The problem of high sludge moisture content can be solved by a variety of methods, the following are some specific solutions:
1. Sludge thickening
Sludge thickening is to reduce the volume of sludge by physical or mechanical methods, while increasing the concentration of sludge, thereby reducing the moisture content. The main methods include:
Gravity concentration: The solid particles in the sludge are settled under the action of gravity to achieve solid-liquid separation. This method is suitable for the thickening of mixed sludge, and the commonly used treatment facilities include gap sludge thickening tank and continuous sludge thickening tank.
Mechanical concentration: the sludge is filtered or squeezed by mechanical force, and the commonly used mechanical concentration methods are plate and frame filter, belt filter and so on. These methods can achieve higher dewatering efficiency and lower water content of the treated sludge.
Two, sludge stabilization technology
Sludge stabilization technology can change the biological and chemical properties of the sludge, reduce its water content and improve stability. Common methods include:
Anaerobic digestion: under anoxic conditions, organic matter in the sludge is decomposed through the action of microorganisms to produce energy such as biogas. This method can not only reduce the amount of sludge, but also recover energy, but it needs to pay attention to the concentration of COD and ammonia nitrogen in the treated supernatant.
Aerobic digestion: Under aerobic conditions, the sludge oxidizes itself and reduces the content of organic matter through the long-term respiration of microorganisms. Aerobic digestion has the advantages of fast speed, high degree of digestion, simple operation and management, but high power consumption.
3. Sludge conditioning
Sludge conditioning is to improve the dewatering performance of sludge and reduce its moisture content by adding chemical agents or using physical methods. Common conditioning methods include:
Chemical conditioning: Add polyelectrolyte (such as cationic PAM), inorganic salt (such as iron salt, aluminum salt), sludge conditioner, new sludge dewatering agent, sludge synergist and other chemical agents, through the electrical neutralization, adsorption bridge and other effects, improve the dewatering performance of sludge. This method is simple to operate, low equipment requirements, but high cost and some biological toxicity.
Physical conditioning: through heating, freezing, ultrasonic and other physical methods, change the physical properties of sludge, improve its dehydration performance.
Sludge drying and dehydration
Sludge drying and dewatering is to further reduce the moisture content of sludge through evaporation, press filtration and other ways. Common methods include:
Natural drying: the sludge is spread out on the drying field and dehydrated by natural evaporation and osmosis. This method covers a large area, and it is easy to produce odor and pollution.
Mechanical dehydration: through the filter press, centrifuge and other mechanical equipment to dehydrate the sludge. Mechanical dewatering has the advantages of small footprint and small odor, but the cost of infrastructure investment and maintenance is high.
Other methods
In addition to the above methods, the following strategies can also be considered to reduce the moisture content of the sludge:
Sludge incineration: Through high temperature incineration, the water in the sludge is evaporated and removed, and the sludge is reduced and harmless. But the incineration process will produce waste gas, waste residue and other pollutants, need to take strict environmental protection measures.
Sludge composting: the sludge and organic waste are mixed for composting treatment, and the organic matter in the sludge is converted into stable humus through the fermentation of microorganisms. This method can realize the resource utilization of sludge, but it needs to pay attention to the environmental control and product quality in the composting process.
In summary, there are a variety of methods to reduce the moisture content of sludge, and the appropriate method should be selected according to the characteristics of sludge, treatment scale and economic cost. At the same time, in actual operation also need to pay attention to environmental protection measures and product quality control and other aspects of the problem.