Reaction under the action of alkyl polyglycosides alone

2022-09-30 09:17:56

Under the action of alkyl polyglycosides alone, the concentration of polysaccharide dissolved from the sludge increased sharply 2 hours before the reaction, the increase of polysaccharide content slowed down gradually 2 to 4 hours, the concentration of polysaccharide gradually decreased 4 to 24 hours later, and the concentration of polysaccharide in the sludge gradually became stable. However, the change of polysaccharide concentration with time under the combined action is slightly different from that under the action of alkyl polyglycosides alone. Under the combined action, the polysaccharide concentration in the sludge increased sharply in the first 2 hours, and then decreased rapidly until the reaction reached a stable state 24 hours later. The reason why the hydrolysis promotion time of the combined action system is shortened may be that the combined action can quickly promote the polysaccharide substances in the sludge to dissolve in the liquid phase in a very short time, so that they can reach a higher concentration, and promote the hydrolysis utilization rate to rapidly increase to be greater than the cracking rate. The dissolved polysaccharide is reused by microorganisms to the solid phase or decomposed into SCFAs, CO2 and other volatile substances and flows into the gas phase, This led to the rapid reduction of polysaccharide concentration under the combined action.

When the dosage of alkyl polyglycosides is 0.3 g/gDS, the concentration of polysaccharides acting jointly at each time point in the whole reaction process is greater than the sum of the concentration of polysaccharides acting solely by lysozyme and alkyl polyglycosides. The effect is particularly obvious within 6 hours before the reaction. At 2h, the maximum difference of polysaccharide concentration was 1032.02 mg/L. Subsequently, the difference of polysaccharide concentration gradually decreased with the extension of reaction time. At the end of the reaction (72h), the polysaccharide concentration in the sludge under the action of lysozyme alone was 33.15 mg/L, and the polysaccharide content in the sludge under the action of alkyl polyglycosides alone was 247.60 mg/L. The polysaccharide concentration in the sludge under the combined action of lysozyme alone and alkyl polyglycosides was 45.04 mg/L greater than the sum of the polysaccharide concentrations under the action of lysozyme alone and alkyl polyglycosides alone. This shows that the combined action plays a great role in promoting sludge hydrolysis at the initial stage of the reaction. With the extension of the reaction time, the role of lysozyme gradually decreases, and the promotion effect of the combined action also decreases. When the reaction is in a stable period, the combined action has no obvious effect on sludge hydrolysis.

The reduction effect of lysozyme alone on excess sludge is small. After 72h treatment, the reduction rate of excess sludge is only 5.92%. The addition of alkyl polyglycosides can greatly promote the reduction effect of lysozyme treated sludge, and the reduction effect gradually increases with the increase of alkyl polyglycosides. When the dosage of alkyl polyglycoside was 0.05, 0.1, 0.2, 0.3 and 0.4 g/gDS, the reduction rate of excess sludge increased by 134.97%, 153.89%, 176.01%, 201.35% and 218.24% respectively. In addition, it can also be seen from Figure 3-7 that the sludge reduction effect under the action of alkyl polyglycosides alone also increases with the increase of alkyl polyglycosides dosage, and when the alkyl polyglycosides dosage is greater than 0.3 g/gDS, the growth rate of the reduction rate slows down. Compared with the combined effect, the dosage of lysozyme improved the sludge reduction effect of APG treatment. When the dosage of alkyl polyglycosides is 0.05, 0.1, 0.2, 0. and 0.4 g/gDS, the sludge reduction rate under the combined action is 32.86%, 15.44%, 16.88%, 19.65% and 20.00% higher than that under the action of alkyl polyglycosides alone. At each concentration gradient, the sludge reduction rate of the combined action is less than the sum of the reduction rates of the single action.