By 2050, it is estimated that around 68% of the global population will live in urban areas[i]. Global urbanisation is increasing the demand for food in urban environments[ii]. Already, urban populations consume up to 70% of all food produced globally[iii]. This demand has sparked a growing interest in innovative ways to grow food in urban spaces. At the beginning of June, I travelled to Brussels, where I attended tours of two urban farms. Both farms are in Cureghem, a district in the municipality of Anderlecht. The area is famous for its historic abattoir, which closed in 2000 but exists today as a food market.
BIGH (Building Integrated GreenHouses) farm was founded in 2015 and is located on the roof of the Foodmet building, a food market and meat hall that is part of the site of the Abbatoirs d’Anderlecht[iv]. BIGH was founded by architect and expert in circular economy Steven Beckers. Not only is BIGH one of the largest rooftop aquaponic farms in Europe with a 2,000m2 greenhouse and a 2,000m2 outdoor vegetable garden[v], but it is also the first circular industrial aquaponic greenhouse on a rooftop. The farm supplies over 180,000 pots of aromatic herbs, 12,000 kilograms of fruits and vegetables such as tomatoes and aubergines, and 20,000 kilograms of rainbow trout each year to supermarkets and restaurants in the area[vi].
Aquaponic farming combines aquaculture (fish farming), and hydroponics (growing plants without soil). Water from the fish tank containing fish waste is pumped into a grow bed. Ammonia and nitrites in the fish waste are broken down by bacteria, creating nitrates that can be absorbed by the plants, acting as a fertiliser[vii]. The plants also clean the water, which is then returned to the fish tank. This farming method is not new and has been used by the Incas and in Chinese rice paddies[viii]. Aquaponics produce a considerably smaller amount of waste than regular fish farming, where wastewater contaminated with ammonia and antibiotics is discharged into nature[ix].
According to Steven, in standard aquaponic systems, including ones that you could start at home, it is usually just the fruit and vegetable produce that is eaten because the recycling of the water means that the fish do not taste very good. BIGH, however, returns very little of the water from the plants to the fish and instead returns condensed steam from the greenhouse back into the tank[x]. BIGH also uses a re-circulating aquaponic system (RAS) with a biofilter that cleans the water every two hours. The RAS uses 100 times less water than conventional open systems[xi]. The fish cannot be fed antibiotics because it would kill the bacteria inside of the biofilter. This also meant that the tour group was not allowed inside the room with the fish in case we passed on any diseases to them.
BIGH has adopted several circular processes. The wasted energy generated from the fridges of Foodmet below is used to power the farm, along with renewable energy from nearby solar panels. Rainwater is also captured and recycled. Finally, carbon dioxide emitted by the fish is recovered and fed into the greenhouse to help the plants photosynthesise[xii].
Bumblebees and insects inside the greenhouses help to pollinate the plants. Along with these insects, particular spaces on the roof are meant to help with biodiversity. Whilst the positive circular economy and biodiversity aspects are exciting, I noted one sustainability drawback: the farm imports thousands of rainbow trout fry each month from a hatchery in Israel to renew its fish population. It is not possible to breed the rainbow trout on site because of the large amount of extra space and technology that would be needed. This transportation process should be considered when looking at the farm’s sustainability as a whole.
The farm also has a social economy labour partnership where local people are employed. Around ten people will be employed in the summer months to help with growing and harvesting. Steven told us how the farm has changed what Cureghem is known for. Whilst residents of the area used to say that they lived next to the abattoir, now they say they live next to BIGH farm.
Despite an ambition to duplicate the BIGH model elsewhere in Belgium and Europe, and there being 60 hectares of rooftops in Brussels that could be used for food-growing urban greenhouses[xiii], BIGH has faced some challenges that limit its expansion. The greenhouse, and therefore rooftop, need to be big enough so that produce can be sold at an industrial scale in order to make a profit. BIGH farm is only just breaking even. Steven told us that in the future, BIGH farm would start to focus on growing aromatic herbs rather than trying to sell tomatoes to a saturated market.
Nearby BIGH, and under the site of Abbatoirs d’Anderlecht, are the Cureghem Cellars. Eclo mushroom farm, founded in 2016 and formerly named ‘Le Champignon de Bruxelles’, rents a third (about 3,000 m2) of this cellar space[xiv]. Eclo grows about 6 tons of king oyster, shiitake, black pearl, and nameko mushrooms each month. This produce is then sold to 300 organic stores and 160 restaurants in Belgium[xv].
Eclo also adopts some principles of the circular economy. Eclo combines waste from organic beer production and industrial bakeries with wood pellets to make the substrate to grow mushrooms in.
The mushrooms are grown in bags containing the substrate. The Eclo factory has various rooms with different temperatures and moisture levels to mimic the seasons. The bags are moved between the rooms during the different stages of mushroom growth. The mushrooms are then harvested directly from the bags. A question that was raised by many on the tour was on the sustainability of the substrate bags, which were made of disposable plastic.
[xii] BIGH- Welcome to BIGH
Gemma recently graduated with a degree in International Development. She is currently studying for an MSc in Sustainable Urbanism, which examines urban planning and urban design through a sustainability lens. “I’m passionate about addressing sustainability challenges in a holistic and pragmatic way. Zero Carbon Academy's diverse range of services targets many of the areas that need support if we are to transition to a liveable future. I’m excited to see the impact that the Academy makes.”