A phenol-degrading bacterium strain PA was successfully isolated from the effluent of petrochemical wastewater. Based on its morphological, physiological and biochemical characteristics, the strain PA was characterized as a Gram-negative, strictly aerobic, nonmotile and short rod-shaped bacterium that utilizes phenol as a sole carbon and energy source. 16S rDNA sequence analysis revealed that this strain is affiliated to Acinetobacter calcoaceticus in the group of Gammaproteobacteria. The strain was efficient in removing 91.6% of the initial 800 mg∙L⁻¹ phenol within 48 h, and had a tolerance of phenol concentration as high as 1700 mg∙L⁻¹. These results indicated that A. calcoaceticus possesses a promising potential in treating phenolic wastewater.

Antibiotic pollution poses a serious environmental concern worldwide, posing risks to ecosystems and human well-being. Transforming waste activated sludge into adsorbents for antibiotic removal aligns with the concept of utilizing waste to treat waste. However, the adsorption efficiency of these adsorbents is currently limited. This study identified KOH modification as the most effective method for enhancing tetracycline (TC) adsorption by sludge biochar through a comparative analysis of acid, alkali, and oxidant modifications. The adsorption characteristics of TC upon unmodified sludge biochar (BC) as well as KOH-modified sludge biochar (BC-KOH) were investigated in terms of equilibrium, kinetics, and thermodynamics. BC-KOH exhibited higher porosity, greater specific surface area, and increased abundance of oxygen-based functional groups compared to BC. The TC adsorption on BC-KOH conformed the Elovich and Langmuir models, with a maximum adsorption capacity of 243.3 mg/g at 298 K. The adsorption mechanisms included ion exchange, hydrogen bonding, pore filling, and electrostatic adsorption, as well as π-π interactions. Interference with TC adsorption on BC-KOH was observed with HCO₃⁻, PO₄³⁻, Ca²⁺, and Mg²⁺, whereas Cl⁻, NO₃⁻, and SO₄²⁻ ions exhibited minimal impact on the adsorption process. Following three cycles of utilization, there was a slight 5.94% reduction in the equilibrium adsorption capacity, yet the adsorption capacity remained 4.5 times greater than that of unmodified sludge BC, underscoring its significant potential for practical applications. This research provided new insights to the production and application of sludge biochar for treating antibiotic-contaminated wastewater.

α-Manganese dioxide (MnO₂) and β-MnO₂ have been prepared by a simple one-step hydrothermal synthesis method. Polyaniline (PANI)/carbon black composites were synthesized in acidic medium by an in situ polymerization method using α-MnO₂, β-MnO₂, and ammonium peroxydisulfate (APS) as chemical oxidant. The morphology, structure, and electrochemical performances are characterized by X-ray diffraction spectroscopy, Fourier transform infrared spectroscopy, scanning electron microscopy, transmission electron microscopy, energy-dispersive X-ray spectroscopy, cyclic voltammetry, charge–discharge test, and electrochemical impedance measurements. The PANI/carbon black composite (PANI/C-2) prepared using β-MnO₂ as oxidant shows significantly better specific capacity performance compared with those prepared using α-MnO₂ and APS as oxidant. Addition of carbon black into the PANI composites prepared via the conventional polymerization method showed improved specific capacitance.