污泥对紫穗槐生长和重金属积累的影响及施用量的确定
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摘要
随着经济发展和人民生活水平的提高,城市污水排水量日益增大,城市污泥作为污水处理的副产物,产量也随之大幅增加,目前各大城市污水厂污泥产量已经大大超出了各污泥处理厂的处理及处置污泥的能力,而且由于我国污泥处理技术起步较晚,跟国际发达国家相比,当前我国仍处于污泥处理工艺落后、设备更新跟不上速度的阶段,加之污泥处置场所容纳能力有限,致使部分污泥未经处理随意堆放的现象时有发生,不仅由于污泥中含有大量重金属元素造成了土壤环境和地表水及地下水的重金属污染,还因为污泥会散发强烈的恶臭气味,影响人们的正常生活和工作,因此,如何合理的处置城市污泥成为刻不容缓需要解决的城市环境问题之一。
紫穗槐是水土保持措施中常用的植物之一,耐干旱,耐碱性强,容易成活并且长势旺盛,在本实验中选用规格相似,株高在23cm左右,基径粗约为0.6cm左右的紫穗槐幼株进行盆栽实验,将经过不同预处理工艺的污泥成品和潮土分别按照一定的比例混合,比较不同浓度的热干化污泥、堆肥污泥及石灰干化污泥对紫穗槐各项生长指标及对不同重金属元素富集能力的影响,并且利用BCR提取法分析污泥中各重金属形态,针对不同存在形态重金属活性不同引入毒性系数,利用公式分别计算出热干化污泥、堆肥污泥及石灰干化污泥连续施用20年的最大施用量,为污泥土地利用提供一定的数据支持。经过实验分析得出的结论有：
(1)施用一定比例的热干化污泥、堆肥污泥和石灰干化污泥都会对紫穗槐富集重金属的能力起到促进作用,按照作用大小排序分别为堆肥污泥>热干化污泥>石灰干化污泥。从不同分组实验中植物体内累积重金属总量情况来看,紫穗槐对不同种类重金属吸收能力有很大的差异,这既与土壤中重金属元素的浓度大小和存在形态有关,也与植物生长对该种元素的需求程度有关,Zn元素、Cu元素均为植物生长所必需的金属元素,植物根部对这两种元素的吸附能力较强；Cd元素、Pb元素不是植物生长所必需的金属元素,所以植物对这两种元素的富集能力相对于Zn元素、Cu元素弱很多。
(2)不同污泥预处理工艺对污泥中各种重金属的钝化作用强弱不同,从整体上来看,堆肥及石灰干化预处理对污泥中Zn元素钝化作用较热干化预处理明显；三种预处理工艺对污泥中Cu元素的钝化作用没有明显差异,Cu元素均以不可被利用的残渣态为主；对于Pb元素,热干化及堆肥预处理效果明显好于石灰干化；对于Cd元素,经热干化及石灰干化处理后,大部分以较稳定的可氧化态和稳定的残渣态存在,而经堆肥处理后结果却刚好相反,污泥中Cd元素活性增强,稳定的结合态含量减少,级不稳定的可交换态和碳酸盐结合态含量增加。
(3)传统的污泥施用量确定方法只是考虑重金属种类,并不注重由于重金属存在形态的活性不同而对土壤环境的影响力大小不同。本实验中按照不同形态重金属的环境风险大小引入毒性响应系数确定污泥堆肥施用量,可交换态毒性响应系数为5,碳酸盐结合态毒性响应系数为4,可还原态毒性响应系数为3,可氧化态毒性响应系数为2,残渣态毒性响应系数为1,分别确定的热干化污泥、堆肥污泥和石灰干化污泥的合理施用量最小值均为Cd元素控制下的的允许施用量,分别为4.93t/(hm2.a),6.01t/(hm2·a)和5.17t/(hm2·a)。
With the development of economy and the improvement of people's living standard, the urban sewage displacement increases day by day, the city as sewage treatment sludge by-products, production has greatly increased, at present the big city sewage sludge factory production has far exceeded the sludge treatment and disposal of plant sludge of ability, and because China's sludge treatment technology start later, with the international advanced countries, the current our country still is in the sludge treatment process behind, equipment updating couldn't keep up with the speed of stage, and sludge disposal sites contain ability is limited, the part of the untreated sludge piles up at will frequently occurred, not only because of the heavy metal element contains a lot of sludge caused soil environment and surface and underground water of heavy metal pollution, but also because the sludge can send out the strong bad odor, influence people's normal life and work, therefore, how to reasonable treatment sludge become the urgent needs to solve the city of one of the urban environment problems.
