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A submerged hollow fiber membrane bioreactor (MBR) with a capacity up to 400 L/d was used for treatment of dyeing wastewater from a printing and dyeing factory in Changzhou, China. The MBR device was operated continuously for 100 days. The removal ratio of COD reached 90% and the COD values of effluent from the reactor were 52-97 mg/L, when the COD values of inlet were 600-1200 rag/L, 10-20% of which were rejected by membranes. The removal ratios for NH3-N and colour were 90-95% and 60-75%, respectively, The result of this work could be used as a reference for the application of MBR technology to dyeing wastewater treatment on an industrial scale. [ABSTRACT FROM AUTHOR]

• Remarkably high NAs were decreased by 33–81 % after industrial WWTPs. • Fe-C electrolysis, ClO 2 oxidation, Fe/Al-based flocculation and activated sludge were effective. • Adsorption, degradation, and precursor deactivation were main removal mechanisms. • Electroplating and printing/dyeing wastewater significantly affect drinking water. • The high concentration diversity of NAs is a major challenge for water treatment. The discharge of industrial wastewater containing high concentrations of N -nitrosamines to the aquatic environment can impair downstream source waters and pose potential risks to human health. However, the transport and fate of N -nitrosamines in typical industrial wastewater treatment plants (IWWTPs) and the influence of these effluents on source water and drinking water are still unclear. This study investigated nine N -nitrosamines in four full-scale electroplating (E-) and printing/dyeing (PD-) IWWTPs, two drinking water treatment plants (DWTPs) in the lower reaches of these IWWTPs, and the corresponding tap water in South China. The total concentrations of N -nitrosamines (∑NAs) were 382–10,600, 480–1920, 494–789, and 27.9–427 ng/L in influents, effluents, source water, and tap water, respectively. The compositions of N -nitrosamine species in different influents varied a lot, while N -nitrosodi-n-butylamine (NDBA) and N -nitrosodimethylamine (NDMA) dominated in most of the effluents, source water, and tap water. More than 70 % N -nitrosamines were removed by wastewater treatment processes used in E-IWWTPs such as ferric-carbon micro-electrolysis (Fe/C-ME), while only about 50 % of N -nitrosamines were removed in PD-IWWTPs due to the use of chlorine reagent or other inefficient conventional processes such as flocculation by cationic amine-based polymers or bio-contact oxidation. Therefore, the mass fluxes of N -nitrosamines discharged from these industrial wastewaters to the environment in the selected two industrial towns were up to 14,700 mg/day. The results based on correlation and principal component analysis significantly demonstrated correlations between E-and PD-effluents and source water and tap water, suggesting that these effluents can serve as sources of N -nitrosamines to local drinking water systems. This study suggests that N -nitrosamines are prevalent in typical IWWTPs, which may infect drinking water systems. The findings of this study provide a basis data for the scientific evaluation of environmental processes of N -nitrosamines. [Display omitted] [ABSTRACT FROM AUTHOR]

The source and fate of N -nitrosamines and their precursors in terms of formation potential (FP) was investigated quantitatively in the city level for the first time. Different sources of nitrosamines and their precursors were investigated in one city in the Yangtze River delta, China. The source water located downstream of the city contained 8.4 ng/L of N -nitrosodimethyamine (NDMA) and 153 ng/L of NDMA FP. The contribution of each discharge source was evaluated based on the concentration, the river water flux, and the amount of wastewater discharges. Textile printing and dyeing wastewater, and electroplating industrial wastewater contained high concentration of nitrosamines and were important discharge sources. Taking NDMA and NDMA FP attenuation by photolysis and biodegradation into consideration, the mass load calculation showed upstream surface water brought about 13 ± 4% of NDMA and 21 ± 3% of NDMA FP to downstream source water. Local wastewater discharges contributed 30 ± 8% of NDMA and 17 ± 2% of NDMA FP to downstream source water. Endogenous formation via amino acids metabolism could contribute 36% of NDMA FP (maximum) to downstream source water. Overall, this study provides a protocol for quantitative evaluation of the nitrosamine contribution to urban water supply from different contamination sources. [Display omitted] • Fate of nitrosamines and precursors in an urban water system were investigated. • Nitrosamines and precursors of various wastewater discharges were characterized. • Upstream input and local wastewater discharges were important nitrosamine sources. • Upstream input, wastewaters and endogenous generation were major NDMA FP sources. [ABSTRACT FROM AUTHOR]

