Background Both EU and Latvian legislation require a significant reduction in volumes of organic waste in the coming years. Currently, around 40% of organic waste is composted, with most of the rest being disposed of in landfills. To reduce the amounts of biodegradable organic waste initially aimed for disposal, qualitative changes will be required to current practices in Latvia. In particular, it is proposed to introduce the biological treatment of waste in the treatment of household waste. Objectives The project aimed firstly to develop and implement an optimal scheme for separate collection of biodegradable waste. It also proposed to develop an appropriate system for processing household waste into high quality compost. The project activities were designed to facilitate the implementation in Latvia of EC legislation concerning the reduction of organic waste disposed in landfills. The project was to take place in two Latvian rural municipalities near to the capital, Riga. It was planned that around 75 tonnes of biowaste would be treated within the project to test two technologies (bioreactor and open-air composting). The results were to be disseminated to local municipalities and waste-management authorities. The experience gained would also be shared with interested parties in other European countries. Results The project achieved its objectives of establishing a functioning collection scheme for household organic waste in two municipalities, Kekava and Stopini. Fourteen collection points were organised in Kekava, and 18 in Stopini. The project carried out an effective information campaign and benefited from the active support of the local population. The separated organic waste collected from the pilot areas amounted to 268 m3 (or 214 tonnes) in Stopini municipality and 468 m3 (or 374 tonnes) in Kekava municipality. The project calculated that this waste would have produced 1.29 Mm3 of landfill gas if it had simply been dumped. The project established the optimal biowaste composition for composting in open-air windrows and stacks. A new composting site was set up in Marupe and an existing site in Stopini was improved. These were used to then carry out large-scale tests of open-air composting methods. A bioreactor was also installed at the Marupe landfill (Kekava municipality) to be used to test a closed composting technology. The bioreactor was unfortunately installed with a significant delay and operated only for the final 1.5 months of the project. Thus, while it was possible to collect some results, the delay meant the project could not adjust the bioreactor to local conditions. The project produced a comparison of the three composting methods (bioreactor, stacks and windrow) for achieving high quality compost. The results were presented in a publication entitled “Bio Waste Management Methods”. The highest quality compost was achieved through the bioreactor. The resulting compost could be used in gardens and for agricultural purposes. However, calculations of composting prices provided by the project show that open-air composting is cheaper than other bio-treatment methods. The cost of €10 per tonne is less than the cost of disposal in new sanitary landfills (around €15 per tonne). Compost prepared in open stacks results in a low quality fertiliser, but one that can safely be used as landfill covering material. The project concluded that the open-air system should be economically sustainable. Both the municipalities involved in the project expect to continue to collect separated biodegradable waste to be composted at the two composting sites. Some other Latvian municipalities have also shown interest in the results of the project. However, although it would be simple to implement, it remains unclear how the sustainable the biodegradable waste collection schemes would be, as the most likely means of financing would have to be through payments by inhabitants.