Olive mill wastewater treatment: an experimental study

Olive oil production, one of the main agro-industries in Mediterranean countries, generates significant amounts of olive mill wastewaters (OMWs), which represent a serious environmental problem, because of their high organic load, the acidic pH and the presence of recalcitrant and toxic substances such as phenolic and lipidic compounds (up to several grams per litre). In Italy, traditional disposal on the soil is the most common way to discharge OMWs. This work is aimed at investigating the efficiency and feasibility of AOPs and biological processes for OMW treatment. Trials have been carried out on wastewaters taken from one of the largest three-phase mills of Italy, located in Quarrata (Tuscany), as well as on synthetic solutions. Ozone and Fenton's reagents applied both on OMWs and on phenolic synthetic solutions guaranteed polyphenol removal efficiency up to 95%. Aerobic biological treatment was performed in a batch reactor filled with raw OMWs (pH =4.5, T=30 °C) without biomass inoculum. A biomass rich of fungi, developed after about 30 days, was able to biodegrade phenolic compounds reaching a removal efficiency of 70%. Pretreatment of OMWs by means of oxidation increased their biological treatability.

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Olive mill wastewater biological treatment by fungi biomass

Water Science & Technology ◽

10.2166/wst.2007.311 ◽

2007 ◽

Vol 55 (10) ◽

pp. 89-97 ◽

Cited By ~ 5

Author(s):

S. Caffaz ◽

C. Caretti ◽

M. Morelli ◽

C. Lubello ◽

E. Azzari

Keyword(s):

Phenolic Compounds ◽

Olive Oil ◽

Biological Treatment ◽

Batch Reactor ◽

Food Industries ◽

Olive Mill Wastewaters ◽

Biomass Activity ◽

The One ◽

By Products ◽

Olive Mill

Olive oil extraction is one of the most important traditional food industries in the Mediterranean region, especially in Italy. In addition to olive oil, this industry produces by-products, in particular olive mill wastewaters (OMWs) and olive husks, which represent a serious environmental problem. OMWs can be rarely treated in a municipal WWTP, using conventional wastewater treatments. A novel biological process has to be considered in order to treat OMWs. Literature data show that yeasts and different kinds of fungi are able to reduce both the organic and the phenolic content of the OMW. The present work is aimed at investigating the growth of a biomass rich in fungi in a batch reactor filled with OMW and its capacity to degrade the organic and phenolic load. The aerobic OMW degradation obtained using this biomass reached a COD and TP removal efficiency of 86 and 70%, respectively. Respirometric tests have been carried out in order to measure the biomass activity on different substrates: OMW and phenolic compounds (gallic and p-coumaric acids). The polyphenolic biodegradation efficiency of fungi biomass was higher than the one of a non-acclimated activated sludge biomass. Fungi biomass was able to completely degrade pure phenolic compounds.

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SBR treatment of olive mill wastewaters: dilution or pre-treatment?

Water Science & Technology ◽

10.2166/wst.2012.068 ◽

2012 ◽

Vol 65 (9) ◽

pp. 1684-1691 ◽

Cited By ~ 2

Author(s):

G. Farabegoli ◽

A. Chiavola ◽

E. Rolle

Keyword(s):

Biological Process ◽

Batch Reactor ◽

Oxygen Demand ◽

Adequate Treatment ◽

Olive Mill Wastewaters ◽

Other Substances ◽

Removal Efficiencies ◽

Pre Treatment ◽

Olive Mill ◽

Gac Adsorption

The olive-oil extraction industry is an economically important activity for many countries of the Mediterranean Sea area, with Spain, Greece and Italy being the major producers. This activity, however, may represent a serious environmental problem due to the discharge of highly polluted effluents, usually referred to as ‘olive mill wastewaters’ (OMWs). They are characterized by high values of chemical oxygen demand (COD) (80–300 g/L), lipids, total polyphenols (TPP), tannins and other substances difficult to degrade. An adequate treatment before discharging is therefore required to reduce the pollutant load. The aim of the present paper was to evaluate performances of a biological process in a sequencing batch reactor (SBR) fed with pre-treated OMWs. Pre-treatment consisted of a combined acid cracking (AC) and granular activated carbon (GAC) adsorption process. The efficiency of the system was compared with that of an identical SBR fed with the raw wastewater only diluted. Combined AC and GAC adsorption was chosen to be used prior to the following biological process due to its capability of providing high removal efficiencies of COD and TPP and also appreciable improvement of biodegradability. Comparing results obtained with different influents showed that best performances of the SBR were obtained by feeding it with raw diluted OMWs (dOMWs) and at the lowest dilution ratio (1:25): in this case, the removal efficiencies were 90 and 76%, as average, for COD and TPP, respectively. Feeding the SBR with either the pre-treated or the raw dOMWs at 1:50 gave very similar values of COD reduction (74%); however, an improvement of the TPP removal was observed in the former case.

