equipment will immediately understand why it is nearly impossible to promote this component of organic farming in the developing world.

Appropriate mechanization for reducing labour requirements is therefore a key issue for the future of organic farming, in industrialized countries as in developing countries. Nevertheless, the development of adequate solutions for this challenge is still in its infancy. Some research and development has been done, for example in equipment for soil-conserving tillage or mulching. One major problem is the very incomplete knowledge about the environmental impact of different mechanization systems and the particular contributions of certain pieces of equipment.

Organic farming, mechanization and profitability

The question may arise as to whether it is convenient to call for increased efforts in appropriate mechanization for organic agriculture at a time when access to farm equipment and particularly tractors for peasants in the developing countries is, for economic reasons, at its lowest point ever, and when even our subsidized over-mechanized farmers are reducing the rate at which they are renewing equipment. The economic assessment of mechanization cannot be regarded separately from the profitability of agriculture as a whole. And there is a lot of evidence to show that when 10 workers produce 50 cars a day, the farming business is no longer profitable at all. All over the world, wherever people make a lot of money out of agriculture, you will find that agriculture is heavily subsidized.

If this means that agriculture is something we can afford as a question of survival and not of profit, we should extend its mandate from mere production to production with conservation, and give it the necessary financing to allow it to meet this global challenge.

Organic farming with appropriate mechanization is one possible answer.

The Chinese vertical Brick Kiln

Fuel Saving Technology transfered from China to Nepal by Henrik Norsker

GATE, the German Appropriate Technology Exchange, a division of GTZ, financed and implemented together with the Ceramics Promotion Project of GTZ in Bhaktapur/Nepal the transfer and testing of a new brick burning technology. This technology of a continuous vertical brick kiln was developed in China, several hundreds are in use in rural China. In combination with an extruder to burn hollow bricks it is - compared to the prevailing Bull trench kiln - saving more than 60% of fuel. It is using coal dust instead of fuelwood, occupying only one seventh of the land and saving investment cost.

In Kathmandu valley where bricks are mainly fired in Bull trench kilns, about 250 kilos are operating from November until the rain starts in June. The kilns are fired with a combination of imported coal, local lignite and firewood. About six plants use Chinese made extruders for production, but most bricks are formed manually.

Hollow bricks

The first phase of the testing programme was demonstrating production of hollow bricks. A small extruder was imported from Thailand. Its advantage over the Chinese made extruders is its low price and that it can more easily be manufactured locally.

The main advantages of hollow bricks over solid bricks are:

Hollow bricks are about 30 % lighter which means fuel saving.

Hollow brick are better insulators making the houses less cold during the winter and less hot during the summer.

As a protection against earthquakes new houses in the valley are constructed with pillars and beams of reinforced concrete. Hollow bricks are ideal for this type of construction.

The hollow bricks are easier to dry and fire evenly.

Production of the bricks has only been going on for three months and it is too early to judge the response of the market. The cost of the bricks will be less than other machine made bricks, but some people feel deceived when buying so much air instead of solid brick and some worry that construction with hollow bricks consumes more mortar.

Vertical brick kiln

In May 19901 went to China to study a small continuous brick kiln that has been developed there. The first prototypes were tested in Tongbai country in the province of Henan. Already 37 private brickworks are using this type of kiln in the country and hundreds more are in use elsewhere in rural China.

The kiln is extremely fuel efficient and it is at the same time simple to construct and operate, making it ideal for rural areas in developing countries. The fuel saving was so high that the figures were hard to believe. Ceramics Promotion Project decided to test the kiln in Nepal and brought three engineers from China to Kathmandu to demonstrate the kiln.

