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Improved anaerobic baffled reactor-anoxic/oxic (ABR-A/O) coupling process was used for printing and dyeing wastewater treatment in our full-scale study, which was able to reach the effluent standard stably, especial for the characteristic pollutants and aromatics removal. According to our results of microbial community analysis by polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE), the divisions of ABR enabled the functional microorganisms to distribute in different compartments and contributed to each compartment of performing its own functions with more efficiency. The first, second, and third compartments are major in macromolecular organics hydrolysis and sulfate reduction, while the main responsibilities of the fourth, fifth, and sixth compartments are aromatic compounds degradation and denitrification. Many kinds of aromatic anaerobic degradation microorganisms were found in our ABR, such as Pseudomonas stutzeri, Dechloromonas aromatic, Pseudomonas putida, and Aromatoleum aromaticum. Initially, abundances of bcrA genes climbed up and then dropped along with the sequential six compartments of ABR and it indicated that the highest aromatics degradation efficiency were obtained at the fifth compartment, rather than other compartments, which was probably caused by its moderate substrate concentration and biodegradability. [ABSTRACT FROM AUTHOR]

The reuse of the printing and dyeing wastewater is limited by its large chromaticity, high alkalinity, high chemical oxygen demand (CODCr), high salinity. In this study, electrodialysis, as a promising technology, was applied for the advanced treatment for printing and dyeing wastewater. With the Design-Expert software and Box–Behnken central composite design method, the optimal operating condition was: operating voltage 85 V, inlet flow rate 1,000 L/h, temperature 25°C, in which the energy consumption was 3.52 kW h/m³ and the desalination processing cost was 0.33 $/m³. The characteristics of the desalination process and membrane pollution were further revealed and discussed. The maximum concentration was obtained at 15,000 mg/L during the concentrated water circulation. And the cation exchange membrane pollution was mainly calcium carbonate, while the anion exchange membrane pollution was organic. In addition, the reversal time fixed at 2 h could effectively reduce membrane fouling. The present work is expected to provide reference technical support for practical industrial applications. [ABSTRACT FROM AUTHOR]

Macadamia nut shells (MNS), an abundant forestry residue rich in cellulose and lignin, were amino modified to adsorb reactive brilliant red (K-2BP). The raw MNS, and the ethylenediamine, diethylenetriamine and triethylenetetramine modified MNS (EMNS, DMNS, and TMNS) were characterized by scanning electron microscopy, laser particle sizer, Fourier transform infrared (FTIR) spectroscopy and thermogravimetric analysis. The effect of pH on the adsorption process of K-2BP was studied and combined with the zeta potential analysis. The adsorption mechanism was explained. The K-2BP dye adsorption capacity decreased as pH increased. Results showed that TMNS had the highest adsorption capacity due to a higher pHPZC which implied a more positive surface charge and more amine and secondary amine on the surface. Thermodynamic analysis verified that the adsorption process was endothermic and spontaneous. The adsorption kinetics of these modified adsorbents was well matched with pseudo-second-order equation, indicating that the adsorption process is chemical adsorption. The Langmuir and Freundlich isotherm models were used to describe the adsorption processes of K-2BP dye onto four kinds of adsorbents. The Freundlich model showed the best statistics, which meant the adsorption of K-2BP onto adsorbents from the aqueous solutions was constant with a monolayer formation. [ABSTRACT FROM AUTHOR]

The performance of simultaneous nitrification and denitrification (SND) via nitrite including partial nitrification and SND was investigated in a pilot-scale-modified anaerobic–anoxic– oxic reactor. Since partial nitrification and SND need a similar requirement on dissolved oxygen (DO) level, a low DO was kept in the operation for achieving SND via nitrite. Results showed that SND via nitrite succeeded between 0.4 and 1.6 mg/L DO concentration. The average total nitrogen (TN) removal efficiency was 67.5%. Four forms of biodenitrification were quantified via the estimation of material balance and calculation of SND. SND via nitrite compared with the other three forms made 32.3% contribution to biodenitrification. The operation of a wastewater treatment plant was continuously studied as a comparison with the pilot reactor. With the same raw water, SND not only saved 82.6% of oxygen consumption as well as 30.4% of carbon source, but also owned a higher effluent quality on TN at 11.2 mg/L. Denaturing gradient gel electrophoresis results showed that after long-term hypoxia acclimation, the dominant denitrifier community changed and the abundance ratio of ammonia-oxidizing bacteria/nitrite-oxidizing bacteria was increased. [ABSTRACT FROM AUTHOR]