Various soil and water conservation measures is commonly used in one of the plants, drought resistance, alkali resistance is strong, likely to survive and grow strong, in this lab choose norms similar, plant height in23cm or so, base diameter is about0.6cm thick around in various YouZhu potted experiment, through the different pretreatment process will be finished and chao soil sludge respectively according to certain mixing ratio, compare different concentration of hot dry sludge, composting, sludge and lime dry sludge on the growth index and various of different heavy metal element enrichment and ability of the influence, and make use of BCR extraction of heavy metal form the analysis of sludge, according to different existence form of heavy metal activity introduced different toxic coefficient, using the formula separately calculated hot dry sludge, composting, sludge and lime dry sludge continuous application of20years of maximum seems to provide certain land use for sludge data to support. After experimental conclusion:
A certain proportion of the hot dry sludge, composting, sludge and lime dry sludge will be the ability of heavy metal concentration of various play a role in promoting, according to the function size order for compost sludge> respectively hot dry sludge> lime dry sludge. From different group experimental plant in the total amount of metal accumulation situation, to various different kinds of heavy metal absorption ability has much difference, this already heavy metal elements in soil and the concentration of the size and the existing form, and plant growth for this element of the demand levels, Zn, Cu elements are elements needed to make plants grow metal elements, the root of the two kinds of element adsorption ability strong; Cd elements, Pb elements not needed to make plants grow metal elements, so plants of the two kinds of elements of the relative to Zn element enrichment capacity, Cu a lot weaker elements.
Different sludge pretreatment technology of all kinds of heavy metals in the sludge the passivation effects of different intensity, from the overall perspective, compost and lime dry the pretreatment on the sludge Zn passivation effects than hot dry elements of pretreatment is obvious; Three kinds of pretreatment process of sludge Cu elements in the passivation effects no obvious difference, Cu elements are not used to the dross of state for the Lord; For Pb elements, hot, dry and compost pretreatment effect was significantly better than the lime dry; For Cd elements, the dry heat of the dry and lime treatment, most of the more stable to oxidation state can be and stable scraps existence state, and the compost processing results but after just the opposite, in sewage sludge Cd element active strengthening, stable combination state content decrease, level of unstable exchange state and carbonate combination state content increased.
The traditional method of determining the applying sludge content just consider heavy metal type, and don't pay close attention to the activity of existence because heavy metal form different soil environment to the influence of different size. This lab according to different forms of heavy metal environmental risk size into toxic sludge seems determined response coefficient compost, can exchange state toxic response coefficient for5, carbonate combination state response coefficient for toxic4, can also YuanTai toxic response coefficient of three, the oxidation state can be toxic response coefficient for2, scraps toxic response coefficient for the state1, hot dry sludge, composting sludge and lime dry sludge are under the control of the permission of4.93t/(hm2·a),6.01t/(hm2·a) and5.17t/(hm2·a).
紫穗槐是水土保持措施中常用的植物之一,耐干旱,耐碱性强,容易成活并且长势旺盛,在本实验中选用规格相似,株高在23cm左右,基径粗约为0.6cm左右的紫穗槐幼株进行盆栽实验,将经过不同预处理工艺的污泥成品和潮土分别按照一定的比例混合,比较不同浓度的热干化污泥、堆肥污泥及石灰干化污泥对紫穗槐各项生长指标及对不同重金属元素富集能力的影响,并且利用BCR提取法分析污泥中各重金属形态,针对不同存在形态重金属活性不同引入毒性系数,利用公式分别计算出热干化污泥、堆肥污泥及石灰干化污泥连续施用20年的最大施用量,为污泥土地利用提供一定的数据支持。经过实验分析得出的结论有：
(1)施用一定比例的热干化污泥、堆肥污泥和石灰干化污泥都会对紫穗槐富集重金属的能力起到促进作用,按照作用大小排序分别为堆肥污泥>热干化污泥>石灰干化污泥。从不同分组实验中植物体内累积重金属总量情况来看,紫穗槐对不同种类重金属吸收能力有很大的差异,这既与土壤中重金属元素的浓度大小和存在形态有关,也与植物生长对该种元素的需求程度有关,Zn元素、Cu元素均为植物生长所必需的金属元素,植物根部对这两种元素的吸附能力较强；Cd元素、Pb元素不是植物生长所必需的金属元素,所以植物对这两种元素的富集能力相对于Zn元素、Cu元素弱很多。
(2)不同污泥预处理工艺对污泥中各种重金属的钝化作用强弱不同,从整体上来看,堆肥及石灰干化预处理对污泥中Zn元素钝化作用较热干化预处理明显；三种预处理工艺对污泥中Cu元素的钝化作用没有明显差异,Cu元素均以不可被利用的残渣态为主；对于Pb元素,热干化及堆肥预处理效果明显好于石灰干化；对于Cd元素,经热干化及石灰干化处理后,大部分以较稳定的可氧化态和稳定的残渣态存在,而经堆肥处理后结果却刚好相反,污泥中Cd元素活性增强,稳定的结合态含量减少,级不稳定的可交换态和碳酸盐结合态含量增加。
(3)传统的污泥施用量确定方法只是考虑重金属种类,并不注重由于重金属存在形态的活性不同而对土壤环境的影响力大小不同。本实验中按照不同形态重金属的环境风险大小引入毒性响应系数确定污泥堆肥施用量,可交换态毒性响应系数为5,碳酸盐结合态毒性响应系数为4,可还原态毒性响应系数为3,可氧化态毒性响应系数为2,残渣态毒性响应系数为1,分别确定的热干化污泥、堆肥污泥和石灰干化污泥的合理施用量最小值均为Cd元素控制下的的允许施用量,分别为4.93t/(hm2.a),6.01t/(hm2·a)和5.17t/(hm2·a)。