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Treatment of Effluents from Hemp-Based Pulp and Paper Industry II. Biological Treatability of Pulping Effluents

Water Science & Technology ◽

10.2166/wst.1994.0469 ◽

1994 ◽

Vol 29 (9) ◽

pp. 165-168 ◽

Cited By ~ 14

Author(s):

Celai F. Gökçay ◽

Filiz B. Dilek

Keyword(s):

Phanerochaete Chrysosporium ◽

Removal Efficiency ◽

Batch Reactor ◽

Paper Industry ◽

Pulp And Paper Industry ◽

Pulp And Paper ◽

Colour Removal ◽

High Concentrations ◽

Biological Treatability

This paper is focussed on the biological treatability studies of pulping effluents from a hemp-based pulp and paper industry. Experiments were conducted by using white fungus, Phanerochaete chrysosporium, in a laboratory batch reactor. It was found that the colour removal efficiency is 75% for pulping effluents in the presence of high concentrations of glucose.

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Detoxification of Olive Mill Wastewaters by Fenton’s Process

Catalysts ◽

10.3390/catal8120662 ◽

2018 ◽

Vol 8 (12) ◽

pp. 662 ◽

Cited By ~ 14

Author(s):

Eva Domingues ◽

João Gomes ◽

Margarida Quina ◽

Rosa Quinta-Ferreira ◽

Rui Martins

Keyword(s):

Process Integration ◽

Combined Treatment ◽

Organic Load ◽

Strong Impact ◽

Water Recovery ◽

Solid Catalysts ◽

Olive Mill Wastewaters ◽

Sea Area ◽

Olive Mill ◽

Fenton's Process

Olive mill wastewaters (OMW) constitute an environmental problem affecting mainly Mediterranean Sea area countries where the olive mill industry is a very important economic sector. The strong impact and management issues of these effluents are mainly due to their seasonality, localized production, and high organic load with high toxic features and low biodegradability. As the olive oil industry is highly water demanding, the search for suitable water recovery strategies requires the development and optimization of advanced treatment technologies. The classical Fenton’s process is an interesting alternative, as it operates at room conditions of pressure and temperature. However, it shows some drawbacks, such as the generation of iron sludges, which require further management. Nevertheless, because of its features that make it industrially desirable, overcoming these limitations has been the focus of researchers in the last years. Bearing this in mind, this paper focuses on the recent research regarding OMW treatment using Fenton’s process. The use of Fenton’s peroxidation treatment at homogenous, heterogeneous, and photo-aided conditions is analysed. The use of solid catalysts may be an interesting way to avoid sludge formation. Light-driven Fenton can also reduce the amount of iron needed for effective degradation. Moreover, Fenton’s process integration in combined treatment schemes is discussed. Finally, remarks regarding its application at full scale are given.

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Pilot-plant results of the electro-Fenton treatment of olive mill wastewaters followed by anaerobic digestion

Water Science & Technology ◽

10.2166/wst.2007.415 ◽

2007 ◽

Vol 55 (12) ◽

pp. 259-265 ◽

Cited By ~ 3

Author(s):

S. Khoufi ◽

F. Feki ◽

F. Aloui ◽

S. Sayadi

Keyword(s):

