Valorisation of agro-industrial by-products, effluents and waste: concept, opportunities and the case of olive mill wastewaters (original) (raw)

A physicochemical–biotechnological approach for an integrated valorization of olive mill wastewater

Bioresource Technology, 2011

An integrated physicochemical-biotechnological approach for a multipurpose valorization of olive mill wastewaters was studied. More than 60% of the wastewater natural polyphenols were recovered through a solid phase extraction procedure, by employing Amberlite XAD16 resin as the adsorbent and ethanol as the biocompatible desorbing phase. Thereafter, the dephenolized effluent was fed to a mesophilic anaerobic acidogenic packed-bed biofilm reactor for the bioconversion of the organic leftover into volatile fatty acids (VFAs). A VFAs concentration of 19 g COD L À1 was obtained, representing more than 70% of the COD occurring in the anaerobic effluent. The biotechnological process was assessed by means of bio-molecular analyses, which showed that the reactor packed bed was mostly colonized by bacteria of the Firmicutes phylogenetic group. The biorefinery scheme developed in this study allowed the obtainment of 1.59 g of polyphenols per liter of wastewater treated and 2.72 g COD L À1 day À1 of VFAs.

Olive mill wastes: Biochemical characterizations and valorization strategies

Process Biochemistry, 2013

The olive mill waste generated from olive oil extraction is a major environmental issue, particularly in Mediterranean areas. The extraction of olive oil is achieved through discontinuous or continuous processes. The two processes yield three fractions: a solid residue and two liquid phases (oil and olive mill wastewater). The characterization of these two by-products showed that they are mainly composed of phenolic compounds, carbohydrates, organic acids and mineral nutrients variably distributed depending on the process employed and the agronomic practices. Untreated olive by-products discharged between November and March into the environment are a major ecological issue for olive oil-producing countries due to their high toxic organic loads, low pH, and high chemical and biological demands. In this context, recent research studies highlight on the treatment approaches and valorization options for dealing with olive mill waste residues, predominantly those allowing for the recovery of valuable natural components such as phenolic compounds, dietary fibers, animal feed, biofuel, biogaz, enzymes, polymers and other. The impact of the chemical heterogeneity and water content of olive mill by-products about these processes of valorization and bioconversion is discussed.

Valorisation of Solid Waste Residues from Olive oil Mills: A Review

The solid waste residues from olive oil mills constitute an environmental threat if disposed of in the natural environment, as it is common practice in many areas. This review summarizes the efforts of the scientific and technical community to develop appropriate technologies for the valorization of these wastes. The majority of the research towards this purpose focuses on the recovery of high-added value compounds, the production of adsorbents, the production of compost or soil amendment products, and applications related to energy generation either through biotechnological processes or through advanced thermal processes.

Valorization of Solid Waste Residues from Olive Oil Mills: A Review

The solid waste residues from olive oil mills constitute an environmental threat if disposed of in the natural environment, as it is common practice in many areas. This review summarizes the efforts of the scientific and technical community to develop appropriate technologies for the valorization of these wastes. The majority of the research towards this purpose focuses on the recovery of high-added value compounds, the production of adsorbents, the production of compost or soil amendment products, and applications related to energy generation either through biotechnological processes or through advanced thermal processes.

Valorization of Lyophilized Olive Mill Wastewater: Chemical and Biochemical Approaches

Sustainability

Lipid composition and antioxidant activity have been carried out in order to valorize the composition of olive mill wastewater extracts with different solvents (supercritical carbon dioxide, n-hexane, dichloromethane and ethanol). The antioxidant activity was evaluated using ABTS (2,2′-azino-bis-(3-ethylbenzothiazoline-6-sulfonic acid)) and DPPH (2,2-diphenyl-1-picrylhydrazyl) tests. The total phenolics and flavonoid contents were, also, determined. The chemical composition of the extracted oil was established, respectively, by gas chromatography–flame ionization detector and high-performance liquid chromatography methods. The results showed that the oleic acid and equivalent carbon number of forty-eight were the major compounds of the analyzed oils. Residual olive mill wastewater from the Sousse region displayed the highest DPPH radical-scavenging activity (31.10 ± 0.10 μg/mL). The chemical analysis of extracts of OMWs showed that the n-hexane fraction contained an abundance of ole...

