Engineering of Water
Quality Control
Theory and Performance of
Deep-Bed Filtration
1,An overview of potable Water
filtration
1.1 Concept of filtration
The filtration processes discussed in here are used
primarily to remove particulate material from water,
the Classification of filtration:
filtration style,granular bed filtration,precoat filter
filter media,sand,anthracite coal,GAC,DE
filtration hydraulic,gravity filters,Pressure filters
rate of filtration,rapid granular bed filter,slow sand filter
distribution of deposit,depth filtration,cake filtration
Dominant Mechanisms,Performance,
and Applications
(1) Cake filtration
? Cake filtration of particulates involves physical removal by
straining at the surface,
? The mechanism of cake filtration is largely physical straining.
? Chemical pretreatments such as coagulation and
sedimentation are not generally provided.
? The source water must be of quite good quality,
(2) Slow sand filtration
? The surface cake of accumulated particulates includes a
variety of living and dead micro- and macroorganisms,
? The biological metabolism of the organisms enhances
removal of particulates.
? As the filter cake develops,the cake itself assumes a
dominant role in particulate removal,
? Because of this,filtrate turbidity improves as the filter run
progresses,and deterioration of the filtrate turbidity is
normally not observed at the end of the filter cycle.
(3) Rapid granular deep-bed filtration
? Depth filtration involves a variety of complex mechanisms to
achieve particulate removal,
? The small particles could be captured in bed by transport and
attachment process in series.
? Transport process are needed to carry the small particles into
contact with the surface of the individual filter grains.
? Attachment mechanisms hold the particles to the surfaces.
? Chemical pretreatment is essential to particulate removal in
depth filtration.
Regulatory Requirements for
Filtration
“community water systems must disinfect all surface
waters and filtration for most surface water
sources……..”
The U.S,Environmental Protection
Agency’s Surface Water Treatment Rule (SWTR)
Filtration processes that do not function on the principles of the processes defined
in the SWTR are called alternative filtration processes,and the log removal for
Giardia cysts or viruses that can be allowed for alternative processes must be
determined for each alternative process.
Removal of Microorganisms by
Granular Bed and Precoat Filtration
在北美, 贾第虫卵和隐孢子虫囊胞所引起的水系传播疾病, 以及
水中一些致病微生物的抗氯性等问题, 促使大家开始关注不同工
艺对水中微生物去除效果, 许多的研究集中在过滤以及相应的混
凝处理技术 。
模型试验研究发现：
? 通过改善混凝和过滤来降低滤后水的浊度, 可以有效去除贾第虫
和隐孢子虫囊胞 。 滤后水浊度越低, 对贾第虫和隐孢子虫囊胞的
去除率越高 。
? 运转良好的传统处理工艺, 通过有效的沉淀或其他的固液分离,
加上随后的过滤处理, 可以组成对原生生物的有效屏障 。
小结：
可以去除原生微生物的过滤工艺包括快滤、慢砂滤、硅藻土过滤和
膜过滤，但应用最为广泛的处理工艺当属凝聚和普通快滤的组合，
通常还涉及絮凝和沉淀。对于常规处理或直接 /直流过滤来说，微生
物有效去除的前提是，必须很认真的控制混凝和过滤过程，以期获
得非常低的滤后水浊度。
根据模型研究和生产试验，去除水中微生物的过程可以归纳为：
? 滤后水浊度应为 0.1ntu或更低；
? 出水浊度较高的滤池成熟期的持续时间应该尽量缩短（少于 1小时）；
? 滤后水浊度一旦超过 0.2ntu，即视为滤池浊度穿透，随即进行反冲
洗。
快滤技术的进展
快滤池的功能
①澄清功能 ②贮留沉积物的功能
三种技术潮流
①在过滤水流方向上开发了上向流过滤、双向过滤、水平流过滤等
②不同种类滤料的组合（多层滤料滤池）
③研究混凝剂种类和投加方法
Quality Control
Theory and Performance of
Deep-Bed Filtration
1,An overview of potable Water
filtration
1.1 Concept of filtration
The filtration processes discussed in here are used
primarily to remove particulate material from water,
the Classification of filtration:
filtration style,granular bed filtration,precoat filter
filter media,sand,anthracite coal,GAC,DE
filtration hydraulic,gravity filters,Pressure filters
rate of filtration,rapid granular bed filter,slow sand filter
distribution of deposit,depth filtration,cake filtration
Dominant Mechanisms,Performance,
and Applications
(1) Cake filtration
? Cake filtration of particulates involves physical removal by
straining at the surface,
? The mechanism of cake filtration is largely physical straining.
