resumo
Effluents discharged from petrochemical facilities are complex and composed of various types of highly toxic contaminants, which necessitates the development of sustainable treatment technologies. Stability is among the most important sustainability criteria of the wastewater treatment processes. In the present manuscript, the standard-reaching rate (eta) index was used to evaluate the stability of the catalytic ozonation process for treating the secondary effluent from the petrochemical industry. A pilot-scale device was designed and implemented for catalytic ozonation. The effluents were taken from the secondary sedimentation tank of a petrochemical wastewater treatment plant in China. A commercially available gamma-Al2O3 was used as the catalyst after a pre-treatment heating step. The catalyst was characterized using scanning electron microscopy. Three mathematical statistics indexes, discrete coefficient (V-sigma), skewness coefficient (C-so), and range coefficient (V-R), were used to analyze the results achieved from the catalytic ozonation process. Continuous operation of the pilot-scale device was monitored for 9 months under an ozone concentration of 36 mg/L and the contact oxidation time of 1 h. The results demonstrated that the stability evaluation grades of chemical oxygen demand (COD) and suspended solids (SS) in the effluent of the catalytic ozonation system were both 3 and A, indicating that the process was relatively stable over a long period of application. The effluent COD compliance grade was also calculated as B, indicating that the effluent COD does not meet the standard and the process parameters need to be further optimized. When the reflux ratio is 150%, the removal rate of COD is the highest (38.2%) and the COD of effluent is 49.34 mg/L. Meanwhile, to enhance the efficiency and stability of the system, the ozone concentration and the two-stage aeration ratio are 40 mg/L and 4:1, respectively. Moreover, the presence of SS in the water of the catalytic ozonation system will result in the waste of ozone and reduce the utilization rate of ozone.
palavras-chave
OZONE; ABSORBENCY
categoria
Science & Technology - Other Topics; Environmental Sciences & Ecology
autores
Zhang, SY; Wang, H; Zhou, YX; Kamali, M; He, XW; Khalaj, M; Xia, Y
nossos autores
Mohammadreza Kamali
Estudante de doutoramento
Mohammadreza Khalaj
Estudante de doutoramentoagradecimentos
This research was funded by The National Water Pollution Control and Treatment Science and Technology Major Project of China (2017ZX07402002-05-02). Mohammadreza Kamali holds a postdoctoral research grant awarded by the Research Council of KU Leuven [PDM/19/104]. Thanks alre also due to the Financial Support of CESAM-Centre for Environmental and Marine Studies, POCI-01-0145-FEDER-007638 (FCT Ref. UID/AMB/50017/2020) and The Project CICECO-Aveiro Institute of Materials, UIDB/50011/2020 & UIDP/50011/2020, which was funded by National Funds through The Portuguese Foundation for Science and Technology/MCTES and The Co-funding by the FEDER, within the PT2020 Partnership Agreement and Compete 2020.