Table 1 Vertical Shaft Kiln

Bull Trench Kiln	Int. combustion hollow brick	hollow brick	Solid brick	Handmade brick
Fired brick weight in kg	2.05	2.00	2.1	2.6	1.75
Moisture content of green brick	abt. 10%	175%	15%	9%	10%
Kilo calories used per kg fired brick	550-650 182	206	181	160

Kiln design

The bricks are stacked in a shaft measuring 1 x 1 meter and with a height of 6 meter. Green bricks are loaded from the top in batches of 224 bricks set in 4 layers. At the bottom of the shaft, bricks are taken out at the same rate with a special unloading devise. In average a batch is unloaded every 1 1/2 hour. The kiln has so far been tested only with coal dust. This is spread out evenly between each layer of bricks during setting. Combustion takes place in the middle of the vertical shaft.

The combustion air enters at the bottom of the shaft and moves up through the already fired bricks, so when the air reach the combustion zone it is preheated to about 750°C. After combustion the hot flue gasses move up through the unfired bricks. The transfer of heat to the bricks is so efficient, that the temperature of the exhaust flue gas is low enough to hold a hand over the top exit.

Kiln construction

The construction of a kiln with two shafts took two months. In China it is done in three weeks, but in Nepal it was harvest time so every second day was a festival. The inner shaft lining was laid with one layer of green bricks. The space between the inner lining and the outer wall was filled with a mixture of rice husk and brick clay. Local masons constructed the kiln under supervision of the Chinese engineers. It is made from local bricks and clay mortar.

The unavoidable problems with getting funding, approval from local authorities etc. had delayed the programme six months and we ended up starting test firing in the middle of the rainy season. The kiln and the coal was soaking wet and the bricks were hardly leather hard when stacked.

Firing was started in the firebox and the kiln operated normally after about five days firing, but it took several weeks for the kiln to dry out.

Test firing was done with a number of different bricks; handmade bricks, extruded bricks, hollow bricks, and extruded solid or hollow bricks with mixed in coal dust. Some typical figures for fuel consumption are given in table 1.

Firing temperature ist 850 - 900 °C. It is easily maintained by adjusting addition of coal and by regular unloading. The kiln worked especially well when firing hollow bricks with coal dust mixed in the clay.

The results were obtained during the rainy season. Bricks batches were unloaded every three hours during the first month of operation, but as the kiln dried and the rain stopped unloading could take place every 60 to 80 minutes. This equals an output of each shaft of 4,000 to 6,000 bricks per 24 hours. 4 to 6 shafts are needed to replace the daily production of a Bull trench kiln.

Economy

As shown, above the fuel saving is considerable, but the kiln has several other benefits:
- Firing temperature is even.
- The quality of the fired bricks can be controlled already 20 hours after loading.
- A kiln with six shafts has the same capacity as a Bull trench kiln but requires only 13% of the land.
- A Bull trench kiln needs costly new metal sheet chimneys every year whereas maintenance cost of the vertical kiln is negligible.
- Operation of the kiln is very simple and unskilled workers in Nepal managed to operate the kiln after a few weeks training. This has particular importance in Nepal where migrating Indian workers have monopolized operation of the Bull trench kilns.
- The kiln works well with coal dust which has a lower price.

Table 2 provides a rough comparison of brick kilns.

Environment

With a fuel saving of at least 50 % a corresponding reduction of flue gas emission is achieved. Additionally the combustion in the vertical shaft kiln is much more thorough compared to the Bull trench kiln.

During firing no black smoke is seen from the chimneys. In Kathmandu valley, the brick works are consuming 30% of the valleys total energy consumption and therefore they are major contributors to adrastically increasing air pollution.

The Bull trench kilns of the valley use about 100,000 tonnes firewood per season in addition to equal amount of coal. This amount of firewood equals the sustainable yield of a forest area of 130,000 hectares in the low lands of Nepal.

Replacing the kilns with vertical shaft kilns would completely eliminate the need of firewood, thereby reducing the grave deforestation problem of the country.

The testing is not yet finished, still the results achieved so far by the GTZ sponsored test programme in Nepal clearly demonstrate the advantages of the vertical shaft kiln over other kiln types available for brick production in developing countries. The kiln's minimum 50% fuel saving carries a promise of saving fuel on a really large scale and it will in areas now relying on firewood save vast areas of forest.

