Application of response surface methodology and semi-mechanistic model to optimize fluoride removal using crushed concrete in a fixed-bed column

ABSTRACT

The aim of this study was to investigate the removal of fluoride from aqueous solutions by using crushed concrete fines as a filter medium under varying conditions of pH 3–7, flow rate of 0.3–0.7 mL/min, and filter depth of 10–20 cm. The performance of fixed-bed columns was evaluated on the basis of the removal ratio (Re), uptake capacity (qe), degree of sorbent used (DoSU), and sorbent usage rate (SUR) obtained from breakthrough curves (BTCs). Three widely used semi-mechanistic models, that is, Bohart-Adams, Thomas, and Yoon-Nelson models, were applied to simulate the BTCs and to derive the design parameters. The Box-Behnken design of response surface methodology (RSM) was used to elucidate the individual and interactive effects of the three operational parameters on the column performance and to optimize these parameters. The results demonstrated that pH is the most important factor in the performance of fluoride removal by a fixed-bed column. The flow rate had a significant negative influence on Re and DoSU, and the effect of filter depth was observed only in the regression model for DoSU. Statistical analysis indicated that the model attained from the RSM study is suitable for describing the semi-mechanistic model parameters.

KEYWORDS:

• Crushed concrete fines
• fluoride
• optimization
• response surface methodology
• semi-mechanistic model

Disclosure statement

No potential conflict of interest was reported by the authors.

ORCID

Seong-Jik Park http://orcid.org/0000-0003-2122-5498

Additional information

Funding

This work was supported by the project ‘Development of Sustainable Remediation Technology for Marine Contaminated Sediments’ funded by the Ministry of Oceans and Fisheries [grant number 20110110]. This study was also carried out with the support of ‘Cooperative Research Program for Agricultural Science & Technology Development [grant number PJ01086103]’, Rural Development Administration, Republic of Korea.