Treatment of table olive washing water using trickling filters, constructed wetlands and electrooxidation

• Published in: Environmental science and pollution research international Vol. 24; no. 2; pp. 1085 - 1092
• Main Authors: Tatoulis, Triantafyllos, Stefanakis, Alexandros, Frontistis, Zacharias, Akratos, Christos S., Tekerlekopoulou, Athanasia G., Mantzavinos, Dionissios, Vayenas, Dimitrios V.
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 2017; Springer Nature B.V
• Subjects: Advances and trends in Advanced Oxidation processes; Agriculture; Aquatic Pollution; Artificial wetlands; Atmospheric Protection/Air Quality Control/Air Pollution; Biofilters; Biofiltration; Biological Oxygen Demand Analysis; Boron; Chemical oxygen demand; Construction costs; Construction planning; Decoloring; Diamonds; Earth and Environmental Science; Economic conditions; Ecotoxicology; Environment; Environmental Chemistry; Environmental Health; Environmental science; Filters; Filtration; Horizontal loads; Mediterranean Region; Olea; Olives; Organic matter; Phenolic compounds; Phenols; Phenols - chemistry; Pollution control; Pollution load; Trickling filters; Washing; Waste Water Technology; Water Management; Water Pollutants, Chemical - chemistry; Water Pollution Control; Water purification; Water Purification - methods; Water treatment; Wetlands; MED, Western Mediterranean; MED; Electrooxidation; Phenols; Biological filter; Hydraulic residence time; Table olive washing water; Constructed wetlands
• ISSN: 0944-1344; 1614-7499
• DOI: 10.1007/s11356-016-7058-6

The production of table olives is a significant economic activity in Mediterranean countries. Table olive processing generates large volumes of rinsing water that are characterized by high organic matter and phenol contents. Due to these characteristics, a combination of more than one technology is imperative to ensure efficient treatment with low operational cost. Previously, biological filters were combined with electrooxidation to treat table olive washing water. Although this combination was successful in reducing pollutant loads, its cost could be further reduced. Constructed wetlands could be an eligible treatment method for integrated table olive washing water treatment as they have proved tolerant to high organic matter and phenol loads. Two pilot-scale horizontal subsurface constructed wetlands, one planted and one unplanted, were combined with a biological filter and electrooxidation over a boron-doped diamond anode to treat table olive washing water. In the biological filter inlet, chemical oxygen demand (COD) concentrations ranged from 5500 to 15,000 mg/L, while mean COD influent concentration in the constructed wetlands was 2800 mg/L. The wetlands proved to be an efficient intermediate treatment stage, since COD removal levels for the planted unit reached 99 % (mean 70 %), while the unplanted unit presented removal rates of around 65 %. Moreover, the concentration of phenols in the effluent was typically below 100 mg/L. The integrated trickling filter-constructed wetland-electrooxidation treatment system examined here could mineralize and decolorize table olive washing water and fully remove its phenolic content.