The Study Of Influencing Factors And Prevention On Scaling Of Leachate Pipe

Leachate is a type of organic wastewater containing large amounts of pollutant with high concentration, and difficult to treat. Now an economical way is to treat it in combination with municipal sewage. On the way of transporting leachate in pipeline to municipal sewage treatment plant, the pipe would be scaled and clogged due to some physical, chemical and biological reasons.To research the scaling mechanism of the leacahte pipe, The paper analyzed the scaling in theory first, then mensurated the leachate's water quality and the makeup of the pipe scaling from Chang'an waste landfill, which is the biggest one in SiChuan , and then studied the main facators influencing the scaling by static and dynamic experiments. The static experiment judged the influence by calcium's losing rate(The faster of the calcium's losing rate, the quicker of the depositing , and the more serious of the scaling degree.), by simulating the transportation of the leachate, the dynamic experiment estimated the influence with the scaling quantity of the pipe. At last, the evaluating methods, prevention and cure against the scaling were brought forward.The study of the scaling from Chang'an Waste Landfill 's leachte pipe showes that the main makeup is calcium carbonate, whose content is about 84.2%.The analyzing of the water quality indicates that the calcium strength is 455.45 mg/L, and the alkalinity is 173.82 mol/L, which supplies the scaling with qualification.The experiment is aiming at the main influence factors on sacling of leachate pipe such as calcium strength, alkalinity, pH, temperature, flux, time , pipe material and so on.The static state experiment shows that when other factors are invariable. The calcium's losing rate will increase with the calcium strength's augment. When the calcium strength are 308.78 mg/L, 494.04 mg/L, 694.75mg/L and 880.01 mg/L, the calcium's losing rate are 39.63%, 49.69%, 58.72% and 69.81%; Also, the calcium's losing rate will rise with the alkalinity or pH's increasing. When the alkalinity are 89.7 mol/L, 104.91 mol/L, 114.86 mol/L, 33.38 mol/L and 170.04 mol/L, the calcium's losing rate are 19.84%, 24.96 %, 26.67%, 31.78% and 43.72%; When pH are 6, 7, 7.5, 8 and 9, the calcium's losing rate are 16.43%, 19.84%, 21.55%, 40.31% and 48.84%. While the temperature changes from 15℃to 35℃, the calcium's losing rate will increase with the augment of calcium strength slowly. The calcium's losing rate will decrease as the time going on. The dynamic experiment indicates that when the pipe's material is uniform, the scaling state will augment with the flux's increasing. when the flux is steady, the PVC pipe's scaling degree will deeper than the PE pipe's.The ways to estimate calcium carbonate's scaling are Langelier's, Ryznar's, Puckorius's and Feitler's methods. The Ryznar's method is in common use. and the most reasonable is Feitler's method. By controlling the water quality , changing the outside condition ,or adding medicament which can preventing the scaling's formation,we can avoid the scaling. The chemical disposing measurement which is widely used can get rid of the scaling.The paper can give scientific reference to the waste ladfill's naturally running and leachate's favourable pipeline transportation.