Background: A hand-held portable direct-reading monitor, including photoionization detector (PID) is renowned for its good sensitivity, considerable dynamic range, and nondestructive vapor detection ability in comparison to the tardy response of the PID in gas chromatography (GC), which its application has been restricted. In this study, the performance of a PID system (MultiRAE Lite) was evaluated as a replacement of GC in the measurement of toluene in a dynamic adsorption system. Methods: The test was done at different relative humidity levels (30%, 50%, and 80%), temperatures (21, 30, 40 ° C), and toluene concentrations (20, 100, 200, and 400 ppm). Results: The PID achieved 48% of all measurements meeting the comparison criterion. The results showed that the performance of the PID could be altered by the variables. The best performance of the PID was at temperature of 21 ° C, the relative humidity of 50%, and concentration of 200 ppm with the percentage of readings achieving the criterion of comparison to 58%, 54%, and 52%, respectively. The averages of the PID readings (mean ± SD at 200 ppm= 207. 9 ± 8. 7) were higher than the reference method measurements averages (mean ± SD at 200 ppm= 203. 5 ± 5. 8). The regression analysis of the toluene results from the PID and the reference method results indicated that the measurements were significantly correlated (r 2 = 0. 93). Conclusion: According to the results, the device response is linear. Therefore, the findings are acceptable in adsorption studies. In this way, the measurement of the sample concentration should be performed using the same instrument before and after the reactor in order to calculate the adsorption efficiency.

Advances in microbial and biotechnology have given great impetus to the filed of pollution control. In some countries efforts are being focused on the application of biotechnology for wastewater treatment. Occurrence of microbial growth inhibitors in the biological reactor will affect their activity, which this in turn will lead to reduced performance of the system in pollutants removal. Restart up of the system, especially in the biological treatment of industrial wastewater, will require abundance time and cost. An effective solution to reduce these problems is to prepare and store dried concentrated sludge bearing the needed microorganisms to be used later. The most effective technique to produce such concentrated sludge is lyophilization in which a stabilized biological solid is produced through rapid freezing and then drying under high vacuum conditions. This study was carried out to investigate the lyophilization effect on the microbial quality of the activated sludge. In this regard, Operational characteristics including OUR, SVI, soluble COD removal efficiency and predominant microorganisms species before and after lyophilization in a lab-scale experiment were used. The results showed that sludge lyophilization had no influence on microorganisms" performance and Operational characteristics of the activated sludge. In addition, there was not a significant change in the sludge properties before and after lyophilization. Sludge microorganisms were viable after lyophilization. So, lyophilization was concluded to be a suitable technology for preparation and preservation of cells in activated sludge because of preserving viability, ease of handling and simplicity.

A wide range of chemicals and dyes are being used in textile industry, and are often found in the wastewater produced. This study attempts to investigate the reduction of COD, TSS, and dye in effluents from the dyeing and washing unit of textile industry, using electrocoagulation process. The reactor is equipped with 10 iron electrodes, connected to a direct current (DC) source in a monopolar electrode configuration. In each stage of the experiment, 2.5 l of the effluent enters the reactor and the effects of a number of important Operational parameters such as voltage, pH, and reaction time is studied on the removal of COD, TSS, and dye parameters. Results show that the optimum Operational conditions are reaction time of 120 min, voltage of 30 V, and pH of 7, which reduces COD, TSS, and dye by 87%, 91%, and 98%, respectively. Therefore, it has been concluded that the efficiency of pollutants removal from the wastewater improves as voltage and reaction time are increased.

Recently, research on the production of ethanol from waste has been accelerating for both ecological and economical reasons, primarily for its use as an alternative to petroleum based fuels. In this study, response surface methodology based 23 -full factorial central composite design was employed to optimize the parameters of ethanol production from Korean food waste leachate. The reducing sugar concentration of the food waste leachate determined by the dinitrosalicylic acid method was 75 g/L. A second order polynomial model was developed to evaluate the quantitative effects of temperature, pH and reducing sugar concentration in order to find an optimum condition for the ethanol production from food waste leachate. From the experimental result, maximum ethanol concentration of 24.17 g/L was obtained at the optimum condition of temperature (38°C), pH (5.45) and reducing sugar concentration (75 g/L). The experimental value (24.17 g/L) agreed very well with the predicted one (23.66 g/L), indicating the suitability of the model employed and the success of response surface methodology in optimizing the conditions of ethanol production from food waste leachate. Canonical analysis indicated that the stationary point was a saddle point for the ethanol yield. Despite being a waste, an ethanol yield of 0.32 g ethanol/g reducing sugar demonstrated the potential of food waste leachate as a promising biomass resource for the production of ethanol.