In Brazil, Latin America’s largest country in terms of population, the City of Sao Paulo is committed to recycle organics. In 2015, the City embarked on a journey towards separate collection of organics, thus enabling the production of high-quality compost.
Modern municipal solid waste (MSW) management aims to reduce the amounts of waste disposed to minimise environmental burden. Separate collection and recycling of organic waste can significantly contribute to achieve targets of mitigating short-lived climate pollutants (SLPC) like methane emissions and reducing leachate. In cities that send MSW mainly unsorted to landfills (or dumpsites), the reduction of organic waste through composting represents a key element in waste management, with the additional capability of producing organic fertilisers and renewable fuels
Organic Waste in Sao Paulo
Sao Paulo is a metropolitan city with almost 12 million inhabitants. The MSW management practice currently comprises collection, transportation, and final disposal without any pre-treatment into two sanitary landfills with biogas capture. But even with a state of art landfill design, incorporating capture of biogas, substantial amounts of methane will still escape to the atmosphere and contribute to global warming.In 2014, less than 2 per cent of MSW was separately collected and recycled.
The potential for organics recycling is there: while in EU cities organic waste represents 25-35 per cent of all MSW, in the case of Sao Paulo the amount comprises 51 per cent, or 6,600 tons per day. Thus, diverting organic waste from disposal can help Sao Paulo in achieving significant recycling rates and reducing SLCPs. Furthermore, these amounts of organics could potentially be transformed into approximately 700,000 tons of compost or 290 million cubic metres of biogas annually. This amount would be sufficient for the needs for cooking and heating for about 500,000 households.
The Strategy for Organic Waste
The City’s 2012 Master Plan for MSW, Planes de gestión integral de residuos sólidos (PGIRS), specifically aims to reduce waste disposal by enhancing separate collection and recycling. The strategy for the diversion of organic waste was developed considering three main pillars that need to interact efficiently:
- Prioritise separate collection of organic waste that, once collected, will be sent to recycling at biological treatment plants; the PGIRS aims to gather up to 70 per cent of all organic waste produced
- Gradual realisation of treatment and recycling facilities for organic waste, including composting and mechanical biological treatment (MBT) facilities
- Overarching and continuous communication activities to raise awareness about the importance of organic waste
There are significant challenges when implementing such an ambitious strategy. They include the lack of participation in separate collection, the “NIMBY” effect local authorities face when searching for locations for composting facilities, and the need to raise awareness about the role and the importance of recycling organic waste among the population. Let’s see what Sao Paulo is doing to put the strategy into practise.
From Strategy to Practise
As a first step, the City launched the Composta Sao Paulo initiative to promote home-composting on a voluntary basis. The initiative has been immensely successful: by 2015, about 5,000 families practiced home-composting regularly, and today more than 10,000 participate in the online platform for Paulistanos,people who compost at home.
The second steps focused on students. There are about 1,100 municipal schools in Sao Paulo; working on and talking about waste management in schools is an excellent way to teach young citizens about the possibilities to prevent waste generation and to recycle. An initiative addresses the recycling of organic waste at schools; the online platform Escolas Mais Orgânicas was launched to acquire data about organic waste management and to enable exchange among the participating schools. Based on these results, in 2016 a handbook on home-composting in schools was realised to support teachers in Sao Paulo who intend to practise composting.
As a next step,Sao Paulo opted to collect organic waste from large producers and to recycle organics at local, small-scale, low tech composting facilities. There are almost 900 street markets, 69 parks, 3,900 squares and green areas in Sao Paulo that produce up to 120,000 tons of organic waste per year. Thus, in 2015, the City started to collect fruit, vegetable, and green waste at street markets located in the Lapa District.
Meat, fish, and cooked food are excluded from collection and treatment to avoid odour emission and potential problems during the composting process, which relies on a low-tech approach without forced ventilation or mechanical turning devices. Organic waste is collected using compostable plastic bags, preventing compost from contamination of otherwise commonly used conventional plastics which only breaks down into smaller pieces physically. Organic waste from the City’s green spaces, delivered by the public maintenance services, are also accepted.
During the same time, the first pilot-plant for composting organic waste was realised in Lapa. The effectiveness of the initiative and the good quality of the compost produced at the Lapa facility lead to the creation of 5 more facilities currently in place, recycling about 15,000 tons of organic waste each year. By 2020, the number will rise to 17 plants.
Windrow composting in Sao Paulo © Marco Ricci
Lessons Learned, Next Steps to be Taken
The experience of Sao Paulo confirms that a clean “feedstock” is needed for obtaining high-quality compost, a product that can be marketed and re-used as organic fertiliser. Collecting organic waste separately at source represents the first step and plays a pivotal role in reducing contamination of organic waste through plastics, glass, and other non-degradable materials.
The decision to realise small-scale composting facilities first allows for the local population to get closer to the production of compost. Composting plants thus act as permanent awareness initiatives; facilities are regularly visited by schools, local authorities, and people interested in gardening and compost use. Today, the facility at Lapa also hosts a plant nursery.
The strategy for Sao Paulo includes the realisation of a set of medium to large-scale composting (or biogas) facilities in the near future, so to manage larger amounts of organic waste. A pilot scheme for collecting organic waste at households has been prepared in 2016 and is planned to be implemented in the near future.
In the long term, these measures will significantly mitigate environmental impacts of current MSW management. As shown in Sao Paulo, all revolutions start with small initiatives that are able to change our daily habits.