Avaliação da eficiência de diferentes métodos de extração da proteína da semente de Moringa oleifera no tratamento de efluente de uma indústria de galvanoplastia

Abstract

Electroplating effluent is generated from the electrochemical process used to deposit a metal layer onto a surface. It is characterized by high concentrations of metals such as chromium, nickel, and copper, in addition to toxic substances. Physicochemical treatment has the ability to minimize the harmful effects on water bodies by removing and reducing organic matter and suspended solids from the effluent. The extraction of protein from Moringa oleifera seeds and its use as a coagulant in effluent treatment offer properties such as maintaining a stable pH range and reducing turbidity, apparent color, and organic matter. This study aimed to evaluate and compare the performance of different methods for extracting protein from Moringa oleifera seeds in treating effluent from an electroplating industry. Coagulants were produced using the following extraction processes: Soxhlet with hexane (T1), ultrasound with hexane (T2), ultrasound with ethanol (T3), and saline solution (NaCl) (T4). Experiments were conducted in duplicate using a Jar-test device to simulate the stages of physicochemical treatment and verify the efficiency of the coagulants over time. Effluent samples were collected after 3 minutes of sedimentation and subsequently at 10-minute intervals (3, 13, 23, and 33 minutes), followed by a filtration stage. Filters were constructed with three layers of geotextile non-woven fabric at the base and filled with 7.5 cm of sand with a grain size of 0 to 0.425 mm and 7.5 cm of sand with a grain size of 0.425 mm to 0.850 mm. For the analysis of the effluent treatment quality, the following parameters were observed: pH, turbidity, electrical conductivity, apparent color, and COD. Analyses were performed in duplicate, and after obtaining the results, ANOVA statistical analysis was applied. For the pH parameter, no variation was observed until the effluent passed through the filtering medium, with values remaining constant throughout the experiment. Electrical conductivity showed no significant deviations compared to the raw sample. Turbidity analysis showed superior results for treatment T4, with turbidity removal values exceeding 80%. During the filtration stage, all treatments demonstrated significant improvement, with removal values exceeding 95%, highlighting the importance of filtration as a complementary step in effluent treatment. Treatment T4 stood out in apparent color removal, achieving a maximum removal value of 96% at the 13-minute collection. COD removal analysis yielded unsatisfactory results, as the treatments contributed to an increase in COD in the treated effluent. The study demonstrated the feasibility of using coagulants produced from protein extraction methods for removing apparent color and turbidity, along with COD associated with filtration. Among the treatments, ultrasound with ethanol (T3) showed notable results; however, the saline solution method outperformed the others.