Island economies, and for all the crisis that they are facing in the wake of global warming, rising pollution, over-fishing, unsustainable tourism, and export driven economies demands a most creative approach. The advantage is through, that as island economies can easily undertake input-output studies, these nations can also undertake the most advanced output-input studies, which are at the core of the methodology for the zero emissions research initiative that the UNU has launched in 1994. After all, islands have all the problems to face the economists and environmentalists can enumerate. Though these states have the advantage that their inherent economies of scale permits them to address the issues at stake in an integrated way, likely to offer models for sustainable development for the rest of the world to learn from.
Indeed, sustainable development requires an integrated approach, a complex systems modelling. And when industry and urban development needed to mimic nature's concept of "all waste equals food," it is easier -though still difficult - to achieve on an island than for a land-locked national. A detailed review of the output of al activities on an island will quickly identify input- imports which are non sustainable, that could be substituted by highly sustainable and low toxic products. The case of beer, cleansing agents and construction materials are cases which demonstrate that the opportunities for local development are legio, but that the vision and the determination seems lacking. It is against this background that the ZERI programme is motivated to provide all the support needed to secure a successful study of the island economies with sustainability as the driving concept behind the development process.
The author already has a long and fruitful association with Fiji where he built his first Integrated Farming System 26 years ago. It consisted of a piggery with digester, algae basin, fish pond with ducks, and vegetable garden in Sawani village, 16 km out of Suva, Capital of Fiji. It provided biogas for cooking and lighting, feed for the fish and ducks, and fertilizer for various crops. Some crop residues were used as pig feed, which was supplemented with wheat bran, wheat pollard and fish meal from local industries. Since then, the author has advocated integrated farming systems in 71 countries and territories, and has demonstrated that individual family integrated farms are viable entities where water is always available, which is always the case in the wet tropics.
The best locations are low-lying lands and marshes, which are marginal and not presently utilized because of easy flooding, and where the soil is suitable for brickmaking it can be sold to finance the integrated farm, which is the success story of Vietnam where the author is involved in a people-oriented eco-farm project.
The objectives have been to provide the individual farm family with affordable means of production for economic and ecological rural development in a self-reliant system without costly inputs or environmental degradation by integrating various agro-industrial activities. They include different livestock using local feeds to produce the daily wastes as raw materials to operate an appropriate digester for primary anaerobic treatment with production of biogas fuel; shallow basins for secondary aerobic treatment with growth of natural algae to produce the required oxygen and the algae used as feed; deep ponds for tertiary treatment & polyculture of fish and macrophytes as food and feed; pond water demineralization with fertilization and irrigation ("fertigation") of various crops using multicropping, aquaponics and aeroponics; and natural processing of crops enhanced with biogas-operated equipment or processes and using the crop and processing residues as livestock feed. So far, in Vietnam, the income of individual families involved with the integrated farms designed by the author are earning up to 20 times the income they used to get with rice monoculture, while doing less routine work. With additional innovations and higher-value crops, the income can be considerably improved. Such highly-rewarding rural development is unique, and unmatched anywhere in the world.
Integrating such a farming system with a brewery to treat and utilize the brewery wastes can be a viable proposition not only for the beer manufacturers themselves, but also for adjacent farmers receiving the brewery wastes and willing to use the integrated farming systems to solve the brewery waste pollution problems while recovering the resources as means of production such as fuel, feed and fertilizer, for their own farm activities.
The wastes are as follows:
(i) Solid Wastes
The solid wastes are the residues from grains and additives used in beer making, and have a high protein and fibre content, They are too indigestible as an effective feed for livestock because of the ligno- cellulose, so it is broken down naturally by growing straw mushroom (Volvariella volvacea) on it with simple means -- a common occupation of farmers in China and Vietnam. It is proposed to try the shitake mushroom (Lentinus edodes), which is the most expensive in the world, using a technique developed in Fijian, China, using brewery wastes and straw instead of cutting down oak trees. Another way of using the solid wastes more economically is to grow selected earthworms of high protein content as chicken feeds, instead of feeding them with grains. The residues can be used as good compost, or used in feed formulation. The livestock produce wastes which are given primary treatment in a digester while producing biogas as fuel for the brewery. There are many digester designs to choose from, and they vary from the brick and concrete one for small digesters which was designed by the author and built at various places in Fiji for more than 20 years, and reinforced concrete or steel ones for big ones, using plug-flow or up-flow, which must be specially designed to suit individual cases. For the pilot project, the brick and concrete digester will be used but with an arched roof instead of the conventional reinforced concrete roof, as shown in Figure 3.