Olive Mill Wastewater: Treatment and Valorization

Springer Water. Springer, Cham, 2023

For more than 7000 years, olive oil production and consumption have been an established tradition in the Mediterranean area. Due to its great dietary and nutritional value, the olive oil industry is quickly growing across the world. Its manufacturing takes place in two ways: press extraction (the traditional method) and the continuous three-phase decanter process. Olive oil is extracted from the fruit of the olive and mixed with water to create a paste. Water is used in some of these steps to squeeze out most of the oil from the olive. The resulting paste is then mixed to increase the percentage of available oil. Both methods produce approximately (20%) olive oil, (30%) solid waste (olive husk) and 50% olive mill wastewater. This olive mill wastewater has a low pH and contains high toxic organic loads, which makes it a major environmental issue for countries producing olive oil. This chapter discusses the various approaches used for the mitigation of wastewater contaminants produced by the olive oil industry. Recent research studies which focused on the valorization options for dealing with olive mill waste residues such as animal feed, biofuel and biogas are also discussed.

An overview on olive mill wastes and their valorisation methods

Waste Management, 2006

Olive mill wastes represent an important environmental problem in Mediterranean areas where they are generated in huge quantities in short periods of time. Their high phenol, lipid and organic acid concentrations turn them into phytotoxic materials, but these wastes also contain valuable resources such as a large proportion of organic matter and a wide range of nutrients that could be recycled. In this article, recent research studies for the valorisation of olive mill wastes performed by several authors were reviewed: second oil extraction, combustion, gasification, anaerobic digestion, composting and solid fermentation are some of the methods proposed. Special attention was paid to the new solid waste generated during the extraction of olive oil by the two-phase system. The peculiar physicochemical properties of the new solid waste, called two-phase olive mill waste, caused specific management problems in the olive mills that have led to the adaptation and transformation of the traditional valorisation strategies. The selection of the most suitable or appropriate valorisation strategy will depend on the social, agricultural or industrial environment of the olive mill. Although some methods are strongly consolidated in this sector, other options, more respectful with the environment, should also be considered.

New Techniques for Treatment and Recovery of Valuable Products from Olive Mill Wastewater

2018

The olive oil industries produce large quantities of wastewater having an enormous amount of pollutants that provide a deleterious effect on environment drastically if discharged without proper treatment. Despite its treatment throughout the extraction process, this liquid waste still contains a very important oily residue, always considered as a pollutant waste. In this context, a new upgrading technique has been developed for the treatment and valorization of olive mill

Olive oil mill wastewater valorisation by fungi

Journal of Chemical Technology & Biotechnology, 2006

This paper presents a brief survey of studies conducted at the Laboratory of Applied and Environmental Microbiology of the University of Tuscia on the possible biotechnological valorisation of olive mill wastewater (OMW) using fungi. Besides being a serious environmental problem, OMW might be a possible resource owing to the presence of added value products (e.g. antioxidants) and of simple and complex sugars as a basis for fermentation processes. To this end the technical feasibility of various fungal fermentative processes either to obtain products of high added value or to improve its agronomic use has been assessed. With regard to the former aspect the following cases of study are described: production of enzymes, such as lipase by Candida cylindracea NRRL Y-17506, laccase and Mn-dependent peroxidase by Panus tigrinus CBS 577.79 and pectinases by Cryptococcus albidus var. albidus IMAT 4735, and exopolysaccharide production by Botryosphaeria rhodina DABAC-P82. As far as agronomic use of the waste is concerned, a process based on the acidogenic fungus Aspergillus niger NB2 and aimed at increasing the phosphorus content of OMW is also reported.