CAST_在线百科全书查询

该工艺与常规SBR法相比，其最大特点是将SBR池分为三个区，生物选择区具有防止污泥膨胀，并可有效去除有机物和脱氮除磷的功能，同时改善了污水的可生化性。兼氧区具有反催化脱氮和除磷以及形成从厌氧区到好氧区的过渡的作用。主曝气区是CAST反应池的主要反应区，具有有机物降解、硝化、除磷的功能。所以在CAST反应池内在空间上有厌氧-缺氧-好氧三种环境，池内混合液为间歇的混合-推流式，但进水仍为间歇式。这些特点有利于有机物的去除和脱氮除磷。原水经格栅和沉砂池预处理后间歇进入CAST反应池的生物选择区，与从CAST反应池主曝气区回流的污泥混合，发生生化反应，然后流入CAST反应池的兼氧区，对由回流污泥中带入的硝酸盐氮进行缺氧反硝化脱氮，也可以将兼氧区调节为厌氧状态进行厌氧释磷，最终混合液流入CAST反应池的的主反应区，进行有机物的降解、硝化和除磷，然后经沉淀排出上清液。

^2.CAST反应器的组成与功能

CAST反应池由生物选择区、兼氧区和主曝气区三部分组成。

^（1）生物选择区

生物选择区位于CAST反应池的前端，区内常设置折流板，以加强污水和回流污泥的混合。生物反应区内COD较高，菌胶团细菌的比增殖速率比丝状菌比增殖速率更快，因此菌胶团是活性污泥中的优势菌种，可以抑制丝状菌的生长，从而有效防止污泥膨胀。同时，在厌氧环境下的生物选择区中，活性污泥中的反硝化菌以污水中的有机物为碳源，对回流污泥带入的大量硝酸盐进行反硝化脱氮，有利于氮的去除，并且在厌氧状态下，聚磷菌释磷，为在主曝气区的好氧状态下过量摄磷创造了先决条件，有利于除磷。此外，在厌氧菌和兼性菌的作用下，许多难降解的复杂有机物被分解为易生物降解的物质，改善了污水的可生化性，提高了CAST反应池的处理效果。

^（2）兼氧区

兼氧区可微量曝气进行反硝化脱氮，或者不进行曝气进行除磷。兼氧区也是从厌氧区到主曝气好氧区的过渡区，使活性污泥细菌受环境突变的影响降低。

^（3）主曝气区

主曝气区是CAST反应池的主要反应区，具有有机物降解、硝化、除磷的功能。在主曝气区曝气、沉淀、排水循环进行，并通过潜污泵进行污泥回流和剩余污泥排放，出水经滗水器排出。

^3.CAST工艺的运行方式

CAST反应池的运行是间歇性的和周期性的循环操作，一般运行周期为4h，其中曝气2h、沉淀1h、排水1h，但运行周期可根据水质水量波动作适当的调整。CAST反应池至少应该有两个，它的运行可划分为4个阶段：

^（1）进水搅拌或曝气阶段

污水与回流污泥同时进入CAST反应池的生物选择区，充分混合接触停留一定时间，，然后流入兼氧区和主曝气区。主曝气区曝气可与进水同步或推迟一定时间开始。

^（2）曝气阶段

当反应池进水达到池中设计水位时，则停止向该反应池进水和污泥回流，并将进水转换到其他CAST反应池，该主曝气区继续曝气，其曝气时间长短由所要求的处理效果而定。

^（3）静置沉淀阶段

CAST反应池停止进水与曝气进行静置沉降，使泥水分离。此时也没有污泥回流。

^（4）排水（闲置）阶段

此时曝气、进水和污泥回流都停止，进行排水，最后进行剩余污泥的排放。

8 中国民用航空局航空安全技术中心

Center of Aviation Safety Technology, CAAC

中国民用航空局航空安全技术中心

9 英语词语

cast

cast1

(past and past participle cast)

[with obj., usu. with adverbial of direction]throw (something) forcefully in a specified direction

猛扔，掷，投，抛

they cast themselves off the cliff.

他们猛地跳下悬崖。

individuals who do not accept the norms are cast out from the group.

不接受标准的个人被群体摒弃。

throw （something） so as to cause it to spread over an area

抛撒

the fishermen cast a large net around a school of tuna.

渔夫们朝一群金枪鱼撒了张大网。

he cast his net far and wide in search of evidence.

他全面撒网以搜寻证据。

direct (one''s eyes or a look) at something

将（视线，目光）投向

she cast down her eyes.

她垂下了双眼。

[with two objs]she cast him a desperate glance.

她绝望地瞥了他一眼。

[with obj.]throw the hooked and baited end of (a fishing line) out into the water

抛鱼钩

[with obj.] register （a vote）

登记（选票），投（票）

votes have been cast in 40 per cent of the seats.

