Co-composting of Olive Mill Waste and Wine-Processing Waste: An Application of Compost as Soil Amendment

Hindawi Journal of Chemistry Volume 2018, Article ID 7918583, 9 pages https://doi.org/10.1155/2018/7918583 Research Article Co-composting of Olive Mill Waste and Wine-Processing Waste: An Application of Compost as Soil Amendment Z. Majbar ,1 K. Lahlou,1 M. Ben Abbou,2 E. Ammar,3 A. Triki,4 W. Abid,3 M. Nawdali,5 H. Bouka,2 M. Taleb,1 M. El Haji,6 and Z. Rais1 1 Laboratory of Engineering, Electrochemistry and Modeling Environment (LEEME), Faculty of Sciences, Fez, Morocco Laboratory of Natural Resources and Environment, University Sidi Mohammed Ben Abdallah, Faculty Polydisciplinary, Taza, Morocco 3 Research Unity: Urban and Costal Environments, University of Sfax, National Engineering School of Sfax, Sfax, Tunisia 4 Research Laboratory: Improvement and Protection of Olive Tree Genetic Resources, Institute of the Olive Tree, Sfax BP1087, Tunisia 5 Laboratory of Chemistry of Condensed Matter (LCCM), University Sidi Mohammed Ben Abdallah, Faculty of Sciences and Technology, Fez, Morocco 6 Laboratory Engineering Research-OSIL Team Optimization of Industrial and Logistics Systems, University Hassan II, Superior National School of Electricity and Mechanic (ENSEM), Casablanca, Morocco 2 Correspondence should be addressed to Z. Majbar; Received 4 May 2018; Revised 22 July 2018; Accepted 8 August 2018; Published 23 September 2018 Academic Editor: Gassan Hodaifa Copyright © 2018 Z. Majbar et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. In order to decrease the environmental harm produced by the agro industries’ wastes’, an investigation of the co-composting of olive mill waste (olive mill wastewater (OMW), olive mill sludge (OMS)) and wine by-products (grape marc and winery wastewater) was done. Three aerated windrows of variable compositions were performed; these windrows differ in terms of their initial composition and the liquid used for their humidification; OMW and wastewater winery were used for humidification to replace water for windrow moistening. Moreover, the main physicochemical parameters (temperature, pH, electrical conductivity, and C/N) were monitored to evaluate the co-composting process. The latter lasted around three months. The elaborated composts were characterized by low C/N ratio, and they were rich in fertilizing and nutriment elements and of low heavy metal contents. The humidification of the windrows with OMW showed effectiveness in improving the windrows temperature, reflected by the high temperatures monitored during the composting process in comparison with the windrow humidified with winery wastewater. Furthermore, a longer thermophilic phase was held in windrows carrying OMS. The valorization of the produced composts for soil amendment significantly improved the soil fertility. Indeed, field experiments showed an increase in radish yield by 10%, the composts were harmless and did not have any phytotoxic effect on radish growth. 1. Introduction The activity of the agro-food industries causes a lot of harm to environment due to the production of huge amounts of waste. In Morocco, the industrial sector generates yearly more than 1.2 million tons of wastes, among which the agrofood industry represents 67% [1]. Consequently, the management and the valorization of these harmful residues are necessary for the environment’’s preservation. The olive oil extraction is an important activity that generates a huge amount of effluent, namely, olive mill wastewater, estimated to 400 000 m3 per year [2]. The OMW is an acidic and dark liquid effluent, with a high organic matter load and high conductivity [3, 4]; its composition varies both qualitatively and quantitatively according to the olive variety, climate condition, cultivation and harvesting practices, the olive storage time, and the olive oil extraction system [3]. 2 In Morocco, the OMW management practice regulated and adopted by the majority of olive oil industries is the storage in evaporation ponds. However, this technique does not reduce the OMW toxicity since large quantities of olive mill sludge (OMS) are produced. These huge quantities represent a significant problem in olive oil industries; therefore, more effective solutions must be developed to remedy this problem. The wine industry is another activity that generates significant quantity of waste; this activity produces large amount of by-products that are represented by solid organic residues (grape marc) and wastewater. The production of one hectoliter of wine produces 18 kg of grape marc [5], which gives an annual production of 7200 tons [6]. Still, the quantity of wine wastewater depends largely on the process used in the industry. The different residues from the wine industry are characterized by low pH and electrical conductivity and high organic matter content [7]. The richness of these by-products in organic matter allows their use for soil fertility improvement [8, 9]. The direct incorporation of these residues could cause serious environmental problems if they are added excessively to the soil in an uncontrolled manner. Consequently, their treatment is crucial before their discharge or use for agricultural purposes. The suitable management of these agro-food wastes is an important strategy for the environment protection. Many investigations have focused on the study of treatment and valorization techniques of these residues at an experimental scale [10–16]. At the industrial level, the treatment of these residues is rare, and the problem of all the available wastes has not yet been solved. Recently, researchers have shown that composting is one of the effective alternatives for the recycling and the valorization of organic wastes [8, 17–22]. It is a degradation process of the organic matter, allowing the achievement of a stable product, rich in humic substances and in fertilizing elements, serving as soil organic amendment [23–25]. The application of compost can have strong ecological environmental values, allowing not only the removal of very expensive chemical fertilizers but also the improvement of the quality of agricultural soils and carbon sequestration [8, 9, 26]. Diverse studies had developed composting of organic waste, such as OMW [19, 24, 27–30], sludge from wastewater treatment [31], and agro-industrial waste [32]. While other studies on the co-composting of olive mill wastewater with poultry manure [25, 27, 33], olive mill wastewater with solid organic waste [20, 34], and date palm with activated sludge [35] have been carried out. The evaluation of the composting process and the study of its environmental impact due to gas emissions have also been the subject of numerous studies [35–38]. Considering the fact that co-composting olive oil waste (OMW and OMS) and wine industry have not gained much attention in previous studies; the aims of this work are as follows: (...truncated)