摘要
目前,城市污水处理及其资源化再生利用已成为当前我国迫切需要解决的重要问题之一。但是以活性污泥法为代表的生化传统工艺以去除COD、BOD_5与SS为主,存在以下缺点:(1)工艺流程长,污水停留时间长,单位面积处理能力小,占地面积较大。(2)氮磷等无机离子去除效率低,水质不能回用。以磷为例,即使生物除磷系统效率达到最高,处理后出水中的总磷浓度也难以达到国家一级排放标准。如要达到总磷浓度<0.5mg/L,仍必须采用进一步化学强化处理。
本文在系统分析城市污水处理技术发展现状基础上,针对目前我国城市污水处理中存在的问题,在国内首次提出了磁种絮凝—高梯度磁分离对城市污水进行处理的新工艺。为此,作者进行了磁种对化学沉淀絮凝除磷的强化机理研究,确定了磁种对化学沉淀絮凝除磷的强化作用。研究发现:磁种在磁种絮凝—高梯度磁分离净化污水中主要起两方面的作用:一是作为磷酸铝沉淀及有机污染物絮凝的载体,强化其絮凝沉降行为;二是赋予沉淀絮凝物强磁性,提高磁分离效率。在此基础上,进一步试验确定了磁种絮凝—高梯度磁分离净化处理典型城市污水的最佳工艺条件,并进行了连续扩大试验。扩大实验结果表明,该工艺对污水中磷、重金属等污染物去除有特效,并能显著降低污水中的COD_(Cr)、BOD_5与SS含量,同时具有很强的杀菌作用。
在最佳工艺条件下:磁种用量0.3g/L、磁场强度0.2特斯拉,混凝剂硫酸铝用量200mg/L,助凝剂PAM用量2mg/L,水流速60—100m/h情况下,城市污水经磁种絮凝—高梯度磁分离处理,可去除其中36~90%COD_(Cr)与几乎全部(>95%)磷。当进水水质为SS 64.4mg/L、COD_(Cr)
武汉”1j}卜学油
卜学}洲台之
154.6mg/L·BODS 46.41109/L、p 0.581119/LI’l勺护,,水经处工,}!)!亏,55降介、
25 .2109几、C00Cr降个582mg几、BO05降个163mg几、P降介、OO3mg几
以下,其’}’CODC:、BOD、、P都达到国家一级引}放标准(CODcl.:60 mg几、
BOD。:20 nlg/L、p:Osnlg/L),55于支近l,·I家一级于11放4、、准(55:Zom留L),
其它污染物指标也得到不同程度的降低。而、,勺进水水质为cODcr 80mg/L、
P2.05mg几时,出水CODcf降至45mg几、P降至o.03mg/L,去除率分别
一司一达43%与98%。
磁种絮凝一高梯度磁分离卜艺将化学除磷的彻底性与高梯度磁分离
的快速性、高效性巧妙地结合起来、该L艺川于城市污水处理具有处理速
度快、占地面积少,设各简单,易f实现净化一体化、自动化,适用范围
广等优点,尤其对污水,士,的磷且有1}常好的去除效果。因此,这一工艺非
常适宜于我国城市小区、小城镇污水处理厂,以及城市大中型污水处理厂
的增能扩容及其出水回川强化处理}_一艺,在我国有厂一阔的应用推广一前景)
Nowadays, municipal sewage treatment and its outflow recycling have become one of the most urgent unsettled problems But the two-stage biology process which is mainly used in municipal sewage treatment in our country, has some shortcomings as follow: (1) long flow small flux and too much room occupation (2) its outflow can't attain to the first degree discharge standard of pollutants for municipal waste water treatment plant of the national(GB 18918-2002). If the phosphorus in the outflow should <0.5mg/L, further chemical disposal must be needed.
On the base of the analysis of current technology used in municipal sewage treatment, the tentative idea of treating municipal sewage using magnetic flocculation and high gradient magnetic separation was first proposed. In this paper, firstly, the mechanism of magnet in magnetic chemical flocculation of phosphorus removal has studied in laboratory. The result showed that the magnet has two effects in magnetic chemical flocculation, one is as a medium to combine the A1PO4 and strengthen the precipitation of the sediment, the other one is heighten the separation efficiency by enduing the deposit with magnetism. Then the scale-up experiment was carried out to find out the best parameters on industrial HGMS. The result shows: the process has special effort on heavy metal removal, and the bacteria were mainly be killed. It can greatly reduce the BOD COD and SS in the municipal sewage
36-90%CODCr and >95% phosphorus can be removed in the best parameter ( Fe3O4 0.3g/L, magnetic field 0.2T, A12(SO4)3 200mg/L, PAM 2mg/L, velocity of flow 60-100m/h). And the outflow can attain to the first degree discharge standard of pollutants for municipal waste water treatment plant of the national(GB 18978-2002). (The inflow: CODCr 154.6mg/L BOD5 46.4mg/L SS64.4mg/L P 0.58mg/L, The outflow: CODCr 58.2mg/L. BOD5
16.3mg/L SS 25.2mg/L, P<0.03mg/L; The first degree of GB18978-2002: CODcr, 60 mg/L, BOD5 20 mg/L SS 20 mg/L. P 0 5mg/L) When the inflow CODcr, 80mg/L, P 2.05mg/L, the outflow CODcr can attain to 45mg/L, P can
attain to 0.03mg/L, the decontamination efficiency can reach 43% and 98%.
Combining the high efficiency of the chemical removal of phosphorus and large inflow of HGMS, the magnetic flocculation and high gradient magnetic separation process have some special advantages in treating municipal sewage: large flux small room occupation simple facility easy to realize incorporation and automation, especially in phosphorus removal. The process which can be widely used in many fields, especially in following three aspects: community or minor city sewage treatment, enlargement of major city sewage treatment plant and the deep treatment of outflow from sewage treatment plant will have a promising prospect in sewage treatment
引文
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