[Treatment of bromoamine acid wastewater by combined ALR-BAC process].

Combined ALR-BAC was used to treat bromoamine acid wastewater. The results showed that the ALR system could run steadily for over 1 months at the BAA concentration 650 mg x L(-1) after one-month acclimation, the decoloration rate of BAA was reached to about 90% within 12 h, and the removal rate of COD was about 50%, the precipitation performance of the suspended microorganism was good. When the influent bromoamine acid concentration was above 200 mg x L(-1), the decolorization products of BAA were easy to undergo auto-oxidation and the yellow intermediate products which were difficult to biodegrade were formed. The BAC process could inhibit the auto-oxidation of the decolorization products effectively, and the decolorization products could be biodegraded gradually. When there were no added sulphate, the concentrations of Br- and SO4(2-) were increased as the COD concentration reduced. Ultimately, the release rates of Br- and SO4(2-) were 72.2% and 66.9%, the COD removal efficiency was about 85.7%.

[Fly ash-catalyzed oxidation of p-nitro phenol with H2O2].

Fly ash was investigated as a catalyst in the oxidation of p-nitro phenol (PNP) with H2O2 at ambient temperature and pressure. The physical and chemical properties of fly ash were analyzed. The effects of fly ash composition, pretreatment methods and other parameters (such as dosage, pH, reaction time and oxidant concentration) on PNP removal rate were studied. It was found that fly ash with larger specific surface area and higher carbon content demonstrated higher catalytic activity. Heat treatment (350 degrees C) on fly ash could effectively improve the PNP removal rate. With an initial H2O2 concentration of 200 mg/L, 60 g/L heat-treated fly ash could remove 62.38% PNP at 25 degrees C, pH = 2. Specific surface area, carbon and metal oxide contents of fly ash play an important role in the catalysis process. The adsorption control experiment showed that adsorption was the main effect (65.97%) in the catalysis process. The activity of the catalyst gradually increased during its reuse. The PNP removal rate could reach 82.47% and 98.72% in the second and third rounds of reuse, respectively. The removal rate remained at about 99% in the rest 9 rounds of reuse. And the catalytic properties decreased after 12 times uses.

[Decolorization of azo dyes using quinone reductase and quinoid compounds].

Using quinoid redox mediator and bacterial cellular quinone reductase, we investigated the decolorization ability of gene-engineered strain Escherichia coli YB and the effects of methylhydroquinone (MHQ) pretreatement on decolorization performance of E. coli JM109 and anaerobic sludge. The results indicate that lawsone is an effective accelerator for azo dye decolorization by E. coli YB overexpressing cellular quinone reductase AZR. In the presence of 0.2 mmol x L(-1) lawsone, 75% Amaranth (1 mmol x L(-1)) can be decolorized in 2 h. E. coli YB can also decolorize high concentration of azo dye in the presence of lawsone. Around 50% Amaranth (5 mmol x L(-1)) is decolorized in 8 h. Compared to lawsone, menadione is a less effective mediator. E. coli YB takes 12 h to reach 70% decolorization in the presence of 2.5 mmol x L(-1) menadione. Repeated decolorization studies showed that E. coli YB had stable decolorizing ability in the presence of lawsone. Four rounds of repeated decolorization can be completed in 12 h. Lawsone can also accelerate the decolorization of azo dyes with complex structures such as Acid Scarlet GR and Reactive Brilliant Red K-2BP. With the optimal LQ concentrations, 70% Acid Scarlet GR and Reactive Brilliant Red K-2BP are decolorized in 9 h and 30 h,respectively. Decolorization performances of E. coli JM109 and anaerobic sludge pretreated with MHQ are improved. After MHQ pretreatment,in the presence of lawsone, 80% Amaranth (1 mmol x L(-1)) can be decolorized in 5 h by E. coli JM109, while more than 75% Amaranth can be removed in 11 h by sludge.

[Adsorption property of chitosan composite resin for nitrite-nitrogen].

A novel composite resin of chitosan supported by activated carbon was prepared using the emulsification cross-linking technique. The adsorption properties of the resin for NO2(-)-N were studied. It is found that there are many developed micropores on the surface of the resin. Due to the addition of activated carbon, the bulk density, skeleton density and void ratio of composite resin are lower than those of the chitosan resin.The adsorption capacity of chitosan composite resin is much greater than the simple compounding made up of activated carbon and chitosan resin. When the temperature is lower than 40 degrees C, the adsorption is a physisorption process primarily caused by electrostatic attraction. The adsorption selectivity of composite resin for NO2(-)-N is affected by the concentration and negative charge number of co-existing anions. The adsorption reachs equilibrium in 60 min with a calculated equilibrium capacity of 0.479 mg/g. The adsorption velocity is high while the adsorption capacity is low. When the temperature is higher than 40 degrees C, the adsorption is a chemisorption process which is endothermic, spontaneous and entropy increasing. The adsorption reached equilibrium in 90 min with a calculated equilibrium capacity of 0.700 mg/g. The adsorption velocity drops while the adsorption capacity increases. The chemisorption and physisorption isotherm equations are conformed to the Freundlich model, and the adsorption process accords with second-order kinetic rate mode.

[Decoloration and bioaugmentation on azo dye by immobilized genetically engineered strain].

Decoloration and bioaugmentation on azo dye are investigated by using immobilized genetically engineered strain Escherichia coli JM109 (pGEX-AZR) on marcroporous foam carriers. The kinetics of the acid red GR decolorization by the immobilized E. coli JM109 (pGEX-AZR) accords with Andrews model proved by our experiments, and the kinetic parameters, mu(max,c), K(c) and K(ic), are found to be 49.2 mg x (g x h)(-1), 710.43 mg x L(-1) and 681.62 mg x L(-1) respectively. For continuous operating in the anaerobic SBRs with 10% inoculation of Escherichia coli JM109 (pGEX-AZR) on marcroporous foam carriers for 32 d, both the tolerance to red GR concentration shock and the colorific removal in the bioaugmented anaerobic SBRs are higher than the control system, and the acid red GR decoloration rate reached 90%. Changes in microbial community have been detected by the RISA, in which the introduced immobilized GEM and preponderant mixed culture were subsisted steadily in sludge systems.