Enhanced nitrogen and phosphorus removal in the A²/O process by hydrolysis and acidification of primary sludge

Abstract

Municipal wastewater treatment suffers the general problems of poor denitrification and low phosphorus removal caused by insufficient carbon sources. Thus, a baffled reactor was developed to provide additional carbon by hydrolysis and acidification of the primary sludge in the A²/O process in order to treat low C/N ratio wastewater. The effects on denitrification and phosphorus removal were evaluated. The results showed that C_TN, C_TP, C_COD, and -N in the effluent were concentrated at 17, 0.5, 30, and 1.6 mg/L, respectively, while the removal efficiencies rose to 69.6, 92.5, 88, and 96.7%, respectively, while dosing acidified primary sedimentation sludge. Compared with control groups that did not receive acidification liquid, C_TN, C_TP, and -N of the effluent were decreased by 8.7, 1.3, and 0.7 mg/L, respectively, and the removal efficiencies were correspondingly increased by 15.6, 22.5, and 1.7%, respectively. These data demonstrated that adding acidified primary sludge effectively improved the removal of nitrogen and phosphorus nutrients.

Keywords:

• Primary sludge
• Hydrolysis acidification
• A²/O process
• Denitrification and phosphorus removal

Acknowledgments

This work was financially supported by National Natural Science Foundation of China (51078008), Natural science fund project of Beijing (8122005), Beijing Education Commission funded project (KZ201110005008), Beijing Science and Technology Innovation Platform funded projects (004000546612010), Universities Innovation Programme of Jinan City (201303076), and Ministry of Housing and Urban–Rural Development Technology Projects (2012-K7-8).

Notes

Presented at the Conference on Water Resources and Urbanization Development, 26–27 September 2012, Tianjin, China