International Journal of Environmental Science and Technology https://doi.org/10.1007/s13762-020-03015-1
ORIGINAL PAPER
B enchmarking of scaling and fouling of reverse osmosis membranes in a power generation plant of paper and board mill: an industrial case of a paper and board mill study
S. Z. J. Zaidi 1,2 · A. Shafeeq 1 · M. Sajjad 1,3 · S. Hassan 4 · M. S. Aslam 5 · T. Saeed 6 · F. C. Walsh 2
Received: 17 July 2020 / Revised: 1 October 2020 / Accepted: 31 October 2020 © The Author(s) 2020
Abstract The present study reports the characterization of reverse osmosis (RO) technology at water treatment plant Cogen-2 in paper and Board mills, Pakistan. RO is a commonly used process to obtain de-mineralized water for high-pressure boiler operation in thermal power plants. Scaling and fouling in three-stage RO plants is a major challenge in chemical industry due to the use of raw brackish water in the power plant of paper and board mills. In our study, the feed water quality of RO was changed from soft water to raw water to make it economical. The cleaning frequency was increased three times than normal, which was unsafe for operation and it was required to control scaling and fouling to achieve the desired result. Differential pres- sures behavior of all stages for 2-month data was observed without acid treatment, and the results of Langelier Saturation Index (LSI) control parameters (temperature, pH, total dissolved solids, calcium hardness, and alkalinity) clearly showed the abnormality. To optimize scaling and fouling of RO, the LSI factor was controlled in total reject water for the next 2 months by acid treatment in feed water. Duration of chemical cleaning and membranes’ life has been extended by fouling and scaling control. Understanding the effect of operational parameters in RO membranes is essential in water process engineering due to its broad applications in drinking water, sanitation, seawater, desalination process, wastewater treatment, and boiler feed water operation. The product flow increased from 18.3 to 19.9 m 3 /h, and this was due to a decrease in the rejection flow from 8.2 to 6.7 m 3 /h. The total reject stream pressure also increased from 8.1 to 9 bar. A lower value of LSI of 1.6 is obtained in the reject water stream after the acid treatment.
Keywords Acid treatment · LSI · Membrane · Reverse osmosis · Fouling
Introduction
Editorial responsibility: Samareh Mirkia.
Raw water cannot be used directly in high-pressure boilers in steam turbine operation due to the total hardness and pres- ence of higher concentrations of total dissolved solids and other salts and chlorides. These solids and salts can strongly corrode and scale in boiler tubes and must be removed prior to feed in the boilers (Ansari and Pandit 2020). In addition, scaling creates a barrier to heat transfer which results in higher fuel consumption and maintenance cost which are required to overcome all these issues (Das et al. 2018). To overcome these issues permanently, the feed water quality must be improved. There are a lot of methods for the treat- ment of raw water in order to maintain water quality and to obtain the desired results of different parameters (pH, total dissolved solids (TDS), hardness, alkalinity, chlorides, silica, and iron) of boiler feed water. For example, there are electrochemical approaches (Zaidi et al. 2018, 2019),
* S. Z. J. Zaidi
zohaib.icet@pu.edu.pk
1 Institute of Chemical Engineering and Technology, University of the Punjab, Lahore, Pakistan 2 Electrochemical Engineering Laboratory, Energy Technology Research Group, Faculty of Engineering and Environment, Engineering Sciences, University of Southampton, Highfield, Southampton SO17 1BJ, UK 3 Paper & Board Mills Ltd, Multan Road, Kasur, Pakistan 4 Mechanical Engineering, Faculty of Engineering and Environment, Engineering Sciences, University of Southampton, Highfield, Southampton SO17 1BJ, UK 5 Institute of Biochemistry and Biotechnology, University of the Punjab, Lahore, Pakistan 6 Department of Chemistry, Government Jinnah Degree College for Women, Lahore, Pakistan
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