灼烧底泥抑制内源磷释放的研究

发布时间：2018-10-20 06:49

【摘要】：目前,覆盖法是一种受到国内外广泛关注的控制内源磷的底泥原位修复技术,而河道底泥和净水污泥对磷也有一定的吸附能力,因此,将两者结合用于河道修复的研究,将会是一种新的思路。本文以灼烧改性的底泥和净水污泥为研究对象,探讨其对外源磷的吸附效果及其在间隙水及底泥不同形态磷中的数量分布,着重讨论了灼烧方式对材料吸附特征的影响以及不同的投加方式对底泥磷迁移转化的作用机制。以太湖梅梁湾底泥、苏州学士河底泥以及苏州某净水厂净水污泥为实验材料,实验采用室内模拟培养方法,借助Rhizon间隙水采样器和Unisense微电极等仪器,测定上覆水、间隙水、沉积物中各种磷的数据并分析磷形态之间的相互转化,以及沉积物微界面物理、微生物特征的变化规律。根据模型方程对上述指标进行拟合,探讨在加入了改性材料后外源磷进入底泥的方式以及底泥中内源磷形态转化的诱发机制。用Langmuir模型拟合后,发现污泥经灼烧改性后具有更大的磷最大吸附量(S_(max)),更小的磷平衡浓度(EPC_0)以及更低的磷饱和度(DSP),并且灼烧后的净水污泥S_(max)(8.55 mg·kg~(-1))比灼烧的底泥(2.64 mg·kg~(-1))更大,这说明灼烧后的净水污泥具有更强的磷吸附和持留能力。在灼烧底泥的研究中发现:当底泥中混入或覆盖灼烧后的沉积物后,两组实验中分别输入的5.985毫克和5.978毫克的外源磷均进入底泥。然而当底泥混入灼烧底泥时,84.18%的外源磷转化为弱吸附态磷,同时当灼烧底泥覆盖在沉积物时,沉积物中的磷被释放,这些磷主要来自于占底泥总磷87.50%的Fe/Al-P。以上现象猜测归因于不同的微环境下,覆盖相比于混合更容易形成厌氧的条件。在灼烧净水污泥的研究中发现:混匀和覆盖对上覆水中磷消失的贡献率几乎一致,明显高于对照试验。但如果考虑灼烧净水污泥与上覆水的接触几率,则混匀条件下,单位净水污泥对磷的吸附量为覆盖条件下的2.3倍。覆盖条件下,间隙水(1-2cm)中溶解性磷酸盐浓度是混匀条件的33.17倍（平均值）,这主要源于覆盖导致溶解氧渗透深度明显降低。混匀条件下,外源磷更易形成Ca-P,而覆盖条件下,易释放的NH_4Cl-P和Fe/Al-P占比更多,这暗示了混匀对底泥微环境的改造更有利于外源磷的吸附和内源磷的持留。从所有实验结果以及对外源磷的吸附、间隙水中磷的控制、底泥微环境的改造、内源磷形态间的转化等方面来看,虽然混匀的施工难度大于覆盖的方式,但混匀技术还是有应用前景的,可以采用“注入灼烧净水污泥”的方法来代替混匀。
[Abstract]:At present, the mulching method is a kind of in-situ remediation technology for controlling endogenous phosphorus, which is widely concerned at home and abroad, and the sediment and purified water sludge also have a certain adsorption capacity for phosphorus. Therefore, the combination of the two methods is applied to the research of channel restoration. It will be a new way of thinking. In this paper, the adsorption effect of exogenous phosphorus and the distribution of phosphorus in different forms of phosphorus in interstitial water and sediment were studied. The influence of burning mode on the adsorption characteristics of the material and the mechanism of different dosing methods on the transport and transformation of phosphorus in sediment were discussed. The sediment of Meiliang Bay in Taihu Lake, the bottom mud of Shuanghe River in Suzhou and the sewage sludge of a water purification plant in Suzhou were used as experimental materials. In the experiment, the overlying water and the interstitial water were measured by means of Rhizon interstitial water sampler and Unisense microelectrode. The data of various kinds of phosphorus in sediments were analyzed, and the transformation of phosphorus forms among them, as well as the changes of physical and microbial characteristics of microinterfaces in sediments were analyzed. According to the model equation, the method of exogenous phosphorus entering the sediment and the mechanism of the transformation of endogenous phosphorus form in the sediment were discussed. After fitting with Langmuir model, it was found that the sludge had larger maximum phosphorus adsorption capacity (S _ (max), lower P equilibrium concentration (EPC_0) and lower phosphorus saturation (DSP), and that S( max) (8.55 mg kg~ (-1) was larger than that of scorched sludge (2.64 mg kg~ (-1), and the activated sludge had higher P adsorption capacity (S _ (max) (8.55 mg kg~ (-1) than that of burned sludge (2.64 mg kg~ (-1). This shows that the activated sludge has stronger phosphorus adsorption and retention ability. In the study of burning sediment, it was found that 5.985 mg and 5.978 mg of exogenous phosphorus were injected into the sediment after mixing or covering the burnt sediment in the two groups. However, when the sediment is mixed with the burning sediment, 84.18% of the exogenous phosphorus is converted into weakly adsorbed phosphorus, and when the burning sediment is covered in the sediment, the phosphorus in the sediment is released, which mainly comes from Fe/Al-P., which accounts for 87.50% of the total phosphorus in the sediment. These phenomena are attributed to different microenvironments, where mulch is more likely to form anaerobic conditions than mixing. In the study of burning clean water sludge, it was found that the contribution rate of mixing and mulching to the disappearance of phosphorus in overlying water was almost the same, which was obviously higher than that of the control test. However, if the contact probability between the burning water sludge and the overlying water is considered, the phosphorus adsorption capacity of the unit purified water sludge is 2.3 times as much as that under the mulching condition. The dissolved phosphate concentration in interstitial water (1-2cm) was 33.17 times higher than that in mixed water (mean value), which was mainly due to the decrease of dissolved oxygen permeation depth. Under mixed conditions, exogenous phosphorus is easier to form Ca-P, and more NH_4Cl-P and Fe/Al-P are easily released under mulching condition, which implies that the modification of mixing to sediment microenvironment is more favorable to the adsorption of exogenous phosphorus and retention of endogenous phosphorus. From all the experimental results as well as the adsorption of exogenous phosphorus, the control of phosphorus in interstitial water, the transformation of sediment microenvironment, the transformation of endogenous phosphorus forms, etc., although the construction difficulty of blending is greater than that of covering, However, blending technology is promising and can be replaced by "injection of burning water sludge".
【学位授予单位】：苏州科技大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TV85

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