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Application of Response Surface Method as an Experimental Design to Optimize Coagulation Tests
Thuy Khanh Trinh,Seok Kang Lim 대한환경공학회 2010 Environmental Engineering Research Vol.15 No.2
In this study, the response surface method and experimental design were applied as an alternative to conventional methods for the optimization of coagulation tests. A central composite design, with 4 axial points, 4 factorial points and 5 replicates at the center point were used to build a model for predicting and optimizing the coagulation process. Mathematical model equations were derived by computer simulation programming with a least squares method using the Minitab 15 software. In these equations, the removal efficiencies of turbidity and total organic carbon (TOC) were expressed as second-order functions of two factors, such as alum dose and coagulation pH. Statistical checks (ANOVA table, R2 and R2(adj) value, model lack of fit test, and p value) indicated that the model was adequate for representing the experimental data. The p values showed that the quadratic effects of alum dose and coagulation pH were highly significant. In other words, these two factors had an important impact on the turbidity and TOC of treated water. To gain a better understanding of the two variables for optimal coagulation performance, the model was presented as both 3-D response surface and 2-D contour graphs. As a compromise for the simultaneously removal of maximum amounts of 92.5% turbidity and 39.5% TOC, the optimum conditions were found with 44mg/L alum at pH 7.6. The predicted response from the model showed close agreement with the experimental data (R2 values of 90.63% and 91.43% for turbidity removal and TOC removal, respectively), which demonstrates the effectiveness of this approach in achieving good predictions, while minimizing the number of experiments required.
Trinh Thi Thanh THUY,Nguyen Thi BINH,Trinh Thi Thu HUONG,Nguyen Thu THUY,Dang Thanh PHUONG,Tran Thi Bao KHANH,Nguyen Thi YEN 한국유통과학회 2021 The Journal of Asian Finance, Economics and Busine Vol.8 No.11
The development of the ethnic minorities and mountainous areas (EMMA) is currently receiving the attention of countries around the world. This is demonstrated through a large number of studies, in many respects, in many different countries. The objective of the study is to find out the current situation of the commodity market in the ethnic minorities and mountainous areas (EMMA) of Vietnam. In particular, the authors will study whether there is a link between the ability to access governmental policies and the characteristics of this commodity market. To achieve the goal, the authors employed the secondary data collection method to gather the relevant information on government policies for EMMA and conducted an interview of seventy (70) enterprises in the Northern midlands and mountainous regions and the Central Coast to clarify the characteristics of commodity market. By Levene’s test, the results showed that the accessibility to governmental policies has a certain influence on the development of the commodity market patterns in the EMMA in terms of diversification of distribution forms and sales method of the business. These findings brought some basic solutions to further enhance the role of the government in developing commodity markets in the EMMA of Vietnam.