Biocompost - Life-Environment Project

Composting



	Volteadora

Working volteadora

Treated material

Visiting the composting plant

Volteadora

COMPOSTING PROCESS

The stalks gathered were used for the composting of organic material in the Waste Treatment Plant FERVASA (Quart de Poblet). This plant registered the entry of 363,120 kg of rice stalks in the year 2002 and 978,610 kg in the year 2003, resulting from the gathering and baling following the harvest, for the purposes of the LIFE Biocompost project. This comes to a total of 1,341,730 kg of rice stalks. Previously, the project had already sent a consignment of more than 7 tons of rice stalks (7,680 kg) coming from the inicial tests and used for preliminary trials in the Treatment Plant.

On the completion date of BIOCOMPOST, FERVASA had 840 bales in storage in their facilities, which corresponds to an approximate weight of 270 tons. The remainder, (more than 1,000 tons) has been treated in the composting processes of the project.

The rice stalk was used in two different treatment lines: in heaps and in silos.

Composting in heaps

9,700 tons of green matter (resulting from the separation of the organic fraction from Valencia’s and another 44 municipalities’ USW’ s (Urban Solid Waste) were mixed with 970 tons of rice stalks, used as a structurant, in the ratio of 1:10 with the organic material. The process consisted of leaving the mixture in heaps for 10 weeks, carrying out approximately 45 turns on the rows of material, for which a self-propelled tumbler was used. The mixture weighing more than 10,000 tons underwent a significant loss in mass, which is a normal occurence in the composting process. 35% of the mass was lost in the refining processes and further losses occurred during the decomposing prosess of the composting. In the end, approximately 2,900 tons of compost were obtained. This compost was sent mainly to vineyards in the regions of Utiel, Requena and Godelleta.

Composting in silos

Another consignment of rice stalks was sent to a line where silos were employed in the process, for which 102 tons of rice stalks were used. The stalks were mixed with another 102 tons of sludge from sewage purifying plants, 100 tons of pruning waste (which, similar to the rice stalk serves as a structurant for the mixture) and 36 tons of green matter.

Two silos, measuring 164 m³, were built for the purposes of the LIFE BIOCOMPOST project. They were both built using reinforced concrete with a lower channel for air distribution and the evacuation of lixiviates.

Following the grinding of the rice stalks and mixing it with the sludge, green matter and pruning waste, the material is lined up into heaps. This is where the composting begins. The mixture remains there for 6-8 days with the rows being turned practically on a daily basis. After this first step, it is transported to the silos where it remains between 6-8 days. This is where the moisture is constantly adjusted by irrigating with lixiviates recirculated from the process. The next step consists of the further grinding in lengths of 30 mm and leaving it to mature for 6-8 weeks. The finished compost is then obtained following a final refinement. The quantity of high quality compost produced in this alternative process line was 85 tons, due once again to the customary reduction in mass during composting.