Bonaire can benefit from circular waste management

Bonaire can take major steps towards a more sustainable and healthier future by managing its organic waste in a circular way. This is shown by the results of the BonCirc project, which explores how waste streams, including the increasing influx of Sargassum seaweed, can be put to better use.

At present, a large share of organic waste, including Sargassum, is disposed of at the Selibon landfill near Lagun. This leads to odour nuisance, smoke, leakage of pollutants and health risks for nearby residents. Valuable resources are also lost in the process.
“The current practice of landfilling is not sustainable,” WUR researchers conclude in the final report. “It may be cheaper in the short term, but the price for nature and society is high.”

Four strategies compared

To identify alternatives, the researchers and local partners examined four waste-processing strategies. These included composting, the use of Black Soldier Fly Larvae (BSFL), anaerobic digestion for biogas production, and combinations of these approaches. The assessment covered social, economic and environmental impacts, ranging from food security to carbon dioxide emissions and investment costs.

All four strategies perform better on sustainability criteria than the current situation. The option combining composting with the use of soldier fly larvae appears particularly promising, both in terms of circularity and practical feasibility. The larvae and compost could be sold to farmers, horticultural producers and the tourism sector as fertilisers and protein-rich animal feed. A rough economic estimate points to relatively high returns and lower processing costs, at around 85 US dollars per tonne of waste.

Raising and processing the larvae requires people with practical and technical skills and could involve small local businesses in the value chain. “A key condition is that the waste streams used for the larvae, such as chicken manure and food waste, are free of contaminants. Appropriate legislation is also needed to allow this form of waste processing,” says project leader Ana Lopez Contreras.

Biogas as an alternative to diesel

Anaerobic digestion is another promising option. This process produces biogas that could replace diesel, reducing greenhouse gas emissions and lowering energy costs. The researchers note, however, that this technology requires greater investment in knowledge and infrastructure.

A fourth, theoretical strategy, in which all waste streams are digested together, scores highest in terms of circularity. Yet contamination risks in Sargassum biomass and sewage sludge limit the use of digestion residues such as digestate in agriculture. Further research is needed to explore how these risks can be reduced.

From problem to resource

The accumulation of floating seaweed currently damages mangroves and seagrass beds, disrupts fisheries and recreation, and can cause health complaints among residents. Since 2018, control efforts have been coordinated by nature organisation STINAPA, using satellite imagery and floating barriers. Managing Sargassum is costly, however, and processing it remains a challenge.

By viewing Sargassum and other organic waste as resources rather than problems, Bonaire could achieve several goals at once, according to the researchers. These include less pollution, more local production, new jobs and a smaller ecological footprint.

Investing in a resilient future

The report concludes that a shift towards circular waste management will only succeed with sufficient investment, clear regulation and close cooperation between government, businesses and residents. Regional cooperation with Curaçao, Aruba and other Caribbean islands could also help to achieve economies of scale.

“Landfilling and waste management are major challenges across the region and in other small island developing states, not just in Bonaire,” says Lopez Contreras. “Circular waste management is an opportunity to make systems more sustainable. It can reduce nuisance in the short term and contribute to a fair, resilient and climate-resilient future for Bonaire. Implementing circular waste processing could serve as an example for other islands in the region.”

The ‘Sustainable and Circular Organic Waste and Sargassum Management on Bonaire’ (in short: BonCirc) project was carried out by Wageningen Food & Biobased Research, Wageningen Social & Economic Research, Wageningen Marine Research, Wageningen Plant Reserch - Field Crops, WEB, SELIBON, LVV, Agriterra, Punta Blanku Chicken Farm and the companies Biobox-E and Together for the Better Good.