Study On Energy Efficiency Of Mesophilic Anerobic Digestion Of Waste Activated Sludge By Ultrasonic Pretreatment

With the development of the municipal econmics,more population,and moer water is to be polluted. So a number of WWTPs have been builded,and the disposal rate of sewage is increasing year by year. The productivity of municipal sludge also increases rapidly. The disposal of sludge not only can pollute environment,but also the disposal of sludge can spend many expenses. Sludge is a useful biology resource,it becomes a more attention-getting discussion in the world's environment circles that how to make the vlum-vast sludge reclamation by scientific process.This subject is to study on energy of mesophilic anerobic digestion of waste activated sludge by ultrasonic disintegrated.The ultrasonic frequency used in this field-test is 20kHz. The power of the equipment of ultrasonic wave is 5kw,.Waste actived sludge is disintegrated by ultrasonic for 90s. The temperature of mesophilic anerobic digestion is 37±1℃.During the mesophilic anerobic digestion, The concentration of volatility organic solid is especially important to the productivity of methane.The test of mesophilic anerobic digestion run with a part of disintegrated sludge, the part of disintegrated sludge is 30% 50% 70%Some conlusions inferred from the mesophilic anerobic digestion are : When the adding ratio of sludge by ulstrasonic disinterated is 30%, The velocity of the reaction of anerobic digestion is very fast. It not only make the concentration of methanogen increase,but also accelerate the reproduction of methanogen.Besides sludge retention time has been shorten to 14 days.When the sludge retention time is 20 days,the energy output / the energy input is 6.8033.Its energy efficiency excelled else.When the adding ratio of the sludge by ulstrasonic disinterated is 50% 70%, the conclusion of mesophilic anerobic digestion is:When the sludge retention time is 20 day,the energy output / the energy input is the highest .Its energy efficiency is 4.66 4.29.When the sludge retention time is 20d 16d, the highest energy of three adding ratio is 30%.In conclusion, this field-test has proved that:making use of the sludge by ultrasonic disinterated ,we do the test of mesophilic anerobic digestion. The energy of output is bigger than the energy of input. So we can make good use of waste actived sludge to reclamated. It established a foundation for the sludge utilization. and economizes much money forwaste water treatment plants.