不同堆腐条件下污泥中多环芳烃变化特征及在土壤—植物中迁移规律

发布时间：2018-01-03 22:00

  本文关键词：不同堆腐条件下污泥中多环芳烃变化特征及在土壤—植物中迁移规律　出处：《沈阳农业大学》2016年博士论文　论文类型：学位论文

  更多相关文章： 污泥堆腐 多环芳烃 迁移规律

【摘要】：近年来,我国污泥产量剧增,寻求合理的污泥处理处置出路已成为急需攻克的难题。污泥经堆腐后土地施用被认为是最有前途的污泥处置方式。多环芳烃是污泥中普遍存在的有机污染物,目前对污泥中多环芳烃去除及在土壤中迁移转化方面研究比较匮乏。为此,本文研究了不同模拟堆腐条件下污泥中14种多环芳烃变化特征、筛选多环芳烃去除条件,揭示污泥堆腐过程中多环芳烃与不同形态腐殖质结合特征,研究了污泥室外堆腐过程中有机质腐熟变化及多环芳烃变化特征。通过田间小区和室内翁栽试验探讨堆腐污泥施用过程中多环芳烃在土壤-植物中迁移规律。取得的主要结论如下：1.沈阳市4座典型污水处理厂污泥的有机质、氮、磷和钾养分含量丰富。重金属Cu、Cd、Pb、Zh、Ni和Cr在各污泥中均被检出,以Zn和Cu为主。在污泥进行土地施用时,Cu和Cd最先成为限制因子,以CJ/T309-2009污泥农用年施用量0.75 kg m-2计算,有1种污泥在酸性土壤上的安全施用年限为10年,其余污泥为28-47年。各污泥中14种多环芳烃总量介于2.63～18.3 mgkg-1,且均以3～4环为主,均来自燃烧源。与CJ/T 309-2009限定值(≤5mg kg-1)相比,有3种污泥的多环芳烃总量分别超标266.7%、48.4%和14.5%。因此,只要施用合理,重金属不再是污泥土地施用的限制因素,但在施用前必须经堆腐无害化预处理,使多环芳烃类有机污染物含量降低。2.室内模拟堆腐试验表明,不同调理剂对多环芳烃去除效果依次为草炭-稻草草炭-花生壳单一稻草单一花生壳单一草炭；随含水量增加,多环芳烃去除率呈先增加后降低变化规律,最佳含水量为55%；随温度增加,多环芳烃去除率呈先增加后降低变化,最佳温度为35℃；随通氧量增加,多环芳烃去除率也呈先增加后降低变化,最佳通氧量为8.64 L h-1kg-1,不通氧时小分子多环芳烃去除效果变差。整体来讲,3-4环PAHs去除效果优于5环、6环和2环。正交试验结果表明,不同因素对多环芳烃去除影响大小依次为调理剂种类含水量通氧量温度。在污泥：草炭：稻草=3：1：2、55%含水量、38℃和通氧量为7.92 Lh-1kg-1堆腐条件下,污泥中多环芳烃去除率最大,为79.6%。3.不同模拟堆腐条件下污泥中总有机碳变化规律与多环芳烃一致。以草炭-稻草为调理剂时胡敏酸碳含量和H/F比增幅大于其它调理剂,35℃时胡敏酸碳含量和H/F比增幅大于其它温度。污泥堆腐过程中胡敏酸碳含量随含水量增加而提高,但55%含水量条件下总有机碳降幅最大。污泥堆腐过程中胡敏酸碳含量和H/F比随通氧量增加而降低,但通氧量为8.64 L h-1 kg-1时总有机碳降幅最大。因此,在污泥堆腐实践中,前期应增加通氧量以提高多环芳烃去除效果,后期减少通氧量以提高腐殖化程度。4.不同模拟条件下污泥堆腐过程中腐殖酸与多环芳烃之间呈正相关,胡敏酸与多环芳烃之间呈负相关(45%含水量和10.8 Lh-1 kg-1通氧量除外),富旱酸与多环芳烃之间均呈正相关,H/F比与多环芳烃之间也呈负相关。堆腐的前15天,多环芳烃在不同形态腐殖质中的含量高低表现为残渣态碱溶态水溶态,堆腐的后15天则表现为碱溶态残渣态水溶态。堆腐前后残渣态多环芳烃含量由2508.0 ng g-1下降为198.8 ng g-1；碱溶态含量由1125.4 ng g-1下降为569.7 ng g-1；水溶态则由137.5 ng g-1下降为27.0 ng g-1。表明随堆腐进行,PAHs与腐殖质结合越紧密,PAHs的生物有效性降低。5.室外堆腐试验结果表明,污泥堆腐结束时总有机碳较堆腐前下降44.9%,C/N比由20.7下降为14.9,H/F比由0.51增加到2.47。堆腐产物结构疏松、颜色为褐色,无明显臭味,有泥土气息。三维荧光光谱和红外光谱显示水溶性有机物共轭结构和芳香结构增多,紫外光谱和红外光谱也显示污泥堆腐后胡敏酸和富里酸芳构化、腐殖化程度提高。堆腐结束时多环芳烃总量去除率为81.4%,表现为3～4环多环芳烃去除效果明显优于5环、6环和2环化合物。堆腐前2-6环芳香烃分布特征表现为4环3环5环6环2环；堆腐结束时已检不出2个苯环的萘和苊烯,而3～6环分布特征表现为4环5环3环6环。6.田间试验表明,堆腐污泥施用(2～25kgm-2)改善了土壤的机械组成,施用量为25kg m-2时的土壤质地已接近沙壤土；土壤有机碳、全氮和全磷肥力水平由6级提高到3-5级。堆腐污泥施用增加了土壤中多环芳烃含量,施用量为25 kg m-2的土壤中多环芳烃含量为137.6 ng g-1,满足荷兰土壤质量控制标准,属于无污染水平(200 ng g-1。)。施用堆腐污泥促进了樟子松苗木和高羊茅生长,但樟子松苗木和高羊茅生长效应分别在施用量超过20kgm-2和10 kg m-2时出现抑制,因此年施用量宜分别控制在20 kgm-2和10 kg m-2以内。忽略多环芳烃降解因素,按年施用量2 kg m-2计算,连续施用19年,土壤中多环芳烃含量为199.9 ng g-1,仍属于无污染水平。此外,多环芳烃在樟子松苗木和高羊茅地上和地下部分的迁移系数均1,且均以小分子化合物为主。樟子松苗木对多环芳烃的富集作用大于高羊茅,并且对小分子多环芳烃的生物富集系数均1,对大分子多环芳烃的生物富集系数1。
[Abstract]:In recent years, China's sludge production surge, to find a reasonable way for sludge treatment and disposal has become an urgent problem. The sludge composting after land application is considered to be the most promising method for sludge disposal. Polycyclic aromatic hydrocarbons are ubiquitous organic pollutants in sludge, the removal and transformation of the soil in the study the lack of polycyclic aromatic hydrocarbons in the sludge. Therefore, this paper studies the different simulation of 14 kinds of polycyclic aromatic hydrocarbons change characteristics of sludge composting conditions, screening of PAHs removal conditions, reveals the sludge composting process of polycyclic aromatic hydrocarbons and different forms of combined humus characteristics, organic matter maturity changes and variation characteristics of polycyclic aromatic hydrocarbons on the outdoor sludge composting process. By the field and indoor test on PAHs Weng planted composting of sewage sludge in the process of migration in soil plant in law. The main conclusions are as follows 1.: Shenyang City 4 sewage treatment plant sludge organic matter, nitrogen, phosphorus and potassium nutrient rich. Heavy metals Cu, Cd, Pb, Zh, Ni and Cr were detected in the sludge, with Zn and Cu. The land application of sludge, Cu and Cd first become a limiting factor CJ/ T309-2009, with years of sludge application was 0.75 kg m-2, there are 1 kinds of sludge in acid soil