| In recent years, along with our country sewage treatment strength continuously strengthen, sludge production is more and more big, the treatment and disposal of sludge problem is also becoming more and more important.Compared with abroad, in the low organic matter content of sludge, inorganic content such as the sediment particle is on the high side.In order t o improve the efficiency of sludge anaerobic digestion, researchers have proposed many pretreatment process, including thermal hydrolysis, alkali treatment, ozone treatment, etc.The thermal hydrolysis is an important area of research, but people pay more attention to the temperature higher than 100℃ high temperature pretreatment, and less on the hydrolysis of below 100 ℃.This research use a CSTR reactor, explore the excess sludge in the process of low temperature thermal hydrolysis, organic matter change ru le and sludge reduction effect.Find out the best in low temperature thermal hydrolysis conditions, and on this basis, to explore the sodium persulfate further impact on the degree of excess sludge to destory. According to the sludge combination degree of cracking the optimum processing conditions and process, and discuss the best pretreatment technology for sludge anaerobic digestion process of reinforcement.Research shows that in low temperature thermal hydrolysis experiments, using 60℃, 70℃, 80℃ pretreatment sludge sample for 12 h respectively, the sludge basically stable. At this point, SCOD increased 17.1 times under the condition of 60℃, SCOD increased 23.3 times under the condition of 70 ℃.Under the condition of 80℃ SCOD increased 25.0 times.70℃ condition is a third higher than 60℃ condition treatment effect, and more than 80 ℃ condition improve treatment effect less than one over ten.Using the SCOD changes before and after low-temperature thermal hydrolysis to define the degree of sludge crack found that the degree of cracking under the condition of 70 ℃ sludge can only reach 22%.Excess sludge hydrolysis under the condition of 70 ℃ for 12 h, through the molecular spectroscopy analysis, found that in the sludge supernatant on solubility cell by-products class material, as some of nucleic acids with conjugated double bond structure and a large number of benzene ring.Under the condition of low temperature thermal hydrolysis, using sodium persulfate as the oxidant, the pyrolysis activation(60-90℃) way to produce sulfate radicals with strong oxidizing to oxidation sludge.Through the experiment found that the sodium persulfate dosage is 0.01 g/g TS, activation temperature is 70℃, reaction time is 90 min, under the condition of sodium persulfate oxidation sludge on cracking degree can reach about 18%. In low temperature thermal hydrolysis before and after adding the sodium persulfate as the oxidant, and no further improve the degree of cracking of the sludge, and the degree of crack is still only about 22% of sludg e, and similarity the results of sludge in low temperature thermal hydrolysis.The excess sludge was pretreatmented with low temperature thermal hydrolysis, then high temperature anaerobic digestion(55 ± 1 ℃) and methane-producing experiment be carried out. The results show that the methane from production increased by 142% in 20 d methane-producing experiment compared with the original sludge, when low temperature thermal hydrolysis of sludge. On low temperature thermal hydrolysis of sludge sequencing batch anaerobic digestion sample way, compared with the original sludge digestion in 34 d cycle, reducing overall sludge TS,is 23%~26%.Shorten the digestion time to 20 d, the low temperature thermal hydrolysis after the sludge digestion of TS decrement also can reach 22%, and the original sludge decrement of TS can reach 17%, the results showed that low temperature thermal hydrolysis of sludge can shorten the time of anaerobic digestion. |
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