Biodiesel produced from seed oils treated with sanitary effluent

Résumé

Oils from Jatropha curcas L. and Ricinus communis L. can be transformed into biodiesel through the transesterification reaction. The plants J. curcas and R. communis are of great importance in northeastern Brazil and has been considered an alternative energy source to fossil fuels. Wastewater can be used to irrigate these plants as it contains nutrients such as nitrogen and phosphorus. This study aimed to evaluate the productive aspects of fertile Jatropha and Ricinus that has been grown with treated domestic sewage. For the Jatropha were used three systems: an anaerobic digester and filter, an anaerobic filter, and a Upflow Anaerobic Sludge Blanket (UASB) reactor. For the Ricinus was used a UASB reactor, an anaerobic lagoon, polishing tank and 4 drains with the planting of castor. Using these systems, the chemical and biochemical oxygen demands were reduced by 93.6, 91.92, and 94.84%, and 98.2, 91.92, and 92.31%, respectively. The average pH in the three treatment systems was 7.0. The oil content of the Jatropha and Ricinus seeds were of 14 – 35% and 46-70% yield, respectively. The acidity of the Jathopha oil was 18.88 mg KOH/g, with a density of 0.911 g/cm³ and kinematic viscosity of 31.49 cSt and the acidity of Ricinus communis was of 0.0003 mg KOH/g, with a density of 0.940 g/cm³ and kinematic viscosity of 248.65 cSt.  The esters of oleic and linoleic acid constituted 45.83 and 30.60% of the oil of Jatropha and Ricinoleic acid was of 79.9% in composition of fatty acids. These results show that Jatropha oil and Ricinus oil treated with domestic sewage has great potential for biofuel production.