Research progress of biological denitrification and nitrogen removal technology promoted by slow release carbon source
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摘要:
随着污水治理要求的愈加严格与公众健康意识的不断提升,水体硝酸盐污染已引起世界各国的普遍关注。目前,生物异养反硝化是去除水中硝酸盐的主要技术手段,其关键制约因素是碳源,而传统外加碳源的弊端也在不断暴露,于是开发适用于生物脱氮工艺的新型缓释碳源成为国内外学者广泛关注的焦点。从促进生物反硝化脱氮的缓释碳源开发必要性出发,详细分析了缓释碳源的种类、促进反硝化的效果、改性方法、影响因素、作用机理及生物膜特性,比较和揭示了天然缓释碳源、改性缓释碳源、人工合成缓释碳源促进反硝化的性能及生物膜群落结构。提出该领域后续研究方向,包括突破反应动力学的限速步骤、优化骨架材料和空间架构、开发新型缓释碳源促进生物脱氮工艺等,以期为缓释碳源促进生物反硝化效率及推广应用提供参考和依据。
Abstract:With the increasingly stringent requirements for sewage treatment and the continuous improvement of public health awareness, the nitrate pollution in water body has caused widespread concern in the world. At present, biological heterotrophic denitrification as the main technical means to remove nitrate in water, the carbon source has been the key restricting factor, and the disadvantages of traditional external carbon source have also been found. Therefore, the development of new slow-release carbon source suitable for biological denitrification process has become the focus of attention of researchers at home and abroad. Starting from the necessity of developing slow-release carbon sources for promoting biological denitrification, the types of slow-release carbon sources, the effect of promoting denitrification, the modification methods, the influencing factors of nitrogen removal, the mechanism of action and the characteristics of biofilm were analyzed in detail. The denitrification promoting performance and biofilm community structure of natural slow-release carbon source, modified slow-release carbon source and synthetic slow-release carbon source were compared and revealed. At the same time, the prospects of breaking through the speed limiting steps of reaction kinetics, optimizing skeleton materials and spatial framework, developing new slow-release carbon sources and promoting biological denitrification process were put forward for the follow-up researches, so as to provide reference and basis for the dissemination and application of slow-release carbon sources to promote the efficiency of biological denitrification.
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图 1 以PCL为缓释碳源的生物脱氮系统微生物群落系统发育树[59]
Figure 1. Phylogenetic tree of microbial community in biological nitrogen removal system using PCL as slow-release carbon source
表 1 天然缓释碳源的改性处理方法及处理效果
Table 1. Modified methods and effects of natural slow-release carbon sources
碳源类型 改性处理方法 处理效果 玉米芯[39] 碱处理,采用0.1 g Ca(OH)2处理每g干物质,处理温度
为70 ℃,处理时间为6 h酶解还原糖量提高2.4倍 小麦秸秆[39] 碱处理,采用0.1 g Ca(OH)2处理每g干物质,处理温度
为95 ℃,处理时间为24 h酶解还原糖量提高3.3倍 稻草、稻壳[40] 25 ℃,pH为7.2~7.5,缓释碳源投加量为5 g/L,NO3 −-N初始浓度为8.8 mg/L NO3 −-N去除率大于80% 小麦秸秆[41] 采用钴-60为辐射源进行辐照,源强为1.11×1015 Bq,
剂量为244.53 Gy/min,钴-60射线平均能力为1.25 MeV反硝化速率提高20% 马铃薯和小麦淀粉[42] 采用溶液湿法共混合低温冻胶成型技术,将淀粉与乙烯
醇溶液冷冻—解冻反复4次脱氮率大于90% 樟树叶[43] 温度为25 ℃,NO3 −-N浓度
为60 mg/L,缓释碳源投加量为12.5 g/L脱氮率大于96% 银杏叶、香樟叶、菖蒲、芦苇花、秸秆、木屑、树皮和松枝[42] 碱处理,3%NaOH溶液浸煮,过滤、水洗,调节pH至中性后于40 ℃烘干至恒定质量 除树皮脱氮率不高(75%)外,其他缓释碳源的脱氮率均在96%~98% 玉米秆[44] 碱处理,3%NaOH溶液浸煮 TN去除率
大于97%表 2 不同类型缓释碳源的反硝化速率对比
Table 2. Comparison of denitrification rates of different slow-release carbon sources
碳源类别 碳源名称 表面积/(m2/L) 温度/℃ 流速/(L/h) 投加量/(g/L) 孔隙率/% 反硝化速率/〔mg/(L·d)〕 天然 原棉[26] 14~30 0.037~0.045 22.1~38.0 87~95 49~82 麦秆[41] 24~26 <0.086 25.4~36.3 79~91 38~53 稻壳[29] 10~30 23.7~35.6 82~96 65~142 人工合成 PHB[55] 1.49 20~25 0.4~0.6 17.5~23.1 65~78 168~980 PCL[58] 0.87 20~25 0.2~0.3 7.2~12.9 15~21 504~3 980 黏结共混聚合物[59] 1.22 20~25 0.3~0.6 10.4~15.3 23~35 36~185 -
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