Reading guidance：Municipal sludge not only contains a lot of water, is filled with all sorts of bacteria, viruses, parasites and heavy metals and other toxic and harmful substances, if not properly treated, extremely e

    Municipal sludge not only contains a lot of water, is filled with all sorts of bacteria, viruses, parasites and heavy metals and other toxic and harmful substances, if not properly treated, extremely easy to cause two pollution. On the other hand, sludge is a kind of resource, a large amount of organic matter and nutrients in sewage sludge, anaerobic sludge energy is huge. Digestion can not only make the basic realization of sludge stabilization, reduction and harmlessness, and sludge digestion process of bio gas can be used for power generation, is a kind of clean and renewable energy; on the other hand, the remaining sludge can be cooked according to its composition characteristics used as fertilizer and fuel or landfill, realize resource. This is more the important significance for China's such a big energy.
1. Sludge anaerobic digestion pretreatment
 A. Sludge anaerobic digestion disposal
   Due to the biodegradability of the sludge solids, complete anaerobic digestion need quite a long time, even retention time is 20-30 D can only reach a moderate degree of degradation can only remove 30% - 50% of the VSS. and huge volume of digestion tank, and infrastructure costs high, complex operation and management and bio gas generation rate is low, poor use of bio gas equipment stability. A major way to improve the efficiency of anaerobic digestion is promoting sludge cell decomposition and intracellular organic matter release, enhanced the biodegradability. Researchers at home and abroad have carried out the research, we currently use ultrasonic and ozone to dispose sludge.
  B. Anaerobic digestion running management
  Anaerobic digestion temperature
  Methane bacteria are very sensitive to temperature, which will directly affect the decomposition rate of sludge and bio gas production. But in practice, the industrialization of anaerobic digestion system to keep the temperature constant is very difficult, in actual operation, the operating temperature can be controlled in a certain range. Such as the Gaobeidian sewage treatment plant of digestive system by 33e~35e operation the required temperature, and the higher the temperature, the heating temperature required to digest raw sludge heat also increases, and the increase of environmental temperature dig-ester heat loss increases, so in engineering mostly by mesophilic digestion. According to the experience of the dig-ester heating need only bio gas produced 35%-45%, can use bio gas power generation provide hot water for heating the sludge digestion, can realize the comprehensive utilization of co-generation and resources.
Agitation
   Digester mixing in order to make sludge fully mixed to microorganisms and nutrients full contact, to improve loading and gas production. Currently used bio gas stirring and mechanical stirring in two ways. Two ways the its characteristics: methane agitation while mixing range, good effect, high digestion rate, but the equipment, high cost, complex pipeline, easy due to corrosion and leakage; mechanical stirring maintenance is relatively small, but once the agitator failure, you need to the dig-ester relief air to repair, influencing the process is relatively large.
Mud discharging
  Commonly used digestion tank sludge is static pressure at the bottom row pump mud and bottom mud. According to the practical experience of Song Xiaoya, due to sludge stirring dead zone exists, the proportion of lower sludge digestion tank is still higher than the upper part of the sludge, mud in the process, bottom of the overflow pipe than major sludge and digestion tank in a relatively small proportion of the sludge, although there are difference of liquid level, but there is no overflow occurs. Therefore the static pressure mud must consider adding auxiliary mud pump.
  2. Effective reclamation utilization of sludge anaerobic digestion- use bio gas to produce power
Bio gas power generation is a process of energy conversion, in the engine cylinder gas is ignited, combustion heat release chemical energy conversion to gas heat energy and pressure energy and gas pressure to push the piston, driven by the engine rotation. Pressure energy is transformed into kinetic energy, engine through a shaft driven generator, the kinetic energy is transformed into electrical energy. According to the calculation, 1 kg dry sludge can produce bio gas 0.35nm3, can power 0.7kwh.
Gaobeidian, China Beijing city sewage treatment plant, the eastern suburbs of Tianjin city sewage treatment plant and sewage treatment plant is Ji Zhuangzi using anaerobic digestion system, producing bio gas digester for mixing and power generation, bio gas generator hot water as heat source heating digestion sludge, realize the comprehensive utilization of co-generation and resources. At present, the Gaobeidian sewage treatment plant sewage treatment capacity is 1 million m3, 4000 m3, sludge treatment, the plant through technical transformation and adjustment process, to maximize the collection of bio gas, bio gas production has been increased to 18 thousand M3, the daily volume of bio gas power generation is maintained at about 30 thousand KWh, the annual power generation of about 10 million kWh (can be saved electricity 5 million yuan), equivalent to about 5000 households a year in electricity.
   We should according to the specific circumstances of the timely development of urban sewage treatment plant sludge bio gas utilization of relevant technical policy, establish the evaluation system of bio gas production of sludge digestion, but also to develop related to the construction and operation of security policies to encourage, through financial subsidies, tax incentives and other economic levers to guide enterprises to actively adopt technology of sludge bio gas resources.
  Sludge is a pollutant, but also a potentially valuable resource available. Sludge anaerobic digestion bio gas utilization is to realize the sludge reduction, stabilization, effective means of harmlessness and unity. In the face of global environmental pollution, the severe situation of energy crisis, the economy can produce bio energy with practical technology to reduce pollution and sustainable development, build a resource-saving and environment-friendly society of national development strategy, it will have more and more broad development prospects. Bio gas technology is the use of the history of the earlier, with the sludge treatment and sludge treatment of attention, by advocating, some technical personnel began to recommend the use of the process of sludge. To solve the difficult problem of sludge.  
 
 
 
   
 

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