Solid-phase microextraction to monitor the sonochemical degradation of polycyclic aromatic hydrocarbons in water

Solid-phase microextraction (SPME) coupled with GC-MS has been used to monitor the degradation of polycyclic aromatic hydrocarbons (PAHs) by ultrasound treatment. Immersion SPME sampling enabled the fast and solventless extraction of target contaminants at the low microg l(-1) concentration level. The developed protocol was found to be linear in the concentration range from 0.1 to 50 microg l(-1) for most target analytes, with the limits of detection ranging between 0.01 and 0.70 microg l(-1) and the relative standard deviations between 4.31 and 27%. The developed SPME protocol was used to follow concentration profiles of aqueous solutions containing 16 PAHs, which were subject to low frequency ultrasonic irradiation. At the conditions employed in this study (80 kHz of ultrasound frequency, 130 W l(-1) of applied electric power density, 30 microg l(-1) of initial concentration for each of the 16 PAHs), sonochemical treatment was found capable of destroying the lower molecular weight PAHs (naphthalene, acenaphthylene, acenaphthene, fluorene, phenanthrene, anthracene, fluoranthene and pyrene) within 120-180 min of irradiation. The higher molecular weight PAHs were more recalcitrant to ultrasound treatment.     

Removal of olive mill waste water phenolics using a crude peroxidase extract from onion by-products

Olive mill waste water (OMWW) originating from a two-phase olive oil-producing plant was treated with a crude peroxidase extract prepared from onion solid by-products. The treatments were based on a 3 × 3 factorial design, employing a series of combinations of pH and H₂O₂, in order to identify optimal operational conditions. The treatment performance was assessed by estimating the removal percentage of total polyphenols. The model established produced a satisfactory fitting of the data (R ² = 0.94, p = 0.0158), while the second-order polynomial equation used to describe the process indicated that peroxidase-catalysed polyphenol removal in diluted OMWW is facilitated at relatively low pH and intermediate H₂O₂ values. A predicted value of 50.7 ± 9.5% removal was calculated under optimal operational conditions (pH 2.76, [H₂O₂] = 3.56 mM). Analysis of an untreated and an optimally treated sample by high performance liquid chromatography revealed that enzyme treatment brought about alteration in the original OMWW polyphenolic profile. The use of peroxidase from onion solid by-products is proposed as an alternative means that could have a prospect in bioremediation applications.     

Analysis of polycyclic aromatic hydrocarbons in wastewater treatment plant effluents using hollow fibre liquid-phase microextraction

A simple and efficient method for the enrichment of low molecular weight polycyclic aromatic hydrocarbons (PAHs) in effluents originating from wastewater treatment plants is presented here. The proposed protocol couples the recently introduced hollow fibre liquid-phase microextraction (LPME) method with gas chromatography-mass spectrometry. Method parameters were controlled and the optimised experimental conditions were: 5 ml aqueous samples, containing 2.5% NaCl w/v, stirred at 1000 rpm, extracted with toluene for 15 min. The developed protocol yielded a linear calibration curve in the concentration range from 0.5 to 50 microg l(-1) for all target analytes (namely acenaphthene, phenanthrene, fluoranthene and pyrene) and limits of detection in the low microg l(-1) level (0.005-0.011 microg l(-1)). The repeatability and inter-day precision of the method varied between 2.7% and 11.3% and 7.9% and 14.4% respectively. The relative recoveries from different types of natural water samples revealed that matrix had a small effect on the hollow fibre LPME process. The developed method was then applied for the determination of PAHs contamination in effluent samples taken from two major municipal wastewater treatment plants. The results were compared with those obtained with solid-phase microextraction. The ability of both microextraction methods to concentrate organic analytes was demonstrated as both methods confirmed the presence of PAHs as well as of phthalates in the examined effluent samples.     

Measuring the antioxidant activity of olive oil mill wastewater using chemiluminescence

A sensitive and simple procedure is described for determining the total phenolic/antioxidant levels of olive oil mill wastewater (OMW), using for the first time Co(II)/ethylenediaminetetracetic acid (EDTA)-induced luminol chemiluminescence. Olive oil wastewater samples were tested for their composition in simple phenolic compounds as a function of the extraction system (two- and three-phase centrifugation systems). The results revealed that the three-phase system had a stronger antioxidant activity and a higher total phenolic content than the two-phase system. The relationship between antioxidant values and total phenolic content is also discussed.     

Sonochemical reduction of the antioxidant activity of olive mill wastewater

The use of ultrasonic irradiation to reduce the antioxidant activity of olive oil mill wastewaters (OMWs) originating from two-phase and three-phase decanters was examined. Sonication of diluted OMW samples was conducted at ultrasonic frequencies of 24 and 80 kHz, an applied power varying between 75 and 150 W, and liquid bulk temperatures varying between 25 and 60 degrees C. At the conditions in question, the reduction in antioxidant activity was found to increase with decreasing temperature and increasing power and frequency. Addition of NaCl in the samples also appeared to enhance reduction. Antioxidant activity of OMW samples was assessed using the recently developed Co(II)/ethylenediaminetetraacetic acid (EDTA)-induced luminol chemiluminescence analytical protocol, while the total phenolic load was measured according to the Folin-Ciocalteu method.     

Monitoring the sonochemical degradation of phthalate esters in water using solid-phase microextraction

The sonochemical degradation of aqueous solutions containing low concentrations of six phthalate esters at an ultrasonic frequency of 80 kHz has been investigated. Ultrasonic treatment was found capable of removing the four higher molecular mass phthalates (di-n-butyl phthalate, butylbenzyl phthalate, di-(2-ethylhexyl) phthalate and di-n-octyl phthalate) within 30-60 min of irradiation. The rest (dimethyl phthalate and diethyl phthalate) were more recalcitrant and nearly complete removal could be achieved only after prolonged irradiation times. The relative reactivity of phthalates was explained in terms of their hydrophobicity. Experiments were carried out at an overall initial phthalate concentration of 240 microg l(-1), values of electric power of 75 and 150 W, temperatures of 21 and 50 degrees C and in the presence of NaCl to study the effect of various operating conditions on degradation. Solid-phase microextraction (SPME) coupled with GC-MS proved to be a powerful analytical tool to monitor the sonochemical degradation of phthalate esters at low microg l(-1) concentration levels, minimising the risk of secondary contamination during sample preparation, a major parameter to consider during phthalates analysis. The advantages as well as disadvantages of using SPME are also highlighted.     

Characterization and dispersion modeling of odors from a piggery facility

Piggeries are known for their nuisance odors, creating problems for workers and nearby residents. Chemical substances that contribute to these odors include sulfurous organic compounds, hydrogen sulfide, phenols and indoles, ammonia, volatile amines, and volatile fatty acids. In this work, daily mean concentrations of ammonia (NH3) and hydrogen sulfide (H2S) were measured by hand-held devices. Measurements were taken in several places within the facility (farrowing to finishing rooms). Hydrogen sulfide concentration was found to be 40 to 50 times higher than the human odor threshold value in the nursery and fattening room, resulting in strong nuisance odors. Ammonia concentrations ranged from 2 to 18 mL m(-3) and also contributed to the total odor nuisance. Emission data from various chambers of the pig farm were used with the dispersion model AERMOD to determine the odor nuisance caused due to the presence of H2S and NH3 to receptors at various distances from the facility. Because just a few seconds of exposure can cause an odor nuisance, a "peak-to-mean" ratio was used to predict the maximum odor concentrations. Several scenarios were examined using the modified AERMOD program, taking into account the complex terrain around the pig farm.