Experiment Research Of Sludge Dewater Ability With Modified Diatomite Earth

Sewage treatment will produce a large number of high moisture content of sludge.The number of sludge is accounted for about0.3%～0.5%of the water treatment (in terms of moisture content97%).It is difficult to be diposed and transported because of the huge volun of sludge.Therefore, we should improve sludge dewatering rate and reduce the sludge volume so as to realize sludge reduction.Nowday,mechanical dewatering is the primary sludge dewatering method. Sludge conditioning with chemical flocculant is a key method to improve the performance of mechanical dewatering.But most chemical conditioners is synthetic, more expensive and high processing cost. At the same time, because the synthetic chemicals in the environment is not easy to degrade and the harm to human body health has not been determined. To seek low cost、environment friendly and effective new flocculant is one of the major research work.Diatomite earth is a natural biological mineral. It is easily biodegradable and the reserves in our country is big. At the same time,it’s price is low.Therefore, this experiment modifided diatomite by roasting, acid leaching and paired with PAM for forming efficiency and economy flocculant.In the experiment the resistance of sludge was setted as evaluation indexe. Through the experiment study optimal modification conditions were:calcination temperature,500℃;roasting time I,2h; sulfuric acid concentration,60%;acid leaching time,3h; liquid-solid ratio,4ml:1g; mass ratio of diatomite and PAM,30:1.Optimum conditions for determination of sludge specific resistance were:the pH value,6～7;filtration pressure,200g/cm2;speed, rotate at a speed of200r/min for30s, and then rotate at a speed of60r/min for5min.At the same time, through the sedimentation experiment, vacuum filtering experiments and centrifugal dehydration experiment, the modified diatomite earth in sludge conditioning showed better dehydration performance than PAM and original diatomite earth.When the dosing quantity of modified diatomite earth was150mg/L, the sludge specific resistance dropped from the original10.33×109s2/g to0.23×109s2/g and the filter cake moisture content dropped from89.4%to58.89%.After adding the modified diatomite earth,the sludge settling velocity was accelerated apparently and settling time was reduced.