摘要
为探究城市污水厂污泥改良水蚀沙土后对地下水的环境风险,检验污水厂污泥作为土壤改良剂改良水蚀沙土的可行性,试验基于污水厂离心脱水污泥对沙土的改良效果,模拟水蚀沙土土层后,利用污泥掺混量为15%的改良水蚀沙土作为0~20 cm土层土壤,通过饱和淋洗的方式分析渗出液水质水量,评价利用掺混城市污水厂污泥的改良水蚀沙土直接作为表层土壤后对地下水的环境风险。结果表明:氮素对地下水的风险较大,且存在较大的持续性风险,TN中硝态氮含量占比较高,硝态氮与TN含量显著相关(r=0.997,P<0.01);深层土壤会发生亚硝化反应,极大地增加地下水亚硝态氮污染风险;渗出液TP峰值为0.18 mg·L^(-1),约是空白淋出液的2.6倍,淋出液COD与亚硝态氮和TP均显著相关(r=0.630,P<0.05;r=0.677,P<0.05),COD所代表的碳源成为改良水蚀沙土地下水亚硝态氮和TP风险的主要限制因素;而污泥的水解酸化在降低渗出液pH的同时,增加了渗出液的COD含量,进而增加地下水风险,试验COD峰值含量为46 mg·L^(-1),约是空白淋出液的2.5倍,pH与COD显著相关(r=-0.760,P<0.01);重金属对地下水风险在试验后期较高,呈现一定的后效性;含泥量为15%的改良沙土在过饱和淋洗过程中会对地下水产生一定的环境风险,表明掺混城市污水厂污泥的改良水蚀沙土在一定条件下可能会对地下水产生影响,需要采取一定污染防控措施来控制风险。
To explore groundwater environmental risk of water-erosion sandy soil amended with municipal sewage sludge and further verify the feasibility of municipal sewage sludge as ameliorant to sandy soil,a saturated leaching test in simulated soil columns was carried out based on the improvement effect of sewage centrifugal dewatering sludge on sandy soil.Sewage centrifugal dewatering sludge was mixed with the sandy soil at a portion of 15%（wet weight） to prepare 0-20 cm soil layer.The quality of exudate was analyzed by means of saturated leaching,and its environmental risk to groundwater was assessed with the improved sandy soil as the surface soil.The results showed that nitrogen had a big,persistent risk.The proportion of nitrate nitrogen in total nitrogen was high.TN content was positively correlated with nitrate nitrogen content（r=0.997,P〈0.01）.Nitrosation happened in deep soil,greatly increasing the risk of nitrite nitrogen pollution of groundwater.Furthermore,the peak value of TP in exudate was 0.18 mg·L^-1,being about 2.6 times the control.The COD content was positively correlated with nitrite nitrogen and TP（r=0.630,P〈0.05;r=0.677,P〈0.05）.The carbon source represented by COD was the main limiting factor affecting the risk of nitrite nitrogen and TP in groundwater;however,sludge hydrolysis and acidification reduced the pH of exudate and increased the exudate COD content,which further increased the risk to the groundwater.The peak value of COD in exudate was 46mg·L^-1,being about 2.5 times the control.There was a positive correlation between pH and COD（r=-0.760,P〈0.01）.The risk of heavy metals to groundwater was higher at the end of the experiment,showing a certain delayed effect.The sandy soil improved with 15% proportion of municipal sewage sludge would have a somewhat environmental risk to the groundwater during the over-saturated leaching process.Thus,some certain pollution prevention and control measures should be taken to control the risk.
作者
黄殿男
谭杰
傅金祥
刘军
张贺凯
赵玉君
李琳
常沙
HUANG Dian-nan TAN Jie FU Jin-xiang LIU Jun ZHANG He-kai ZHAO Yu- jun LI Lin CHANG Sha(Liaohe River Basin Water Pollution Control Institute, School of Municipal and Environmental Engineering, Shenyang Jianzhu University, Shenyang 110168, China）.)
出处
《生态学杂志》
CAS
CSCD
北大核心
2017年第10期2926-2932,共7页
Chinese Journal of Ecology
基金
辽宁省教育厅科学研究项目(LJZ2016028)
沈阳建筑大学博士后基金(SJZUBSH201625)
国家水体污染控制与治理科技重大专项(2014ZX07202-011)资助
关键词
污泥
沙土
水蚀
地下水
环境风险
sludge
sandy soil
water erosion
groundwater
environmental risk
