Reading guidance：With the popularity of the sewage treatment plant, more and more small sewage plant, but the sewage treatment sludge treatment and has brought great difficulties, especially financial problems. The slu

     With the popularity of the sewage treatment plant, more and more small sewage plant, but the sewage treatment sludge treatment and has brought great difficulties, especially financial problems. The sludge treatment and disposal although there are a lot of ways, such as hot and dry, compost, incineration, but based on the investment and operation cost is high, but also have great pollution byproducts, such as dioxin. And by adding calcium to achieve sludge drying, curing and sterilization process, the investment is small, quick, stable effect and other characteristics, more suitable for in the economic underdeveloped area in small waterworks and digestion sludge after further processing.
1. Basic principle
      Lime stabilized sludge drying technology is a use of additives on the urban sewage treatment plant sludge drying, stabilization and resource processing method. Use with lime heating agent, through efficient sludge drying system of organic sour sludge drying, dehydration, modified, to stability of inorganic material transformation. Dried sludge residue can replace limestone in cement raw material, to achieve the resources of sludge, and solve the problem of sludge treatment process in the secondary pollution problem. In addition, according to the dehydration of calcium hydroxide into calcium oxide this principle, after high temperature calcination, food additives, recovery and repeated use, to achieve the recycling of raw materials.
       Mix sludge with fine limestone evenly; there will be chemical reaction between limestone and sludge.
1kgCaO+0.32kgH2O→1.32kgCa(OH)2+1177kJ
      According to this kind of reaction, add every one-kg quicklime, about 0.32-kg water will be made into calcium hydroxide. Heat produced in the reaction can evaporate 0.5 kg water. Lime and water reaction for producing calcium hydroxide, will continue to produce further reaction with other substances in the sludge, such as generating reaction of compound calcium hydroxide and carbon dioxide (CO2):
     This reaction is 1.32kgca (OH) 2 0.78kgco cheering, 21.78kgcaco3 0.32kgh2o 2212kj further increased the amount of solids, heating evaporation of a small amount of water, thus increasing the treated sludge solid content. In addition, Cao, Ca (OH) 2 can also react with amorphous silica (SiO2) and alumina (Al2O3). Through these main chemical reaction, will produce the following effects: due to the effect of alkaline substances Ca (OH) 2 resulting in sludge pH value increased, sludge temperature increases due to the exothermic reaction, reaction combines the free water, also due to the exothermic reaction, a part of free water is evaporated.  
2. Final result
A. Further dehydration: moisture content is reduced to below 60% from 80% to 85%.;
B. Sterilization: the increase of PH and temperature can kill bacteria in order to guarantee safe production;
C. Passivate heavy metal ions;
D. Change quality and granulation;
E. Semi-dehydration and solidification in order to reduce moisture content;
3. Sludge dispose process
      Belt type filter press dewatering water rate is about 75 - 82% of the sludge, the sludge feeding screw conveyor and weighing spiral sludge by measuring backward to the reactor, at the same time, lime from the storage tank by adding to the conveyor precision mixing reactor, both fully mixed into the rotary dryer for dry and dehydrated, finished sludge through conveyor chain output after emergency dumps stacked laundry or direct loading Sinotrans, according to different purposes to different destinations. In the mud shaftless screw conveyor openings and the addition of accident gate valve and accident (old). The spiral reaction for continuous reaction, can be arranged in the system operation mode according to the running time of sludge dehydration machine.
4. Sludge disposal with adding calcium
     Sludge treatment of municipal waste water treatment plant sludge with calcium sludge has been in line with the requirements of landfill. But in the actual operation, it is found that, without the indoor placement of calcium and dry sludge viscosity is larger, sent directly to the landfill site is easy to cause the bulldozer track slip. In addition, the moisture content is less than 45%, and the physical properties are close to the soil and are difficult to dissolve in water. Its mud has been in line with the "urban sewage treatment plant sludge disposal sludge mixture" to do the requirements of covering soil. And the soil is alkaline, which can effectively neutralize the present partial acid leach-ate of landfill site. So it can be mixed with garbage landfill or as landfill cover soil. As covered with soil, can achieve the purpose of resource utilization of sludge, and reduce the cost of the final disposal.
     Sludge by adding calcium drying, the moisture content to reduce greatly, greatly reducing the sludge product, the treated sludge performance improved, sludge can reach the harmless, stabilization effect, easy storage and transportation, the technical route of investment, operating cost low especially for small and medium-sized sewage treatment plant is the gospel. So sludge and calcium in its technology is used in the promotion of small and medium-sized cities.
  
 
 
 

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