0628_Pre-treatment of SWRO pilot plant for desalination using submerged MF membrane...

Title: Pre-treatment of SWRO pilot plant for desalination using submerged MF membrane process: Trouble shooting and optimization
Journal: Desalination
Authors: Seongpil Jeonga, b, Yonghea Parka, Seockheon Leea, Janghong Kimc, Kwanhyung Leec, Jeawoo Leec and Hyo-Taek Chonb

a Water Research Center, National Agenda Research Division, Korea Institute of Science and Technology, 39-1, Haweolgok-Dong, Sungbuk-Gu, Seoul 136-791, Republic of Korea
b Department of Energy Resources Engineering, College of Engineering, Seoul National University, Seoul 151-744, Republic of Korea
c Department of Environmental Engineering, Korea University, Jochiwon-eup, Chunngnam 339-700, Republic of Korea

The original and creativity of paper: The paper aim to compare the performance of two kinds of pre-treatment process for SWRO: conventional pre-treatment process and submerged MF membrane pre-treatment process. Moreover, the optimization of submerged MF membrane pre-treatment process and coagulation dosing has been done.

All results of this paper obtained by operating SWRO pilot plant couple with two kinds of pre-treatment processes (i.e., membrane and conventional pre-treatment processes) for one year. The result of the comparison of pretreatment processes found that membrane pre-treatment process provided higher permeate flux and RO rejection rate than conventional process. However, the permeate turbidity of both processes are not significant different.  

Results of coagulant optimization using batch test showed that:
-    For all MF membrane types (i.e., 2.5 ?m, 1.2 ?m, 0.45 ?m), increasing of coagulant dose reduced turbidity of permeate water. Additionally, the optimum dose of FeCl3 was estimated to be at least 1.5 mg/L.
-    The turbidities of effluents of all membranes decreased when pore sizes decreased. However, the decreasing tendencies of those three membranes were identical.
-    In order to prevent leaking during filtration process, membrane filtration system should be conducted at low vacuum pressure or operated using high stable permeability membrane.
-    The optimization of coagulation process was defined as the lowest turbidity condition according to variations of the coagulant dose and pH. The optimum conditions for pH and coagulant dose ranged from 6 to 7 and from 8 to 10 mg/L of FeCl3, respectively.

Moreover, foam formation was investigated. It is found that foaming potential was affected by the colloidal particles and NaOCl concentrations.  It is reported that the higher amount of colloidal matters, higher form formation. Therefore, the foam formation can be controlled by reducing the amount of colloidal matters and also NaOCl. 

By Monruedee Moonkhum
Email: moon@gist.ac.kr
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