In Nepal and many other developing countries, the brick industry is the major industrial energy consumer and the fuel saving would improve the overall economy and reduce emission of pollutants.

The kiln can be used for any type of bricks, but when setting up programmes for introducing this new kiln it is worthwhile to consider introduction of production of hollow bricks too.

In Nepal the test programme will be continued until May 1992 and a programme for dissemination of the kiln throughout Nepal is in the planning. German Appropriate Technology Exchange (GATE) is now planning to introduce the kiln in Pakistan and possibly elsewhere.

Table 2	Bull Trench	Hoffmann	Vertical Shaft
Comparative analyses of kilns	kiln	kiln	kiln (6 shafts)
Brick production per 24 hours	25,000	30,000	24,000
Construction time	2 months	6-9 months	2 months
Construction cost (in Nepalese rupees)	300,000	6,000,000	900,000
Imported cost component	nil	US $ 30,000	nil
Maintenance cost in rupees (42 rs = 1 US $)	100,000	50,000	negligible
Fuel consumption k.cal. per kg fired brick	550	450	200
Time before brick quality is known	20 days	10 days	20 hours
Average rejection rate of fired bricks	10%	5%	5%
Area required for kiln operation	700 m3	1100 m3	100 m3

If you are interested in more information, please address your enquiry to Klaus Rudolph in GATE.

Biogas-lnvestment encouraged with public funds

by Hartlieb Euler and Monika Heilig-Polak

Biogas technology clearly benefits the user: it saves him the cost of the energy it replaces and in many cases working time as well. The biofertilizer produced in the fermentation process is a high-quality fertilizer that costs nothing.Hygieneimproves.Forwomeninthedevelopingcountries,inparticular, biogas technology spells progress - smoke-free kitchens and more convenient cooking. For all these reasons it is often assumed that the use rat whose home the biogas plant is built should also bear the cost of the plant. Biogas plants are not in the same category as roads or public utilities, runs the argument, so why should the state pay for the investment.

In fact, however, biogas technology benefits the community as a whole. Sewage treatment protects water supplies and the environment, reduced deforestation helps to prevent erosion, and, in addition, biogas technology helps save foreign exchange.

In many developing countries, ignorance of the benefits to society on the one hand, and a shortage of public funds on the other prevent the state from adequately subsidizing the implementation of biogas technology.

Levels of subsidization differ widely from country to country. In the "classical" biogas countries such as India and China most of the initial investment for a biogas plant is borne by the state. These are also the countries where the technology is most widespread.

In some other developing countries hybrid forms have evolved: part of the cost is borne by the plant operator (farmers, institutions, municipalities), and part by the community (state, agricultural organization, project).

In industrialized countries, e. 9. Germany, the cost is partially borne by the state, by means of a range of structural instruments - including tax benefits for investments linked to environmental protection, statutory regulations, preferential loans, direct subsidies (30 - 70%) for renewable energies, and promotion of research and training.

Less affluent states lack the financial means for such a wide-ranging system of incentives. In such countries plant construction tends to be assisted by providing government engineers and masons. But the cumbersome state administrative apparatus often leads to inefficiency, paralyzing the initiative of private artisans, business and banks and their willingness to contribute to the investment funds needed.

This is where Technical Cooperation (TC) comes in. Its purpose is to involve the various groups in order to achieve optimum intermeshing of the contributions they can make in establishing the technology. TC projects should encourage the willingness of operators, mediators (banks, artisans, small businesses) and representatives of society (NGOs, farmers' organizations, the state) to invest.

To this end, most TC projects help the state decision-making body to take over and organize this process of mediation and cost-sharing in the longer term. In cooperation with government agencies, a whole package of measures have been developed within the framework of TC to promote the establishment of biogas technology.

