Evaluation of chemistry and key reactor parameters for industrial water treatment applications of the UV/O3 process.

In this study, the main influence factors of combined UV/O3 process in practical industrial application were explored through laboratory trials and industrial pilot tests. Dimethyl phthalate (DMP) was analyzed as the research subject through different experiments in laboratory. The degradation effect of organic compounds by O3 and UV/O3 processes in different air distribution methods was compared independently, and the mechanism of free radical generation by the two processes was analyzed. This study found that the combined UV/O3 process for organic matter mineralization is clearly better than that of independent effect of O3 process as mixed gas-liquid distribution method was superior to the bubble aeration method. The experimental conditions included inlet O3 concentration between 70 and 75 mg/L, reactor internal relative pressure at 0.3 MPa, contact reaction time of 12 min, DMP mineralization efficiency reaching 63.07%. The calculated dosing ratio of O3 in the dynamic experiment was around 0.74 mg CODCr/mg O3. The results showed that the best effect in wastewater treatment was achieved when the conditions of ultraviolet lamp irradiation intensity and the O3 dosage reached 822.88 W/m2 15 mg/L and utilized in conjunction with biochemical reactions. The resulting CODCr concentration of effluent reached 39.8 mg/L. Finally, it is determined that the main influence factors affecting the economically efficient operation of UV/O3 process were the efficient O3 distribution mode, control of the relative pressure within the reactor, proportion of ozone addition and light source configuration.

Sustainable pyrolytic sludge-char preparation on improvement of closed-loop sewage sludge treatment: Characterization and combined in-situ application.

Aiming at closed-loop sustainable sewage sludge treatment, an optimal and economical pyrolytic temperature was found at 400-450 °C considering its pyrolysis efficiency of 65%, fast cracking of hydrocarbons, proteins and lipids and development of aromatized porous structure. Fourier-transform infrared (FTIR) and X-ray diffraction (XRD) tests demonstrated the development of adsorptive functional groups and crystallographic phases of adsorptive minerals. The optimal sludge-char, with a medium specific surface area of 39.6 m2 g-1 and an iodine number of 327 mgI2 g-1, performed low heavy metals lixiviation. The application of sludge-char in raw sewage could remove 30% of soluble chemical oxygen demand (SCOD), along with an acetic acid adsorption capacity of 18.0 mg g-1. The developed mesopore and/or macropore structures, containing rich acidic and basic functional groups, led to good biofilm matrices for enhanced microbial activities and improved autotrophic nitrification in anoxic stage of an A/O reactor through adsorbed extra carbon source, and hence achieved the total nitrogen (TN) removal up to 50.3%. It is demonstrated that the closed-loop sewage sludge treatment that incorporates pyrolytic sludge-char into in-situ biological sewage treatment can be a promising sustainable strategy by further optimization.

[Degradation of the Nitrogenous Heterocyclic Compound Quinoline by O3/UV].

The influences of various factors including initial concentration of quionline solution, static duration after reaction, initial pH, HCO3-on the degradation of quinoline by O3/UV were analyzed in this study. In addition, the degradation mechanism and pathways were also analyzed. The results showed that reaction rate constants and removal rate of quinoline decreased with the increase of the initial concentration of quinoline. The best degradation efficiency of quinoline was achieved under the alkaline conditions (pH 7-9). Removal rate of quinoline was obviously influenced by HCO3-, and was reduced by 42.01% within 6 min when the concentration of HCO3- was 100 mg·L-1. There was neglected effect of static duration after reaction on the removal rate and mineralization rate of quinolone. The intermediate products of quinoline were mainly 8-hydroxyquinoline, 5-hydroxyquinoline, 2(1H)-quinoline ketone, 2-pyridinecarboxaldehyde and so on. The main degradation pathways of quinoline in the O3/UV system were addition reaction, substitution reaction and electrophilic substitution mediated by O3 and·OH.