Experiment Of Sludge Treatment In Full-scale Two-phase Integrated Sludge Thickening And Digestion Reactor

With the social and economic development, the urbanization of the Three GorgesReservoir area, the increasingly high requirements of environmental protection, thesewage treatment rate will continue to increase, and the production of sludge willcontinue to increase, the sludge treatment and disposal problems can not be ignored. Inthe Three Gorges reservoir area, many sewage treatment plants had been built, theprocessing technology for the sludge reduction and stability was very defective., and thesludge disposal mostly used mechanical dewatering and direct landfill, so the sludgeproblem had posed serious threat to the water environment in the Three GorgesReservoir area. Therefore, the sludge treatment and disposal technology for the specificcircumstances of the Three Gorges reservoir area is essential.In this paper, combined the theory of the modern high-speed anaerobic reactor andthe design of the gravity concentration pond, and the problem of the pilot TISTD reactorwas clear, we had designed and developed the full-scale TISTD reactor. The full-scaleTISTD reactor was designed on the scale of2m3/d, the dosing rate of25%, the effectivevolume of8m3, the total high4.63m (not including stent height, which the reaction zoneheight is2.2m). And the chamber of the reactor was been dividided two parts, calledouter chamber and inner chamber, the effective volume of each room are4m3, the outerchamber was used for sludge dewatering, and the inner chamber was used for theanaerobic digestion of sludge.According to the startup of the full-scale TISTD reactor at the room temperature,the result shows that after the startup of about97d, the reactor monitoring indicatorshad stabilized, marking that the startup of the reactor had completed,and the incomingsludge moisture content is99.65%~99.81%,and the VS/TS is0.60~0.80,the dischargedsludge moisture content reaches93.41%to94.55%, VS/TS becomes0.45~0.50,the VSSremoval efficiency is about35%, indicating that the digestion effect of the reactor wasmore obvious than ordinary gravity thickener and digestion tank; the pH value range ofthe reactor chamber was ranged between6.5and7.5within the pH range of themethanogenic bacteria, no VFA was accumulated and the reaction inside the roomcentral of VFA/ALK was ranged from0.1to0.35, indicating that the digestive processwas smoothly. After the startup of the full-scale was completed, the daily gas productionwas650L/d, which accounted for49.33%methane content, indicating that the efficiency of organic matter into methane was high, and according to the test of thesurface electron microscopy, we found that methane production inside the reactorbacteria was dominated by Methanosarcin.In order to test the full-scale TISTD reactor startup at different condition, we usedthree different pretreatment of the sludge, for example, alkali, acid, heat. After thesludge pretreatment by alkali, acid, heat, the results show that the concentration of VFAand SCOD was increased rapidly early and lately slowed with the treatment time. ThePH value changed in the liquid phase, a downward trend after the alkali treatment, aupward trend after the acid treatment, a downward trend after the heat treatment at60°C,70°C,80°C, and a upward trend after the heat treatment at90°C. And thealkali pretreatment was better than heat treatment, heat treatment was better than acidtreatment.