Dynamic performance of a fungal biofilter packed with perlite for the abatement of hexane polluted gas streams using SIFT-MS and packing characterization with advanced X-ray spectroscopy.

The use of Fusarium solani fungi in an expanded perlite packed biofilter was investigated for the treatment of a hexane polluted waste gas stream using selected ion flow tube mass spectrometry (SIFT-MS). The latter analytical technique proved to be of utmost importance to evaluate the performance of the biofilter at high time resolution (seconds) under various transient conditions, analogous to industrial situations. The biofilter was operational for 277 days with inlet loads varying between 1 and 14 g m-3 h-1 and applying an empty bed residence time of 116 s. The results showed a positive behaviour of the biofilter against different types of disruptions such as: (i) changes in the relative humidity of the inlet gas, (ii) stopping the carbon supply for 1, 5 and 10 days, (iii) varying the inlet hexane concentration (step increases and intermittent pulses) and (iv) limiting the availability of nutrients. X-ray imaging (both conventional 2D µCT and X-ray fluorescence, XRF) was applied for the first time on biofilter media in order to get insight in the internal structure of expanded perlite and to visualise the biomass growth. The latter in combination with online porosity measurements using SIFT-MS provides fundamental information regarding the biofiltration process.

Malondialdehyde measurement in oxidized foods: evaluation of the spectrophotometric thiobarbituric acid reactive substances (TBARS) test in various foods.

The ability of the spectrophotometric thiobarbituric acid reactive substances (TBARS) test to determine malondialdehyde (MDA) in various food matrices was evaluated. MDA was extracted from the foods; the extract reacted with thiobarbituric acid (TBA); and the formed TBA-MDA adduct was measured spectrophotometricaly at 532 nm. In parallel, the TBA-MDA adduct was analyzed with high-performance liquid chromatography (HPLC) coupled with fluorescence detection. Oils and unprocessed and uncooked meat and fish products did not exhibit any significant difference in the amount of MDA measured by the two methods, indicating that the major substance reacting with TBA and forming an adduct that absorbs at 532 nm was MDA. However, in products such as dry nuts, pork sausages, cooked fish, and gouda cheese, an overestimation of MDA was observed, indicating that TBARS test was unsuitable for accurate determination of MDA. Furthermore, the results in the present work suggest that the overestimation of MDA by the TBARS test as it was applied is related to the interference of other than secondary lipid oxidation products.

Ciprofloxacin ozonation in hospital wastewater treatment plant effluent: effect of pH and H2O2.

The ozonation of ciprofloxacin was studied in hospital wastewater treatment plant effluent with focus on parent compound degradation, degradation product identification and residual antibacterial activity. Before ozonation, ciprofloxacin sorption on suspended solids was tested as a function of temperature (10.0-27.5 degrees C) and pH (3, 7 and 10). Temperature did not significantly affect ciprofloxacin sorption while sorption was highest at pH 7 (logK(d)=4.7) compared to pH 3 (logK(d)=4.3) and 10 (logK(d)=3.9) (n=3). Ozonation was slowest at pH 7 with ciprofloxacin half life times of 29 min, compared to 19 and 27 min at pH 10 and 3, respectively. Addition of 10-1000 microM H(2)O(2) increased ciprofloxacin half life times up to 38 min, probably influenced by competition with H(2)O(2) for ozone as well as radical species. Ciprofloxacin ozonation products were identical as previously detected during ciprofloxacin ozonation in deionized water and revealed strong pH dependence. Residual antibacterial activity was measured by agar diffusion tests. For Pseudomonas fluorescens and Escherichia coli, reduction of antibacterial activity was related to the parent compound degradation, while degradation products indicated to be the main compounds with respect to the antibacterial activity against Bacillus coagulans.