ENBIS-12 in Ljubljana

9 – 13 September 2012 Abstract submission: 15 January – 10 May 2012

Water Quality Function Deployment

11 September 2012, 10:00 – 10:20


Submitted by
Shuki Dror
Shuki Dror (ORT Braude College), Natalia Zaitsev (ORT Braude College)
The main goal of this study is to create a framework for technology selection, enabling a water supplier to improve the quality of tap water.
The Quality Function Deployment (QFD) is utilized as an instrument for ranking the relevant technologies. The QFD is designed to reveal where the quality of water characteristics requires improvement and to translate the deficiencies into demands on technical water characteristics and ultimately into relative importance of relevant technologies.
First, we range the wishes and the conceived preferences of the final customers (“voice of the customer” – VOC) for tap water quality. Customers’ requirements for tap water quality are obtained by a survey, which includes two groups of questions, aimed to assess the desirability of six separate characteristics of water quality, and to estimate the gap between the desired water quality and its perceived present state. The six characteristics are: odor, turbidity, color, calcification (scaling), taste, and absence of biological pollutants. In order to assess the required improvement level of each characteristic to the customer, we define the importance level of a characteristic as the mean of the importance of the characteristic multiplied by the mean gap between the desired level and the perceived present situation for the same characteristic.
In the next stage, we conduct an expert survey, which consists of two groups of questions.
In the first group, the expert is asked to estimate the influence of technical parameters of the water on the perceived characteristics of the water quality as provided by the customers. The relative importance of the following 10 parameters were calculated using QFD method: hardness, acidity, chlorine/chloramines, fluoride, nitrate, chloride (salinity), solid colloids, total organic carbon, iron, and dissolved oxygen.
The second group of questions in the expert survey comprises relevant water treatment technologies and their effect on the technical parameters. Again the experts estimated the contribution of each one of the relevant technologies to the improvement of the technical water parameters and the relative importance were calculated.
The list of technologies includes more than a dozen principal technologies, such as: desalination, microfiltration, granular filtration (sand/coal bedding), UV sterilization, reduction of acidity, chlorination, etc.
To construct the water QFD two matrices representing the questionnaire results have to be analyzed. Normalized improvement scores are calculated at each of the three hierarchical levels: customer requirements, technical parameters and technologies. The components to be improved at each of the above levels are selected by means of the MSE (Mean Square Error). We find that the desalination is the vital technology for improving water quality.

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