• 关键词：非饱和带  强化反应层  脱氮试验  地下水污染

• 基金项目：国家自然科学基金重点项目（No.41731280）

• 孙柒国
• 中国海洋大学环境科学与工程学院, 青岛 266100

• 郑西来
• 1. 中国海洋大学环境科学与工程学院, 青岛 266100;2. 中国海洋大学海洋环境与生态教育部重点实验室, 青岛 266100

• 胡荣庭
• 中国海洋大学环境科学与工程学院, 青岛 266100

• 田飞飞
• 中国海洋大学环境科学与工程学院, 青岛 266100

• 摘要：自然堆肥过程中，畜禽养殖产生的粪污渗滤液入渗土壤非饱和带.高浓度有机氮在微生物作用下经由复杂的地球化学过程转化为各种含氮物质，其中硝酸盐迁移能力较强，在降雨条件下入渗地下水，造成区域性地下水硝酸盐污染.在非饱和带中构建由木屑和壤土组成的强化反应层，通过间歇性的原位淋溶脱氮试验，系统地研究了非饱和带含水量及COD、硝态氮、亚硝态氮和氨氮的浓度变化规律，评价了强化反应层的脱氮能力.研究结果表明：①反应层中木屑材料的强吸水特性使得灌水后短时间内反应层含水量大幅提升，形成有利于反硝化进行的厌氧环境.木屑通过水解作用释放大量溶解性有机碳，供给反硝化微生物进行脱氮.②在入渗硝态氮浓度为170.00 mg·L^-1条件下，反应层对硝态氮去除率最高可达97.63%.反应层脱氮量随处理水量增加而提升，当上层为砂土时脱氮量最高，可达24.61 g·m^-3.③反应层中的NO₃^--N发生了完全反硝化，出水中NO₂^--N浓度低于0.5 mg·L^-1，几乎不发生积累.同时，反应层中发生的DNRA过程使氨氮浓度小幅升高.强化脱氮反应层可阻控硝酸盐污染地下水.

• Abstract：In the process of natural composting, the leachate produced by livestock and poultry culture infiltrates into the unsaturated zone. High-concentration organic nitrogen is transformed into various nitrogen-containing substances through complex geochemical processes under the action of microorganisms. The nitrate is easier to move than others, so it may be able to infiltrate into groundwater under the condition of rainfall and to result in regional groundwater pollution. In this paper, an enhanced reactive layer composed of sawdust and loam was constructed in the unsaturated zone. By means of intermittent in-situ leaching denitrification test, the changes of water content and the concentration of COD, nitrate, nitrite and ammonia in unsaturated zone were systematically studied, and the denitrification performance of the reactive layer was evaluated. The results show:① Due to the high water absorption capacity of sawdust materials in the reactive layer, the water content of the reactive layer was greatly increased immediately after the irrigation, forming an anaerobic environment conducive to denitrification. The sawdust materials also released a large amount of dissolved organic carbon through hydrolysis, which provided carbon and energy sources for denitrifying microorganisms. ② At the infiltration nitrate concentration of 170.00 mg·L^-1, the removal rate of nitrate nitrogen could be up to 97.63%. The nitrogen removal amount through the reactive layer increased with the increasing treated water amounts. The nitrogen removal amount was highest (24.61 g·m^-3) when the upper layer was sandy soil. ③The NO₃^--N in the reaction layer was completely denitrified. The concentration of NO₂^--N in water was lower than 0.5 mg·L^-1 and there was almost no accumulation. Meanwhile, the DNRA process in the reaction layer slightly increased the concentration of ammonia. Given above, the enhanced reactive layer can efficiently prevent nitrate from contaminating groundwater.

• Key words：unsaturated zone  enhanced reactive layer  denitrification test  groundwater pollution

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