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.

Keywords

• activated dolomite
• decolourisation
• textile dye wastewater
• adsorption
• wastewater treatment