Efficient and convenient pretreatment to enhance waste activated sludge anaerobic hydrolysis by iron porphyrin biomimetic enzyme

Abstract

A novel biomimetic enzyme was applied in the pretreatment of waste activated sludge (WAS) for enhancing the hydrolysis properties. An iron porphyrin complex was efficiently synthesized and purified. In comparison with the blank test, iron porphyrin complex used as biomimetic enzyme could significantly improve the sludge disintegration. Hydrogen peroxide was not the main influencing factor. During the pretreatment process, concentrations of the ammonia nitrogen (NH4 +-N) and reducing sugar (RS) both almost increased, which indicated that the protein and polysaccharide in sludge were effectively decomposed. Results demonstrated that the optimum treatment time and temperature of this biomimetic enzyme was at 7 hours and 40 °C, respectively. The efficient and economical dosage of the biomimetic enzyme used in treatment sludge digestion was 1%. Under the optimal treatment condition, the SCOD/TCOD ratio, the rate of VSS reduction, the concentrations of NH4 +-N and RS reached the values of 65.3%, 38.4%, 215.9 mg/L and 65.9 mg/L, respectively. And the possible mechanism of iron porphyrin biomimetic enzyme to promote anaerobic hydrolysis of WAS had been proposed. Therefore, the application of biomimetic enzyme was a desirable method in the WAS pretreatment.