以10种农业废弃物为基料的地下水反硝化碳源属性的实验研究

发布时间：2018-11-15 20:18

【摘要】：为了选择理想的农业废弃物作为优质碳源,同时作为生物膜载体应用于可渗透反应墙(PRB),通过反硝化作用去除地下水中的硝酸盐.选择小麦秸秆、玉米秸秆、稻秆、大豆秸秆、玉米棒、稻壳、甘蔗渣、杨树枝、木屑、芦苇共10种农业废弃物进行元素分析实验、浸溶实验和长效浸出实验研究.元素分析实验结果显示,10种农业废弃物的C、N、H元素含量分别为38%~48%、5%~7%、0.5%~2.5%.短效浸出实验表明,甘蔗浸出液的总有机碳(TOC)浓度最高,均值可达38.66 mg·g~(-1),大豆秸秆、水稻秸秆、玉米秸秆、稻壳、杨树枝和小麦秸秆为8.04~15.30 mg·g~(-1),其他均值约为2.36~6.33 mg·g~(-1).但是,大部分农业废弃物均释放一定量的含氮物质.其中,硝酸盐及亚硝酸盐释放量均低于0.05 mg·g~(-1),氨氮释放量低于0.30 mg·g~(-1),凯氏氮除木屑、玉米棒、杨树枝释放量较低,其余均高于0.80 mg·g~(-1),最高可达1.65 mg·g~(-1).同时,秸秆类材料浸出液具有一定的色度,其中稻杆的色度最高,其值为1025.选择浸出液TOC浓度较高的甘蔗渣、玉米秸秆、稻壳、小麦秸秆及凯氏氮浓度较低的玉米棒和木屑作为理想碳源材料,进行长效浸出实验.结果表明,6种材料的TOC能迅速达到高位平衡状态,且溶出速率稳定,浸出液的高效液相色谱(HPLC)和气-质谱联用仪(GC/MS)分析表明,其主要成分为有机酸、糖类、含氮有机物和酯类等物质.其中,有机酸主要为甲酸、乙酸、草酸、富马酸等小分子有机酸、糖类主要为纤维二糖、葡萄糖、果糖和木糖.脱氮效能实验表明,6种农业废弃物硝酸盐去除率均达到80%以上,脱氮速率均达到1.00~2.00 mg·cm~(-3)·d~(-1)(以N计).综上,这6种材料均可作为地下水硝酸盐污染原位修复的理想碳源填充材料.
[Abstract]:In order to select ideal agricultural waste as high quality carbon source and as biofilm carrier to remove nitrate from groundwater by denitrification in permeable reactive wall (PRB),). Ten kinds of agricultural wastes, including wheat straw, corn stalk, rice stalk, soybean straw, corn cob, rice husk, bagasse, poplar branch, sawdust and Reed, were selected for elemental analysis, leaching experiment and long-term leaching experiment. The results of elemental analysis showed that the contents of C _ (N) H in 10 kinds of agricultural wastes were 38% and 48%, respectively, and about 0.5% and 2. 5%, respectively. The results of short-effect leaching showed that the concentration of total organic carbon (TOC) in sugarcane leachate was the highest, the mean value was 38.66 mg g ~ (-1). The average value of poplar branch and wheat straw was 8.04g ~ (-1) and 6.33 mg / g ~ (-1), respectively. However, most agricultural wastes release a certain amount of nitrogen. The release of nitrate and nitrite was lower than 0.05 mg g ~ (-1), ammonia nitrogen was lower than 0.30 mg g ~ (-1), Kjeldahl nitrogen was removed from sawdust, corncob and poplar branch. The rest were above 0.80 mg g ~ (-1) and the maximum was 1.65 mg g ~ (-1). At the same time, the leachate of straw material has a certain chroma, among which the rice stalk has the highest chroma, its value is 102525. Bagasse, corn straw, rice husk, wheat straw, corncob and sawdust with lower concentration of Kjeldahl nitrogen were selected as ideal carbon source materials for long-term leaching experiment. The results showed that the TOC of the six kinds of materials could rapidly reach the high equilibrium state and the dissolution rate was stable. The analysis of (HPLC) and GC/MS showed that the main components of the six materials were organic acids and sugars. Nitrogen-containing organic compounds and esters and other substances. Among them, organic acids are mainly formic acid, acetic acid, oxalic acid, fumaric acid and other small molecular organic acids, carbohydrates mainly for fiber disaccharide, glucose, fructose and xylose. The experiment of nitrogen removal efficiency showed that the nitrate removal rate and nitrogen removal rate of all six agricultural wastes were over 80% and 1.002.00 mg cm~ (-3) d-1 (in N) respectively. In conclusion, these six materials can be used as ideal carbon filling materials for in situ remediation of nitrate contamination in groundwater.
【作者单位】：南京大学地球科学与工程学院;
【基金】：国家水体污染控制与治理科技重大专项(No.2012ZX07204-003) 国家自然科学基金重点项目(No.41230640)~~
【分类号】：X71;X523

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