Volume 21 - 2019

Searching for low cost, accessible, simple implementation, and environmentally friendly adsorbents has been one of the concern of researchers in recent years. Therefore, the aim of this study was to investigate the efficient phenol removal from a synthetic aqueous solution using iron-coated pumice and LECA as an available adsorbents. Bath adsorption experiments were carried out to evaluate the effects of the independent variables such as pH (3-5-7-9-11), initial concentration of phenol (10-50mg/L), contact time (10-60 min) and different concentrations of pumice and LECA (0.2-1 g/100 cc) on the phenol adsorption. The results of the experiments showed that there was a direct relationship between the phenol removal efficiency and increasing the contact time and the adsorbent dosage but it has reverse relationship with the increasing of pH and phenol initial concentration. The optimal condition of parameters for phenol removal were 200 rpm agitation speed, 0.6 g adsorbent dosage, 30 min contact time, and 20 mg/L initial phenol concentration. The study of isotherm and kinetic models showed that the experimental data of the phenol adsorption process were correlated with Freundlich (R2pumice=0.9749, R2LECA=0.9487) and Pseudo-second order (R2pumice=0.9745, R2LECA=0.9486) models. Based on this study’s results, the modified pumice and LECA have a high ability to remove the phenol compounds from aqueous solution.

Biological treatment is one of the most preferable strategies to complete and safe removal of pollutants. Pyrene (PY) is the first member of high molecular weight polycyclic aromatic hydrocarbons (HMW-PAHs) that represents various concerns to biological life and human health. In this study, two different algal strains exhibited different capability to degrade PY along 30 days of incubation in the light. Dry weight, total chlorophyll, and carotenoids were growth parameters that were determined to detect robust of two algal strains to get used of PY as a source of carbon. Oscillatoria sp. could degrade 95% while Chlorella sp. could degrade 78.71 % of PY (50 mg/L) after 30 days of incubation. Both algal strains could completely remove 10 and 30 mg/L of PY. On the other hand, the degradation capability of Oscillatoria sp. was significantly exceeded than Chlorella sp. under the same incubation condition and at (50 and 100 mg/L) of PY.

Recently, the exploration of new alternatives to common organic solvents in combination with non-conventional energy sources is a subject of intense research and development as tools for green extraction of plant-derived natural products. This paper deals with the use of low frequency ultrasound (100 W, 32 kHz) and pulsed electrical fields (0.86 kV cm-1, 13 Hz) to raise the efficiency of the extraction of selected plant species rich in valuable phenolic compounds.Four types of natural deep eutectic solvents were applied for the ultrasound-assisted extraction of silymarin from milk thistle among which a choline-chloride-based mixture with glycerol was proved to be the most promising one. Additionally, the usage of high ultrasound power significantly increased the concentration of sylimarin as compared to traditional ethanol extraction, generating rapidly for 10 min considerable temperature rise as a side effect under non-cooling conditions. The application of PEF as a pre-treatment for 0.8 s to the extraction allowed reducing the ethanol percentage in the ethanol/water mixtures giving comparable phenolic yields, without any, or very little, increase in temperature. As such, optimized power intensity in conjunction with appropriate solvent system provides a potential to improve the release of thermally unstable bioactive compounds under mild processing conditions.

The ability of the anaerobic mixed bacterial culture from an upflow anaerobic sludge blanket (UASB) bioreactor to convert blends of olive mill wastewaters (OMWs) with synthetic glucose medium or molasses into ethanol simultaneously with organic acids (OAs) was studied in the present work. All fermentations were conducted by free cells under non-aerated conditions at 37 οC and the effect of OMWs concentration on ethanol and OAs production was investigated. The highest amount of bioethanol (14.7 g L-1) was produced during fermentation of 45 % v/v OMWs mixed with synthetic glucose medium (5 % w/v) in only 28 hours. In mixtures of 30 % v/v OMWs and molasses solution (3 oBe) 13.4 g L-1 of bioethanol were produced. Also, 16.2 g L-1 of succinic acid were produced, when 65 % v/v OMWs mixed with synthetic glucose medium. Moreover, totally 11.6 g L-1 of varied OAs (succinic, malic, butyric and acetic) observed in mixtures of 35 % OMWs with molasses. Finally, it has been shown that the 14C-labelled glucose uptake rate (GUR) by biomass was strongly correlated to fermentation rate.