Removal of fluoride and turbidity from semiconductor industry wastewater by combined coagulation and electroflotation

Abstract

A B S T R A C TReduction of toxic dissolved fluoride and CaF 2 nanoparticle pollution is a critical environmental problem for the semiconductor industry. In this study, suspended matter and fluoride are simultaneously eliminated by combining coagulation and electroflotation. The EF cell was equipped with DSA titanium coated with ruthenium oxide (Ti/RuO 2 ) as anode and stainless steel as cathode. High turbidity removal efficiency is achieved by using EF as a separation technique. The effect of the following parameters: electrolysis time, coagulant concentration, initial pH, nature of neutralizing salt and current intensity was studied. Removal efficiencies of both fluoride and CaF 2 nanoparticles are satisfactory. Under optimum conditions, the solid-liquid separation efficiency is about 97% in terms of turbidity removal which corresponds to a residual turbidity of 4.4 NTU complying with the standard limit (5 NTU), while fluoride efficiency removal may reach 73% corresponding to 10 mg/L, which is below the environmental recommendations.

Defluoridation of drinking water using a new flow column-electrocoagulation reactor (FCER) - Experimental, statistical, and economic approach

“…In order to meet this limitation, different techniques have been used to reduce fluoride concentration, such as electrodialysis (Tahaikt et al, 2004), membrane separation (Ndiaye et al, 2005), adsorption (Zuo et al, 2008), coagulation-electroflotation (Aoudj et al, 2016), and electrocoagulation (EC) (Vasudevan and Oturan, 2014;Kim et al, 2016). Recent studies have demonstrated that the EC method is an attractive alternative for water defluoridation (Un et al, 2009;Aoudj et al, 2010;Kim et al, 2016), because the EC method does not require chemical handling, it is easy to perform, and remarkably reduces the sludge volume and the required space (Zhu et al, 2007;Emamjomeh and Sivakumar, 2009).…”

Energy efficient electrocoagulation using a new flow column reactor to remove nitrate from drinking water – Experimental, statistical, and economic approach

“…generation (Daneshvar et al, 2004;Emamjomeh and Sivakumar, 2005;Aoudj et al, 2016). In the current study, to explore the influence of this key operating parameter on water denitrification, several sets of experiments were carried out at for 30 min at three different CDs (1, 2, and 3 mA/cm 2 ).…”

Removal of Eriochrome Black textile dye from aqueous solution by combined electrocoagulation–electroflotation methodology

“…In order to verify the effect of the potential value applied in the electrocoagulation process, the following potential values were investigated: 2.0 to 9.0 V. In fact, it is known (Gonçalves et al 2016;Aoudj et al 2016) that increasing the potential implies an increase in the formation of the…”