Clarification of factors that affect the flux performance of hollow fiber membranes during ultrafiltration using design of experiments

In this paper, the separation of humic substances from oily wastewater was investigated using Hollow Fiber membranes. Consideration was given to the increse of membrane permeability or flux of the Ultrafiltration process. Specifically, several factors which were temperature, pressure, time, pH and surface area of membrane, were studied. The Design of Experiments (DOE) methodology was used to investigate the effect of the factors. From the analysis of variance (ANOVA), it was determined that the pH and temperature of feed solution, time of separation process and transmembrane pressure are significant. The results of this study help to increase the permeability of membranes, thus contributing to a more sustainable filtration system

Modeling of preparation conditions of PES ultrafiltration hollow fiber membranes using statistical regression techniques

Mathematical modeling of the spinning process is crucial for a better understanding of the process variables and process functionality in membrane development. Due to the broad use and key importance of mathematical models in chemical process engineering, experimental design is becoming essential for the rapid development and validation of these empirical models. This work used the design of experiment methodology and aimed to predict the performance of ultrafiltration systems for water treatment by considering the statistical regression technique as an important approach for modeling flux. The utilization of regression modeling was also explored to show the principle elements for predicting flux in the spinning process. In order to investigate how proficient the statistical regression technique is at approximating the predicted value for flux, a real spinning experiment was conducted in this study. In this experiment, 30 samples of data were collected based on a half fractional factorial experiment with design resolution V, as well as 4 replications of center points and 10 axial points. The spinning factors that were investigated are the dope extrusion rate, air gap length, coagulation bath temperature, bore fluid ratio, and post-treatment time for predicting the corresponding flux. The regression model obtained shows that there is a correlation between the experimental data and predicted values. The results of the proposed model can be used to give a good prediction of the spinning process during membrane fabrication

Involvement and Challenges of School Guidance and Counselling Teacher Towards Special Needs Students

Implementation of guidance and counselling services in schools requires School Guidance and Counselling Teachers (SGCT) to provide this services to all students, whether the mainstream students or Special Needs Students (SNT), as outlined in the Buku Rekod Perkhidmatan Bimbingan dan Kaunseling (Guidance and Counselling Services Record Book). This situation has challenged SGCT especially in meeting the specific needs of SNT. This raises questions regarding the involvement of SGCT in providing guidance and counselling services especially to SNT as well as challenges faced in implementing such services. Therefore, a qualitative study has been conducted to answer the questions. This study involved six SGCT who serve in schools that adopt the Integrated Special Education Program or the Inclusive Education Program. Semi-structured interview questions have been used to obtain relevant information. The finding of this study shows that there are direct and indirect SGCT's involvements with SNT. While the challenges that GBKS face in carrying out guidance and counselling services are divided into three themes, namely the challenges characterized by SGCT, challenges characterized by SNT and challenges characterized by the Organization. The findings of this study can provide information on the implementation of guidance and counselling services to SNT and can be used as an improvement of the existing guidelines to increase the involvement of SGCT in providing guidance and counselling services especially to SNT

Acid pretreatment of WC-Co for surface roughening and cobalt removal prior to CVD diamond coating

Chemical vapor deposition (CVD) diamond coatings are being developed to be applied on carbide cutting tools to enhance wear resistance and increase tool life. As a prerequisite, for ensuring adhesion of CVD diamond on tungsten carbide substrate, it is necessary to prepare high surface roughness and to remove the cobalt on tungsten carbide surface during the pretreatment. In this study, a two step acid pretreatment was examined for those purposes. Etching using modified Murakami's reagent was initially performed to roughen the surface. Subsequently, the carbide was immersed in nitric acid to remove cobalt. Concentration of the acid solutions and reaction time were varied. Results showed that the initial step by modified Murakami's reagent etching resulted in a surface roughness of Ry = 6.95 µm, which is a 15% increase from the average initial surface roughness. The second step by nitric acid immersion on modified Murakami's reagent etched carbide samples resulted in carbide surfaces with zero cobalt content, confirming the effectiveness of the pretreatment. © (2013) Trans Tech Publications, Switzerland

A study of operational factors for reducing the Fouling of hollow fiber membranes during wastewater filtration

AbstractFouling of membranes is the most important problem in wastewater filtration since the sustainability of the process is highly influenced by the fouling rate. Possible ways for fouling control are through feed water pre-treatment, operational conditions and membrane cleaning. This paper studies the operational conditions that affect the fouling of hollow fiber ultrafiltration membranes during the separation of wastewater. Specifically, several factors which are temperature, pressure, time, pH and surface area of membrane, are studied. The Design of Experiments methodology is used to investigate the effect the factors. The results of this study help to reduce the fouling of membranes, thus contributing to a more sustainable filtration system