Changes to levels of microcontaminants and biological responses in rainbow trout exposed to extracts from wastewater treated by catalytic ozonation

A novel physical-biochemical treatment of refinery wastewater

As of 2022, China has achieved a crude oil processing capacity of 918 million tons, leading to a notable escalation in the production of refinery wastewater. The composition of refinery wastewater is intricate and diverse, posing a substantial challenge to its treatment. In order to facilitate appropriate discharge or reuse, an exhaustive separation process is imperative for refinery wastewater. Conventional pre-treatment processes typically employ inclined plate separators and dissolved air flotation (DAF) for the removal of oil and suspended solids (SS), while sequencing batch reactor (SBR), oxidation ditch, or biological aerated filter (BAF) are employed for the biological treatment process. However, these approaches encounter challenges such as a large spatial footprint, suboptimal treatment efficiency, and high energy consumption. In response to these challenges, this study introduces a novel integrated apparatus consisting of a high-efficiency oil remover (HEOR), coalescence oil remover (COR), and an airlift-enhanced loop bioreactor (AELR). A pilot-scale test was conducted to evaluate the performance of this integrated system in practical field applications. The pilot-scale tests reveal that, without the addition of chemical agents, the petroleum removal efficiency of "HEOR + COR" system was 1.2 times that of DAF. Compared with the SBR system, AELR's volume loading was increased by 1.56 times. The effluent quality achieved in the pilot-scale tests attained parity with that the original process. The "HEOR + COR + AELR" system exhibited energy and carbon emissions reduction of 28% and 30% compared to the "DAF + SBR" system, respectively. Therefore, the operating costs was reduced by approximate 1 Chinese Yuan (CNY) per ton of treated water. This technological advancement serves as a valuable reference for the implementation of low-carbon treatment of refinery wastewater.

Construction of triphase interface for catalytic ozonation of polluted water

The utilization efficiency of ozone determines the cost of catalytic ozonation in water treatment. Herein, a triphase catalytic system was constructed by aerating ozone through a CeO2 loaded Al2O3 ceramic membrane (CeO2-CM) for disinfection and antibiotic degradation. Ozone aeration and a packed catalyst system (CeO2-Packing) were set as the controls. Results showed that CeO2-CM reduced the ozone escape by 34.6%-56.2%. The ozone utilization capacity of CeO2-CM for E. coli inactivation was 33.1% and 33.8% higher than those of CeO2-Packing and ozone aeration, respectively. The ozone utilization capacity of CeO2-CM for sulfamethoxazole degradation was 88.5% and 183.1% higher than those of CeO2-Packing and ozone aeration, respectively. CeO2-CM, with the lowest ozone escape and highest ozone utilization efficiency, significantly enhanced the performance of catalytic ozonation in disinfection and antibiotic degradation. This work proposes a feasible strategy for minimizing ozone consumption in water treatment.

A critical review over the removal of paracetamol (acetaminophen) from synthetic waters and real wastewaters by direct, hybrid catalytic, and sequential ozonation processes

Paracetamol (PCT) or acetaminophen is a widely prescribed drug to treat fever and mild to moderate pain. The PCT uptake by animals and humans is not complete, being excreted through their urine to contaminate the aquatic/natural environments. Trace amounts of this drug have been found in sewage sludge, hospital wastewaters, wastewater plant treatments, surface waters, and even drinking water. PCT denatures proteins and oxidize lipids in cells with damage of their genetic code. Its toxicity over macrophytes, protozoan, algae, bacteria, and fishes has been reported. Ozonation methods have been proposed as efficient treatments to solve this pollution. This comprehensive and critical review is focused on the application of ozonation processes to remove PCT polluted water from different sources, like natural waters, synthetic waters, and real wastewaters. The fundamentals, operating variables, and best results by direct ozonation and hybrid catalytic ozonation are described, with attention to produced reactive oxygen species and their oxidative action. Single ozonation, catalytic modification of materials, and hybrid non-catalytic processes are detailed as direct ozonation methods. Ozonation with metal-based catalysts and photolytic and photocatalytic ozonation as hybrid catalytic methods are analyzed. Sequential non-biological and biological treatments with ozone and ozonation for wastewater remediation in treatment plants are described. Reaction sequences proposed for PCT mineralization are finally discussed, showing the initial formation of hydroquinone and 2-hydroxy-4-(N-acetyl)-aminophenol and their consecutive evolution to ultimate carboxylic acids like oxalic and oxamic. The ability of the methods to destroy these acids and their iron- and/or copper-complexes explains their mineralization performance.