Effects of carbon–nitrogen ratio on nitrogen removal in a sequencing batch reactor enhanced with low-intensity ultrasound

Objectives:The purpose of this study is to increase the denitrification and phosphorus removals by the oxygen control of the anaerobic or anoxic period using the circulation of the supernants through the settled sludge and multi-step addition of raw wastewater during the operation of the internal circulation sequence batch reactor (ICSBR).Methods:The internal circulation pipe at the bottom of SBR is installed to circulate the supernatant into the settled sludge layer to create anoxic condition of non-aeration period instead of a stirrer in a SBR. And it is attempted to develope the SBR that properly uses the organic materials of the raw wastewater as a carbon source by the feeding the raw wastewater at a suitable time of the reaction period.Results and Discussion:Dissolved oxygen (DO) concentration of the reactor decreases more rapidly with an internal circulation to which the uniform pressure division method is applied, increasing the efficiency of about 40%. As the multi-step addition of raw wastewater proceeds, the nitrogen concentration of effluent is lowered and the C/N (Carbon/Nitrogen) ratio is higher, the nitrogen removal rate is higher.Conclusions:Circulating the supernatant to the bottom through settle sludge was effected to properly control the dissolved oxygen in the reaction tank, thereby improving the denitrification efficiency by about 68%. Even the higher the C/N ratio at the step addition can be expected the higher the nitrogen removal, it is noteworthy that the optimum feeding ratio of the multi-step addition may be different depending on the C/N ratio.

Download Full-text

Nitrogen removal, sludge activity and bacterial community in a sequencing batch reactor at different ciprofloxacin and ibuprofen concentrations

Environmental Technology & Innovation ◽

10.1016/j.eti.2021.101814 ◽

2021 ◽

pp. 101814

Author(s):

Shengyu Yuan ◽

Zichao Wang ◽

Yueyue Wang ◽

Huan Yang ◽

Youtao Song ◽

...

Keyword(s):

Bacterial Community ◽

Nitrogen Removal ◽

Sequencing Batch Reactor ◽

Batch Reactor ◽

Sludge Activity

Download Full-text

Evaluation of predominant factor for shortcut biological nitrogen removal in sequencing batch reactor at ambient temperature

Bioprocess and Biosystems Engineering ◽

10.1007/s00449-019-02117-6 ◽

2019 ◽

Vol 42 (7) ◽

pp. 1195-1204

Author(s):

Wookeun Bae ◽

Seungjin Kim ◽

Seongjun Park ◽

Hodon Ryu ◽

Jinwook Chung

Keyword(s):

Ambient Temperature ◽

Nitrogen Removal ◽

Sequencing Batch Reactor ◽

Batch Reactor ◽

Biological Nitrogen Removal ◽

Predominant Factor ◽

Biological Nitrogen

Download Full-text

Excess nitrogen accumulation in activated sludge in sequencing batch reactor with a single-stage oxic process

Water Science & Technology ◽

10.2166/wst.2009.003 ◽

2009 ◽

Vol 59 (3) ◽

pp. 573-582 ◽

Cited By ~ 3

Author(s):

Xiao-ming Li ◽

Dong-bo Wang ◽

Qi Yang ◽

Wei Zheng ◽

Jian-bin Cao ◽

...

Keyword(s):

Activated Sludge ◽

Nitrogen Removal ◽

Sequencing Batch Reactor ◽

Ph Value ◽

Batch Reactor ◽

Nitrogen Loss ◽

Single Stage ◽

Synthetic Wastewater ◽

Nitrogen Accumulation ◽

Excess Nitrogen

It was occasionally found that a significant nitrogen loss in solution under neutral pH value in a sequencing batch reactor with a single-stage oxic process using synthetic wastewater, and then further studies were to verify the phenomenon of nitrogen loss and to investigate the pathway of nitrogen removal. The result showed that good performance of nitrogen removal was obtained in system. 0–7.28 mg L−1 ammonia, 0.08–0.38 mg L−1 nitrite and 0.94–2.12 mg L−1 nitrate were determined in effluent, respectively, when 29.85–35.65 mg L−1 ammonia was feeding as the sole nitrogen source in influent. Furthermore, a substantial nitrogen loss in solution (95% of nitrogen influent) coupled with a little gaseous nitrogen increase in off-gas (7% of nitrogen influent) was determined during a typical aerobic phase. In addition, about 322 mg nitrogen accumulation (84% of nitrogen influent) was detected in activated sludge. Based on nitrogen mass balance calculation, the unaccounted nitrogen fraction and the ratio of nitrogen accumulation in sludge/nitrogen loss in solution were 14.6 mg (3.7% of nitrogen influent) and 0.89, respectively. The facts indicated that the essential pathway of nitrogen loss in solution in this study was excess nitrogen accumulation in activated sludge.

Download Full-text