Reading guidance：Paper making sludge is a kind of pollutant matter produced in disposing paper-making sewage. Without proper disposal, it will cause bad influence to environment. Generally, paper-making sludge is mix s

    Paper making sludge is a kind of pollutant matter produced in disposing paper-making sewage. Without proper disposal, it will cause bad influence to environment. Generally, paper-making sludge is mix sludge including sludge in first settling pond and two stage biochemical treatment sludge. Some paper-making sewage treatment plants will produce flocculation sludge of three stage processing unit. Generally speaking, the organic matter content in pulp and paper mill sludge is 62%, mainly of cellulose, dry sludge fiber content can reach 38.12%. relevant experts through of papermaking sludge and sewage sludge chemical composition and calorific value of experimental study found, papermaking sludge and sewage sludge after appropriate treatment as a source of energy use.
   Carbonized sludge by heating and pressure is in the sludge microbial cell lysis, so that the organism water more easily released. Carbonized sludge by ordinary mechanical dewatering can remove about 75% water. Because of the lack of evaporation process in the technology, greatly save energy consumption in operation and sludge carbonization process preserves the sludge in the vast majority of carbon values, is conducive to the energy recovery and utilization of carbide. Sludge and compared to incineration, carbonized sludge is the biggest advantage is that there is no secondary pollution.
  1. Carbonization classification of sludge
   A. High-temperature carbonization: dry sludge to moisture content of 30%. Then, enter carbonization furnace to pelletize. Under normal pressure, temperature is controlled at 650 degree centigrade to 980 degree centigrade.
   B. Middle-temperature carbonization: dry sludge to moisture content of about 90%; then, sludge will enter carbonization furnace for decompostion. Under normal pressure, temperature is controlled from 430 degree to 540 degree centigrade.
   3. Low-temperature carbonization: no dehydration before carbonization; pressure should be controlled at about 10 Mpa. Carbonization temperature is about 315 degree centigrade. The sludge produced by carbonization can be used as the raw material for biomass fuels after the dehydration of the sludge is produced.
2. Composition and charateristics of sludge after carbonization
   Sludge by carbonization furnace after carbonization, more than 80% of the organic matter decomposition vaporization, 20% organic matter remaining by carbonization. Residual carbide sludge is black granular carbide, which accounted for 25 of fixed carbon ash accounted for 40%, 50% to 70%, the particle size of 1to5mm. granular carbide has the following characteristics: 1) low density, light weight 2); high porosity, large specific surface area; 3) can be adsorbed when wet sludge volume 30% to 40% water; 4) good decolorization and deodorization performance; 5) the absorption of solar heat efficiency is high; 6) rich in calorific value; 7) suitable for microbial growth on the surface. Because the carbonized sludge have more variety the characteristics, applicable to a variety of occasions, so it has a great development potential in the appropriate supporting conditions of sludge carbonization technique.
  3. Effective utilization of carbonized sludge
 A. Absorb materials
     Sludge active carbon can be used as adsorption agent and used for deodorization activated carbon from sewage sludge to do, sludge activated carbon containing carbon content is slightly low, only 177~700 mg / g sludge activated carbon in treatment of organic wastewater, COD adsorption capacity and adsorption equilibrium time is higher than that of commercial activated carbon. And used the sludge activated carbon if not renewable can used for fuel. In the aspect of deodorizing and carbonized sludge for hydrogen sulfide and methyl mercaptan has good deodorization effect.
 B. Snow melting agent
   Activated carbon due to its absorption of the heat of the sun's high efficiency, itself will absorb oxygen in the air and heat up, is also commonly used in the production of snow melting agent.
  C. Used as gardening materials
   Carbonized sludge can be used to improve quality of soil and add water permeablitity, breathability and water retaining property. Sludge can absorb fertilizer and emiss gradually. Therefore, it is ususally applied to improving soil and garden.
  D. Hygroscopic agent and dehydrant agent
  The carbonized sludge due to wet when the adsorption characteristics of the sludge volume 30 to 40% moisture, commonly used in the hygroscopic agent and dehydrating agent. In the filter press dewatering process, we usually need to aid, general use is lime and ferric chloride conditioner, if you join the carbonized sludge filter press, sludge dewatering will reduce 1%.% to 3%.
  E. Fuels
   Industrial output value of high way can also be carbonized sludge yield and biomass, such as straw, forestry processing waste, livestock manure and other, after processing simulation of coal gas formation process, can be made into a new kind of tasteless, high calorific value, burning time of environmentally clean biofuels, such as supporting the project with thermal power plant, the thermal power plant flue gas to dry sewage sludge dewatering, can reduce costs, can also be as fuel as auxiliary fuels in thermal power plant, for thermal power plant every year to save millions of energy costs.
  

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