Optimization studies for water defluoridation with two-stage coagulation processes using new industrial-based chemical coagulants

Hooi Ren Lim, Chee Ming Choo, Chien Hwa Chong, Voon Loong Wong

Research output: Contribution to journalArticlepeer-review

Abstract

The fluoride removal capability of a new industrial-based chemical coagulant (Formula A) in one- and two-stage coagulation treatments was investigated in present study. Three main controlling factors, the coagulant concentration, reaction time and the initial pH of Formula A were studied on the fluoride removal accordingly, with the aid of other coagulants: Ecogent F-Loc, potassium ferrate (K 2FeO 4), and sodium aluminate (NaAlO 2). Response surface methodology (RSM) was adopted to analyse the controlling factors on the fluoride removal efficiency (R%) using Box-Behnken designs (BBD). The coagulant concentration of Formula A shows the most significant effect on R% and better fluoride removal capability at an initial pH 12. Nevertheless, the R% has been shown to be independent of reaction time. Response optimisation revealed the highest R% (70.12%) can be achieved at 1000 ppm, 10 min of reaction time and initial pH of 2. Furthermore, K 2FeO 4 has a better R% in low pH regions of 2 to 4. Additionally, K 2FeO 4 achieved the highest R% (84%) at 1190 ppm and pH 9 with 8.5 min of reaction time. In a single coagulation stage, the use of Formula A or K 2FeO 4 are not able to meet Environmental Quality (Industrial Effluent) Regulations 2009 with discharge Standard B as specified by Department of Environment Malaysia, while a two-stage coagulation process can meet Standard A. Specifically, the combined formulation of using Ecogent F-Loc(1)- Formula A(2) and NaAlO 2(1)- Formula A(2) were able to achieve treated water with less than 2 ppm fluoride. Moreover, recycling treated water also plays a major role in helping industries meet the strict treatment standards.

Original languageEnglish
Article number102179
JournalJournal of Water Process Engineering
Volume42
Early online date17 Jun 2021
DOIs
Publication statusE-pub ahead of print - 17 Jun 2021

Keywords

  • Box-Behnken design
  • Chemical coagulant
  • Fluoride
  • Optimization
  • Response surface methodology
  • Two-stage processes

ASJC Scopus subject areas

  • Biotechnology
  • Safety, Risk, Reliability and Quality
  • Waste Management and Disposal
  • Process Chemistry and Technology

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