The methods of reducing the moisture content of sludge with high moisture content can be summarized as follows:
Natural drying:
Methods: The sludge was spread out on the drying field which was paved with sand and gravel, and the sludge was dehydrated by evaporation, infiltration and clear liquid overflow.
Features: Need to dry the field, covers a large area, easy to produce odor, management process requires manpower and material resources.
Mechanical dehydration:
Methods: The sludge was removed by pressure filtration and centrifugation.
Features: Compared with natural drying, mechanical dehydration has the characteristics of small footprint and small odor, but the infrastructure investment is large and the maintenance cost is high. Mechanical dehydration can significantly improve the solid content of the sludge, generally up to 20% to 30%, so as to achieve a reduction in the volume of wet sludge.
Adjust feed concentration:
Principle: If the feed concentration is too high, exceeding the processing capacity of the filtration equipment, it will lead to a high solid content of the filtrate.
Operation: The feed concentration needs to be adjusted to match the processing capacity of the filtration equipment.
Adjust the operating parameters of the filter equipment:
Methods: For example, adjust the filtration speed and filtration pressure to ensure the normal operation of the filtration equipment.
Note: Too fast or too slow filtration speed, insufficient filtration pressure, etc., may lead to high solid content of filtrate.
Improve sludge properties:
Methods: By adjusting the pH value of sludge and increasing the organic content of sludge, the dewatering property of sludge was improved.
Effect: The moisture content of sludge can be reduced.
Optimized filtration conditions:
Methods: Adjust the parameters of pressure, time and material of filter cloth to find the best filtration conditions.
Note: It is necessary to pay attention to the maintenance and maintenance of the filter press to ensure the normal operation and use of the equipment.
Use of chemical agents:
Methods: Chemical agents such as sludge enhancer and sludge conditioner were selected and used reasonably to improve the dewatering property of sludge before filtration.
Note: It is necessary to control the dosage and use of the agent to achieve the best dehydration effect.
Biological conditioning method:
Methods: The physical and chemical properties of sludge were improved by adding microbial agent or anaerobic digestion, and the dewatering performance was improved.
Effect: At the same time, it can also reduce the use of chemical agents and reduce the treatment cost.
Combined dehydration process:
Methods: According to different types of sludge, the combined dewatering process was adopted, such as the combination of biological conditioning method and press filtration method, or the combination of filtration method, centrifugal method and press filtration method.
Effect: It can improve the dewatering effect and reduce the moisture content of sludge.
In practical applications, the appropriate method of reducing water content or a combination of methods should be selected according to the specific type of sludge, treatment requirements and cost-effectiveness factors.