BACKGROUND AND OBJECTIVE: Unsystematic waste and sewage sludge disposal is a major public health threat. Today, the use of easy, inexpensive, and natural treatment such as compost is one of the main priorities for the treatment of these materials.
METHODS: In this experimental study, organic waste samples were prepared from household waste and sludge samples were prepared from municipal sewage treatment plant. Reactors R₁ and R₂ (for compost and vermicompost, waste), and R₃ and R₄ (for compost and vermicompost, waste and sewage sludge mixtures) were selected. Waste and sludge stabilization were evaluated by some indexes such as: (C/N), (VS), (TOC) and (TC), (FC) and (TP) and (TN).
FINDINGS: The level of VS in R₁, R₂, R₃ and R₄ decreased from 89.09, 89.09, 85.29 and 85.29 to 75.58, 64.04, 62.75 and 61.22, respectively. C/N values in R₁, R₂, R₃ and R₄ reached 28.08, 22.48, 21.31, and 18.60 during the process. Fecal coliforms in R₂, R₃ and R₄ decreased by 100, 93 and 99%, respectively. The vermicompost quality in R₂ and R₄ reactors was better than other reactors, but the R₄ reactor reached this condition one week earlier.
CONCLUSION: According to the results of this study, vermicompost reactor containing organic waste and sewage sludge is well-prepared for the high rate stage of composting process. In order to achieve optimal composting conditions in accordance with valid standards, the composting stage should be included in the work plans.