Combined ultrasound with Fenton treatment for the degradation of carcinogenic polycyclic aromatic hydrocarbons in textile dying sludge.

To develop an effective method to remove the toxic and carcinogenic polycyclic aromatic hydrocarbons (CPAHs) from textile dyeing sludge, five CPAHs were selected to investigate the degradation efficiencies using ultrasound combined with Fenton process (US/Fenton). The results showed that the synergistic effect of the US/Fenton process on the degradation of CPAHs in textile dyeing sludge was significant with the synergy degree of 30.4. During the US/Fenton process, low ultrasonic density showed significant advantage in degrading the CPAHs in textile dyeing sludge. Key reaction parameters on CPAHs degradation were optimized by the central composite design as followed: H2O2 concentration of 152 mmol/L, ultrasonic density of 408 W/L, pH value of 3.7, the molar ratio of H2O2 to Fe2+ of 1.3 and reaction time of 43 min. Under the optimal conditions of the US/Fenton process, the degradation efficiencies of five CPAHs were obtained as 81.23% (benzo[a]pyrene) to 84.98% (benz[a]anthracene), and the benzo[a]pyrene equivalent (BaPeq) concentrations of five CPAHs declined by 81.22-85.19%, which indicated the high potency of US/Fenton process for removing toxic CPAHs from textile dyeing sludge.

Dechlorane Plus in house dust from E-waste recycling and urban areas in South China: sources, degradation, and human exposure.

Dechlorane Plus (DP) was measured in house dust from e-waste recycling and from urban and rural areas of South China, with geometric mean concentrations of 604, 14.5, and 2.89 ng/g, respectively. Dechlorane Plus in house dust in the e-waste area originated from e-waste recycling activities, whereas household appliances served as a major source of DP in urban house dust. The isomer ratios (f(anti) ) of DP in most dust samples from the e-waste area were significantly lower than those in the urban and rural dust samples and the commercial mixture. Several [-1Cl + H] and [-2Cl + 2H] dechloro-DPs were identified in house dust from the e-waste area, and an a-Cl(11) DP was qualified with concentrations of <55.1 ng/g. Photolytic degradation experiments were conducted by exposing anti-DP, syn-DP, and commercial DP solutions to ultraviolet (UV) light. The slight difference in isomeric half-life derived by photodegradation, as well as the lower f(anti) values in the e-waste combusted residue, suggest a significant influence of isomer-specific thermal degradation of DP during e-waste burning on isomer composition in house dust in the e-waste area. The average estimated daily intakes (EDIs) of DP via house dust ranged from 0.06 to 30.2 ng/d for adults and 0.14 to 121 ng/d for toddlers in the studied area. The average EDIs of a-Cl(11) DP for adults and toddlers in the e-waste area were 0.07 and 0.18 ng/d, respectively.

[Biotreatment of chrolobenzene-contained waste gas in trickling biofilters enhanced by SDS].

Biofitlers inoculated P. putida strain and packed respectively with ACOF and ceramic pellets were employed to purify the chlorobenzene contained gases. An anionic surfactant, sodium dodecyl sulfonate (SDS) was introduced to trickling liquid to investigate its effect on the performance of biofilters. The result of microorganism cultivation shows that the inhibition to P. putida will be occurred when the SDS concentration in culture medium exceeded 35 mg/L. Addition of SDS in trickling liquid at concentration of 25 mg/L reduce the acclimatization periods and improve the performance of biofilter at stable condition. For the ACOF biofilter, the optimum SDS addition concentration is 25 mg/L, and the maximum elimination capacity of 234.7 g/(m3 x h) could be achieved. 18% - 20% of SDS in trickling liquid was lost after five days operation, but the lose could not reduce the efficiency of biofilter evidently.

Photochemical degradation performance of quinoline aqueous solution in the presence of hydrogen peroxide.

Photochemical degradation performance of quinoline aqueous solution in the presence of H2O2 was carried out, and some intermediates produced during quinoline degradation were also identified tentatively. The experimental results showed that the advanced oxidation of quinoline by UV/H2O2 process accorded well with the pseudo first order kinetics, and the dependence of concentrations of H2O2 and quinoline, and pH value on the photodegradation kinetics has been investigated in detail. It is found that the concentrations of hydrogen peroxide and quinoline have opposite effect on photodegradation kinetics. That means the photodegradation rate of quinoline increased significantly as the hydrogen peroxide concentration increasing, while the photodegradation rate decreased critically as the initial concentration of quinoline increasing. It also concluded that the photodegradation of quinoline by H2O2/UV process is more favorable under alkali solution than acid solution.

Feasibility study of photoelectrochemical degradation of methylene blue with three-dimensional electrode-photocatalytic reactor.

The photoelectrochemical degradation of methylene blue in aqueous solution was investigated with three-dimensional electrode-photocatalytic reactor. It was found that the methylene blue could be degraded more efficiently by photoelectrochemical process than by photocatalytic oxidation or electrochemical oxidation alone. The decolorization efficiency and COD reduction were 95% and 87% for a photoelectrochemical process, respectively, while they were only 78% and 68% for a single electrochemical process and 89% and 71% for a single photochemical process. The TOC reduction of the former also reached as high as about 81% within a reaction time of 30.0 min. And these degradation reactions conformed to pseudo-first-order kinetics.