Table Olive Wastewaters Research Articles

Two-Step Wastewater Treatment: Sequential Ozonation - Aerobic Biodegradation

Ozonation of wastewater from olive related industries has been carried out after dilution with synthetic urban wastewater. The advantages of the application of different acidic and basic cycles during the ozonation process have been shown. Biodegradability of the final effluent measured as the biological oxygen demand to chemical oxygen demand ratio has significantly been increased (100–144% for table olive wastewater and 24–60% for olive oil wastewater). Aerobic biological experiments conducted by using non-acclimated microorganisms confirmed the suitability of the biodegradation after the chemical oxidation pre-treatment. A kinetic model based on a free radical mechanism has been used to simulate experimental results. Both chemical oxygen demand and dissolved ozone concentration profiles are well fitted by the model. The aerobic biodegradation process has been modeled by utilizing the Monod equation.

Joint Treatment of Wastewater from Table Olive Processing and Urban Wastewater. Integrated Ozonation - Aerobic Oxidation

Integrated ozonation-aerobic biodegradation of table olive wastewater (diluted 1:25 with synthetic urban wastewater) is presented as a suitable technology to purify this kind of effluent. Use of ozone is recommended as a pre-treatment step since it shows a high reactivity toward phenolic compounds (found in this type of wastewater) reducing, at the same time, the alkalinity of the media for further biological processing. An ozone dose of 45 mg L–1 (flow rate 20 L h–1) for a period of 35 min has been found to achieve the following goals: decrease pH, decrease phenolic content, and increase of biodegradability. The aerobic oxidation process followed first order kinetics as measured by COD depletion profiles versus time. The Arrhenius expression k = 183exp(–2214/T) was obtained for experiments of ozonated wastewater biodegradation completed at different temperatures and neutral pH.

Effects of single and combined ozonation with hydrogen peroxide or UV radiation on the chemical degradation and biodegradability of debittering table olive industrial wastewaters

Chemical oxidation of debittering table olive wastewaters using ozone alone and combined with hydrogen peroxide or UV radiation has been studied. The effect of oxidant concentrations on COD, BOD, TC (total carbon), aromatic content and colour of wastewaters has been observed. COD reduction of 80 or 90% can be reached with ozone doses between 3 and 4 g in the presence of 10 −3 M initial hydrogen peroxide concentration (2.4 g at the conditions investigated) or 254 nm UV radiation while moderate reductions of TC can be achieved (between 40 and 60%). Both the aromatic content and colour nearly completely disappear with less than 0.5 g of ozone applied. Along the reaction pH of wastewaters diminishes from 12 to 7.5. Biodegradability of wastewaters, measured as BOD/COD, increases from 0.16 (untreated wastewaters) to nearly 0.7 or 0.8 when using ozone combined with hydrogen peroxide (2.95 g O 3 fed during 2 h and 2.4 g H 2O 2 initially charged) or UV radiation (3.98 g O 3 fed during 2 h and 2.65×10 −6 Einstein s −1) as the oxidising systems, respectively.