Oily wastewater is one of the most challenging streams to deal with especially if the oil exists in emulsified form. In this study, electrospinning method was used to prepare nanofiberous polyvinylidene fluoride (PVDF) membranes and study their performance in oil removal. Graphene particles were embedded in the electrospun PVDF membrane to enhance the efficiency of the membranes. The prepared membranes were characterized using a scanning electron microscopy (SEM) to verify the graphene stabilization on the surface of the membrane homogeneously; while FTIR was used to detect the functional groups on the membrane surface. The membrane wettability was assessed by measuring the contact angle. The PVDF and PVDF / Graphene membranes efficiency was tested in separation of emulsified oil from aqueous solutions. The results showed that PVDF-Graphene nanofiber membrane exhibited better performance than the plain PVDF nanofiber membrane with average water flux of 210 and 180 L.m-2.h-1, respectively. Both membranes showed high oil rejection with more than 98%.
In this work, the removal of hardness was studied from tap water taken from Aljadriya municipal water network-Baghdad. A parallel plate electrochemical cell was constructed using two graphite electrodes as anode, and three aluminum electrodes as cathodes. The electrodes were connected to a power supply that provides direct electrical current to the cell. Results showed that a removal efficiency of 85% can be obtained at pH of 7.5and electrical voltage of 28.5 volt with retention time of 60 minutes. The high efficiency for hardness removal suggested that the electrochemical technique might be used as an alternative technique for hardness removal.
IGBT (Insulated-gate bipolar transistor), is used widely in high voltage applications, it is very important to realize the doping profile in order to understand the design and the electrical performances of such devices. The performance depends on the layer, doping, and a carrier distribution among each layer. A specific selected layer can be added with precise properties for enhancing the device and increase the low current operate requirement. In this paper, an IGBT device is an enhanced and better performance achieved by the addition of a heavily positive doped intermediate layer. The collector current is decreased from 0.05 mA to 0.03 mA at 600 V. Decreasing the current results in higher efficient device by decreasing the amount of heat produced by the device.
In this work a practical comparison has been done between the conventional coagulation and flocculation method and Ballast flocculation as a primary settling procedure that was used to treat sewage water in Al-Zaafraniya apartment complex. The results show that the conventional method using alum as coagulant 75 mg/L, gives removal efficiencies of Total suspended solid TSS 50-60%, BOD 30-40% and total phosphorus TP 40% at total time of 60 minutes. While the Ballast flocculation method using alum 75 mg/L , polyelectrolyte 1.5 mg/L and sand 10 mg/l (70µm) gives removal efficiencies of TSS 50-70%, BOD 30-40% and TP 68% at total time less than 22 minutes.From the above, a conclusion can be noticed that the Ballast flocculation method means reduction in equipment size and footprint area more over efficiency in total phosphorus removal.
Aerobic granular activated sludge is an attractive and promising process for intensive and high-rate biological nutrient removal (BNR) and secondary clarification in a single reactor. This work reports the performance of aerobic granular sludge sequential batch reactor (SBR) seeded with flocculated activated sludge collected from an Iraqi municipal wastewater treatment plant, using synthetic wastewater. The conditions under which the successful cultivation of aerobic granular sludge was done are as follows: influent chemical oxygen demand (COD) was 1100 mg/l, volumetric exchange rate was 50%, aeration time was 10 hr, anoxic time was 2 hr aeration and sludge settling time was about 0.5 min. After 90 days, the dominant granules size was 1.5-3.5 mm. The granules became regular in shape with smooth surface, sharp boundaries and compact in structure. The biomass concentration in the reactor in terms of MLSS was 4100 mg/l. Sludge volume index (SVI) was 60 ml/g. High synthetic COD removal and simultaneous nitrification and denitrification during aerobic phase was observed. Subjection of the mature granules to a low COD municipal wastewater the activity of the granules was significantly reduced.
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