玉米秸秆碳源释放特征及反硝化效果

通过静态和动态实验研究了玉米秸秆的碳源释放规律,并考察其浸出液作为反硝化碳源对高、中、低硝酸盐氮的去除效果。实验结果表明,玉米秸秆可有效地释放碳源物质,静态实验中,固液比为1:30时单位质量碳源释放的COD最多达254 mg/g,释放速率最快为13.37 mg/(g·d);动态实验中,秸秆长度为3 cm、水力停留时间(HRT)为48 h时,单位质量碳源释放的COD最多达826.26 mg/g,COD的速率最快为26.65 mg/(g·d)。反硝化过程中pH变化不明显,在7.0~8.0范围之间浮动。以玉米秸秆浸出液为反硝化碳源对中、低浓度的硝酸盐氮具有较好的去除效果,去除率保持在80%以上,甚至高达94%,但对高浓度的硝酸盐氮去除率仅在60%~80%之间。研究表明,玉米秸秆有较强的持续供碳能力,是一种经济合适的碳源材料,采用玉米秸秆浸出液作为去除地下水中硝酸盐氮的生物反硝化碳源是可行的。

Characteristics of COD release in corn straw and its denitrification effect

COD release of corn straw was studied by the static and dynamic experiments, and the corn straw lixivium was investigated as the denitrification carbon source to examine its removal efficiency on high, medium and low concentration of nitrate nitrogen.The experimental results showed that corn straw could release carbon source continuously.In the static test, COD release of unit mass of carbon was up to 254 mg/g and the highest rate of carbon release was 13.37 mg/(g·d) when solid-liquid ratio was 1:30.In the dynamic test, COD release of unit mass of carbon was up to 826.26 mg/g and the highest rate of carbon release was 26.65 mg/(g·d) when the corn straw was 3 cm in length and HRT was 48 h.During denitrification process, pH changes were not very noticeable, fluctuating between 7.0 and 8.0.The corn straw lixivium as the denitrification carbon source had better removal efficiency for medium and low concentration of nitrate nitrogen with its nitrate removal efficiency at 80%, even up to 94%.However, the removal efficiency of nitrate for high concentration of nitrate nitrogen was only between 60% and 80%.The research showed that the corn straw was a kind of economical and suitable carbon source because of its continuity of carbon supply, and it was feasible to use the corn straw lixivium as the bio-denitrification of carbon source for nitrate removal in groundwater.