Utilization of Alyssum mucilage as a natural coagulant in oily-saline wastewater treatment

Abstract

Wastewater treatment with natural coagulants is an area that is well-researched and covered in the literature, but new research in this current and ongoing field is still interesting. The present analysis was conducted as the first study to investigate the use of Alyssum mucilage as a new, natural, and cost-effective coagulant for the treatment of synthesized bilge water. To the best of the authors' knowledge, no previous study has specifically devoted to implementing a systematic analysis of a new coagulant (Alyssum mucilage) within the framework of central composite design-response surface methodology (CCD-RSM), adaptive neuro-fuzzy inference system (ANFIS), and artificial neural network (ANN). Thus, to spot the lights over the mentioned gaps, the current study was undertaken as the first attempt to perform highly comprehensive mathematical, kinetic, and statistical analyses for a quantitative definition of the coagulation-flocculation process of oily-saline wastewater treatment using Alyssum mucilage. In this study, three process-related parameters, such as coagulant dose, contact time, and pH, were introduced for modeling, optimization, and cost analysis of the investigated application. At the optimum conditions (coagulant dose = 40.5 mg/L, pH = 7.05, and contact time = 34.9 min) of Alyssum mucilage, the maximum chemical oxygen demand (COD), turbidity (TU), and surfactant removal efficiencies were obtained as 84.63 %, 96.25 %, and 99 %, respectively. Under the optimum conditions (coagulant dose = 301.8 mg/L, pH = 6.53, and contact time = 23.1 min) of poly aluminum chloride (PAC), used as a comparative polymerized metal coagulant, the maximum COD, TU, and surfactant removal efficiencies were determined as 92.30 %, 99.92 %, and 99 %, respectively. Compared to CCD-RSM, ANFIS and ANN showed high accuracy with R 2 values more than 0.990 for both PAC and Alyssum mucilage. The kinetic study revealed that the second-order model performance was superior to the first-order model. Fourier-transform infrared spectroscopy (FTIR) analysis of Alyssum mucilage demonstrated that the functional groups presented in the composition of this coagulant caused coagulation and bonding between the particles. Furthermore, the zeta potentials of bilge water, coagulant, and treated bilge water indicated that the possible mechanism of the coagulation would be adsorption and bridging.