Psychosocial study

In order to assess the impact of odours in the vicinity of the Organic Treatment and Recovery Plant (ETVO), various studies were carried out in accordance with the integrated strategic odour elimination plan defined by Valorsul. As part of this, a psychosocial study was carried out to assess the discomfort caused by odours in the population surrounding the ETVO and to identify any socio-economic factors that could bias the results.
The study concludes that around 56 per cent of residents in the research area do not experience any discomfort related to the occurrence of bad smells. Only 12% of residents say they perceive odours coming from the ETVO, but this situation is considered tolerable in all areas, with the exception of the Alto dos Moinhos area, where there is moderate discomfort, which is nevertheless classified as acceptable. It should be noted that in that area it was found that around half of the complaints were due to odours from solid waste collection.

In summary, the paper concludes that the measures implemented by Valorsul to eliminate odours from the ETVO and reduce the nuisance to the local population have a small-scale effect, since there are other factors such as noise from power lines and odours from solid waste collection that also need to be minimised/eliminated by the responsible entities.

Keen Sense’ Programme

At the same time, the ‘Refined Sense’ programme was also developed. This consists of a group of citizens who live near the ETVO perimeter and have the voluntary task of reporting odours whenever they are detected and believe they are coming from ETVO. To do this, the volunteers receive training and a card with a personal code and a contact number to send an SMS to whenever a bad odour is detected.

Air treatment
With regard to controlling odour emissions, the plant has an exhaust air extraction and treatment system designed to treat the air collected in the plant's various process areas, including the air coming from the various pieces of equipment that release odours. The extracted air is treated in two biofilters, one closed and the other open (the latter is previously acid washed using a scrubber to ensure the removal of ammonia). There is also independent equipment for neutralising odours as a complement to the above treatment.

The Phyto-Remediation Forest
In order to minimise the possible odours emanating from the facility, Valorsul drew up a project to upgrade the surroundings of the facility.
Through a Landscape Architecture Intervention for the surrounding areas, a ‘Phyto Remediation Forest’ was created to reduce the undesirable effects of the odours emitted. The 43,012 square metres were specially afforested.
Using nature itself to preserve the environment is the basic principle we intend to use, preferably using vegetation that is resistant to the main polluting agents, to create a vegetation barrier that minimises the harmful effects of the unpleasant odours that come from the process of working organic waste in the composting process at the plant.

The term ‘phytoremediation’ refers to the use of plants alone or in association with microorganisms to contain or stabilise various environmental contaminants. Plants remove many pollutants from the air, such as NOx, SOx and FLOx. The Phyto Remediation Forest has around 1,455 trees, individually installed in tree pits reinforced with garden soil, properly drained and watered by a programmable drip irrigation system.
In addition to its phyto-remedial functions in minimising odours, this forestry intervention has contributed to Amadora's Municipal Afforestation Plan (where 100,000 trees are to be planted), with the approximate sequestration of around 4.74 tonnes of CO2 per year.