Research On The Mechanism Of CEPT And The Characteristics Of The Sludge Discharged From The Process

According to the policy of the disposal of civil sewage, a large number of wastewater treatment plants and establishments will be built in the later 10 to 20 years in our country in order that the scheduled aim of the wastewater treatment rate will be achieved. For the concentration of organic substance in the sewage is low in our southern cities, the Chemical Enhanced Primary Treatment (CEPT) technique, which can remove more pollutant at less cost and greatly increase the removal of organic substance in primary treatment process, is widely researched and applied in China and oversea. By the research of the mechanism of CEPT treating with civil sewage and the characteristic of the chemical sludge discharged from it, this thesis is aiming at establishing the base for the further application of CEPT.It has been found that the removal of COD will increase with the augment of PAC dose. But if the dose of PAC exceeded a given range, the removal of COD showed fluctuation with the further augmentation of PAC and the turn-pointing of removal of COD was not clear. The removal of dissolved organic substance is finite. When the dose of PAC is increased, the effect of flocculation was presided by the reacting zone according to the mechanism of flocculation.The output of chemical sludge in CEPT was researched quantificationally, the quantity of chemical sludge with the change of dosages of coagulants was summarized. Compared with the sludge from conventional primary settling tank, the weight of sludge produced from CEPT is about 2.0 times as much and the volume of its sludge is about 4.0 times as much.The removal of undissolved solid by CEPT was over that of conventional settling tank. But the condensation and fluidity performance of the former is inferior to that of the latter. As to the wastewater treatment plant in CEPT, the reasonable interval to discharge sludge is 4.5h.The design of sludge-hopper in sedimentation-tank and operation of discharging sludge need to be standardized. It can avoid sludge-floating insettling tank efficiently. For the viscidity coefficient of chemical sludge is bigger than that of the sludge from conventional primary settling tank, the gradient of pipeline and the loss of water head ought to be ample properly during the design of the sludge-pipeline and sludge-pump.