Pilot-scale biodegradation of swine manure via Chrysomya megacephala (Fabricius) for biodiesel production

Highlights: • Swine manure was converted into C. megacephala larvae in a pilot scale plant. • Larvae drying method was established to improve the properties of feedstock oil. • The oil components from C. megacephala larvae fed swine manure was reported. • Properties of C. megacephala larvae biodiesel met the EN 14214 standard. - Abstract: Swine manure may cause environmental pollution and resource waste if not handled properly on pig farms. In this paper, the technology for pig manure biodegradation and biodiesel production using Chrysomya megacephala (Fabricius) is described. About 700 kg of fresh pig manure (73% moisture) can be converted within one week into 18.2 kg dried larvae biomass containing about 21.11% oil in a pilot plant. The properties of the oil extracted from the larvae meal treated with three different drying methods were compared, indicating that the drying method may affect the properties of feedstock oil. The acid value (1.9 mg KOH/g), iodine value (86.3 gI/100 g), melt point (3.1 °C) and peroxide value (0.08 meq/kg) of the oil extracted from the larvae treated with both boiling water and oven-drying were superior to the values of the larvae treated with either oven-drying or sun-drying directly. The main fatty acids of the swine manure C. megacephala larvae oil were found to be composed of palmitic acid (36.91%), oleic acid (27.67%), palmitoleic acid (10.89%) and linoleic acid (9.49%). Most of the properties of the biodiesel converted from the feedstock oil by alkaline-catalyst transesterification met the EN 14214 standard in terms of density (0.89 g/cm3), viscosity (5.1 mm2/s), ester content (96.6%), flash point (138 °C), cetane number (56), water content (0.02%) and acid value (0.28 mg KOH/g). This study suggests that the swine manure-grown C. megacephala larvae could be a feasible feedstock for a large-scale biodiesel production