对40%的席位投了票。

[with obj.](Hunting)let loose （hounds） on a scent

(猎)放开（猎狗）以探寻嗅迹

[no obj.](Hunting)(of a dog） search in different directions for a lost scent

(猎)（狗）四处探寻失踪的嗅迹

the dog cast furiously for the vanished rabbit.

这条狗疯狂寻找那消失的野兔嗅迹。

[with obj.]let down (an anchor or sounding line)

抛锚；放测深索

[with obj.]immobilize (an animal, especially a cow) by using a rope to cause it to fall on its side

用绳子绊倒（动物，尤指母牛）

[with obj. and adverbial of place]cause (light or shadow) to appear on a surface

投射（光，影）

the moon cast a pale light over the cottages.

苍白的月华洒落在农舍上。

running costs were already casting a shadow over the programme.

运转费已使该计划蒙上阴影。

cause (uncertainty or disparagement) to be associated with something

把（怀疑，轻视）加诸

journalists cast doubt on the government''s version of events.

新闻记者质疑政府对该事件的解释。

I do not wish to cast aspersions on your honesty.

我不想污蔑你的诚实。

cause （a magic spell） to take effect

使（魔咒）生效，施法

the witch cast a spell on her to turn her into a beast.

巫婆施法，把她变成了野兽。

the city casts a spell on the visitor.

这座城市把游客迷住了。

[with obj. and adverbial of direction]discard

抛弃

he jumped in, casting caution to the wind.

他跳了进去，把小心谨慎抛到了九霄云外。

shed (skin or horns) in the process of growth

（生长过程中）蜕（皮）；脱（角）

the antlers are cast each year.

鹿角每年都要脱一次。

(of a horse) lose (a shoe)

（马）失（蹄铁）

[with obj.]shape (metal or other material) by pouring it into a mould while molten

浇铸（金属等）

make (a moulded object) in this way

铸造

a bell was cast for the church.

为教堂铸造了一口钟。

arrange and present in a specified form or style

安排，表现

he issued statements cast in tones of reason.

他以理性的口吻发表声明。

calculate and record details of (a horoscope)

用（星相）占卜

[no obj., usu. with adverbial of direction](in country dancing) change one''s position by moving a certain number of places in a certain direction along the outside of the line in which one is dancing

（乡村舞蹈中的）转向（舞者沿外线移动位置）

noun名词

an object made by shaping molten metal or similar material in a mould

铸件，塑件

bronze casts of the sculpture.

雕塑的青铜铸件。

(亦作 plaster cast)a mould used to make such an object

模子，模型

(亦作 plaster cast)a bandage stiffened with plaster of Paris, moulded to the shape of a limb that is broken and used to support and protect it

（支撑或保护断肢的）石膏绷带

an act of throwing something forcefully

猛扔，掷，投，抛

he grabbed a spear for a third cast.

他抓住标枪，做第三次投掷。

(archaic)a throw or a number thrown at dice

(古)掷骰子；掷骰的点数

(Fishing)a throw of a fishing line

(渔)抛钓丝

(Brit.)the leader of a fishing line

(英)接钩绳

[in sing.][with adj. or noun modifier]the form or appearance of something, especially someone''s features

形状；外观，外貌

she had a somewhat masculine cast of countenance.

她的面容有些男相。

the character of something

特性，特点

this question is for minds of a more philosophical cast than mine.

这个问题适合那些比我更具哲学头脑的人。

the overall appearance of someone''s skin or hair as determined by a tinge of a particular colour

（人的）肤色或发色

the colours he wore emphasized the olive cast of his skin.

他穿的衣服颜色突出了他橄榄色的皮肤。

a slight squint

轻度斜视

he had a cast in one eye.

他一只眼睛轻度斜视。

a convoluted mass of earth or sand ejected on to the surface by a burrowing worm

（钻洞的蠕虫排放到表面的）泥土堆，沙堆

a pellet regurgitated by a hawk or owl

（鹰或猫头鹰的）颗粒状呕吐物

a search made by a hound or pack of hounds over a wide area to find a trail

（猎狗）探寻嗅迹

(Austral./NZ)a wide sweep made by a sheepdog in mustering sheep

(澳/新西兰)（牧羊犬赶拢羊群时的）四周搜寻

常用词组

be cast in a – mould

be of the type specified

为某种类型

he was cast in a cautious mould.

他生性谨慎。

cast one''s eyes over

have a quick appraising look at

快速查看

he was invited to cast his eyes over the exhibition.

他应邀粗略参观一下展览。

cast one''s mind back

think back to a particular event or time

回顾，回忆

he cast his mind back to the fatal evening.

他回忆起那不幸的傍晚。

来自《新牛津英汉双解大词典》

10 OSPF中的cost

cost值是OSPF协议来进行选路的是依据。

cost值的计算方法：cost=10^8/带宽（带宽的单位是bps）

由此看出 cost值越小，带宽越大。

所以OSPF选路时，是选择cost值最小的。