Anaerobic Digestion ◽

High Energy ◽

Water Recovery ◽

Combined Process ◽

Integrated Technology ◽

Mediterranean Countries ◽

Olive Mill Wastewaters ◽

Pre Treatment ◽

Treatment Step ◽

Olive Mill

In this work, we investigated an integrated technology for the treatment of the recalcitrant contaminants of olive mill wastewaters (OMW), allowing water recovery and reuse for agricultural purposes. The method involves an electrochemical pre-treatment step of the wastewater using the electro-Fenton reaction followed by an anaerobic bio-treatment. The electro-Fenton pre-treatment process removed 66% of the total polyphenolic compounds and subsequently decreased the OMW toxicity from 100 to 66.9% which resulted in improving the performance of the anaerobic digestion. A continuous lab-scale methanogenic reactor was operated at a loading rate of 10 g COD/L day without any apparent toxicity. Furthermore, in the combined process, a high overall reduction in COD, suspended solids, polyphenols and lipids content was achieved by the two successive stages. Moreover, this combined process which was experimented at a real scale (25 m3 digester), demonstrated its technical feasibility and opens promising perspectives for industrial application in the Mediterranean countries due to its easy conception and its high energy (methane) production.

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Effect of hot acid hydrolysis and hot chlorine dioxide stage on bleaching effluent biodegradability

Water Science & Technology ◽

10.2166/wst.2007.210 ◽

2007 ◽

Vol 55 (6) ◽

pp. 39-46 ◽

Cited By ~ 3

Author(s):

C.M. Gomes ◽

J.L. Colodette ◽

N.R.N. Delantonio ◽

A.H. Mounteer ◽

C.M. Silva

Keyword(s):

Acid Hydrolysis ◽

Chlorine Dioxide ◽

Biological Treatment ◽

Kraft Pulp ◽

Sequencing Batch Reactor ◽

Batch Reactor ◽

Organic Load ◽

Activated Sludge System ◽

Eucalyptus Kraft Pulp ◽

Complete Sequences

The hot acid hydrolysis followed by chlorine dioxide (A/D*) and hot chlorine dioxide (D*) technologies have proven very useful for bleaching of eucalyptus kraft pulp. Although the characteristics and biodegradability of effluents from conventional chlorine dioxide bleaching are well known, such information is not yet available for effluents derived from hot acid hydrolysis and hot chorine dioxide bleaching. This study discusses the characteristics and biodegradability of such effluents. Combined whole effluents from the complete sequences DEpD, D*EpD, A/D*EpD and ADEpD, and from the pre-bleaching sequences DEp, D*Ep, A/D*Ep and ADEp were characterized by quantifying their colour, AOX and organic load (BOD, COD, TOC). These effluents were also evaluated for their treatability by simulation of an activated sludge system. It was concluded that treatment in the laboratory sequencing batch reactor was efficient for removal of COD, BOD and TOC of all effluents. However, colour increased after biological treatment, with the greatest increase found for the effluent produced using the AD technology. Biological treatment was less efficient at removing AOX of effluents from the sequences with D*, A/D* and AD as the first stages, when compared to the reference D stage; there was evidence of the lower treatability of these organochlorine compounds from these sequences.

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Pilot-plant results of the electro-Fenton treatment of olive mill wastewaters followed by anaerobic digestion

Water Science & Technology ◽

10.2166/wst.2007.384 ◽

2007 ◽

Vol 55 (12) ◽

pp. 67-73 ◽

Cited By ~ 2

Author(s):

S. Khoufi ◽

F. Feki ◽

F. Aloui ◽

S. Sayadi

Keyword(s):

Anaerobic Digestion ◽

High Energy ◽

Water Recovery ◽

Combined Process ◽

Integrated Technology ◽

Mediterranean Countries ◽

Olive Mill Wastewaters ◽

Pre Treatment ◽

Treatment Step ◽

Olive Mill

In this work, we investigated an integrated technology for the treatment of the recalcitrant contaminants of olive mill wastewaters (OMW), allowing water recovery and reuse for agricultural purposes. The method involves an electrochemical pre-treatment step of the wastewater using the electro-Fenton reaction followed by an anaerobic bio-treatment. The electro-Fenton pre-treatment process removed 66% of the total polyphenolic compounds and subsequently decreased the OMW toxicity from 100 to 66.9%, which resulted in improving the performance of the anaerobic digestion. A continuous laboratory-scale methanogenic reactor was operated at a loading rate of 10 g COD/L per day without any apparent toxicity. Furthermore, in the combined process, a high overall reduction in COD, suspended solids, polyphenols and lipids content was achieved by the two successive stages. Moreover, this combined process which was experimented at a real scale (25 m3 digester) demonstrated its technical feasibility and opens promising perspectives for industrial application in the Mediterranean countries because of its easy conception and high energy (methane) production.

