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General comment The maximum processing capacity of the processing unit = 30 tons of CCV (green coconut shell) / day, generating 20 m³ of LLCV (green coconut shell liquid), therefore, the inventory was calculated for processing 30 tons, producing 443m³ of biogas an 203,67 m³ biomethane and 13m³ of other gases .
The LCCV has in its composition, fermentable sugars, phenolic compounds, cations (calcium, magnesium, potassium and sodium) and anions (chloride, bicarbonate and sulfate), besides high values of COD and BOD that indicate the need for adequate treatment for the wastewater generated in the process of green coconut shell processing (GCR).
The LCCV is the result of pressing (by compression cylinders) after the coconut shell is crushed. The main emissions of this effluent, considering 30% production in relation to the initial amount of CCV are: BOD (12.36 g/L), COD (19.5±3.0 g/L), total tannins (1.785 ± 0.51g/L), total sugars (13.53g/ L), ammonia (0.225 g/L), nitrite (0.012 g/L), nitrate (0, 021 g/L), total phosphorus (0.039 g/L), total solids (15.59 ± 0.6 g/L), total inorganic solids (1.86 ±0.2 g/L), total volatile solids (14.73±0.5 g/L).
The captured LCCV was processed in the Biomass Laboratory at Embrapa Agroindustry Tropical, using a pilot-scale UASB (Upflow Anaerobic Sludge Blanket) reactor built with PVC pipes, with a working volume of 16.8 L, height of 1.95 m, and internal diameter of 0.1 m.
In the biomethane production process, from 20 m3 of LCCV, nutrients considered necessary for greater efficiency of production were added to the reactor. The nutrients added were ammonium chloride (13.4 kg), dipotassium phosphate (12Kg) ammonium sulfate (4.8kg) calcium chloride dihydrate (0.5 kg), iron dichloride tetrahydrate (0.096 kg), boric acid (0.002 kg), zinc chloride (0.002 kg), copper chloride dihydrate (0, 002 kg), manganese (ii) chloride tetrahydrate (0.0024 kg) ammonium molybdate tetrahydrate (0.002 kg), aluminum chloride hexahydrate (0.004 kg), cobalt chloride hexahydrate (0.0096 kg), sodium hydroxide (10 kg), ammonia (10kg).
The process of obtaining biogas from 20m3 of LCCV emits 310 m3 of methane, 120 m3 of carbon dioxide, 13 m3 of other gases and 0.072 m3 of total sludge solids.
A UASB reactor, operated at an organic loading rate of 10 kg COD (chemical oxygen demand) / m3, a hydraulic retention time of 156 h, can remove 80% of the COD and 78% of the total tannins from CCV producing 19.4m3 of biomethane per cubic meter of CCV per day.
The total amount of energy spent to process 20 m3 of LCCV was 618.1 kWh
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