Effect Of Ultrasonic Disintegration On Enzyme Activities And Analysis Of Hydrolyzate

Ultrosonic disintegration as a pretreatment of waste water activated sludge(WAS), was not only able to change the structure of the flocs but also the activity ofthe extracellular (proteases, α-glucosidase) and nitrate reductase. Content of slowdegradation organic matter (proteins, polysaccharides) in liquidus changed. Ultrosonicdisintegration could shorten the reaction time of WAS anaerobic hydrolysis andincrease the rate of reaction. This paper studied the changes of enzyme activities andorganic matter dissolution under the different ultrasonic energy density and frequency.The impact of the hydrolysis acidification rate and the kinetics model was analyzedand created.The test results showed that ultrasonic energy promote the enzyme activity withina certain range. With an ultrosonic energy density of0.48kW/L, the enzyme activitywas showing a rising trend. Under the0.96kW/L and1.44kW/L, enzyme activitytrend showed a rising trend and then decreased. When it was1.92kW/L, enzymeactivity decreased with the increasing of disintegration time. Intracellular enzymesand extracellular enzyme showed a maximum activities in different ultrasonic energydensity. The activity of nitrate reductase was3.23times than the original sludge withthe energy density of0.96kW/L. In the case of protease and α-glucosidase, they were2.79times and3.48times with the energy density of1.44kW/L. The disintegrationconditions with enzyme activities increased were selected. It was found that theconcentrations of proteins and polysaccharides increased with the disintegration time.This was due to the cracking of extracellular polymeric substances (EPS).Disintegration effect with a energy density1.44kW/L was better than0.96kW/L.Temperature was another positive factor.Releasing of protein and the polysaccharide could increase the concentration ofthe substrate in hydrolysis reaction. While the improvement of the enzyme activitiescould effectively accelerate the enzymatic reaction rate. Considering orgicconcentration and enzyme activities,0.96kW/L15min was chosen.0.48kW/L5min asa comparison was the initial disintegration condition. Tests were carried out in normalatmospheric temperature, medium temperature and high temperature, respectively.Preatment could promote hydrolysis acidification rate. The reaction temperature wasanother influencing factor. The increase of temperature would weaken thedisintegration. As the temperature increased,0.48kW/L,5min groupe and the control group were close to the0.96kW/L,15min on the protein and polysaccharideconcentration, the rate of hydrolysis and acid production. Effect of ultrasonic was nolonger obvious while temperature became to be the main factor that determine the rateof hydrolysis and acid production rate. The protein and the polysaccharide hydrolysisrate is slower at room temperature. With the increase of ultrasonic power and time,anaerobic hydrolysis acidification rate increase. Disintegration with0.48kW/L,5minwas not obvious than untreated sludge. Ultrasonic pretreatment promoted acidproduction rate, the control group,0.48kW/L,5min and0.96kW/L,15min acidproduction rate were47.52,51.92and326.13.