Treatment of hospital wastewater by electron beam technology: Removal of COD, pathogenic bacteria and viruses.

The effective treatment of hospital sewage is crucial to human health and eco-environment, especially during the pandemic of COVID-19. In this study, a demonstration project of actual hospital sewage using electron beam technology was established as advanced treatment process during the outbreak of COVID-19 pandemic in Hubei, China in July 2020. The results indicated that electron beam radiation could effectively remove COD, pathogenic bacteria and viruses in hospital sewage. The continuous monitoring date showed that the effluent COD concentration after electron beam treatment was stably below 30 mg/L, and the concentration of fecal Escherichia coli was below 50 MPN/L, when the absorbed dose was 4 kGy. Electron beam radiation was also an effective method for inactivating viruses. Compared to the inactivation of fecal Escherichia coli, higher absorbed dose was required for the inactivation of virus. Absorbed dose had different effect on the removal of virus. When the absorbed dose ranged from 30 to 50 kGy, Hepatitis A virus (HAV) and Astrovirus (ASV) could be completely removed by electron beam treatment. For Rotavirus (RV) and Enterovirus (EV) virus, the removal efficiency firstly increased and then decreased. The maximum removal efficiency of RV and EV was 98.90% and 88.49%, respectively. For the Norovirus (NVLII) virus, the maximum removal efficiency was 81.58%. This study firstly reported the performance of electron beam in the removal of COD, fecal Escherichia coli and virus in the actual hospital sewage, which would provide useful information for the application of electron beam technology in the treatment of hospital sewage.

Petal-like CoMoO4 Clusters Grown on Carbon Cloth as a Binder-Free Electrode for Supercapacitor Application.

The development of supercapacitors with a high energy density and power density is of great importance for the promotion of energy storage technology. In this study, we designed and prepared petal-like CoMoO4 clusters combined with carbon cloth as an excellent self-standing and binder-free electrode for asymmetric supercapacitors. Due to the abundant electrochemical active sites, the promising electron conduction, and ion diffusion rate, the CoMoO4@carbon cloth (CoMoO4@CC) electrode exhibits an excellent electrochemical performance. The results show that the CoMoO4@CC material exhibits a high specific capacitance (664 F/g at a current density of 1 A/g) and an excellent cycle stability (capacitance remains at 84.0% after 1000 cycles). The assembled symmetrical supercapacitor has an energy density of 27 Wh/kg when the power density is 600 W/kg. Even at a higher power density (6022 W/kg), it still maintains a good energy density (18.4 Wh/kg).

Treatment of pharmaceutical wastewater by ionizing radiation: Removal of antibiotics, antimicrobial resistance genes and antimicrobial activity.

In present study, the treatment of real pharmaceutical wastewater from an erythromycin (ERY) production factory by gamma irradiation was investigated. Results showed that a variety of antimicrobial resistance genes (ARGs), involving MLSB, tet, bla, multidrug, sul, MGEs and van genes and plentiful 9 bacterial phyla were identified in the raw wastewater. In addition to ERY, sulfamethoxazole (SMX) and tetracycline (TC) were also identified with the concentration of 3 order of magnitude lower than ERY. Results showed that the abatement of ARGs and antibiotics was much higher than that of antimicrobial activity and COD. With the absorbed dose of 50 kGy, the removal percentage of ARGs, ERY, antimicrobial activity and COD was 96.5-99.8%, 90.0%, 47.8% and 10.3%, respectively. The culturable bacteria were abated fast and completely at 5.0 kGy during gamma irradiation. The genus Pseudomonas was predominant in raw wastewater (56.7%) and its relative abundance decreased after gamma irradiation, to 1.3% at 50 kGy. With addition of peroxymonosulfate (PMS, 50 mM), the antimicrobial activity disappeared completely and ERY removal reached as high as 99.2% at the lower absorbed dose of 25 kGy. Ionizing radiation-coupled technique is a potential option to treat pharmaceutical wastewater for reduction of antibiotics, ARGs and antimicrobial activity.

