Showing papers by "Deli Wu published in 2012"

Fenton-Like Oxidation of Refractory Chemical Wastewater Using Pyrite

Abstract: Fenton-like reaction technologies are attracting considerable attention due to the high oxidizing ability, especially in the treatment of refractory chemical contaminants. However, some disadvantages in traditional Fenton reagents limited its wide application. In this study, pyrite, a natural iron bearing mineral, was used as a new kind of Fenton-like catalyst in the treatment of textile wastewater. The catalytic activity of pyrite and the parameters influencing the removal of Chemical Oxygen Demand (COD) and Biochemical Oxygen Demand (BOD5), such as pyrite dosage, H2O2 concentration, pH, and suspended solids (SS) had been systematically examined. Results showed that pyrite exhibited a high catalytic reactivity over a wide pH value range. At the optimal conditions, a COD removal rate of 70% and an increase in the mass ratio of BOD5/COD (B/C) from 0.25 to 0.56 were achieved in the presence of 9.7 mM H2O2 and 10 g/L pyrite at initial solution pH value of 9.0. And what’s more, a rapid decrease in solution pH and a high level of iron were observed when pyrite was added to the wastewater, probably due to the oxidative dissolution of pyrite. Consequently, Apart from the heterogeneous process, it was found that a homogeneous interaction between ferrous iron and H2O2 in a classical Haber-Weiss mechanism was also occurred. The wonderful reactivity of pyrite makes it be used as catalyst for the oxidative technology to treat the original wastewater without the need to pre-adjust the solution pH.

Effect of Inorganic Anions on Reduction of Nitrobenzene in Water by Structural Ferrous Iron

Abstract: Nitrobenzene is an important contaminant existed in water and wastewater widely. Because of its toxicity to organisms, it is hardly biodegradable. A new structural Fe(II): Ferrous Hydroxy Complex (FHC) was prepared with ferrous sulfate to investigate the reduction of nitrobenzene by structural ferrous iron. This study focused on the effects of inorganic anions on the reactivity of FHC towards nitrobenzene. It was found that soluble Fe(II) could hardly reduce any nitrobenzene within 2h while FHC could reduce nitrobenzene to aniline rapidly within 0.5h. Various anions such as CO32-, PO43-, SiO32-, S2- might have significant impact on the reactivity of structural Fe(II) in nitrobenzene reduction. These anions would slow down the rate of the reaction. Among these anions, SiO32- and PO43- had a greater effect on the reduction of nitrobenzene than CO32- and S2-. Structural ferrous iron (SFI) was prepared by two ways: (i) Aqueous Fe2+ was directly added to wastewater, then adjusted the pH value of water to 8-9; (ii) FHC prepared in advance was added to wastewater, SFI(II). Results indicated that the effect of anions on reactivity of SFI(I) was greater than that of SFI(II). When the initial concentration of nitrobenzene was 60mg/L and ferrous iron dosage was 240mg/L, NO3- with the concentration of 4mM had little effect on the reduction of nitrobenzene by both forms of Fe(II); NO2- had greater effect on reactivity of SFI(I) than that of SFI(II).

Catalytic iron internal electrolysis biological fluidization filler and preparation method thereof

Abstract: The invention discloses a catalytic iron internal electrolysis biological fluidization filler and a preparation method thereof, falling into the field of wastewater treatment The filler comprises the following materials by weight: 10-15% of a casing, 80-90% of catalytic iron, and 0-5% of specific gravity regulating material The preparation method comprises the steps of pressing catalytic iron into catalytic iron internal electrolysis material of certain shape, and filling the catalytic iron internal electrolysis material and specific gravity regulating material into the casing, or directly filling the catalytic iron internal electrolysis material into the casing with regulating function, to obtain fluidizable biological filler According to the invention, the defect of easy blocking of catalytic iron internal electrolysis is solved, while the technical merits of catalytic iron internal electrolysis filler, such as low cost, easy availability, environment friendliness, strong reducing ability, good effect, and wide pH adaptability, are fully retained

Method of hydrolysis-catalytic iron-aerobic coupling for treating poisonous and harmful hard-degradation waste water

Abstract: The invention pertains to the technical field of treatment of waste water, and particularly relates to a method of hydrolysis-catalytic iron-aerobic coupling for treating poisonous and harmful hard-degradation waste water, which comprises the following steps: waste water after primary treatment directly enters an up flow type hydrolysis system 1 and stays for 4.0-10.0 hours; the effluent enters an electrolytic cell in the catalytic iron; the mass ratio of iron scraps and copper scraps in the electrolytic cell of the catalytic iron is 1:1 to 20:1, the bulk specific weight thereof is 0.1 to 0.3, the contact time thereof in a filling area is 0.5 to 2.0 hours, and the reflux ratio of the effluent refluxing to the up flow type hydrolysis system is 20 to 100 percent; the effluent enters an aerobic biological treatment system and stays for 6.0 to 12.0 hours; then the effluent enters a solid-liquid separation system with a reflux ratio of sludge being 10 to 50 percent; and the effluent of the solid-liquid separation system refluxes to the electrolytic cell of the catalytic iron with the reflux ratio being 20 to 200 percent. Under the premise of fully playing the function of different treatment units and maintaining the treatment effect and respective advantages, the treatment method of waste water realizes the coupling synergetic action of the three units, strengthens the impact of the system to water quality and water quantity load, reduces a plurality of steps of pretreatment, effectively improves the removal rate of ammonia nitrogen, and can be flexibly adjusted.