What are the commonly used sludge treatment and disposal methods?
Common sludge treatment methods include: concentration, digestion, dehydration, drying, incineration, solidification and comprehensive utilization. In addition, there is also the final disposal method of sanitary landfill. Among them, sludge concentration, digestion and dehydration are the main treatment methods that are currently widely used. Common sludge treatment systems are divided into four categories: ① Concentration → mechanical dehydration → disposal of dehydrated filter cake; ② Concentration → mechanical dehydration → incineration → disposal of ash; ③ Concentration → digestion → mechanical dehydration → disposal of dehydrated filter cake; ④ Concentration → digestion → mechanical dehydration → incineration → disposal of ash.
The disposal of sludge varies according to the type, nature, generation state, source and other conditions of the sludge. The various disposal methods are as follows.
(1) For stable sludge without outflow, dissolution, odor or spontaneous combustion, it can be directly discarded on the ground or landfilled.
(2) Although sludge will produce odorous organic matter, it will not flow out or dissolve. It can be directly disposed of on the ground, buried in layers, or mixed with soil in suitable areas. It can also be converted into stable and harmless substances (such as water, carbon dioxide, nitrogen, etc.) through combustion, wet oxidation, etc., and the remaining inorganic matter can be disposed of on the ground or in a landfill.
(3) Sludge that has an impact on the environment but is not large in quantity needs to be buried directly underground due to factors such as dissolution, gas and odor generation, and flammability.
(4) Sludge containing harmful substances needs to be solidified before being disposed of on land or in the sea.
(5) When sludge disposal is difficult and can be concentrated in large quantities, in order to save resources and energy, it is necessary to consider the recycling of useful components of sludge.