Catalytic ozonation of norfloxacin using Co3O4/C composite derived from ZIF-67 as catalyst.

In this study, Co3O4-carbon composite was synthesized by calcined metal organic framework (MOF) ZIF-67 and used as efficient catalysts for ozonation of norfloxacin (NOF). The MOF-derived Co3O4-C composite remained similar polyhedrons structure of ZIF-67, suggesting that Co3O4 was well-dispersed in Co3O4-C composite. Furthermore, a larger amount of surface carbon-oxygen functional groups were distributed on Co3O4-C composite, which resulted in the diversification of active sites for catalytic ozonation reaction. NOF degradation and mineralization could be effectively enhanced in Co3O4-C/O3 process. Moreover, NOF mineralization by catalytic ozonation strongly depended on the solution pH, while other operational conditions, such as O3 concentration and catalyst dosage had not obvious influence on it. Co3O4-C composite could significantly accelerate O3 decomposition to produce active free radicals (such as •OH), which enhanced the mineralization of NOF. The possible catalytic mechanism of Co3O4-C composite was proposed. Additionally, after five consecutive use of Co3O4-C composite in catalytic ozonation process, there was no obvious decrease in TOC removal efficiency, indicating a stable performance of Co3O4-C composite, which was suitable for the catalytic ozonation for wastewater treatment.

Effective biosorption of uranium from aqueous solution by cyanobacterium Anabaena flos-aquae.

Anabaena flos-aquae, a typical species of cyanobacterial bloom, was employed as a useful biosorbent for uranium removal. Batch experiments were conducted to examine the effects of different parameters on the uranium uptake amount of Anabaena flos-aquae. The maximum adsorption capacity of 196.4 mg/g was obtained under the optimized experimental conditions. The calculations of kinetic and thermodynamic results proved the adsorption process was endothermic, chemisorption, and spontaneous. The adsorption of uranium onto Anabaena flos-aquae was better defined by the Langmuir model, which indicated the process was a monolayer sorption. In addition, the characterization of the biosorbent before and after uranium sorption implied that the dominant functional groups participated in the uranium adsorption process were hydroxyl, amino, and carboxyl. In conclusion, the environmentally friendly and biocompatible characteristics of Anabaena flos-aquae suggest that it can be a promising biosorbent for uranium removal.

Efficiency and mechanism of the phytoremediation of decabromodiphenyl ether-contaminated sediments by aquatic macrophyte Scirpus validus.

Phytoremediation is an economic and promising technique for removing toxic pollutants from the environment. Freshwater sediments are regarded as the ultimate sink of the widely used PBDE congener decabromodiphenyl ether (BDE-209) in the environment. In the study, the aquatic macrophyte Scirpus validus was selected to remove BDE-209 from three types of sediments (silt, clay, and sand) at an environmentally relevant concentration. After 18 months of phytoremediation experiment, S. validus significantly enhanced the dissipation rates of BDE-209 in all the sediments compared to the controls. Average removal rates of BDE-209 in the three treatments of silt, clay, and sandy sediments with S. validus were respectively 92.84, 84.04, and 72.22%, which were 148, 197, and 233% higher than that in the control sediments without S. validus. In the phytoremediation process, the macrophyte-rhizosphere microbe combined degradation was the main pathway of BDE-209 removal. Sixteen lower brominated PBDE congeners (di- to nona-) were detected in the sediments and plant tissues, confirming metabolic debromination of BDE-209 in S. validus. A relatively higher proportion of penta- and di-BDE congeners among the metabolites in plant tissues than that in the sediments indicated further debromination of PBDEs within plants. The populations and activities of microorganisms in the sediments were greatly promoted by S. validus. Bacterial community structure in BDE-209-contaminated rhizosphere sediments was different from that in the control rhizosphere sediment, as indicated by the dominant proportions of ß-proteobacteria, δ-proteobacteria, α-proteobacteria, Acidobacteria, and Chloroflexi in the microbial flora. All these results suggested that S. validus was effective in phytoremediation of BDE-209 by the macrophyte-rhizosphere microbe combined degradation in aquatic sediments.