• COVID-19's impacts on water quality were first studied with fluorescence technique. • One of the main pollution sources in study water body was identified. • Shutdown & production cutdown of industries due to the pandemic weakened pollution. • Fluorescent component's intensity reduced during the domestic and global pandemic. In 2020, a sudden COVID-19 pandemic unprecedentedly weakened anthropogenic activities and as results minified the pollution discharge to aquatic environment. In this study, the impacts of the COVID-19 pandemic on aquatic environment of the southern Jiangsu (SJ) segment of Beijing-Hangzhou Grand Canal (SJ-BHGC) were explored. Fluorescent component similarity and high-performance size exclusion chromatography analyses indicated that the textile printing and dyeing wastewater might be one of the main pollution sources in SJ-BHGC. The water quality parameters and intensities of fluorescent components (WT-C1(20) and WT-C2(20)) decreased to low level due to the collective shutdown of all industries in SJ region during the Spring Festival holiday and the outbreak of the domestic COVID-19 pandemic in China (January 24th to late February, 2020). Then, they presented a gradual upward trend after the domestic epidemic was under control. In mid-March, the outbreak of the international COVID-19 pandemic hit the garment export trade of China and consequently inhibited the production activities of textile printing and dyeing industry (TPDI) in SJ region. After peaking on March 26th, the intensities of WT-C1(20) and WT-C2(20) decreased again with changed intensity ratio until April 12th. During the study period (135 days), correlation analysis revealed that WT-C1 and WT-C2 possessed homology and their fluorescence intensities were highly positively correlated with conductivity and COD Mn. With fluorescence fingerprint (FF) technique, this study not only excavated the characteristics and pollution causes of water body in SJ-BHGC, but also provided novel insights into impacts of the COVID-19 pandemic on production activities of TPDI and aquatic environment of SJ-BHGC. The results of this study indicated that FF technique was an effective tool for precise supervision of water environment. [ABSTRACT FROM AUTHOR]

The treatment of dye-containing wastewater generated from textile industries is still a challenge, and various technologies, including physical, chemical and biological ones have been used. In recent years, the ionizing radiation (usually including gamma ray generated by radionuclide, such as 60Co and 137Cs, and electron beam generated by electron accelerator) technology has received increasing attention for degrading refractory or toxic organic pollutants in wastewater because of its unique advantages, such as no chemical additives, fast reaction rate, strong degradation capacity, high efficiency, flexibility, controllability. Compared to the conventional wastewater treatment processes, ionizing radiation technology, as a disruptive wastewater treatment technology, is more efficient for the decolorization and degradation of dyes and the treatment of dye-containing wastewater. In this paper, the recent advances in the treatment of dye-containing wastewater by ionizing radiation, in particular by electron beam (EB) radiation were summarized and analyzed, focusing on the decolorization and degradation of various dyes. Firstly, the formation of various reactive species induced by radiation and their interactions with dye molecules, as well as the influencing factors on the removal efficiency of dyes were discussed. Secondly, the researches on the treating dye-containing wastewater by electron beam radiation technology were systematically reviewed. Then, the decolorization and degradation mechanisms by electron beam radiation were further discussed in detail. And the integrated processes that would contribute to the advancement of this technology in practical applications were examined. More importantly, the recent advances of electron beam radiation technology from laboratory to application were reviewed, especially successful operation of dye-containing wastewater treatment facilities in China. And eventually, current challenges, future research directions, and outlooks of electron beam radiation technology were proposed for further advancing this technology for the sustainable development of water resources. [Display omitted] • The treatment of dye-containing wastewater is still a challenge. • Advances in dye-containing wastewater treatment by EB were summarized and analyzed. • Mechanisms of dye decolorization and degradation by EB were discussed in detail. • EB is more efficient for the decolorization and degradation of dyes. • Challenges, future directions and outlooks of EB technology were proposed. [ABSTRACT FROM AUTHOR]