With the development of economy and the improvement of people's living standard, the urban sewage displacement increases day by day, the city as sewage treatment sludge by-products, production has greatly increased, at present the big city sewage sludge factory production has far exceeded the sludge treatment and disposal of plant sludge of ability, and because China's sludge treatment technology start later, with the international advanced countries, the current our country still is in the sludge treatment process behind, equipment updating couldn't keep up with the speed of stage, and sludge disposal sites contain ability is limited, the part of the untreated sludge piles up at will frequently occurred, not only because of the heavy metal element contains a lot of sludge caused soil environment and surface and underground water of heavy metal pollution, but also because the sludge can send out the strong bad odor, influence people's normal life and work, therefore, how to reasonable treatment sludge become the urgent needs to solve the city of one of the urban environment problems.
Various soil and water conservation measures is commonly used in one of the plants, drought resistance, alkali resistance is strong, likely to survive and grow strong, in this lab choose norms similar, plant height in23cm or so, base diameter is about0.6cm thick around in various YouZhu potted experiment, through the different pretreatment process will be finished and chao soil sludge respectively according to certain mixing ratio, compare different concentration of hot dry sludge, composting, sludge and lime dry sludge on the growth index and various of different heavy metal element enrichment and ability of the influence, and make use of BCR extraction of heavy metal form the analysis of sludge, according to different existence form of heavy metal activity introduced different toxic coefficient, using the formula separately calculated hot dry sludge, composting, sludge and lime dry sludge continuous application of20years of maximum seems to provide certain land use for sludge data to support. After experimental conclusion:
A certain proportion of the hot dry sludge, composting, sludge and lime dry sludge will be the ability of heavy metal concentration of various play a role in promoting, according to the function size order for compost sludge> respectively hot dry sludge> lime dry sludge. From different group experimental plant in the total amount of metal accumulation situation, to various different kinds of heavy metal absorption ability has much difference, this already heavy metal elements in soil and the concentration of the size and the existing form, and plant growth for this element of the demand levels, Zn, Cu elements are elements needed to make plants grow metal elements, the root of the two kinds of element adsorption ability strong; Cd elements, Pb elements not needed to make plants grow metal elements, so plants of the two kinds of elements of the relative to Zn element enrichment capacity, Cu a lot weaker elements.
Different sludge pretreatment technology of all kinds of heavy metals in the sludge the passivation effects of different intensity, from the overall perspective, compost and lime dry the pretreatment on the sludge Zn passivation effects than hot dry elements of pretreatment is obvious; Three kinds of pretreatment process of sludge Cu elements in the passivation effects no obvious difference, Cu elements are not used to the dross of state for the Lord; For Pb elements, hot, dry and compost pretreatment effect was significantly better than the lime dry; For Cd elements, the dry heat of the dry and lime treatment, most of the more stable to oxidation state can be and stable scraps existence state, and the compost processing results but after just the opposite, in sewage sludge Cd element active strengthening, stable combination state content decrease, level of unstable exchange state and carbonate combination state content increased.
The traditional method of determining the applying sludge content just consider heavy metal type, and don't pay close attention to the activity of existence because heavy metal form different soil environment to the influence of different size. This lab according to different forms of heavy metal environmental risk size into toxic sludge seems determined response coefficient compost, can exchange state toxic response coefficient for5, carbonate combination state response coefficient for toxic4, can also YuanTai toxic response coefficient of three, the oxidation state can be toxic response coefficient for2, scraps toxic response coefficient for the state1, hot dry sludge, composting sludge and lime dry sludge are under the control of the permission of4.93t/(hm2·a),6.01t/(hm2·a) and5.17t/(hm2·a).
引文
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3陈同斌,郑袁明,陈煌等.北京市土壤重金属含量背景值的系统研究[J].环境科学,2004,25(1)：116-117.
4程五良,方萍,陈玲,等.城市污水厂污泥土地利用可靠性探讨[J].同济大学学报,2004,32(7)：940-941.
5董丽华,李压男,常素云等.沉积物中重金属的形态分析及风险评价[J].天津大学学报,2009,42(12)：1112-11114.
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