pH对热处理污泥厌氧发酵产氢的影响

Effect of pH on Fermentation Hydrogen Production from Heat Pretreated Sludge

采用自制连续流厌氧发酵产氢反应器,接种经过50min热处理的污泥,以蜜糖废水为底物,探讨pH值的变化对反应器运行中产氢和产酸的影响。在进水COD浓度为5000mg/L、温度为37℃、HRT为6h、负荷为67kgCOD/(m·3d)的条件下,分别在pH为6.0、5.5、5.0、4.5时对反应器内产氢产酸等情况进行实验研究。结果表明:在pH为6.0和pH为4.5出现了两个产氢能力的峰值,最高产氢能力达到7.90L/(L·d),平均分别为6.95L/(L·d)和6.75L/(L·d)。pH减小的过程中,反应器产气能力从18L/(L·d)下降到10.3L/(L·d);气相产物中氢气的含量从39%上升到52%;挥发酸总产量随pH下降而减少,其中乙酸和丁酸的含量为挥发酸总量的53%和36%左右,乙酸和丁酸和丙酸的比例与系统产氢能力和产气中氢气含量有明显的相关性。

A continuous anaerobic fermentation reactor for bio-hydrogen production,50min heat pretreated sludge was inoculated and using molasses wastewater as substrate to investigate the influence of pH on fermentation hydrogen production and VFAs production.Under the COD of influent organic wastewater concentration 5,000 mg/L with temperature of 37℃,HRT 6h and organic loading rate of 67 kgCOD/（m3·d）,biogas production capability,hydrogen content and VFAs production were examined to study the operation characteristics of the reactor at pH 6.0,5.5,5.0 and 4.5.Experiment results showed that two peak hydrogen production capability value were found in pH 6.0 and 4.5,with the best hydrogen production capability as 7.9 L/（L·d）,average as 6.95 L/（L·d） and 6.75 L/（L·d） respectively.Biogas production capability decreased from 18 L/（L·d） to 10.3 L/（L·d） and hydrogen content in the biogas rose from 39% to 52% and yield of VFAs was decreased with the decline of pH,the proportion of acetate and butyrate was 53% and 36% of the total VFAs.Hydrogen production capability and hydrogen content in the biogas have a significant correlation with the proportion of acetate,butyrate and propionic.