|Bioconversion of Organic Residues for Rural Communities (UNU, 1979)|
|Indian experience with algal ponds|
As early as 1949, Spoehr and Milner (1) suggested that mass culture of algae would help to overcome global protein shortages. The basis for their optimism was that algae had a crude protein content in excess of 50 per cent and a biomass productivity of the order of 25 tons/ha/year. Ironically, in spite of the lamentably low per capita protein supplies in many parts of the world, mass cultivation of algae has received only casual interest. The United Nations Environmental Programme (UNEP) is emphasizing nitrogen fixation and nutrient recycling through a programme that will establish microbiological centres (MIRCENS), and it is hoped that this will stimulate interest in micro-algae technology as a component of an integrated recycling system for rural communities.
There are a number of relatively large production systems for micro-algae, using completely synthetic nutrients. These systems are expensive, not only because of the high cost of land and the technology required but also in terms of water use and the price of inorganic nutrients. Even an optimistic cost extrapolation indicates that production expenses will be US$2 - 3 per pound of crude algae, or US$4 - 6 per pound of crude protein. For reasons of economy alone, it is therefore necessary to use organic wastes for industrialized production of algal protein feed.
In India, we are developing an integrated waste recycling system, in which algal production forms an integral part (2). This is significant from both the biological and the environmental point of view. This system can provide, simultaneously, fuel (methane), feed algae (for fish, livestock), fish, manure for crops, and water for irrigation. The two main objectives of the All India Co-ordinated Project on Algae are: a. to develop rural-based recycling systems involving agriculture-aquaculture-pisciculture, and b. to develop viable, economical, rural-oriented systems for algal biofertilizers for rice that will help to relieve the pressure on chemical nitrogen supplies without impairing crop productivity. This will provide a cyclic instead of a linear system of nutrient supply.