The effluent is used to grow algae in shallow basins by photosynthesis while producing oxygen during the day to give secondary treatment to the remaining wastes by oxidation. At least two basins should be provided, used on alternate days to allow algae to grow undisturbed for one day for optimum yield. The algae are also flushed every two days into deep ponds as fish feed. Most algae basins fail when the accumulated dead algae consume more oxygen than what is produced by the live ones. It is also better to make use of a natural resource to feed fish rather than letting it rot in the basins.
The highly-mineralized effluent flowing into the deep ponds also encourages prolific growth of various plankton as fish feeds. So fish polyculture, which has been widely practiced in China for centuries, can produce 10 to 15 tons of fish per hectare per year without having to add artificial feed except for grass grown on the edges of ponds to feed the grass carp. Five or more other kinds of fish are used to feed on the different plankton produced daily, which is important because any feed, natural or artificial, that is not consumed is a potential pollutant.
The fish in turn produce their own wastes which are treated naturally by the self-purification capacity of the pond water, and the mineralized effluent is then used to irrigate and fertilize all kinds of crops in aquaponic floats made of bamboo or organically produced plastic panels on half the pond surface, on in aeroponic towers and greenhouses on land -- all current practices in China.
(ii) Liquid Wastes
Too much water is used in beer making for cleaning purposes - between 20-30 tons to make one ton of beer in developing countries, and at least 7 tons in the developed ones, which makes treatment of liquid wastes very expensive, and even prohibitive in the poorer nations. So the first logical step is to reduce this wastage of water, first by better housekeeping and then by using organic cleaners instead of caustic soda and other toxic materials. The BOD varies between 1,000 and 1,500 mg/l, and the COD is 508 more. Such a huge quantity of water should be recycled, but not in digesters because of the prohibitive costs involved, but in a minimum of two long and narrow primary ponds of 1 metre deep for at least two days' retention.
As for the algae basins in (i) above, the design of the ponds should also provide for their individual flushing into the deep fish ponds by gravity, as clearly shown in Figure 2, in order to avoid the problem of dead algae accumulation. It must be added that cleaning the primary ponds is not as easy as cleaning the algae basins, and can put the plant out of action for many days, so the need to flush the primary ponds every two days becomes much more important. The discharge of so much dead organic matter into fish ponds or rivers can also create some major pollution problems as well, because of depletion of the dissolved oxygen.
(iii) Waste Heat
The waste heat from the brewing process should be recovered and used to heat water for washing the equipment or other uses. The biogas generated from the livestock wastes is a convenient source of fuel for the same purpose in the pilot project. For a full-size treatment plant for the whole brewery, electricity can be generated from the biogas to supply most of the brewery needs.
Recovery of the waste heat is not urgent in the pilot plant, so this work is better left to the other bigger pilot projects of ZERI.
(iv) Carbon Dioxide
Much carbon dioxide gas is emitted during the brewing process and can be recovered for use in the brewery itself or bottled under pressure and used for draught beer. Unfortunately, the equipment is still relatively expensive for the small breweries, and it is hoped that less expensive equipment will be available for trial in this pilot plant. Other possibilities such as the use the carbon dioxide in greenhouses, or its conversion into sodium bicarbonate for higher production of high-protein spirulina, will be tried instead.
(v) Spent Yeast
The technologies are already available for recovery and reuse of yeast, and for manufacture of some pharmaceuticals, with the residues mineralized in bio-oxidation ponds before using them to fertilize fish ponds. This pilot project will not be involved in such work, as it will be dealt with on a bigger scale in other ZERI plants.