Evaluation of ecotoxicity of typical surfactants for leather manufacture by luminescent bacteria

Content: Surfactants are used as auxiliaries in every wet processing process of leather production and discharged into wastewater, which would cause potential ecological risks. In this paper, fresh luminescent bacillus liquids were employed to evaluate the ecological toxicity of six surfactants, including anionic, cationic and non-ionic surfactants, and mixture of two typical ionic and nonionic surfactants after a 15-min exposure period. Non-ionic surfactants AEO and Tween80 showed slight light inhibition ie.10-35% to luminescent bacteria. The toxicity of anionic surfactants with polar sulfonic group was: penetrant T(EC50=406.81mg/L) ＞SDBS(EC50=573.37mg/L). The toxicity of cationic surfactants was: DTAB（EC50=10.68mg/L）＞SKC （EC50=73.96mg/L）. The addition of nonionic surfactants reduced the toxicity of ionic surfactants. 1-1 mixture of SKC and AEO: EC50=80.17mg/L, 1-1 mixture of SDBS and AEO: EC50=624.34mg/L. These results provided ecological parameters for the selection of surfactants in the process of ecological leather production. Take-Away: 1. The toxicity measurement by luminescent bacteria, which is simple and convenient, was used to evaluate the toxicity of surfactants, and the reproducibility was improved in our study. 2. The toxicities of six different surfactants was evaluated by EC50 which provided ecological parameters for the selection of surfactants in the process of ecological leather production

Design and optimization of oxygen lance for 210 T converter

In order to satisfy the requirements of modern steelmaking for high oxygen supply intensity and high efficient smelting, the oxygen lance of 210 t converter with different structures are simulated by numerical simulation. The effects of the number of nozzles, Mach number and inclination angle on the velocity distribution, coalescence behavior and the impact area of the jet are discussed. The results demonstrate that compared with the five-hole oxygen lance, the increase of the number of nozzles accelerates the attenuation of jet and increases the coalescence of jet. At the same inclination angle, the change of Mach number has almost no influence on the jet. At the same Mach number, the increase of inclination angle causes the range of impact increases and the strength of impact decreases. Based on effective impact area, the optimal oxygen lance is scheme 9