Abstract
ABSTRACT The cultivation of microalgae is a possible destination for vinasse, a residue from the sugar and alcohol industry. This use can help reduce the costs of microalgae production and remediate this residue rich in nutrients. However, the physicochemical characteristics of vinasse limit its use for microalgae growth at low concentrations, except when the residue is pretreated. This work aimed at optimizing the vinasse pretreatments of centrifugation and adsorption by smectite clay and activated charcoal on laboratory scale in terms of amounts of materials used and time spent, making them more viable on larger scales. The optimized processes were then compared in productive, economic, and environmental terms. The dilution of treated vinasse with distilled water resulted in similar growth of Chlorella vulgaris to those obtained with the dilution in BG11 medium, indicating that the addition of nutrients in culture media is not necessary. Although microalgae growth occurs in higher concentrations of vinasse treated by adsorption, the results show that centrifugation required less processing time, has cheaper processing costs, and generated much less residue. Centrifugation treatment has greater economic and environmental viabilities and was more sustainable than the adsorption, even though the algae did not grow in the centrifuged residue in concentrations as high as it did after the adsorption treatment. Therefore, this article brings a new view about the economic and environmental aspects on the use of pretreated vinasse for microalgal growth, giving a lucrative destination for a highly polluting waste.
Highlights
The production of ethanol from sugarcane releases high volumes of vinasse, whereas 1 L of ethanol generates about 12 L of vinasse (UNICA, 2017)
According to Silva, Griebeler and Borges (2007), sugarcane vinasse carries high mineral and organic nutrients, which has led to its application as a soil fertilizer
The need to improve vinasse quality, so reducing fertirrigation-related problems, has been investigated by Rocha, Lora and Venturini (2008). They analyzed the life cycle and feasibility of vinasse biodigestion, dewatering and combustion, concluding that such techniques are necessary for alternative uses of vinasses, likewise the search for other destinations for the residue, that are welcome and can help mitigate the related environmental problems
Summary
The production of ethanol from sugarcane releases high volumes of vinasse, whereas 1 L of ethanol generates about 12 L of vinasse (UNICA, 2017). According to Silva, Griebeler and Borges (2007), sugarcane vinasse carries high mineral and organic nutrients, which has led to its application as a soil fertilizer. The excessive application of the residue in the soil can generate its salinization, and such vinasse use is controlled by governmental agencies (SILVA; GRIEBELER; BORGES, 2007). The need to improve vinasse quality, so reducing fertirrigation-related problems, has been investigated by Rocha, Lora and Venturini (2008). They analyzed the life cycle and feasibility of vinasse biodigestion, dewatering and combustion, concluding that such techniques are necessary for alternative uses of vinasses, likewise the search for other destinations for the residue, that are welcome and can help mitigate the related environmental problems
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