Study On Reduction Of Sludge And Wastewater Treatment In MBR By Thermal Hydrolysis

The treatment and disposal of excess sludge have become a difficultproblem in a wastewater treatment plant. In this paper, the thermalhydrolysis was applied to disintergrate the activated sludge in order todiscuss the influence of thermal hydrolysis on the characteristics of theactivated sludge. It was studied the realization possibility of using thethermal hydrolysis disintegration directly in the sequencing batchmembrane bioreactor to reduce sludge as well as treating wastewater. Thetreatment characteristics of thermal hydrolysis simultaneous process werealso studied.The effect of thermal hydrolysis on sludge properties at differenttemperatures and action times was studied by batch test, and the dissolvinglaws of some indexes were analyzed. In order to study the influence degreeof temperature and action time on ΔSCOD which was used to indicate theefficiency of sludge thermal hydrolysis reaction, a mathematical model ofsludge thermal hydrolysis reaction was established and validated. And onthe basis of these analyzes, two laboratory scale sequencing batchmembrane bioreactors (SBMBRs) were operated in parallel for a long period to evaluate the influence of sludge thermal hydrolysis on sludgeyield and permeate quality. The following results were achieved.(1)It was found that thermal treatment could induce biomass death andintracellular product release. The content of soluble organics(SCOD)、TNand TP in the solution increased after thermal treatment.(2)The pH value and sludge activity were declined when thetemperatures and action times increased, and sludge settleability anddewatering performance got worse.(3) With the independent variable of temperature(T) and action time(t),the mathematical model with dependent variable of ΔSCOD is ΔSCOD=y=e-1.932t0.38T1.785. The model showed that the influence sequence wasas following: T>t.(4) It shows the simultaneous thermal hydrolysis could decrease theaverage sludge yield. The increase in the amount of thermo-hydrolyzedsludge would result in a decrease in sludge yield. The results showed thatthe average sludge yield of treatment reactor decreased by32.5%and36.4%compared with comparison system when the amount ofthermo-hydrolyzed sludge was0.8%and1.7%of inflow, respectively.(5)The simultaneous thermal hydrolysis had no significantly effluenceon the removal rate of COD and NH+4-N in SBMBR but it had greateffluence on the removal rate of P which increased the difficulty of Premoval.