What are the difficulties of sludge drying

At present, the problem of deep sludge dewatering is that the equipment investment and operation cost of thermal drying technology is too high, and it is difficult to promote. Due to the selection of conditioner, the chemical conditioning method has not achieved sludge reduction, and has a series of adverse effects on the back-end disposal.

In sludge drying treatment, mechanical dewatering can only remove free water and part of interstitial water existing between sludge particles; the binding force between capillary water and sludge particles is strong, which needs higher mechanical force and energy; the content of internal binding water is related to the proportion of microbial cells in sludge, so it is not feasible to use mechanical method to remove this part of water, but need to use mechanical method High temperature heating and freezing measures.

From the point of view of destroying the water binding form of sludge, the energy provided by heat drying technology can destroy the water binding in sludge cells and realize deep dehydration. Heat drying technology uses steam, smoke ventilation and so on, resulting in high treatment cost, large amount of tail gas, large amount of cooling water, at the same time, there are also problems such as odor and dust secondary pollution and dust risk. The investment and operation cost of sludge thermal drying method are generally high, which leads to higher construction requirements and conditions of sludge thermal drying.

From the point of disposal approach, the leachate containing chloride ion and high COD will have a greater impact load on the landfill leachate system after entering the landfill by adding chemical salts and lime. If incineration is carried out, due to the addition of more inorganic substances, the calorific value will decrease and the ash content will increase. Especially after the addition of alkaline substances such as quicklime, the furnace of the power plant will be corroded and scaling, which is difficult to meet the requirements of incineration.