Pathogens Evolution During the Composting of the Household Waste Mixture Enriched with Phosphate Residues and Olive Oil Mill Wastewater

The composting of the household waste mixture enriched with phosphate residues and olive oil mill wastewater was assessed by monitoring the activity of micro-organisms during composting. During the composting process, the mixture exhibited a proliferation of actinomycetes during the thermophilic phase and during the maturation phase. Their quantities range from 11 × 102 UFC/g MF at the beginning of the process to 3.45 × 106 UFC/g MF at the end of the process. The Pseudomeunas aeruginosa and total fungi concentration show also an increase during composting from 0.2 × 106 UFC/g MF and 3.7 × 106 UFC/g MF at the start of composting to a maximun of 4.1 × 106 UFC/g MF, 5.1 × 106 UFC/g MF after 30 days. While other pathogenic microorganisms show a distinct decrease as fecal coliforms decrease from 8 × 106 UFC/g MF to 12 × 103 UFC/g MF; Escherichia coli (E. Coli) from 7.9 × 106 UFC/g MF to 14 × 103 UFC/g MF; Fecal streptococci (S.F) varied from 7.1 × 106 UFC/g MF to 10 × 104 UFC/g MF ; Staphylococcus aureus (Staph) decreased from 5.2 × 106 UFC/g MF to 8 × 104 UFC/g MF; Clostridial spores (SCR) reduced from 6.8 × 106 UFC/g MF to 11 × 103 UFC/g MF at the end of composting. A good relationship could be noted between actinomycetes and available phsosphore, and between total fungi and NTK. The pathogenic bacteria, Staph, SCR, CF, E. Coli, S.F., show more correlations with available organic components T.O.C, O.M., C/N, mainly present in the early phases of composting. The germination test shows that the water-soluble extracts of the initial stages of composting give low germination indices (GI) between 8.18 and 3.20%. After one month of composting, a successive increase of (GI) is observed to reach a maximum of 93.67% for compost after 150 days. These results provide an idea of the quality and maturity of this compost.