Photocatalytic treatment of black table olive processing wastewater

The photocatalytic treatment of an effluent from black table olive processing over TiO2 suspensions was investigated. The study focused on the effect of various operating parameters on the treatment efficiency including initial organic load, catalyst type, concentration and reuse, and addition of hydrogen peroxide. Initial organic load, expressed in terms of chemical oxygen demand (COD), was studied in the range 1-8 g/L, anatase TiO2 concentrations in the range 0.25-2 g/L and H2O2 concentrations in the range 0.025-0.15 g/L. Treatment efficiency, which was assessed in terms of COD, total phenols, aromatics and color reduction, generally increased with decreasing initial COD and increasing contact time, catalyst and H2O2 concentrations; however, for H2O2 there was a maximum dosage above which performance deteriorated. Depending on the conditions employed, nearly complete decoloration (>90%) could be achieved, while mineralization never exceeded 50%. Shake-flask tests with non-acclimated activated sludge showed that both the original and photocatalyzed effluents were degradable aerobically with the biodegradation rate of the original effluent being three times greater than the oxidized one. On the other hand, photocatalytic oxidation of the original effluent was at least two orders of magnitude faster than its biological oxidation to achieve comparable levels of degradation.     

Electrochemical treatment of textile dyes and dyehouse effluents

The electrochemical oxidation of textile effluents over a titanium-tantalum-platinum-iridium anode was investigated. Batch experiments were conducted in a flow-through electrolytic cell with internal recirculation at current intensities of 5, 10, 14 and 20A, NaCl concentrations of 0.5, 1, 2 and 4% and recirculation rates of 0.81 and 0.65 L/s using a highly colored, synthetic effluent containing 16 textile dyes at a total concentration of 361 mg/L and chemical oxygen demand (COD) of 281 mg/L. Moreover, an actual dyehouse effluent containing residual dyes as well as various inorganic and organic compounds with a COD of 404 mg/L was tested. In most cases, quantitative effluent decolorization was achieved after 10-15 min of treatment and this required low energy consumption; conversely, the extent of mineralization varied between 30 and 90% after 180 min depending on the operating conditions and the type of effluent. In general, treatment performance improved with increasing current intensity and salinity and decreasing solution pH. However, the use of electrolytes not containing chloride (e.g. FeSO4 or Na2SO4) suppressed degradation. Although the acute toxicity of the actual effluent to marine bacteria Vibrio fischeri was weak, it increased sharply following treatment, thus suggesting the formation of persistent toxic by-products.     

Boron-doped diamond anodic treatment of olive mill wastewaters: Statistical analysis, kinetic modeling and biodegradability

The electrochemical treatment of olive mill wastewaters (OMW) over boron-doped diamond (BDD) electrodes was investigated. A factorial design methodology was implemented to evaluate the statistically important operating parameters, amongst initial COD load (1000-5000 mg/L), treatment time (1-4 h), current intensity (10-20 A), initial pH (4-6) and the use of 500 mg/L H₂O₂ as an additional oxidant, on treatment efficiency; the latter was assessed in terms of COD, phenols, aromatics and color removal. Of the five parameters tested, the first two had a considerable effect on COD removal. Hence, analysis was repeated at more intense conditions, i.e. initial COD values up to 10,000 mg/L and reaction times up to 7 h and a simple model was developed and validated to predict COD evolution profiles. The model suggests that the rate of COD degradation is zero order regarding its concentration and agrees well with an electrochemical model for the anodic oxidation of organics over BDD developed elsewhere. The treatability of the undiluted effluent (40,000 mg/L COD) was tested at 20 A for 15 h yielding 19% COD and 36% phenols' removal respectively with a specific energy consumption of 96 kW h/kg COD removed. Aerobic biodegradability and ecotoxicity assays were also performed to assess the respective effects of electrochemical treatment.     

Enhancing the impact of online hotel reviews through the use of emoticons

Online consumer reviews (OCRs) have received increasing scrutiny in recent years. The present study focuses on the effect of OCRs on consumers’ perceptions and attitudes, when pictorial representation of consumer emotions is used in online hotel reviews. A 2?×?2 experimental study is designed to examine the effect of two independent variables: review valence (positive vs. negative) and emoticons use (no emoticons vs. emoticons). Research findings show that positive OCRs result in more positive attitude and higher booking intention. Interestingly, the presence of emoticons in negative reviews strengthens the review credibility and usefulness, but attenuates consumers’ attitude towards the hotel and their booking intention. Managerial implications and research opportunities are discussed.