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Cuban delegates get a Swedish view of nature-based and decentralized solutions

As part of the InnovaCuba collaboration developed over the past three years between SEI and the Agency for the Environment in Cuba, SEI hosted a Cuban delegation in August 2022. They visited Swedish sites that mix climate change adaptation with a focus on circular value chains for water and the bioeconomy.

Karina Barquet, Ana Calvo / Published on 23 August 2022

InnovaCuba promotes innovation for adaptation to climate change through entrepreneurship in water supply and sanitation in vulnerable coastal areas, with an eye toward fostering a “bioeconomy”. The program is based on two key assumptions.

First, to increase resilience to climate change, a society must increase the level of material circularity in its economy, or in other words, keeping resources from becoming waste. Second, enhanced commitments to higher levels of circularity within the Cuban economy will create more opportunities for local innovation and entrepreneurship.

Recent field visits to locations in Sweden for InnovaCuba partners over the first week of August showed these principles in practice.

InnovaCuba project team visiting Stockholm Royal Seaport (Norra Djurgården).

InnovaCuba project team visiting Stockholm Royal Seaport (Norra Djurgården). Photo: Ana Calvo.

The visit of the Cuban delegation was a perfect opportunity to showcase that the program’s assumptions are not just theory; they are a reality in Sweden, and a reality that does not always need to be high-tech.

Karina Barquet, Senior Research Fellow and InnovaCuba's principal researcher

The director from the Cuban Environmental Agency and experts from other institutes visited the Stockholm Royal Seaport and Trosa’s human-made wetland, two examples of how ecosystem services can be integrated in landscape planning to assist with water management. These sites show how nature-based solutions help city planners manage water flows while promoting wellbeing in urban areas.

While designing the conversion of Stockholm Royal Seaport (Norra Djurgården) from an industrial area into a residential neighbourhood, city planners kept climate change adaptation in mind from the very start. Among the innovative solutions visitors observed during the guided tour were low-lying green areas that catch surface water run-off and stormwater, replacing ditches and pavement to sewers; green spaces for recreation; and “green corridors” that link grass patches and gardens among apartment buildings to help insects to thrive.

Similarly, Trosa, a small coastal town located in the south of the Stockholm region, uses a double treatment system for wastewater: a treatment plant and a human-made wetland. The wetland provides time for sedimentation of small particles and for bacteria to decompose the compounds wastewater contains, thus improving water quality in the river and bay. In addition, the wetland is also used as a recreational area, where town residents can enjoy green spaces close by.

Urban planners can also integrate their cities into the surrounding green spaces and agricultural lands in Sweden by taking into consideration what has been called “brown gold”. Sewage from household toilets contains nitrogen and phosphorous in high amounts, which, when treated and returned to the soil, can help grow agricultural crops.

Wastewater treatment and recycling solutions

Karl-Axel Reimer, the head of unit ecology and water protection for Södertalje municipality, presented Hölö farm to the InnovaCuba visitors. A patented treatment technique allows the farmer to make use of sewage collected from  vacuum toilets in the surrounding areas as a fertilizer.

Sewage from vacuum toilets contains less water than from normal toilets, reducing transport costs. After treatment, the resulting sludge is free from pathogens and can be used on agricultural land safely.

The toilet’s vacuum could be powered by the sun, using solar cells, which was of particular interest in the context of Cuba, where electricity shortages are common. A ship-based solution from Ecobarge also sparked interest because it could be designed to meet specific needs in electrical supply and wastewater treatment for coastal areas around the country.

At a smaller scale, Kiholm community in Södertäjle use so-called dry toilets in every bathroom in the allotment association (koloniförening). The toilets separate urine from faeces, which are collected in septic tanks for treatment offsite. A pipe connects the toilet’s urine collector to a container outside. Neighbours can use a water pump that mixes urine from the outside container with water, in a 4:1 ratio, to water their gardens.

A pipe connects the toilet’s urine collector to a container outside.

A pipe connects the toilet’s urine collector to the container outside. After mixed with water, it is used to water gardens at Kiholm. Photo: Ana Calvo.

Both solutions described above facilitate the upcycling of nutrients back into the soil while providing a wastewater treatment solution for areas disconnected from a centralized wastewater management system. A common challenge is that the transport of sewage water can be inefficient because of its high weight, compared to the low concentration of nutrients per volume.

At the Swedish University of Agricultural Sciences, Professor Björn Vinnerås explained his vision on water sanitation and introduced an innovative solution that tries to address the inefficiency linked to transporting treated sewage to recycle its nutrients back into the soil. After using a urine-diverting toilet with an “urine trap”, urine is then processed through an alkaline treatment and dehydrated to a powder containing high concentrations of nitrogen and phosphorous per volume.

The powder can be used as a long-lasting, dry and easy way to transport fertilizer. In addition to having the potential to reintroduce compounds back into the agricultural system, it could also reduce the costs and dependency on artificial fertilizers in agriculture.

Fly larvae solutions

Another project InnovaCuba visited at the Swedish University of Agricultural Sciences (SLU) showcased larvae of the black soldier fly (Hermetia illucens). The larvae rapidly increase in mass over three weeks. High in proteins and fat content, they make good food for hens and fish – and they eat organic waste.

Although the expertise required for breeding the larvae is high, this solution could both provide income from selling larvae to feed livestock and assist in returning nutrients into the agricultural system. The waste that makes the black soldier fly larvae fat could be organic waste or food that would otherwise go uneaten.

Observing how larvae of the black soldier fly (Hermetia illucens) consumes organic waste at the Swedish University of Agricultural Sciences.

Observing how larvae of the black soldier fly (Hermetia illucens) consumes organic waste at SLU. Photo: Ana Calvo.

Closing the loops with nature-based solutions – whether with human-made infrastructure or animals as intermediaries – could make good sense for treating water and strengthening the bioeconomy in Cuba, as well as in Sweden. The projects visited still need to be expanded to larger scales to make a difference in climate resilience and more. After exploring how nature-based and off-grid solutions can work in practice, the InnovaCuba project could assist in untapping the potential for the future of bioeconomy in Cuba – and perhaps eventually in Sweden as well.


Updated 1 September 2022: The sentence regarding Ecobarge was added. Read more about Ecobarge here:

Written by

Karina Barquet
Karina Barquet

Team Leader: Water, Coasts and Ocean; Senior Research Fellow

SEI Headquarters

Design and development by Soapbox.