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Olive Mill and Olive Pomace Evaporation Pond’s By-Products: Toxic Level Determination and Role of Indigenous Microbiota in Toxicity Alleviation

Applied Sciences ◽

10.3390/app11115131 ◽

2021 ◽

Vol 11 (11) ◽

pp. 5131

Author(s):

Houda Ben Slama ◽

Ali Chenari Bouket ◽

Faizah N. Alenezi ◽

Ameur Khardani ◽

Lenka Luptakova ◽

...

Keyword(s):

Olive Oil ◽

Oil Extraction ◽

Soil Toxicity ◽

Mediterranean Countries ◽

Three Phase ◽

Indigenous Microbiota ◽

Recalcitrant Waste ◽

By Products ◽

Olive Mill

Diverse vegetable oils are extracted from oleagenic trees and plants all over the world. In particular, olive oil represents a strategic socio-economic branch in the Mediterranean countries. These countries use either two or three-phase olive oil extraction systems. In this work, we focus on the by-products from three-phase olive oil extraction, which are the liquid olive mill wastewater (OMW) and the solid olive mill pomace (OMP) rejected in evaporative ponds. The disposal of this recalcitrant waste poses environmental problems such as the death of different species of insects and animals. In-depth ICP-OES analysis of the heavy metal composition of OMW and OMP revealed the presence of many metals ranging from non-toxic to highly toxic. The LC-HRMS characterization of these by-products indicated the presence of several secondary metabolites harmful to humans or to the environment. Thus, we aimed to identify OMW and OMP indigenous microbiota through metagenomics. The bacterial population was dominated by the Acetobacter (49.7%), Gluconobacter (17.3%), Gortzia (13.7%) and Nardonalla (5.3%) genera. The most abundant fungal genera were Nakazawaea, Saccharomyces, Lachancea and Candida. These microbial genera are responsible for OMW, OMP and soil toxicity alleviation.

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Fundamentals and Technoeconomical Analysis of Exploitation of Olive Mill Wastewater to Highadded Vale By-Products

Linnaeus Eco-Tech ◽

10.15626/eco-tech.2010.023 ◽

2017 ◽

pp. 216-223

Author(s):

C.A. Paraskeva ◽

E. C. Arvaniti ◽

V.G. Papadakis

Keyword(s):

Olive Oil ◽

Membrane Filtration ◽

Nutritive Value ◽

Pure Water ◽

Polyphenol Content ◽

Mediterranean Countries ◽

Olive Mill Wastewaters ◽

Short Period ◽

Western Greece ◽

Olive Mill

The olive oil industry is very important in many Mediterranean countries, both in terms of wealth and tradition. The extraction of olive oil generates huge quantities of high organic wastewaters with toxic constituents that may have a great impact on land and water environments. Series of laboratory experiments, based on the technology of membrane filtration (Ultrafiltration and Nanofiltration and/or Reverse Osmosis), have been carried out for the fractionation of olive mill wastewaters into fractions with nutritive value, phytotoxic action and pure water. Based on these results, a pilot plant of membranes installed in an olive oil mill enterprise for an entire harvesting period and appropriate experiments were performed. The study showed that a fraction of pure water up to 75% can recovered and fractions that contained concentrate nutritious and polyphenol content can be isolated and further exploited in order to reduce the, indeed, high cost of the suggested treatment process. In this study, a techno-economic analysis for the implementation of the suggested method for the Region of Western Greece is presented. The present study took into account the fixed and the operational costs of the equipment, the costs for the infrastructure and land, the costs for the maintenance, etc., considering the treatment of 50,000 tones per harvesting period in the Region of Western Greece. The study showed that the establishment of one central treatment manufacture could reduce the uncontrolled disposal of OMW and their final discharging in the aqueous receptors. The exploitation of the nutritious content of the fractions as manure in fertilizers together with the polyphenol content that can be used as components of ecological herbicides can depreciate the total cost in a very short period of 1.5 years.

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