? Chemical pretreatments such as coagulation and
sedimentation are not generally provided.
? The source water must be of quite good quality,
(2) Slow sand filtration
? The surface cake of accumulated particulates includes a
variety of living and dead micro- and macroorganisms,
? The biological metabolism of the organisms enhances
removal of particulates.
? As the filter cake develops,the cake itself assumes a
dominant role in particulate removal,
? Because of this,filtrate turbidity improves as the filter run
progresses,and deterioration of the filtrate turbidity is
normally not observed at the end of the filter cycle.
(3) Rapid granular deep-bed filtration
? Depth filtration involves a variety of complex mechanisms to
achieve particulate removal,
? The small particles could be captured in bed by transport and
attachment process in series.
? Transport process are needed to carry the small particles into
contact with the surface of the individual filter grains.
? Attachment mechanisms hold the particles to the surfaces.
? Chemical pretreatment is essential to particulate removal in
depth filtration.
Regulatory Requirements for
Filtration
“community water systems must disinfect all surface
waters and filtration for most surface water
sources……..”
The U.S,Environmental Protection
Agency’s Surface Water Treatment Rule (SWTR)
Filtration processes that do not function on the principles of the processes defined
in the SWTR are called alternative filtration processes,and the log removal for
Giardia cysts or viruses that can be allowed for alternative processes must be
determined for each alternative process.
Removal of Microorganisms by
Granular Bed and Precoat Filtration
在北美, 贾第虫卵和隐孢子虫囊胞所引起的水系传播疾病, 以及
水中一些致病微生物的抗氯性等问题, 促使大家开始关注不同工
艺对水中微生物去除效果, 许多的研究集中在过滤以及相应的混
凝处理技术 。
模型试验研究发现：
? 通过改善混凝和过滤来降低滤后水的浊度, 可以有效去除贾第虫
和隐孢子虫囊胞 。 滤后水浊度越低, 对贾第虫和隐孢子虫囊胞的
去除率越高 。
? 运转良好的传统处理工艺, 通过有效的沉淀或其他的固液分离,
加上随后的过滤处理, 可以组成对原生生物的有效屏障 。
小结：
可以去除原生微生物的过滤工艺包括快滤、慢砂滤、硅藻土过滤和
膜过滤，但应用最为广泛的处理工艺当属凝聚和普通快滤的组合，
通常还涉及絮凝和沉淀。对于常规处理或直接 /直流过滤来说，微生
物有效去除的前提是，必须很认真的控制混凝和过滤过程，以期获
得非常低的滤后水浊度。
根据模型研究和生产试验，去除水中微生物的过程可以归纳为：
? 滤后水浊度应为 0.1ntu或更低；
? 出水浊度较高的滤池成熟期的持续时间应该尽量缩短（少于 1小时）；
? 滤后水浊度一旦超过 0.2ntu，即视为滤池浊度穿透，随即进行反冲
洗。
快滤技术的进展
快滤池的功能
①澄清功能 ②贮留沉积物的功能
三种技术潮流
①在过滤水流方向上开发了上向流过滤、双向过滤、水平流过滤等
②不同种类滤料的组合（多层滤料滤池）
③研究混凝剂种类和投加方法