Intervention in the finance market

Only few farmers or institutions can finance the relatively high initial investment out of their own funds. Loans are often beyond the reach of smaller farmers in particular, because
- the banks are reluctant to do the work involved in arranging smaller loans;
- the farmers have no collateral to offer;
- the banks have little or no experience with loans for biogas plants;
- the interest ist too high;
- the banks have little or no experience with credit lines for biogas technology.
Assistance measures to counteract this include the following:
- establishment of a credit line with a development bank or rural organization;
- re-insurance of the loan (collateralization);
- contributing to the interest (reduction of interest);
- award of a single, non-repayable grant;
- drafting of guidelines for the granting of loans.

Businesses or artisans wanting to construct the plants do not always have the funds needed for transport, tools and preliminary services, either. They too can be helped with the above loan-assistance measures. However, they do not always approach the bank. Should this be the case, they are assisted by supplying tools, equipment and means of transport.

Import of materials

As a rule, biogas plants are built from locally available materials. Occasionally, however, materials have to be imported, in particular accessories such as refrigerators or lamps. Most imported materials and appliances are subject to heavy customs duties. The shortages that this results in can be reduced by the following measures:
- government permission to import materials and appliances duty-free; - establishment of a store for materials which are only occasionally available;
- centralizing imports of materials that are hard to obtain or which it is not worthwhile importing in small quantities;
- encouraging local production of materials which are in short supply; - assistance in transporting the materials in question.

Know-how

Only in a few places is the know-how that is needed to build and operate biogas plants available, adequately developed and accessible to potential plant operators. This shortfall is compensated by the following measures: - public relations/advertising;
- training artisans, technicians and engineers in plant design and construction:
- training of users in plant operation and maintenance;
- advisory services, and employment of experts in government and nongovernmental organizations;
- coordination of activities;
- research and development. A goal of Technical Cooperation is that project activities should gradually be transferred to government and nongovernmental organizations, private banks and businesses. However, this process does not always develop at the level desired, because the social institutions often suffer from a shortage of funds.

The Sun was there before You

Appropriate technologies for preserving fruits and vegetables

by Siaka Kone

A workshop was held from 15 to 17 July 1991 in Bamako on appropriate technologies for preserving market garden products (fruits and vegetables). This meeting was initiated and organized by the Coordination Committee for NGO's Activities (CCA-ONG) in Mali, and was financed by GATE within the scope of the ISAT project (Information Service on Appropriate Technologies).

The thirty participants came from various socio-professional backgrounds: researchers, representatives of NGOs working in the field of grassroots development and representatives of producer groups. The main triumph of this workshop was to have brought together these various actors involved in the process of technical innovation in the field of fruit and vegetable preservation.

Primarily, contributions concentrated on drying as a method of preserving fruit and vegetables. Apparently the researchers, who presented some 50% of the contributions, have not dealt with the problems of drying to date. The producer groups presented both their experience with trials using "modern" solar driers and using traditional, local methods in an attempt to find a solution to the practical problems facing them as regards preservation and storage.
The present situation is that none of the equipment developed in Mali's research centres has reached even a pre-dissemination stage. None of the innumerable models of driers developed have managed to get at least a dozen or so working simultaneously in the field - and that despite the pressing preservation problems confronting the producer.

This situation dramatically reflects the cruel reality which all too often exists between the various actors involved in the research and development and in practical production. In the case of drying as a preservation technique in particular researchers have not looked beyond the challenge of developing equipment with a "fantastic" technical performance, in their conception of improved technology.

The necessity of the equipment being appropriate for and accepted by the group of users, of it being culturally and financially accessible to this target group appears to have escaped them. The consequence of this situation is that in a given socioeconomic milieu we see a conflict between local, traditional technologies and new technologies.

The solution to the conflict presupposes a new approach on the part of those involved in research. This new approach, based on gearing research work to solving the actual problems of the target group, future users of the technology, must take as its starting point the current practices of the user group.

If this way were taken there would be implicit support of improved local technologies. This is all the more important since, as we have seen from discussions at the workshop, for a lot of people appropriate technology is synonymous with new technology. Local, traditional technology, its shortcomings remedied, is however by its very nature the most appropriate technology in a given domain.

