Experimental Study On Process Coupled With Carbon Dioxide And Limestone Bed Contactor To Improve Water Chemical Stability

The Pearl River Delta mainly takes the Pearl River water as the water source,ho-wever,the water quality presents the characteristics of low hardness and alkalinity,resulting in a poor chemical stability of effluent water, which is corrosion to waterdistribution pipe network.The current water quality stability method can not eff-ectively control pipe corrosion.This article bases on the impact effects on chemicalstability of effluent water through a pilot study combined carbon dioxide with li-mestone contact column,to analysis the feasibility of the new technology on cotr-olling pipe corrosion.Essence of the new technology takes as follows:Firstly,prior tolimestone filtration,CO2was dosed into the reservoir water,that is acidifycation.Seco-ndly,CO2takes reaction with CaCO3which occurs in the filler filled in a limestonebed contactor.Thus, the water alkalinity, hardness and pH value are improved, so asto improve the water chemical stability and ease of corrosion of water pipe network.This article takes the limestone bed contactor design parameters into considera-tion,respectively,makes a detailed study on questions how the height of packing,paki-ng size and contact time work on water chemical stability,involving the contactorbackwash properties.At the same time,it also makes experiment in different carbondioxide content and different contact time to find out the influence to water chemicalstability.Results show that carbon dioxide degassing or not greatly influence thewater chemical stability.If the effluent water does not carbon dioxide degassing,thenwater residual more carbon dioxide,which reduce the water pH value,thus directlyimpact on the water chemical stability index,and the water chemical stability may begetting worse.If the effluent water do carbon dioxide degassing,then the waterchemical stability have greatly improvement.Experiment also found that the newtechnology do not significantly affect on water heavy metal content and turbidity,possibly due to the low content in heavy metal,and the combined process is after thesand filter which remove most of the suspended impurity,result of a low content inturbidity.The combined process is not only convenient but also safe in operation,thenresulting in a widely applying overseas.This paper is from the viewpoint ofeconomics and technology,an inquiry is made into the feasibility of the combinedprocess,and compared with carbon dioxide-lime hyphenated technology and traditional alkali technology.Then comparative the advantages and disadvantages ofthe three technology above,in order to provide certain references in the selectionprocess in water chemical stability improvement.