问题 单项选择题

对于A/O法,污水Q=40000m3/d,TN=25mg/L,Ns=0.15kg/BOD5/kgNLSS·d,进入曝气池的BOD5=180mg/L,处理后出水的BOD5=20mg/L,MLSS=3000mg/L,厌氧段与好氧段停留时间比为tA:to=1×3,则A池也具有去除BOD机能,tA为( )h, to为( )h。

A.2.4;7.2
B.1.2;3.6
C.3.0;9.0
D.3.5;10.5

答案

参考答案:A

解析: 按污泥负荷公式,曝气池容积为
V=Q×Sa/(X×Ns)=40000×180/(3000×0.15)m3=16000m3
总停留时间=16000/(40000/24)h=9.6h,
则A池停留时间为2.4h,O池停留时间为7.2h。

推断题
阅读理解

Life gets noisier every day and very few people can be free from noise of some sort or another. It doesn't matter where you live--in the middle of a modern city, or a faraway village--the chances are that you' ll be disturbed by jet planes, radios, oil - powered engines, etc. We seem to be getting used to noise, too. Some people feel quite lonely without background music while they' re working.

Scientific tests have shown that total silence can be a very frightening experience for a human being. However, some people enjoy listening to pop music which is very loud, and this can do harm to their eardrums(耳鼓). The noise level in some discos is far above the usual safety level for heavy industrial areas.

One recent report about noise and concentration(专心) suggested that although a lot of people say that any noise disturbs their concentration, what really influences their ability to concentrate is a change in the level of noise. It goes on to say that a background noise which doesn't change too much(music, for example) may even help people to concentrate.

小题1:According to this passage, the noise pollution         .

A.has become the worst in the countryside

B.has become better in big cities

C.has spread from cities to villages

D.has been controlled in modern cities小题2:Some people have their hearing harmed        .

A.while listening to pop music

B.in complete silence

C.when speaking loudly

D.while watching TV小题3:Scientists have discovered that what prevents people from concentrating on something is        .

A.all kinds of noise

B.changes in the level of noise

C.background noise

D.popular music