The needs and problems existing in the field of cultivation systems and waste management
concerning elements and energy, as well as pollution, health, environment, and economy are
described. The lack of reproducible biofertilisers of high quality calls for an efficient use of
organic waste as a renewable raw material. Each 100000 inhabitants in Sweden generate
organic waste with considerable economic values in terms of nitrogen, phosphorus, and
potassium; US$ 600000 from the organic fraction of municipal solid waste and US$ 900000
from human excreta as liquid organic waste, meanwhile only US$ 160000 is recovered from
the sewage sludge after the wastewater has passed the wastewater treatment plants. Most of
the existing systems for handling solid and liquid waste are of old-fashioned design and cause
large losses of nutrient elements. Therefore, pollution of air, water, soil, and vegetation,
mainly by emissions from organic uaste, continues. Bioconversion is microbial transformation
and upgrading of various organic wastes to products of high value. The elements can be
efficiently recycled in completely closed local bioconversion systems with subsystems for
collection, pre-processing, processing, and application of end-products. Solid and liquid
organic waste from the municipality can provide renewable raw material for manufacturing
of reproducible biofertilisers and of biogas. Suggestions are made on how to improve the
present situation by the re-orientation of technology. A scenario for bioconversion by the
year 2010 is presented. © 1998 Elsevier Science B.V. All rights reserved.