This work employed a rotating packed bed (RPB) as an ozone contactor to produce ozone water. The effects of various operating conditions including the rotational speed of RPB, the gas and liquid volumetric flow rate, the concentration of gaseous ozone, and liquid treatment capacity of the packing on the quality of ozone water and the volumetric mass-transfer coefficient were investigated. The contrast experiments between the RPB and a stirred tank reactor (STR) reveal that ozone concentration in the ozone water produced by the RPB reached 77% of the saturated ozone concentration in water, compared to only 49% by the STR. The RPB not only shows a high absorption efficiency for ozone, but also exhibits the advantages of fast and continuous operation, making it an efficient ozone contactor for the production of ozone water.

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In this paper, soil collected from garden was cultured in thermostated incubator. Adding heavy metal elements to the soil and the effects of compound action of heavy metal lead (Pb), zinc (Zn) and cadmium (Cd) on soil enzymatic activities were studied. The results showed that single metal Pb and Cd can increase urease activity, but that of Zn inhibits its. Coexist Pb/Cd or coexist three metals in soil inhibited the urease activity, whereas coexist Pb/Zn and Zn/Cd promoted its. Single heavy metal Pb, Zn and Cd were all negative value, which indicated that single metal can inhibit catalase activity. Either coexist Pb/Cd, Pb/Zn or Zn/Cd in soil was increased the catalase activity, while coexist three metals in soil restraining its.