Decolourisation of Real Industrial and Synthetic Textile Dye Wastewater Using Activated Dolomite

Abstract

Textile effluent accounts for 22% of the total industrial wastewater produced in Malaysia. Due to their ubiquitous use in organic dyes, inefficiently treated textile wastewaters pose environmental and health hazards. Colour, chemical oxygen demand, biochemical oxygen demand, toxic metals and microbes are the commonly targeted water quality parameters in untreated textile fluids. Furthermore, their non-biodegradability and high colour intensity may reduce aquatic diversity by blocking the sunlight. Recently, physical treatment, principally adsorption, has been conducted. Dolomite has additional features, such as performing as a heavy metal and microbe remover. This study employed dolomite for treating textile dye wastewater from a commercial textile manufacturer and synthetic effluent containing methyl orange. Different sizes of dolomite were activated at different temperatures and subsequently added to the water samples in varying amounts. After 2 h of agitation at 100 rpm and sedimentation for 24 h, their absorbance reading was taken. Their morphological, decolourisation percentage, chemical oxygen demand reduction percentage and bacterial growth post-treatment were examined. Despite variances in dolomite’s capacity to decolourise colours, the treatment proved effective in decolourising dyes, removing chemical oxygen demand and reducing bacterial growth. The most significant percentages of decolourisation observed were 98.7% for real textile dye wastewater (RTDW) and 78.0% for synthetic textile dye wastewater (STDW), while for chemical oxygen demand, reductions were 66.7% for RTDW and 73.9% for STDW, respectively. As for microbe growth inhibition, the highest growth reduction percentages were 99.7% and 98.6% for RTDW and STDW, respectively.

Anionic Dye Alizarin Red S Removal Using Heat-Treated Dolomite

“…In addition to clay minerals, carbonate minerals such as calcite (Cal) and dolomite (Dol) were also studied for the removal of color dyes before and after heat treatment. Previous results showed that Dol will decompose into Cal, magnesium oxide, and carbon dioxide at temperatures of 700 • C [10,11], 800 • C [12,13], or 900 • C [14]. Dol heated at 800 • C for 4 h was evaluated for the removal of dyes basic violet 16 ) from initial concentrations of 10 to 50 mg/L (constant mass volume ratio of 1.5 g/0.5 L of solution) [15].…”

“…Dol heated at 800 • C for 4 h was evaluated for the removal of dyes basic violet 16 ) from initial concentrations of 10 to 50 mg/L (constant mass volume ratio of 1.5 g/0.5 L of solution) [15]. Also, Dol heated for 5 h at 300, 700, and 900 • C was evaluated for the removal of methyl orange (MO), C.I.13025, (C 14 H 14 N 3 NaO 3 S) [14]. In a binary solution made of reactive black 5 (RB5) and Congo red (CR), Dol treated at 900 • C showed preferential adsorption of CR over RB5 and was attributed to inner-sphere complexation with amine groups since CR and RB5 contain two vs. one amine functional groups [16].…”

Heat Treatment of Calcite to Enhance Its Removal of Color Dye Alizarin Red S

“…In addition to the previously mentioned minerals, carbonated minerals such as calcite (Cal) and dolomite (Dol) were also evaluated for their removal of color dyes before and after heat treatment. For example, Dol heated to 800 • C was tested for the removal of single and binary dyes [28], and Dol heated to 300, 700, and 900 • C was tested for the removal of an anionic dye, methyl orange (MO) [29]. Because of the strong affinity of ARS for calcium and phosphorus, CaCO 3 and H 3 PO 5 were utilized to synthesize calcium phosphate hydroxyapatite (Ca-Hap), which was tested for its removal of ARS under different physical and chemical conditions [30].…”