[Influence of Ciprofloxacin on the Microbial Community and Antibiotics Resistance Genes in a Membrane Bioreactor].

A membrane bioreactor (MBR) was used to treat ciprofloxacin (CIP)-contaminated artificial wastewater. The microbial community structure and the abundance of antibiotic resistant genes (ARGs) in the MBR were studied at four CIP dosages (0, 5 mg·L-1, 10 mg·L-1, and 15 mg·L-1). The results showed that Proteobacteria and Bacteroidetes remained the dominant phylum, with relative abundances of 57.5% and 12.7%, respectively, as the dosage of CIP was increased from 0 mg·L-1 to 15 mg·L-1. Rhodocyclaceae, Chitinophagaceae, and Comamonadaceae became the dominant family with abundances of 29.96%, 5.44%, and 6.60%, respectively. Methyloversatilis, Ferruginibacter, Zoogloea, and Comamonas became the dominant genus, with relative abundances of 21.70%, 7.56%, 5.24%, and 4.15%, respectively. The decrease of Chao1, ACE, and Shannon and the increase of Simpson indicated a decrease in microbial abundance and diversity. The relative abundances of Nitrosomonas, Nitrospira, Alcaligenes, and Nitrobacter decreased, which caused a decrease in the NH3-N removal rate. A CIP-ARGs analysis revealed that the relative abundances of gyrA, gyrB, and parC were increased, beginning after the sludge was dosed with 5 mg·L-1of CIP for 33 days, which augmented the risk for microbial drug-resistance.

[Removal of AOX and Chroma in Biologically Treated Effluent of Chemical Dyestuff Wastewater with Nanoscale Ni/Fe].

Nanoscale Ni/Fe was applied to biologically treated effluent of chemical dyestuff wastewater. The removal rates of absorbable organic halogens (AOX) and chroma were investigated at different Ni loadings (0-5%), initial wastewater pH (4.1-10.0), Ni/Fe dosage (1-5 g x L(-1)) and reaction time (0.5-96 h). The results showed that the removal rates of AOX and chroma firstly increased and then decreased with the increase of the Ni loading, while continuously increased with the decrease of the initial wastewater pH and the increase of Ni/Fe dosage. The optimal condition was Ni loading of 1%, initial wastewater pH of 4.1 and Ni/Fe dosage of 3 g x L(-1), under which 29.2% of AOX and 79.6% of chroma were removed after 24 h reaction, and 50.6% of AOX and 80.7% of chroma were removed after 96 h reaction. GC-MS analysis revealed that toxicants such as chlorinated anilines, p-nitroaniline, 4-methoxy-2-nitroaniline and halogenated hydrocarbons were efficiently removed.

[Removal of AOX, Chroma and TOC in Chemical Dyestuff Wastewater with Iron Scraps-Fenton-Coagulation Combined Process].

Iron scraps-Fenton-coagulation process was applied to chemical dyestuff wastewater. The removal performance of absorbable organic halogens(AOX), chroma and total organic carbon (TOC) was investigated at different molar ratios of Fe2+ to H2O2 (1:3-1:15), iron scraps reaction time (2-5 h) and Fenton reaction time (20-80 min). The results showed that the removal ratios of AOX, chroma and TOC firstly increased and then decreased with the decrease of the molar ratio of Fe2+ to H2O2, while continuously increased with the increase of iron scraps and Fenton reaction time. The optimal condition was determined as Fe2+:H2O2 ratio of 1:8, iron scraps reaction time of 4 h and Fenton reaction time of 60 min, under which 94.2% of AOX, 93.7% of chroma and 27.2% of TOC were removed. A comparison study revealed that the iron scraps-Fenton-coagulation combined process could achieve much better removal of AOX, chroma and TOC than any other single or combined processes of iron treatment, Fenton oxidation and coagulation. GC-MS analysis revealed that halogenated compounds and anilines were efficiently removed, as well as nitrobenzenes, phenols, benzaldehydes, ethers, nitriles and heterocyclic compounds.·OH was found to devote much in the Fenton reaction according to the tert-butyl alcohol trapping hydroxyl radicals test.

[Removal of AOX in Activated Sludge of a Chemical Pharmaceutical Industry with Fenton Oxidation].

This study aimed to remove AOX (adsorbable organic halogens) with Fenton oxidation from activated sludge in a chemical pharmaceutical industry. The influences of H2O2 dosage, Fe2+ dosage and reaction time were investigated, based on which the reaction conditions for AOX removal were optimized, and the reaction mechanism was discussed. The optimized reaction conditions were as follows:0.90 mol·L-1 of H2O2, 0.045 mol·L-1 of Fe2+[n (Fe2+):n (H2O2) of 1:20] and reaction time of 2 h. Under the optimized conditions, 70.7% of AOX in the sludge and 78.5% of AOX in the supernatant were removed. GC-MS analysis revealed that eleven organic halides were detectable in the original sludge. After Fenton reaction, only three organic halides were detectable, and their peak areas were reduced by 40%-50%. Toxic and hazardous non-AOX organic matters such as xylene, diisobutyl phthalate were also effectively removed.

[AOX Pollution in Wastewater Treatment Process of Dyeing and Dyestuff Chemical Industries].

Selecting six large-scale dyeing factories and four large-scale dyestuff chemical factories in the well-developed Yangtze River Delta region, this study aimed to investigate the AOX pollution status in the raw wastewater as well as in the activated sludge treatment system. The components of AOX were characterized by GC-MS. Results showed that AOX concentration was low in wastewater from the six dyeing enterprises, ranging 0. 15-1. 62 mg.L-1 in the raw wastewater and 0. 06-1. 30 mg.L-1 in the biologically treated effluent. All the biologically treated effluent met the emission limits of 8 mg.L-1 in the Discharge Standard of Water Pollutants for Dyeing and Finishing of Textile Industry. Sludge in five factories with AOX was below 621 mg.kg-1, only one factory was with high AOX concentration of 3 280 mg.kg-1. By comparison, AOX concentration greatly varied between the wastewater from dyestuff chemical factories, was 1. 70 mg.L-1 to 78. 72 mg.L-1 in the raw wastewater and was 1. 88 mg.L-1 to 33. 11 mg.L-1 in the biologically treated effluent. AOX concentration in the activated sludge was as high as 960-2,297 mg.kg-1. Chlorobenzenes, chloronitrobenzenes, chloroanilines, chlorine nitroanilines and halophenols were typical TOX components detectable in the dyestuff chemical wastewater. Halophenols and chlorine nitroanilines could be efficiently removed. Single chloroanilines and single chloronitrobenzenes seemed to be easier removable than polychlorinated anilines and polychlorinated nitrobenzenes. Polychlorinated benzenes were also easily removal but the products chlorobenzene was hard to remove.

Biodecolorization of Naphthol Green B dye by Shewanella oneidensis MR-1 under anaerobic conditions.

The anaerobic decolorization of metal-complex dye Naphthol Green B (NGB) by a metal-reducing bacterium, Shewanella oneidensis MR-1, was investigated. S. oneidensis MR-1 showed a high capacity for decolorizing NGB even at a concentration of up to 1000mg/L under anaerobic conditions. Maximum decolorization efficiency was appeared at pH 8.0 and 40°C. Addition of iron oxide caused no inhibition to the NGB decolorization, while the presence of ferric citrate, nitrite, or nitrate almost completely terminated the decolorization. Biosynthesis of nanomaterials was observed coupled with the degradation of NGB when thiosulfate was added. The Mtr respiratory pathway was found to be responsible for the decolorization of NGB by S. oneidensis, in which extracellular electron shuttle also plays a positive role in promoting the decolorization.