Abstract
Biodiesel is a renewable, non-toxic and sustainable biofuel, considered to be the main candidate for a fossil fuel alternative in many countries. However, its manufacturing process results in about 0.2 to 3 L of effluent per litre of biodiesel produced. In addition to an inherently high organic load, its composition includes by-products, traces of unreacted chemicals and catalysts, which inhibit microorganism growth and prevent its direct treatment by tertiary methods. In this context, this work aims to evaluate the combination of the coagulation-flocculation technique with dissolved air flotation (DAF). Real wastewater samples were obtained by synthesising biodiesel from soybean oil in-loco and performing the required washing procedures. The highest turbidity reduction efficiency (92.03%) was obtained using 1200 of clay. By using response surface methodology, it was possible to analyse the effect of the chosen experimental factors and show that the best results (81.28%, 58.95% and 89.34% for turbidity, oil and grease and chemical oxygen demand - respectively) were obtained using 925 of clay and 1000 of coagulant. Ultimately, clay proved to be an efficient coadjutant in the removal of organic matter, oils, grease, suspended solids and soluble organic matter from the biodiesel wastewater. Moreover, its low cost over traditional flocculants makes it an attractive alternative to industrial wastewater treatment processes.
Highlights
The recent worldwide attention given to renewable energy sources is a result of raised concerns over long-term effects of global warming and new developments in the petroleum geopolitics [1]
The microbubbles bond to the particles, increasing their buoyancy and allowing them to rise to the surface [16]. In this manuscript we report the application of a combined CF-Dissolved Air Flotation (DAF) process – using clay as coadjutant agent – in the pre-treatment of wastewater produced during biodiesel washing, a required purification step in the biofuel production
Wastewater samples were provided by the Laboratory of Alternative Technologies (LTA) of the Federal University of Sergipe, were the biodiesel washing (BW) effluent was obtained from the biodiesel production on a bench-scale process
Summary
The recent worldwide attention given to renewable energy sources is a result of raised concerns over long-term effects of global warming and new developments in the petroleum geopolitics [1]. In this context, owing to several other advantages regarding their sustainability, technical. The biodiesel must be washed thoroughly, in order to remove by-products and other contaminants. This process is well-known as biodiesel washing (BW) and yields an effluent rich in unconverted oil, traces of the catalyst and significant amounts of alcohol used in production [6, 7]. For each litre of biodiesel produced, approximately 0.2 to 3 L of wastewater is formed during BW [8]
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