Research On The Effects Of Modified Activated Carbon Fiber On The Microwave Pretreatment Of Sludge

Anaerobic digestion is not only cost-effective, but also can achieve sludge reduction and resources recycling. In the anaerobic digestion process, hydrolysis acidification is the limiting step. In recent years, for this limiting step, many scholars put forward sludge pretreatment before the anaerobic digestion. Microwave pretreatment is one of pretreatment technologies, but efficiency of microwave pretreatment is not high. By adding activated carbon fibers to the sludge can improve the effect of microwave pretreatment. The main contents include that modified activated carbon fibers are prepared by means of dip-sintering, choosing the best modified activated carbon fiber by response surface methodology, analysing microwave sludge treatment effect of modified and unmodified activated carbon fiber,exploring effect of microwave pretreatment and anaerobic digestion in different material dosages and microwave processing time.The results showed that, once-dipped, 108 ml of deionized water and 191 ml of ethanol, the SCOD is 4399 mg / l; twice-dipped, 135 ml of deionized water and 135 ml of ethanol, the SCOD is 4539 mg / l; 2 twice-dipped is better than once-dipped. The modified carbon fiber of twice-dipped,which antioxidant properties and microwave reflectance better than the modified activated carbon fiber of once-dipped and unmodified activated carbon fiber, and it's tangent of the dielectric loss angle less than once-dipped modified activated carbon fiber and unmodified activated carbon fiber.With the increase of activated carbon fiber dosage, the concentration of SCOD, proteins, polysaccharides and DNA were increasing. The treatment effect of sludge with adding modified activated carbon fiber is better than the treatment effect of sludge with adding unmodified activated carbon fiber after microwave; The microwave treatment effect of mechanically stirred sample is better that not mechanically agitated sample. With the dosage of 0.16 g unmodified activated carbon fiber / gVS, the sample's SCOD, proteins, polysaccharides, DNA concentration of adding the modified activated carbon fibers and mechanically stirred were 3508,2048,385.54 and 171.88mg/l, increased by 36.61%, 29.29%, 27.66% and 77.95% than only microwave peocessing.Time is an important factor which affects the effect of microwave pretreatment. When microwave power is 800 W and the processing time is 4min, the sample's concentration of SCOD, proteins, polysaccharides and DNA were 3665,2136,414 and 162mg/l,respectively increased 32.41%, 30.56%, 26.60% and 63.64% than alone microwave treatment. With the increase in processing time, all the moisture content of sludge is decreasing in the case of three treatments. If processing time is same, the maximum moisture content of sample is the sludge adding unmodified activated carbon fiber,while the minimum moisture content of sample is the sludge which only microwave treatment.Add different absorbing materials to sludge, the anaerobic digestion sludge's efficiency of sludge is different after microwave treatment. 100 ml of thickened sludge adding modified carbon fiber can product methane 230 ml on 30 days, while product methane 150 ml on 30 days without absorbing materials.