Sludge solidification stabilization technology aims at disposing sludge whose moisture content is 75% to 85%. The quality of sludge gets changed by adding special solidification and stabilization materials. The physics and chemical quality tends to stabilization. Solidification refers to the process where the physics quality gets changed by improving sludge intensity and reducing water permeability. Stabilization refers to transferring the shape of heavy metals contained in sludge and establishing internal closed system in order to change the chemical quality of sludge. 

All inner sludge of sewage plants are from the process of sludge disposal and collection. The sludge output is very high in this process. In china, about 50 million ton sludge whose moisture is about 75% is produced every year. The annual increase speed is 10%. The moisture content of sludge from sewage plants in cities is higher. There are many organic matters difficult to degrade, such as phosphorus, nitrogen, heavy metals and pathogenic microorganism. Secondary pollution will be caused if the sludge hasn’t been disposed properly. Till now, there are some methods to dispose sludge such as building material utilization, incineration, land utilization and landfill. Compared with other methods, landfill holds advantages of less cost and easy operation, it is widely used. However, there are many problems created in the process of landfill. For example, the real physical behavior of dehydrated sludge may not meet the soil mechanics requirements. After being washed and immersed by rain, sludge in landfill sites will become slurry. When it is raining, sludge may flow out with percolate in landfill site. Great pollution may be caused to landfill environment in the process of landfill. As a result, a great amount of soil and sand needs to be added in the process of landfill. But landfill volume will be reduced by about 50%.

Zhengzhou Taida sludge cements solidification disposal method: mix and stir sludge and solidification materials uniformly according to a certain proportion. Then start solidification and stabilization disposal.
This method holds advantages: sludge can be reused; inorganic mineral matters can be increased; the solidification materials consumption can be reduced; less disposal cost can be achieved; relevant processes are easy to operate; it is an effective sludge disposal technology. 

When solidify the harmful sludge, there will be chemical reaction between water in cement and sludge. Gel will be produced in the chemical reaction. Harmful sludge granularity will be contained in the gel and be hardened to cement solidified body which is mainly composed of hydration reaction products of cement, 3CaO·SiO3 packed in sludge granularity. Harmful matters of sludge will be enclosed in solidification system. Then, solidification and stabilization will be achieved.
  It is proved by practices that cement solidification is an effective way to dispose heavy metals. In the process of solidification, cement holds a higher PH value. In alkaline conditions, heavy metal ion in sludge produces hydroxide and carbonate which is difficult to dissolve in water. Some heavy metal ion can be fixed in the crystal lattice of the cement matrix, which can effectively avoid the leak of heavy metal.