YUEYaoxu,YANXiaolei,QINShiyi,et al.Pilot Study of Circulating Granulation Fluidized Bed for Concentrated Water Softening and Pipeline Scale Inhibition[J].China Water & Wastewater,2026,42(5):41-46.
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Pilot Study of Circulating Granulation Fluidized Bed for Concentrated Water Softening and Pipeline Scale Inhibition

China Water & Wastewater[ISSN:1000-4062/CN:12-1073/TU] volume: 第42卷 Number: 第5期 Page: 41-46 Column: Date of publication: 2026-03-01
Author(s):
YUE　Yaoxu1; 2;  YAN　Xiaolei3;  QIN　Shiyi3;  HU　Ruizhu1; 2;  HUANG　Tinglin1; 2
（1. School of Environmental and Municipal Engineering， Xi’an University of Architecture and Technology， Xi’an 710055， China； 2. Collaborative Innovation Center of Water Pollution Control and Water Quality Security Assurance of Shaanxi Province， Xi’an University of Architecture and Technology， Xi’an 710055， China； 3. Shaanxi Water Development Water Supply Group Co. Ltd.， Xi’an 710016， China）
Keywords:
circulating granulation fluidized bed;  reverse osmosis concentrate;  high-hardness water softening;  scaling index;  pipeline scaling
Abstract:
This study conducted a pilot-scale investigation on concentrated water softening and pipeline scale inhibition using a combined system comprising a chemical crystallization circulating granulation fluidized bed and a circulating agglomeration granulation fluidized bed (collectively referred to as the circulating granulation fluidized bed system). The feed water was reverse osmosis (RO) concentrate from an ultrafiltration-RO (“dual membrane”) groundwater treatment plant in Shaanxi Province. Under the optimal operating conditions—upflow velocity of 80 m/h, seed crystal dosage of 225 g/L, sodium hydroxide dosage of 500-550 mg/L, hydrochloric acid dosage of 50-55 mg/L, and polyacrylamide (PAM) dosage of 1.00 mg/L—the removal rates for total hardness and calcium ions reached 60% and 88%, respectively. The treated effluent exhibited a turbidity of 0.2-0.5 NTU and a pH of 7.10. The chemical cost was calculated to be 2.14-2.35 CNY/m3. The scaling propensity indices of the effluent were as follows: Langelier saturation index (LSI) of -0.37, Ryznar stability index (RSI) of 7.77, and Puckorious scaling index (PSI) of 6.65, collectively indicating a low potential for pipeline scaling. Surface element analysis via EDS and XRD confirmed that the primary component of the crystalline particles was high-purity CaCO3. The pilot-scale results demonstrate that the circulating granulation fluidized bed system can effectively remove hardness and alkalinity from the concentrate, reduce the tendency of calcium carbonate scaling in pipelines, and thereby provide a theoretical basis and data support for its practical application in dual membrane groundwater treatment plants.
Last Update: 2026-03-01