We must however say here in the defence of the researchers that many of their activities take place within the scope of externally financed programmes, often linked to the adaptation or modification of a particular piece of equipment designed somewhere else, and having proved itself in a distant country under entirely different geographical, climatic and sociocultural conditions.

In conclusion, the author would like to call on all actors involved in technological innovation, and technology transfer to concentrate more on improving existing, local, traditional technologies in the relevant fields.

These technologies, which are no less than the most direct expression of the heritage and sociocultural identity of the target group, use local resources and local expertise. The technology will thus be perfectly adapted to the target group to benefit from technical innovation, and the target group will be in a position to understand it, design, maintain and repair it.

In the case of drying technology in the Sahel zone this means working on improving the hygienic conditions of simple air drying, for example. Rather than concentrating on dreaming up equipment which appears to the target group to be complicated to manage, use the sun as far as possible - the sun was there before you!

Development strategies for fragile lands

Conference in Panama
by Jurgen Carls

Tropical deforestation is one of the major fragile land issues of the 1990s. The Humid Tropical Lowland Conference (17 - 21 June 1991) in Panama had therefore been organized to examine strategies for and management approaches to the sustainable development of humid tropical lowlands in Latin America and the Carribean.

The Republic of Panama was chosen as the conference venue because it is one of the few countries in Latin America within the humid tropical lowlands and has accessible sites for field visits.

The conference was organized by Development Strategies for Fragile Lands (DESFIL), a US non-governmental organization. DESFIL assists US-AID (Agency for International Development) in their regional program to arrest the degradation of natural resources in Latin America and the Caribbean.

Although the conference focused on the Latin America/Caribbean region, the participants and presentations also considered promising practices from Africa and Asia. Approximately 200 participants from 18 countries attended the conference, including a few representatives from Europe. In five sessions the conference worked out recommendations on natural resource management.

· Natural resources and sustainable development:

Population growth in the last decade exceeded 2 % in almost all countries in tropical Latin America, so competition for land and natural resources has also increased.

The causes of nonsustainable use of tropical forest resources fall into three broad categories: poverty, ignorance and institutional failure, which has two facets: market failure and policy failure.

High deforestation is a result of the interaction among these causes.

The reforms needed to rectify institutional failures, particularly policy failures, are:
- correction of constant underpricing of
tropical forest resources;
- initiation of environmental accounting within national income frameworks;
- reduction in infrastructure projects encroaching upon topical forests.
Activities designed to cope with natural resource degradation, such as incentives for reforestation and soil conservation, should be functionally integrated into a particular country's economic development model. All potential economic development policy effects must be indentified before designing and implementing programmes and projects to stop and reverse the processes of natural resource degradation.
Management of protected areas and national parks:

A broad definition of "protected areas" must be used to describe examples that range from low-impact agriculture to national parks.

The "protected areas" and "natural parks" concepts are accepted in Latin America as important tools for the establishment and management of large areas in Panama for example 13.9% of the national territory is protected in 11 "Parques Nacionales", two "Refugios de Vida Silvestre" and two "Areas Recreativas". The aim is to increase these protected areas to 18 % of the national territory.

The basic requirements for developing the human and physical infrastructure needed to manage natural park areas are as follows in order of priority:
- on-site staff with adequate professional
training;
- organizational and management planning;
- protected area policy, Laws, regulations and fee collection;
- environmental education outreach program;
- research facilities.

Case studies from Latin America demonstrate that the funds and facilities available are not usually sufficient to guarantee the protection of demarcated areas.
Non-timber forest products and ecotourism

Central America has 250 "wild land protected areas" covering 13% of the region's land mass. About 75 areas are homelands to or exploited by indigenous populations.

A wide array of products can be extracted from these forests without adversely affecting the ecosystems e. 9. medicine, germplasm, fruits, nuts, craft materials, products for industrial uses (e. 9. fibre), ornamentals, fish and game.

