导　　师： 解利昕

学科专业： 080502

授予学位： 硕士

作　　者： ;

机构地区： 天津大学

摘　　要： 反渗透脱盐技术是水处理中脱盐和净化的主要方法之一,具有能耗低、无污染、适应性强、便于操作、运行费用低等显著特点。目前水的净化-预处理工艺是制约反渗透工程的瓶颈,开展此项研究意义重大;反渗透进水的主要指标淤泥密度指数/(SDI/),能反映进水中胶体对反渗透膜的影响程度,有必要对影响SDI测试结果的各种因素进行研究,对分析反渗透进水SDI不达标的原因,采取有效的预处理措施有积极的意义。 本文对两种不同的水样城市自来水和渤海海水进行了预处理方法的探讨。研究结果表明:对于城市自来水用5μm滤芯过滤+1μm滤芯过滤和1μm滤芯过滤+1μm滤芯过滤两级滤芯过滤可以作为小型反渗透的预处理工艺;采用混凝-沉淀-砂滤工艺可以将自来水SDI降到3以下,但工艺受砂滤粒径,砂滤高度,滤速,混凝剂的种类、用量,试验温度、pH值、盐分含量等因素的影响。选用ALCl/_3 11mg//L,砂滤粒径0.6-0.9mm,厚度60cm,滤速10m//h的工艺能把SDI降到2.31。在混凝-沉淀-微滤工艺中,微滤出水水质不受混凝剂用量的影响,但合适的混凝剂用量能减缓膜通量的衰减。对于渤海海水,烧杯混凝试验结果表明,FeCl/_3+聚丙烯酰胺可以有效降低浊度,采用混凝-沉淀-砂滤处理后的SDI仍然很大,砂滤后采用微滤进一步处理,SDI降至2.48,微滤通量衰减缓慢,物理清洗后基本恢复。 SDI随测量时间间隔的减小,计量容量的减小而增大;水中很小量的SS能反映较大的SDI,不同水样中的颗粒和胶体种类和含量不同,对SDI的影响程度也不同;合格的SDI必然有很低的浊度,但低浊度不能确保SDI的合格;水中的天然有机物如腐殖酸对SDI有影响,浓度增大,pH值增大、水中含盐量的减小,均使SDI变大。铁胶体、铝胶体的存在对SDI有影响,随着浓度、pH值的增大,SDI也变大,当纯水中铁含量大于20ppb后,SDI高于3,水中铝含� Reverse osmosis/(RO/) is one of the main processes for the water purification and desalination.It has remarkable merits of low energy consumption ,no pollution, strongly compatibility, convenient operation,low operating cost and so on. But the pretreatment technologies are the bottlenecks of the RO application Accordingly,it is very important to carry out the studies on water pretreatment. Silt density index/(SDI/) is the RO feedwater main requirement, which can reflect the effect of the colloid on the RO membrane. Researching the factor affecting the SDI test result has a positive significance to analyze the reason feed water SDI not to reach the requirment, and to take the effective pretreatment. The pretreatment methods was discussed in this paper by treating two kind of different water samples:tap water and the Bohai Sea sea water.It showed that:for tap water, 5μm cartridge filter+1μm cartridge filter or 1μm cartridge filter+1μm cartridge filter can be used as pretreatment step for small type RO system; Using the coagulation - precipitation– sand filtration craft could make tap water SDI to fall below 3, which was affected by sand particle size, bed depth, sand filtration rate, coagulant type, coagulant amount used, experiment temperature, pH value, salinity content . Selecting ALCl/_3 11mg//L, sand particle size 0.6 - 0.9mm, bed depth 60cm, sand filtration rate 10m//h ,SDI can achieve 2.31. In the coagulation - precipitation - MF craft, coagulant amount had no effect on the quality of water filtered by MF , but the appropriate coagulant amount can slow down the membrane flux depression. In the Bohai Sea sea water experiment, the beaker coagulation tests result indicated that: the FeCl/_3 + PAM for coagulant had the best turbidity reducing effect. The SDI after coagulation -precipitation– sand filtration is still very big, which can be reduced to 2.48 by adding microfilters as further processes. MF flux depression is slow, and it can be basical restored by physical cleaning. The research of

关 键 词： 反渗透 预处理 混凝 微滤 胶体

领　　域： [环境科学与工程]