Cocomposting of Olive Mill Wastewater with Manure and Agro-industrial Wastes

Abstract

The use of olive mill wastewater (OMW) for composting was studied by the addition of this liquid waste to a mixture of olive husks, poultry manure and confectionery wastewater. The composting process was compared with that of another pile of similar composition, but without olive mill wastewater. In order to study the effects of both composts on plant yield and soil properties, a field experiment was carried out with potato. Three amendments were applied: manure and two composts with same rate 30 tonnes/ha. The olive mill wastewater addition produced compost with higher organic matter concentrations and higher electrical conductivity, and a stabilized and humified organic matter lower than the compost produced without olive mill wastewater. The olive mill wastewater compost application to soil did not injure plants, producing a similar plant yield to both compost without olive mill wastewater and manure. The olive mill wastewater compost application to soil also improved the chemical and physicochemical properties of the soil mainly fertilizing elements such as calcium, magnesium, nitrogen, potassium and phosphorus. With respect to potato yield, both composts showed higher plant production in comparison to manure, reaching a potato yield of 46 and 47 t/ha in amended soil with compost with and without OMW, respectively.