铬对厌氧生物处理过程的抑制作用

本文研究了重金属铬离子(Cr~(3+)和Cr~(6+))对厌氧生物处理过程抑制作用的规律.结果表明,Cr~(3+)日引入量分别在低于20mg/L,36—109mg/L和高于145mg/L时,厌氧体系分别受到轻度、中度和重度抑制(即引起产气率下降分别为低于20％、20—40％和大于40％);日引入Cr~(6+)浓度小于14mg/L,无抑制作用;36mg/L或高于70mg/L时,厌氧体系分别受到中度或重度抑制.单位污泥干重所允许承受Cr~(3+)和Cr~(6+)日引入量分别为低于0.1％(62.6 mg-N/kg)和0.04％(44.4mg-N/kg).在引入Cr~(3+)的情况下,维持厌氧体系正常运行的溶解态铬离子浓度应小于0.5mg/L,超过2.5mg/L时,体系受到重度抑制;在引入Cr~(6+)的情况下,允许浓度为 0.4 mg/L,超过2.8 mg/L为重度抑制.

Inbibition of Chromium to the Anaerobie Digestion

The inhibition of Chromium ion to anaerobic diges-non process was studied. The major toxicity to the anaerobic system was caused by the dissolved Chromium ion in the digestion system. When the daily addition dosage of Cr+3 to the digestion system was less than 20mg/L, betweeu 36-109mg/L and higher than 141mg/L. gas production would be reduced by less than 20%, 20-40% or higer than 40%, corresponding to light, significant, and serious inhibition effects, respectively. There was no inhibition observed when the daily addition dosage of Cr+6 was less than 14mg/L, while the daily addition of Cr+6 was roached to 36mg/L and more than 70mg/L, the inhibition effects were sign ficant and serious, respectively. When the percentages of daily addition amount of Cr+3 and Cr+6 in active sludge (dry weight) were less than 0.1% and 0.04%, it did not show any effec: on the digestion process. In order to keep good running of the anaerobic digestion system, the concentration of dissolved Cr+3 in digestion solution shuld be less than 0.5mg/L. When the concentration of Cr+3 was more than 2.5mg/L, the inhibition effect was serious, while for Cr+6, the corresponding levels were 0.4mg/L and 2.8mg/L, respectively.