Search

This study investigated the promotion and control of dissolved oxygen (DO) concentration of the closed-type aeration tank via practical experiments in the wastewater treatment system of a 5-star hotel in Taipei. As with limited and treasured space in Taiwan, before the completion of the sewer system construction in cities, to utilize the mat foundation under large buildings as the space of sewage treatment plant still has been one of the alternatives of those sewage treatments. However, aeration tanks constructed in the mat foundation of buildings have smaller effective water depth, which will cause a lower total transfer amount of DO. Controlling the total exhaust gas flow rate can increase the pressure on such closed-type aeration tanks. The DO concentration thus may increase according to Henry's Law. Furthermore, it may enable operators to adjust the DO concentration of the aeration tank more precisely and thus sustain optimal operating conditions in these treatment facilities. Practical experiments indicated that the DO concentration of aeration tank maintains an average of 3.8 mg l-1, obtaining the optimum operating conditions. The efficiency of the biological treatment facilities in the mat foundation could be markedly improved. [ABSTRACT FROM AUTHOR]

Many studies have focused on heavy metal characteristics in sewage sludges and sludge-amended soils other than lime-stabilized sewage sludge (LS). Thus, the aerobically digested sewage sludge cake (13.61 % solids) sampled from the Min-Sheng Wastewater Treatment Plant in Taipei City, Taiwan was lime-stabilized for studying the effects of the lime treatment on fractionation and extractabilities of heavy metals (Cu, Pb, Cr, and Zn) in sewage sludge, using various extraction tests.For comparative objective, oven-dry sewage sludge without liming (unlimed sludge (S)) was also studied. The results of this study revealed that the percentages of the metals extracted from lime-stabilized sludge (pH = 12.05) and the amounts of the metals fractionated to the organically-bound fraction (30% H202 + 0.02 M HNO3 (pH2), 85 deg. C) in unlimed sludge were both in the order of Cu > Ph > Cr > Zn, meaning that the more the heavy metals (e.g., Cu) were fractionated to the organically-bound forms in unlimed sludge, the more unstable they were in the sludge after lime-stabilized. On the other hand, the metals (e.g., Zn) in lime-stabilized sludgewas more stable when they have less affinity for organics. Single extraction conducted at various pHs revealed that this effect was due to the irreversible dissolution of organics and some metals having a higher affinity for organics (e.g., Cu) at very high pH during processing and air drying of lime-stabilized sludge. Therefore, examining the fractionation of heavy metals in sewage sludge is useful for expecting heavy metal stability in the sewage sludges after lime-stabilized. [ABSTRACT FROM AUTHOR]

Research of 2,4-chlorophenol and 2,4,6-trichlorophenol in aqueous solution using the photo-Fenton process was conducted in two parts. Thefirst part of the study explored the treatment efficiency and reaction rate expression of 2,4-chlorophenol and 2,4,6-trichlorophenol. With respect to the simulated experimental data, the relationship between the reaction rate for 2,4-chlorophenol and 2,4,6-trichlorophenol and H2O2 concentration was expressed as a first-order reaction and that between the reaction rate and the Fe(II) concentration was a saturation-type reaction. In the second half of this study, chlorohydroquinone, catechol, dichlorocatechol, and dichlororesorcinol were found in the photo-Fenton process by GC/MS. Some of these identified intermediates were more toxic than the primary compound. [ABSTRACT FROM AUTHOR]