One Step Bioremediation of Olive-Oil-Mill Waste by Organoinorganic Catalyst for Humics-Rich Soil Conditioner Production

Abstract

A new, simple, and rapid one-step integrated method for the biotechnology treatment of raw olive oil mill waste (OMW) is discussed. The innovations introduced involve primarily the application of microaerobic composting processes for OMW bioremediation plus the addition of both a zeolite and a tailor-made biocatalyst extremely rich in soil microorganisms. The latter operates at a wide pH range and provides, apart from soil microorganisms, nutrients to the compost, enhancement to the bio-oxidative phase and acceleration of biochemical reactions during bioremediation. The basic parameters affecting the bioprocess, i.e., electrical conductivity, pH, C/N ratio, specific weight, ash, organic matter, total organic carbon, total Kjeldahl nitrogen, microorganisms, humic substances, and total polyphenols, were monitored systematically to provide insight into the process and evaluate the product obtained. After a biotreatment of just 60 d, a significant reduction in polyphenols (91.4%) and an increased humic substances content (8%)—both serving as maturation indices—were observed. The OMW compost received is stable, free of toxic compounds and pathogens, affords a richness in cenose and a high humic substances content, both vital for soil fertility. Applications of the OMW product received, both in laboratory-scale and field cultivations, confirm its suitability as a first-class soil conditioner for organic farming.