Co-composting with herbal wastes: Potential effects of essential oil residues on microbial pathogens during composting

Abstract

Because of the increasing use of herbal essential oils (EO) in pharmacology, medicine, and food processing, global EO production grows at a rapid rate, generating large amounts of plant residues worldwide. The use of herbal residues for co-composting with various wastes offers a novel option for eco-friendly and cost effective waste management. However, the biologically active compounds remaining in the herb residues may affect microbial activity in the composting biomass, thereby influencing final compost quality. In this review, we summarize and evaluate current literature on the occurrence and survival of pathogens in composts, the beneficial effects of using herbal residues as bulking agents, and the potential antipathogenic effects of six herb species belonging to the Lamiaceae family as follows: lemon balm (Melissa officinalis L.), oregano (Origanum vulgare L.), lavender (Lavandula angustifolia Mill.), rosemary (Rosmarinus officinalis L.), thyme (Thymus vulgaris L.), and sage (Salvia officinalis L.).