Small-scale, tropical rain forest cultures developed a complex system of subsistence technologies that have permitted hundreds of years of continuous exploitation of the forests. Political, economic and technological changes in the last two decades have disturbed these traditional patterns of exploitation.

The protection and management of the tropical lowlands must therefore involve the participation of the peasant and indigenous societies that exploit these fragile areas.

Indigenous management appears to be the next best thing to primary forests for species diversity, and the best for ethnobotanical species.

Apart from extracting products from forests, ecotourism could also be promoted as an instrument of sustainable development.

Sustainable land management in the developing world

Workshop in Chiang Mai, Thailand
Michael Bosch

In view of the rapid degradation of soils in the developing countries, due to erosion, compaction or salinization - to mention just a few causes coupled with the increasing need for food, conservative management of existing land resources represents a growing challenge. How can sustainable land management be accomplished in practice? This was the question addressed by about 200 specialists who attended the international "Workshop on Evaluation for Sustainable Land Management in the Developing World" held from 15 to 21 September in Chiang Mai (Thailand).

The workshop was attended by scientists from national and international agricultural research institutes and universities, as well as representatives of other international organizations, associations and development aid agencies from some 50 countries.

While it is generally accepted that sustainable land management is necessary, the actual meaning of the term remains rather vague. The workshop had therefore set itself the goal of establishing the concepts and principles needed to evaluate "sustainable management", including quantification. The following definition of sustainable land management was chosen as a basis from which to proceed: "A package of technologies which together promote agricultural productivity, ensure an economic and social yield and protect or enhance the quality of the environment and the soil "

The problems were presented in papers delivered at nine technical sessions, which dealt with agroclimatic, environment-related, pedological, agronomic and economic guidelines, "stewardship" and methodology/ quantification.

The International Society for Soil Science (ISSS) was a co-organizer of the workshop. In the technical sessions, much time was therefore devoted to discussing soil-related question. Much was said about both the importance of organic matter in soil and the role of nutrients and the physical properties of soil. Soil cultivation and erosion protection methods were also discussed.

Only a few speakers addressed the actual theme of the workshop, i. e. how "sustainable land management" should be defined and above all how it should be measured. According to one of the papers delivered, "it is extremely difficult to quantify changes in land qualities, owing to natural or anthropogenic variability. There are many methods of measuring land qualities with regard to agricultural productivity (e. 9. the FAO Framework for Land Evaluation). But these measurements do not relate the land qualities adequatly to agricultural yields.

Production specialists have so far underestimated the importance of economic questions with regard to sustainable land management. The fact that three economic discussion papers were also presented must therefore be considered a success. However, they dealt mainly with macro-economic consideration.

An anthropologist pointed out that there are also other factors which influence the acceptance of sustainable land management methods by farmers. The following are some of the factors he mentioned:
- The farmers do not see the problem. - The technology works only under certain conditions.

Combatting erosion in the Phillipines.
- The farmer has a better technology at his disposal.
- The innovation creates new problems.
- Land ownership rights stand in the way of innovation.
- The innovation has a negative social impact.

In order to test the sustainability of alternative land management technologies their effects must be predicted. This can be done with models. By means of multi-factor model calculations it is possible to predict not only how the organic matter or ground water availability will develop, but also the economic consequences of management systems for entire catchment areas. A number of models were presented, including one that makes use of the "Geographic Information System" (GIS).

The workshop worked out recommendations for evaluating sustainable land mangement: In view of the accelerating degradation of available land resources, international efforts are urgently needed to create a framework for systematic evaluation of the sustainability of land management systems. The ISSS, FAO and other organizations, as well as those attending the workshop were therfore invited to participate in the establishment and coordination of such a framework.
Greater emphasis must be placed on the role of social, cultural, anthropological and economic factors in the acceptance of sustainable land management systems. An international working group should be assigned the task of examining proposed methodologies.
Statistical methods for verifying sustainability should be worked out. A network of long-term experiments should be set up to evaluate sustainable technologies.
Quantitative indicators and critical data sets should be developed. The methods of environmental accounting must be improved.