问题 单项选择题

将100mL活性污泥静止沉淀30min后测得沉淀污泥体积为30mL,混合液污泥浓度MLSS为3000mg/L,MLVSS为2100mg/L,则该污泥的容积指数SVI值为(),污泥()。

A.SVI为145,不可能会发生污泥膨胀

B.SVI为100,不会发生污泥膨胀

C.SVI为15,不会发生污泥膨胀

D.SVI为0.015,可能会发生污泥膨胀

答案

参考答案:B

解析:

SVI值在70~150之间污泥沉降性能良好,不会发生污泥膨胀,当SVI值大于200时,将会发生污泥膨胀。

单项选择题 A1/A2型题
单项选择题

Robert Moody, 52, is an experienced police officer. Much of his work involves dealing with (16) and gang (团伙)problems in the schools of his community. Knowing that many kids often (17) trouble, he decided to do something about it. So in 1991 he began to invite small groups of kids to go fishing with him on his day (18) .

Those fun trips had a(n) (19) impact. A chance encounter in 2000 proved that. One day, (20) working security at a school basketball game, Moody noticed two young guys (21) . He sensed trouble between them. (22) one of them headed toward Moody and gave him a hug. "I (23) you. You took me (24) when I was in fifth grade. That was one of the (25) days of my life. "

Deeply touched by the boy’ s word, Moody decided to create a foundation (基金会)that (26) teenagers to the basics of fishing in camping programs. "As a policeman, I saw (27) there was violence, drugs were always behind it. They have a damaging (28) on the kids," says Moody.

By turning kids on to fishing, he (29) to present an alternative way of life, "When you’ re sitting there waiting for a (30) ," he says, "you can’t help but talk to each other, and such (31) can be pretty deep. "

"Talking about drugs helped prepare me for the peer(同龄人)pressures in high school," says Michelle, 17, who (32) the first program. "And I was able to help my little brother (33) drugs. "

Moody faces (34) in three years, when he hopes to run the foundation full-time. "I’ m living a happy life and I have a responsibility to my (35) to give back," Moody says. "If I teach a kid to

fish today, he can teach his brother to fish tomorrow. \

31().

A. concerns

B. interests

C. conversations

D. emotions