Search

A recombinant human androgen receptor yeast assay was applied to investigate the occurrence of antiandrogens as well as the mechanism for their removal during gray wastewater and coking wastewater treatment. The membrane reactor (MBR) system for gray wastewater treatment could remove 88.0% of antiandrogenic activity exerted by weakly polar extracts and 97.3% of that by moderately strong polar extracts, but only 32.5% of that contributed by strong polar extracts. Biodegradation by microorganisms in the MBR contributed to 95.9% of the total removal. After the treatment, the concentration of antiandrogenic activity in the effluent was still 1.05 μg flutamide equivalence (FEQ)/L, 36.2% of which was due to strong polar extracts. In the anaerobic reactor, anoxic reactor, and membrane reactor system for coking wastewater treatment, the antiandrogenic activity of raw coking wastewater was 78.6 mg FEQ/L, and the effluent of the treatment system had only 0.34 mg FEQ/L. The antiandrogenic activity mainly existed in the medium strong polar and strong polar extracts. Biodegradation by microorganisms contributed to at least 89.2% of the total antiandrogenic activity removal in the system. Biodegradation was the main removal mechanism of antiandrogenic activity in both the wastewater treatment systems. [ABSTRACT FROM AUTHOR]

Diisopropylthiourea (DPT), an intermediate of a widely used cephalosporin, has been found to be one of the most refractory components in cephalosporin synthesis wastewater. This compound cannot be completely removed by conventional biological processes due to its antimicrobial property. Ionizing radiation has been applied in the decomposition of refractory pollutants in recent years and has proved effective. Therefore, the decomposition of DPT by γ-irradiation was studied. The compound was irradiated at the dose of 150-2000 Gy before a change of concentration and UV absorption of the solutions was detected. Furthermore, the decomposition kinetics and radiation yield (G-value) of DPT was investigated. The results of radiation experiments on DPT-containing aqueous showed that the DPT can be effectively degraded by γ-radiation. DPT concentration decreased with increasing absorbed doses. G-values of radiolytic decomposition for DPT (20 mg/L) were 1.04 and 0.47 for absorbed doses of 150 and 2000 Gy, respectively. The initial concentration and pH of the solutions affected the degradation. As the concentration of substrate increased, the decomposition was reduced. The decrease of removal rate and radiation efficacy under alkaline condition suggested that lower pH values benefit the γ-induced degradation. UV absorption from 190 to 250 nm decreased after radiation while that from 250 to 300 nm increased, indicating the formation of by-products. [ABSTRACT FROM AUTHOR]

Industrial wastewaters containing 2-mercaptobenzothiazole (MBT), a widely used chemical additive, usually cannot be treated properly by conventional biological methods, thus cause an environmental risk. Ionizing radiation was proposed as a method for abatement of several refractory pollutants from water. The paper investigated MBT degradation using irradiation technology. The decomposition kinetics was described, and the transformation and the change of biodegradability were discussed. The results of gamma radiation experiments on MBT-containing aqueous solutions indicated that reactive radicals resulting from water radiolysis effectively degrade MBT and improve the biodegradability of the solutions. At a 20 mg/L MBT concentration, the removal of 82% was achieved at the absorbed dose of 1.2 kGy. The results of specific oxygen uptake rate (SOUR) test showed that MBT was decomposed into biodegradable products, after irradiation at 20 kGy. Radicals attacked the sulfur atoms of the studied molecule leading to the release of sulfate ions, but the mineralization of organic carbons was rather weak. Initial concentration significantly affected the degradation efficacy of MBT by gamma radiation. [ABSTRACT FROM AUTHOR]

In this study, a lab-scale biological anaerobic/anaerobic/anoxic/membrane bioreactor (A³-MBR) was designed to treat wastewater from the ethanol fermentation of food waste, a promising way for the disposal of food waste and reclamation of resources. The 454 pyrosequencing technique was used to investigate the composition of the microbial community in the treatment system. The system yielded a stable effluent concentration of chemical oxygen demand (202 ± 23 mg/L), total nitrogen (62.1 ± 7.1 mg/L), ammonia (0.3 ± 0.13 mg/L) and total phosphorus (8.3 ± 0.9 mg/L), and the reactors played different roles in specific pollutant removal. The exploration of the microbial community in the system revealed that: (1) the microbial diversity of anaerobic reactors A1 and A2, in which organic pollutants were massively degraded, was much higher than that in anoxic A3 and aerobic MBR; (2) although the community composition in each reactor was quite different, bacteria assigned to the classes Clostridia, Bacteroidia, and Synergistia were important and common microorganisms for organic pollutant degradation in the anaerobic units, and bacteria from Alphaproteobacteria and Betaproteobacteria were the dominant microbial population in A3 and MBR; (3) the taxon identification indicated that Arcobacter in the anaerobic reactors and Thauera in the anoxic reactor were two representative genera in the biological process. Our results proved that the biological A³-MBR process is an alternative technique for treating wastewater from food waste. [ABSTRACT FROM AUTHOR]