Investigação do processo de ozonólise no tratamento de um efluente proveniente da degomagem enzimática do óleo de soja

Abstract

Energetic sector industries, such as biodiesel producers, stand out in the manufactured fuel industry. This is due to the tendency to increase its production over the years, which is related to the requirement to incorporate biodiesel into diesel oil. With the increase in production, there is also a proportional increase in the generation of effluents, coming from the different manufacturing processes of this biofuel. Liquid effluents from vegetable oil treatment have complex characteristics that prevent their direct release into the environment and they also hinder their treatment by conventional processes. Among the available technologies, Advanced Oxidative Processes (AOPs) are presented as a promising and effective alternative for the treatment of these effluents, in order to avoid contamination of water resources during their disposal. In this sense, the objective of this work was to evaluate the efficiency of the ozonolysis process in the treatment of an effluent from the enzymatic degumming process of soybean oil from a biodiesel producing industry in the state of Rio Grande do Sul. For that, experiments were carried out in a batch reactor using an ozone generator (O3), where they were analyzed variables of hydrogen potential (pH) and process time from 0 to 120 minutes, with a fixed concentration of 65 mg O3 L -1 . In addition, the possibility of applying a post-treatment with the addition of Calcium Chloride (CaCl2) was verified. The monitoring of the effluent treatment as a function of time considered the evaluation of the acute toxicity of the raw and treated effluent, using the micro crustacean Artemia salina as a bioindicator and the reduction of the compounds determined by Gas Chromatography coupled to Mass Spectrometry (GC-MS). The results indicated a greater reduction in toxicity in 15 minutes of ozonolysis at pH 5.86 followed by the addition of CaCl2. The analyzes in the GC-MS indicated that, in treatment times longer than 15 minutes, there was the formation of by-products that may be associated with increased toxicity in the samples. This effect indicates that the ideal would be to interrupt the ozonolysis process at pH 5.86 in the initial minutes of the treatment, in order to avoid the formation of toxic byproducts, as well as the possibility of O3 saturation in the medium, due to the high reaction time and flow constant of 65 mg O3 L -1 . Also, the monitoring of the degradation of organic matter present in the effluent as a function of time showed a reduction in turbidity after the chemical precipitation with CaCl2, achieving a reduction efficiency of up to 98.62 %. Thus, it is concluded that an application of the ozonolysis process together with CaCl2 presents itself as an alternative for the treatment of the effluent of enzymatic degumming of soybean oil.