Optimization studies for water defluoridation with two-stage coagulation processes using new industrial-based chemical coagulants. (August 2021)

• Record Type: Journal Article
• Authors: Lim, Hooi Ren; Choo, Chee Ming; Chong, Chien Hwa; Wong, Voon-Loong
• Is Part Of: Journal of water process engineering. Volume 42(2021)
• Publication Date: 2021-08
• Subjects: Fluoride -- Two-stage processes -- Optimization -- Chemical coagulant -- Response surface methodology -- Box-Behnken design; Water-supply engineering -- Periodicals; Saline water conversion -- Periodicals; Seawater -- Distillation -- Periodicals; Sanitary engineering -- Periodicals; Sewage -- Purification -- Periodicals; 627
• DOI: 10.1016/j.jwpe.2021.102179
• Languages: English
• ISSNs: 2214-7144

Abstract

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 (K2 FeO4 ), and sodium aluminate (NaAlO2 ). 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, K2 FeO4 has a better R% in low pH regions of 2 to 4. Additionally, K2 FeO4 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 K2 FeO4 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 NaAlO2 (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.