Degradation of Phenol in Pharmaceutical Wastewater using TiO2/Pumice and O3/Active Carbon

Phenol is a toxic organic compound that detectable in the pharmaceutical wastewater, and therefore it should be eliminated. This study aims to degrade phenol in the pharmaceutical wastewater treatment using Advanced Oxidation Processes (AOPs) include the photocatalytic process applying Titanium Oxide (TiO2) that immobilized on pumice stone (PS), as well as ozone process with O3 and O3/granulated activated carbon (GAC). Degradation system used two configuration reactors that worked alternately at pH 3 and 9. Photocatalysis was conducted for 4 hours in the photoreactor that equipped with mercury lamp as a photon source, while ozonation was performed for 1 hour in the cylinder glass reactor contained an ozone generator. Phenol degradations were done by photocatalysis, ozonation, photocatalysis followed by ozonation and vice versa. The FESEM-EDS and XRD results depicted that TiO2 has impregnated on pumice stone and FESEM characterization also indicated that the photocatalyst spread across the surface of the pumice stone. BET analysis results in an increased surface area of the PS-TiO2 by 3.7 times, whereas bandgap energy down to 3 eV. It can be concluded that ozone process (with O3/GAC) that followed by photocatalysis at pH 9 could treat the liquid waste with phenol concentration 11.2 down to 1.2 ppm that nearly according to the discharge standards quality (1 ppm). Copyright © 2020 by Authors, Published by BCREC Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0).

Steady-state Optimality Analysis for Investigating the Energy Optimal Operation of Representative Natural Gas Liquefaction Cycles

AbstractThis study examined the energy optimal operation of representative natural gas liquefaction cycle processes such as propane precooled mixed refrigerant (C3MR) process, dual mixed refrigerant (DMR) process, and modified single mixed refrigerant (MSMR) process. Steady-state optimality analysis in dynamic simulation environment was conducted to explore the operational behavior of each cycle. From this analysis, a steady-state optimality map that describes the relation between cost function and decision variable is obtained. By exploring this map a promising optimizing variable is discovered which further can be used to develop an energy optimizing control structure for the liquefaction process. Despite the same basic working principles, the operational behavior of the three cycles is dissimilar. The DMR has the narrowest optimal operation range while in the MSMR cycle the optimum value of cost function spans in relatively wide range of decision variable. The feasible operation of C3MR and DMR is bounded by the suction temperature of mixed refrigerant compressor while in the MSMR cycle this constraint is inactive. Based on the steady-state optimality analysis the temperature difference between the warm-end inlet and outlet MR streams (TD) were proposed to be a promising optimizing variable for the C3MR and DMR process while for the MSMR process the optimizing variable is the flow rate ratio of heavy and light mixed refrigerant (HK/LK ratio)

Effect of Microwave Pretreatment on Some Properties of Bamboo (Gigantochloa apus) for Bioethanol Production

Pretreatment of lignocellulosic biomass plays an essential role in bioethanol production as an alternative biofuel. This process reduces biomass recalcitrance in order to improve cellulose digestibility for saccharification and further fermentation reactions. In this study, microwave (MW) pretreatment was done on bamboo (Gigantochloa apus) to investigate the resulting physicochemical properties and bioethanol produced. Bamboo was irradiated in the microwave at different power (100-600 Watt) and irradiation time (5-20 minutes) followed by Water Soluble content (WSC) and lignin analysis. Simultaneous saccharification and fermentation (SSF) using cellulase enzyme was also done in five different treatment combinations (C1-C5) to investigate the effect of produced reducing sugar and bioethanol. The result shows that increasing MW power and irradiation time could decrease WSC gradually. The lowest WSC of 0.3% was obtained at 600-Watt MW power and 20 minutes irradiation time. Lignin content decreased from 18.9% to 16.0% concerning increasing irradiation time from 5 to 20 minutes under 300-Watt MW power. SEM images show that partial disruption and micro-scale pores existed in pretreated samples. The highest amount of ethanol was obtained at 24 hours fermentation for pretreated bamboo at 300-Watt MW power for 15 minutes followed by cellulase enzyme addition. The overall results showed that microwave pretreatment is a prospective method for future bioethanol production from bamboo due to effective WSC reduction and lignin degradation in a relatively short period of time