New Sogama composting plant in Areosa (Cerceda, A Coruña)

The new Areosa composting plant will have the capacity to produce up to 4,000 tonnes of quality fertiliser for application without restrictions on agricultural land. Over €2.5 million has been invested in the construction of the new facility. The composting plant represents an excellent example of the circular economy and its chief objective is to close the loop for organic waste selectively collected in the municipalities that choose to use its services, thereby contributing to higher recycling rates in Galicia. The contract for the construction of the plant was awarded to FERGO GALICIA, with the GRUPO VALTALIA acting as a subcontractor.

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Technical process

FCC Aqualia central, Inodoro

On arrival at the plant, the materials undergo an initial pretreatment stage, in which recyclable elements that have been deposited erroneously in the brown container (metals, plastics, glass, etc.) are mechanically separated. For this purpose, the facility is equipped with a bag opener supplied by Industrias LEBLAN. This bag opener has a throughput capacity of 35 tonnes/hour and a bag opening efficiency rate of over 95%.

The material is deposited onto a conveyor belt and undergoes magnetic separation by means of a Regulator-Cetrisa electromagnetic overband separator with a belt width of 1,200 mm, which enables the recovery of over 90% of ferrous metals. The organic waste is then unloaded into 3 composting trenches of 35 metres in length, 6 metres in width and 3 metres in height, covered using Bianna Recycling Covertech technology, and spread by means of a semi-automatic trolley system. The trenches are fitted with automatic aeration and irrigation systems to facilitate biological exchanges and the commencement of intensive fermentation. Parameters such as oxygen and temperature are automatically controlled within the trenches, thereby creating optimum conditions to accelerate the decomposition of the organic matter.

Following this first stage, the duration of which is estimated at around 7 weeks, the pre-compost is transferred by wheel loader to the composting building, where it is arranged in the form of piles and turned periodically to facilitate the aeration of the waste mass.

Refining takes place in the following stage, where a trommel screen, supplied by Industrias LEBLAN, removes impurities in order to obtain a compost of optimum quality. The rotary trommel screen has a capacity of 14 tonnes/hour, a diameter of 2.5 metres, a length of 6 metres, and perforations of 10 mm in the first section and 25 mm in the second section. This enables the stream to be divided into 3 fractions, classified in accordance with grain size: a fraction of larger than 25 mm, which is managed as reject and therefore undergoes mechanical or energy recovery; a fraction of between 10 and 25 mm, which gives rise to a product known as coarse compost or mulch, which is suitable for crop protection; and a fraction of less than 10 mm. The latter fraction is deposited on a densimetric table with a capacity of 12 tonnes/hour. This unit has a vibrating table and implements fluidised bed technology to separate light elements from heavy elements by means of air currents and vibration. This enables inert impurities to be separated from the compost. The final fertiliser can be used as an organic soil amendment and has beneficial properties for the protection of agricultural land.

Allgaier Mogensen S.L.U. supplied 2 new FM 150 densimetric tables for the Sogama plant. The objective is to avail of 100% of the bio-stabilized material. These densimetric tables enable the preparation of the heavy inorganic fraction in order to to recover glass, and conditioning of the organic fraction for the generation of energy by means of incineration. The equipment has efficiency rates and uptime of over 98%, which together with more than 30 years of experience, makes Allgaier Mogensen the benchmark for this application.

The plant is equipped with concrete storage units to store the different fractions recovered throughout the process.

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Plant Report published in: #48 FuturENVIRO March 2018