on the safe use of life for 10 years, the remaining sludge is 28-47. The sludge in 14 total PAHs ranged from 2.63 to 18.3 mgkg-1, and with 3 to 4 rings are mainly from combustion sources. With the CJ/T 309-2009 limit value (= 5mg kg-1) compared with the total PAHs in 3 kinds of sludge were 266.7% and 48.4% 14.5%. exceed the standard, therefore, as long as the application is reasonable, the heavy metal is no longer limiting factors for land application of sludge, but the application must be approved by the composting harmless pretreatment, the aromatic hydrocarbon content of organic pollutants Simulation experiments show that the.2. indoor composting decreased, different bulking agents on PAHs removal followed by peat peat - straw peanut shell peanut straw single single single peat; with increasing water content of PAHs removal rate showed a trend of decrease after the first increase, the optimum water content is 55%; with the increase of temperature, the removal rate of polycyclic aromatic hydrocarbons the change was reduced after the first increase, the optimum temperature is 35 DEG C; with the increase of oxygen, PAHs removal rate was decreased after the first increase, the optimum oxygen content is 8.64 L h-1kg-1, no oxygen molecules PAHs removal effect becomes worse. Overall, 3-4 ring PAHs removal effect was better than the 5 ring, 6 ring and 2 rings. The orthogonal experiment results show that the effect of different factors on the removal of PAHs is in turn type oxygen moisture conditioner temperature. In the sludge: peat: straw moisture =3:1:2,55%, 38 DEG C and oxygen Composting conditions for 7.92 Lh-1kg-1, the maximum removal rate of polycyclic aromatic hydrocarbons in sludge, 79.6%.3. simulation of different variation of total organic carbon in sludge reactor under the condition of rot is consistent with PAHs. Peat - straw as a conditioner when the content of Hu Min acid carbon and H/F was larger than other than the conditioner, 35 degrees of Hu Min acid and H/F carbon content an increase in temperature is larger than that of the other. The content of Hu Min in the process of sludge heap rot acid carbon increased with water content increasing, but the 55% moisture conditions of total organic carbon in the largest decline. Sludge heap of humic acid carbon content and H/F ratio with the composting process of oxygen increased, but the amount of oxygen for a maximum of 8.64 L H-1 kg-1 the decline of total organic carbon in sludge composting. Therefore, in practice, should be early increase of oxygen to improve the removal efficiency of PAHs, reduce oxygen later in order to improve the degree of humification of different.4. under simulated conditions of humic acid in the process of sludge heap rot Positive correlation with PAHs, there was a negative correlation between Hu Min acids and polycyclic aromatic hydrocarbons (45% water and 10.8 Lh-1 kg-1, except oxygen) between rich dry acid and polycyclic aromatic hydrocarbons were positively correlated between H/F ratio and PAHs is also negatively related. 15 days before composting, the content of polycyclic aromatic hydrocarbons in performance different forms of humus in the residual alkali soluble water soluble, composting after 15 days showed alkali soluble fraction of water soluble. Before and after composting residual PAHs decreased from 2508 ng to 198.8 g-1 ng g-1; alkali soluble content decreased from 1125.4 ng to 569.7 g-1 ng g-1; water soluble by 137.5 ng g-1 decreased to 27 ng g-1. showed that with composting, PAHs and combined humus more closely, the bioavailability of PAHs reduced.5. outdoor composting test results showed that the sludge composting at the end of the total organic carbon decreased by 44.9% compared with the heap rot before C/N than by 20.7 闄嶄负14.9,H/F姣旂敱0.51澧炲姞鍒，

本文编号：1375744