Table Olive Wastewater: Problem, Treatments and Future Strategy. A Review

Abstract

The table olive industry produces a high quantity of wastewater annually. These wastewaters are very problematic because of their characteristics of high organic matter, high phenolic content, high salinity and conductivity. The quantities in which they are produced are also a serious problem. The worldwide production of table olives reached 2,550,000 tons in the last five campaigns, with the European Union contributing to 32% of total production. The problem of these wastewaters is focused on the Mediterranean area where the highest quantity of table olives is produced and to a lesser extent on the United States and South America. Countries like Spain produce around 540,000 tons of these wastewaters. At present, there is no standard treatment for these wastewaters with acceptable results and which is applied in the industry. Currently, the most common treatment is the storage of these wastewaters in large evaporation ponds where, during the dry season, the wastewater disappears due to evaporation. This is not a solution as the evaporation ponds depend completely on the climatology and have a high number of associated problems, such as bad odors, insect proliferation and the contamination of underground aquifers. Different studies have been carried out on table olive wastewater treatment, but the reality is that at the industrial level, none has been successfully applied. New and promising treatments are needed. The current review analyzes the situation of table olive wastewater treatment and the promising technologies for the future.

Treatment of Water and Wastewater for Reuse and Energy Generation-Emerging Technologies

“…Municipal solid wastes are attracting more obstructive legislation with respect to landfill disposal of the biodegradable fraction [4,8]. The treatment process for these organic fractions is biological wastewater treatment.…”

“…Wastewater, which is the biggest waste stream from municipalities, petrochemical, pharmaceuticals, food, textile, agricultural, polymer and paper industries and so on contain high contaminants of oil and salts of organic and inorganic compounds [1][2][3][4][5]. This strikes as a major ecological problem with high environmental impacts when discharged into the ecosystem without proper treatment.…”

“…Therefore, the quest for clean water and clean environment has resulted in various environmental protection agencies setting stringent discharge limits [3,4]. Conversely, there are always variations in wastewater qualities which have different impacts on the environment [2][3][4], where a proper wastewater treatment incorporated with primary, secondary and advanced treatment strategies seems to more viable [1,3,4]. The primary treatment involves separating the solids from the liquids via filtration or sedimentation, whereas the secondary treatment removes the dissolved solids and other contaminants through chemical precipitation and biological process [4,6,7].…”

A Comparative Study on Trichoderma harzianum and a Combination of Candida/Bacillus as Tools for the Bioremediation of Table Olive Processing Water

“…Egypt, Turkey, Algeria, Syria and Morocco are high producers, with a total production of 1,223,500 tons (season 2015/2016). The United States and some South American countries (Argentina, Mexico and Peru) are also important producers, and contribute 70,500 and 151,500 tons (season 2015/2016), respectively [ 1 , 2 ].…”

Processing Wastewaters from Spanish-Style cv. Chalkidiki Green Olives: A Potential Source of Enterococcus casseliflavus and Hydroxytyrosol

“…The development of sustainable remediation processes is a tough challenge and bioaugmentation via the use of exogenous fungi (white-rot fungi, Aspergillus niger , Geotrichum candidum , Trichoderma harzianum ), microalgae ( Nannochloropsis gaditana ), or activated sludge has emerged as a feasible, green, and cost-effective approach. However, recent findings highlight the limited adaptability of these microbial cells to GOW and their limited ability to degrade the toxic organic constituents (i.e., phenolic compounds) [ 2 , 5 , 6 ]. A. niger has been recognized as metabolically superior against the other tested microorganisms in terms of phenol degradation and phytotoxicity reduction [ 3 ].…”