Application of PARAFAC Technique to Compare Fluorescence Property of Different Dissolved Organic Matters

Objectives : It provides a detailed procedure for analyzing dissolved organic matter (DOM) by the PARAFAC technique and aims to identify compare different fluorescent components of DOM with various water sources.Methods : PARAFAC modeling was performed based on the PARAFAC tutorial by Stedmon et al. [11] using a total of 160 samples originated from wetlands, river, wastewater treatment plant influent and effluent. The procedure includes data preprocessing, initial model creation, outlier analysis, split-half analysis, core consistency, and sum of squared error analysis (SSE). After finishing the model validation step, the samples were analyzed through the verified PARAFAC model.Results and Discussion : An initial model with 2 to 4 components was created, and as a result of outlier analysis, the four WWTP Influent samples were removed as outliers. As a result of SSE analysis, the model with two components has a relatively higher SSE value than the model with three or four components. In the case of core consistency, the model with 2, 3, and 4 components scored 99.6%, 94.9%, and 65.7%, respectively. As a result of the split-half analysis, the spectra of the model having the three components of the split data were the same, so it was finally determined that the number of three components was appropriate in the model. The DOM samples were analyzed by the developed PARAFAC model. It was confirmed that the ratio of humic components was higher in the order of WWTP effluent ≈ wetland > river > WWTP influent, and the ratio of protein components affected by microbial activity was in the order of WWTP influent > river > wetland ≈ WWTP effluent.Conclusion : In this paper, the procedure of PARAFAC modeling was described and the DOM fluorescence properties were compared. This research provides a practical method for increasing the utilization of the PARAFAC model in the water treatment research field. In addition, the result of the PARAFAC model is useful data to control DOM efficiently in water treatment facilities.