单选题In sewage treatment, the term maceration refers to the process of （）A breaking up solid matter into fine particlesB precipitating non-decomposed waste in a collection tankC chemically adjusting the sewage ph to 7-0D eliminating bacterium coli from the

maceration

A.aeration tanks

B.settling tanks

C.disinfection agent(消毒剂

D.anaerobic bacteria(厌氧菌)

A、Charge card

B、Credit card

C、A and B only

D、Charge card

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

A.(1)

B.(2)

C.(3)

D.(1)(2)(3)

浸渍(maceration)

A.boiler

B.separator

C.incinerator

D.treatment lological sewage

A.agitation function

B.bacteria

C.chemica

D.oxidizing function

In credit mix, tenor refers to ______.

A．term of loan

B．term structure of loan

C．term of asset

D．term structure of asset

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

●The term, (74) loop, refers to a loop that is contained within another loop.

(74)A.program

B.nested

C.statement,

D.Network