Disinfector in the sewage biological treatment plant usually

A.aeration tanks

B.settling tanks

C.disinfection agent(消毒剂

D.anaerobic bacteria(厌氧菌)

How to manage sewage?

请根据以下内容回答 60～64 题

A．An organ of higher plants， usually subterranean and having several functions，including the absorption and conduction of water and dissolved minerals， food storage，and anchorage of the plant in the soil. It is distinguished from the stem by its structure，by the manner in which it is formed， and by the lack of such appendages as buds and leaves.

B．It grow horizontally， as a food-storing organ， beneath the surface of the ground， and enables a plant to reproduce itself.It has nodes， buds，and tiny leaves and does not die when cut； replanted， it yields new plant.

C．both A and B

D．neither A nor B

第 60 题 一种起运输作用的器官是（ ）

Based on the laser operation treatment of three patients。what can we infer from the passage?

A．Laser light treatment is safe and effective．

B．Laser light treatment is dangerous and ineffective

C．Laser light treatment still requires much more studies．

D．Government should encourage doctors to do research of laser light treatment on the human body．

Biological treatment may use __ to treat sewage (1)living organisms (2)chemicals (3)additives

A.(1)

B.(2)

C.(3)

D.(1)(2)(3)

A.agitation function

B.bacteria

C.chemica

D.oxidizing function

第三组：

The sewage treatment system must be capable of discharging an effluent that comes within the limits of the tests. Sewage can be treated biologically so that it may be discharged with minimal damage to ecosystem. Biological treatment involves the use of living organisms to treat the sewage within the sewage treatment plant so the liquids and sludge discharged are within the standards specified.

Biological treatment plants are usually built up as a module and consist of various sections.

Waste matter collected from the ships sanitary appliances is led through a sanitary piping system to the treatment module. The solid matter is broken up by passing it through a screen or a series of revolving cutters. The broken up solid material, together with the waste liquid, passes into a tank containing bacteria which require oxygen and a nutrient to propagate. The nutrient is contained in the solid waste material, and oxygen is supplied by bubbling compressed air through the broken up waste. The propagated bacteria change the waste material into a sludge by aerobic digestion. The sludge is finally treated to kill the coliform. bacteria before it is passed overboard.

When a biological sewage plant is started up, such as when activating a new ship or after cleaning out the tank, a pellet containing bacteria is introduced into the tank. It takes approximately one week for the bacteria to propagate and make the system fully effective. The choice of sanitary appliance cleaners requires extreme care, as many cleaners are toxic to the active bacteria. Once a biological sewage plant is made active it should not be shut down. If it is it will have to be reactivated again because the bacteria will die without a supply of nutrients and oxygen.

Bacteria that require oxygen for their survival are referred to as aerobic. Aerobic bacteria are normally used in ships&39; sewage treatment equipment. Other forms of bacteria that do not require oxygen are referred to as anaerobic. Anaerobic bacteria are used in shore based sewage treatment works where methane is obtained as a by-product for use as fuel.

This passage is mainly about

A.sewage treatment methods

B.the various sections of a sewage treatment plants

C.biological sewage treatment system

D.how the sewage treatment plants are started up

A.boiler

B.separator

C.incinerator

D.treatment lological sewage

A.FECmightcorrespondtoadestinationIPsubnet，butitmightalsocorrespondtoanytrafficclassthat theedgeLSRconsiderssignificant.

B.FECisagroupofIPpacketsthatisforwardedoveradifferentpath，butwiththesameforwarding treatment.

C.FECisagroupofIPpacketsthatisforwardedoverthesamepath，andwiththesameforwarding treatment.

D.FECisagroupofIPpacketsthatisforwardedoveradifferentpath，butwiththedifferentforwarding treatment.

E.FECisagroupofIPpacketsthatisforwardedoverthesamepath，butwithadifferentforwarding treatment

Most marine biological sewage treatment plants consist of all the following statements except ______.

A.aeration(通风) tanks

B.settling tanks

C.disinfection agent(消毒剂)

D.anaerobic bacteria(厌氧菌)