Research on accelerating excess sludge hydrolysis by adding lysozyme and removing nitrogen and phosphorous in sludge hydrolysis liquid

The experiment adopted a coupled way combining enzyme and alkali to enhanced sludge hydrolysis. Effects of lysozyme dosage and enzyme-catalyzed reaction time on sludge hydrolysis were carried out. Results showed that lysozyme effectively promoted cell lysis , enhanced sludge hydrolysis and dissolved out cell intracellular organic substance. While the optimal dosages of lysozyme (by TS) were 120mg/g, the dissolve organic substance reached maximum quantity under enzyme-catalyzed reaction time 72 hours. The dissolve quantity of SCOD, amylose, albumen and VFAs were 10461.321mg/L, 352.278 mg/L, 1650.275 mg/L and 1455.136mg/L with 120mg/g lysozyme added, increasing 222%, 222%, 215% and 348% accordingly compared with control group with no lysozyme added. The way coupled struvite precipitation process with air stripping could remove PO₄^3- and NH₄^--N in sludge hydrolysis liquid, which provided good way for utilization low nitrogen and phosphorus concentration sludge hydrolysis liquid. The maximum removal rate of PO₄^3- and NH₄^--N reached 75.6% and 97.5%.