Nutrient recovery from olive by-products through vermicomposting with Eisenia andrei

Lombrics

Barhoum Kharbouch, Hicham Lakhtar, Sandrine Amat, Sevastianos Roussos, Claude Perissol, Steven Criquet, Nathalie.Dupuy_, Abdelhamid El Mousadik

In this study, Eisenia andrei potential for detoxification of the olive by-products was evaluated. A standard mixture containing 600 g of olive pomace (OP), 300 g of horse manure and 100 g of wheat straw was imbibed by various olive mill wastewater (OMW) ratios (0%, 10%, 25% and 50%) to prepare four mixtures (M1, M2, M3 and M4 respectively), then inoculated with adult earthworms. The biological parameters related to earthworm’s biomass gain and reproduction rate were better in the mixture M1 which used as control mixture (10.7 mg worm^-1 day^-1 and 0.17 cocoons worm^-1 day^-1 respectively) followed by M2 and M3. When OMW ratio exceeded 50% of OMW (M4), mortality of earthworm occurred after 7 days of incubation. The reduction of phenol concentration was higher in mixture M1 (91%) compared to other mixtures (M2: 72%, M3: 54%). The C/N ratio decreased in all mixtures to reach values ​​between 17 and 22 at the end of vermicomposting process. The phytotoxicity test revealed that the overall germination index was greater than 80% in M1, M2 and M3, which showed that vermicompost produced can be used as organic amendment for biological and sustainable agriculture.