Amount Of Olive Mill Wastewater Research Articles

Fed‐batch fermentation of olive mill wastewaters for lipase production

AbstractIn the Mediterranean basin countries, huge amounts of olive mill wastewaters (OMW) are produced by the olive oil industry. It constitutes a serious environmental problem, nevertheless its composition turns OMW into a potential growth medium to lipolytic microorganisms. The aim of this work was to study lipase production as well as OMW degradation in fed‐batch cultures of Candida cylindracea CBS 7869, Candida rugosa CBS 2275 and Yarrowia lipolytica W29 (ATCC 20460). Besides the improvement of lipase production, the fed‐batch approach enhanced the effluent degradation, since it led to good COD and lipids reduction, both higher than 50%. C. rugosa achieved the highest value of lipase productivity (130 U L−1 h−1), in parallel with highest lipids reduction (77%). This study demonstrates that OMW are becoming a competitive and valuable growth medium in fermentation processes with lipolytic microorganisms. The fed‐batch strategy used proved to be an efficient approach to enhance lipase production from OMW and to reduce significantly the final organic load of the medium. Copyright © 2012 Society of Chemical Industry

Investigation of municipal and olive mill wastewater co‐treatment in activated sludge–powdered activated carbon (AS‐PAC) systems

AbstractBACKGROUND: The purpose of this study was to investigate the co‐treatment of olive‐mill wastewater (OMW) and municipal wastewater in activated sludge systems operating in the absence and presence of different adsorbent materials and to study the role of sorption and biodegradation in total phenols removal.RESULTS: Batch experiments were initially conducted to investigate total phenols' adsorption capacity on activated sludge (AS), olive pomace (OP) and powdered activated carbon (PAC). According to the results, PAC presented the best adsorption capacity. Three sequencing batch reactors (SBRs) were also operated, treating municipal wastewater and different amounts of OMW. The first SBR contained AS (AS‐System), the second AS and OP (AS‐OP System) and the third AS and PAC (AS‐PAC System). All SBRs operated sufficiently in the presence of 1% v/v OMW, achieving mean COD and total phenols removal efficiency higher than 86% and 85%, respectively, and satisfactory settling capacity. Increase of OMW concentration to 5% v/v affected the performance of SBRs, resulting in mean COD removal efficiencies that ranged between 61% (AS‐OP System) and 80% (AS‐PAC System).CONCLUSION: Among the SBRs used, the AS‐PAC System operated with highest performance in the presence of 1 and 2.5% v/v OMW, and showed better stability in the presence of 5% v/v OMW. Calculation of total phenols mass flux revealed that biodegradation was the principal mechanism of their removal. The highest values of mean biotransformation rates were calculated for the AS‐PAC System and ranged between 2.0 and 40.6 d−1 for different experimental phases. Copyright © 2012 Society of Chemical Industry

Energetic valorisation of olive mill wastewater impregnated on low cost absorbent: Sawdust versus olive solid waste

The oil extraction industry generates two by-products, an aqueous effluent, olive mill wastewater (OMWW) and a solid residue, olive mill solid waste (OMSW). OMWW is considered as the major pollutant in the Mediterranean area causing severe environmental threats. The main problem regarding the disposal of OMWW is to find an environmental and economical viable solution. A new valorisation strategy has been carried out which includes the following steps: (a) absorption of OMWW on low-cost renewable absorbents, (b) natural evaporation of the water and (c) energy recovery by combustion of the impregnated absorbents. Sawdust and OMSW were selected as low-cost renewable absorbents. Thermal behaviour of the impregnated samples was studied under inert and oxidative atmosphere from 20 °C to 900 °C using thermogravimetric analysis (TGA). Kinetic parameters were obtained and compared for the different samples. Gaseous emissions such as CO2, CO and volatile organic compounds (VOC) were measured under oxidative conditions at 500 °C, 600 °C and at 700 °C in a fixed bed reactor. The results indicate that for samples containing the same amount of OMWW, the reaction time of impregnated sawdust is lower compared to impregnated OMSW. Combined treatment of OMMW proposed in this study may be a promising method for the reduction of their environmental impact and for the energetic valorisation of the organic content of OMWW.

Screening of strains of Lentinula edodes grown on model olive mill wastewater in solid and liquid state culture for polyphenol biodegradation

In Morocco, the olive industry produces great amounts of olive mill wastewater (OMW) yearly in a short period (250 000 m 3 of liquid wastes in four months, November–February). Phenolic compounds are largely responsible for the phytotoxicity and antimicrobial effects of OMW. Several studies have been carried out on biological and enzymatic treatments of OMW. However, the use of OMW to produce value-added products, e.g. mushroom cultivation, are less explored. This research aimed to select shiitake mushroom strains capable of growing on OMW, involving decolorization, removal of total phenol, and high production of mycelial biomass. Sixteen strains of Lentinula edodes were evaluated for their tolerance to OMW, apical growth rate, and biomass production on agar media. The highest biomass yields were recorded in four strains (Le118, Le119, Le121, Le122) grown in the presence of 20% (v/v) OMW. The ability of these pre-selected strains to decolorize and to remove total phenol from OMW was then assessed in liquid culture, without nutritional supplements. The strain Le119 of L. edodes showed 65% decolorization, and 75% elimination of total phenol according to the Folin–Ciocalteu assay. Laccase production was the main lignolytic activity observed, and one of its isoforms stained on native PAGE with p-phenylenediamine as substrate at pH 5.0.

Strategy for olive mill wastewater treatment and reuse with a sewage plant in an arid region

This study was conducted to evaluate the treatability of OMW (olive mill wastewater) with sewage and sewage sludge, which could supplement nutrients and microbes required for OMW treatment and reduce its possible toxicity. The amount of OMW added to an aeration tank was based on the loading difference between the designed and actual COD loads, while the amount added to anaerobic digestion for energy recovery was determined by CH4 production. The COD removal efficiencies were 70-85% for both systems. Compost of OMW with dried sewage sludge also showed a similar temperature profile without OMW addition. This strongly suggested that OMW can be treated at a sewage plant without pretreatment and the treated effluent can be reused in irrigation for an arid region.

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 degrees 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.

Use of olive mill wastewater compost for crop production

Vast amounts of olive mill wastewaters (OMW) are produced in Mediterranean countries, where their treatment and disposal are becoming a serious environmental problem. Increasing attention has been paid to discovering a use for OMW and a wide range of technological treatments are available nowadays for reducing their pollutant effects and for their transformation into valuable products, the most suitable procedures being found to involve recycling rather than the detoxication of these wastes. Direct application of OMW to soil has been considered as an inexpensive method of disposal and recovery of their mineral and organic components but, because of their organic acid and phenol contents, OMW are also a source of pollution. By using composting technologies, it is possible to transform either fresh OMW or sludge from pond-stored OMW mixed with appropriate plant waste waterials (carriers) into organic fertilizers (composts) with no phytotoxicity to improve soil fertility and plant production, the process involving the microbial degradation of the polluting load of the wastes. Results of field and pot experiments using OMW-composts to cultivate horticultural and other crops have shown that yields obtained with organic fertilization are similar, and sometimes higher, to those obtained with a balanced mineral fertilizer. A comparison between the macro and micronutrient contents of plants cultivated with organic or mineral fertilizers did not generally reveal important differences. However, the cases of iron and manganese are worth mentioning as their bio-availability may be linked to the soil humic complexes originated by the OMW organic fertilizers.