The effect of copper, zinc, chromium, and lead on the anaerobic co-digestion of waste activated sludge and septic tank sludge in Hanoi was studied in the fermentation tests by investigating the substrate degradation, biogas production, and process stability at the mesophilic fermentation. The tested heavy metals were in a range of concentrations between 19 and 80 ppm. After the anaerobic tests, the TS, VS, and COD removal efficiency was 4.12%, 9.01%, and 23.78% for the Cu(II) added sample. Similarly, the efficiencies of the Zn(II) sample were 1.71%, 13.87%, and 16.1% and Cr(VI) efficiencies were 15.28%, 6.6%, and 18.65%, while the TS, VS, and COD removal efficiency of the Pb(II) added sample was recorded at 16.1%, 17.66%, and 16.03% at the concentration of 80 ppm, respectively. Therefore, the biogas yield also decreased by 36.33%, 31.64%, 31.64%, and 30.60% for Cu(II), Zn(II), Cr(VI), and Pb(II) at the concentration of 80 ppm, compared to the raw sample, respectively. These results indicated that Cu(II) had more inhibiting effect on the anaerobic digestion of the sludge mixture than Zn(II), Cr(VI), and Pb(II). The relative toxicity of these heavy metals to the co-digestion process was as follows: Cu (the most toxic) > Zn > Cr > Pb (the least toxic). The anaerobic co-digestion process was inhibited at high heavy metal concentration, which resulted in decreased removal of organic substances and produced biogas.

中文翻译：

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重金属对废活性污泥和化粪池污泥厌氧消化过程的影响

通过研究底物降解，沼气产生和中温发酵过程的稳定性，在发酵试验中研究了铜，锌，铬和铅对河内废活性污泥和化粪池污泥厌氧共消化的影响。被测重金属的浓度范围为19至80 ppm。厌氧测试后，添加的Cu（II）样品的TS，VS和COD去除效率分别为4.12％，9.01％和23.78％。同样，Zn（II）样品的效率分别为1.71％，13.87％和16.1％，Cr（VI）样品的效率分别为15.28％，6.6％和18.65％，而TS，VS和COD去除效率在80 ppm的浓度下，记录的Pb（II）添加样品分别为16.1％，17.66％和16.03％。因此，沼气产量也分别下降了36.33％，31.64％，31.64％，与原始样品相比，浓度为80 ppm的Cu（II），Zn（II），Cr（VI）和Pb（II）分别为30.60％。这些结果表明，Cu（II）对污泥混合物厌氧消化的抑制作用大于Zn（II），Cr（VI）和Pb（II）。这些重金属对共消化过程的相对毒性如下：Cu（毒性最大）> Zn> Cr> Pb（毒性最小）。在高重金属浓度下，厌氧共消化过程受到抑制，这导致有机物的去除减少并产生了沼气。这些重金属对共消化过程的相对毒性如下：Cu（毒性最大）> Zn> Cr> Pb（毒性最小）。在高重金属浓度下，厌氧共消化过程受到抑制，这导致有机物的去除减少并产生了沼气。这些重金属对共消化过程的相对毒性如下：Cu（毒性最大）> Zn> Cr> Pb（毒性最小）。在高重金属浓度下，厌氧共消化过程受到抑制，这导致有机物的去除减少并产生了沼气。