Grade is dealt with ( primary treatment)

One it deals with to be in order to get rid of floating thing of water and suspend the solid mainly, have neutralization or mediate the function to deal with in order to do second succeeding ( secondary treatment) . One is it it includes to be as follows, mainly to deal with

Screen out ( screening) : Used to get rid of bigger solid first before other treatment method. The bar sifting ( screen) In general urban sewage disposal, set up dealing with the front of the factory more, the purpose formerly moves and gets rid of the thicker material in water. The bar sifting types used have the following several today: Thick bar removed with the roller chain of artificial or mechanical circulation ( The generally daily one) , the regular type bar is sifted, the turning round type bar is sifted, the vibration type bar is sifted and the centrifugal bar is sifted ( The last three are used in industrial waste water treatment extensively) .

Sediment ( sedimentation) : Is it get rid of to suspend the object water to use. The nature that the solid exists is different to suspend, precipitating can be divided into three kinds: Precipitate alone ( discrete) , is it is it precipitate to congeal to mix ( flocculent settling) Precipitate with layer ( zone settling) .

Precipitate it in the course of subsiding alone, the particle maintains its independence all the time, size, form and density do not change. Flying dust, cinder and sinking the sand pool ( grit chamber) The sediment of China belongs to this kind. It is that the particle in the course is condensed as subsiding to mix and congeal the emergence that is precipitated ( agglomerate) Function, subside speed and particle size will change at any time, general family waste water, paper pulp, papermaking for example their waste water. Layer precipitating and including being congealed the check form structure that the state suspended substance forms by the glue ( lattice structure) ,Lower with the bulk floor, on settle by liquid and precipitated solid of because it last interface not obvious, such as alum glue feather ( floc) And the sediment of the active mud,etc. are all.

The oil is separated: To freedom ( free) With floating ( floating) The type oil can make use of the gravity to clarify ( gravity clarification) Way from waste water in come out separation. It is it utilize proportion of oil the little than that of water, it can float at separator surface and move except that.: If the oil presents the state of dispersing ( dispersed) ,Need to join and condense or help and congeal the pharmaceutical first in front of the gravity separator ( coagulant aids) ,Add coagulant make oil with heavy object combine relatively, can is it get gravity precipitate trough to subside. The air floats and eliminates ( air flotation) Result that often applies to promote the oil and separates too.

Emulsification ( emulsified) The oil must be utilized and heated first or the chemical medicines destroy their emulsification states, become freedom after the attitude, make use of gravity precipitate or air float except that separate.

Float and eliminate ( flotation) : It float not more blow surface of watering except that. It float except that course gas been last liquid, make their become oversaturation, is it dissolve gas to emit under atmosphere pressure, the organization make little bubble with suspend the material or the oil combine, reduce proportion, promote the result of separating.

Mediate with neutralization: Used to reduce or control the change of the characteristic of the waste water, enable a succession of treatment course to under reasonable circumstances go on. For example, lower the change of the process system midstream quantity of physical chemistry, and cooperate with the medicine adding machine, control it with the medicine amount. Or control pH properly, keep the normal function of the biological process system