Resolution of conflict of reduced sludge production with EBPR by coupling OSA to A2/O process in a pilot scale SBR

Anwar Khursheed; Faris Mohammad A Munshi; Abdulaziz Ibrahim Almohana; Abdulrhman Fahmi Alali; Mohab Amin Kamal; Shamshad Alam; Omar Alrehaili; Dar Tafazul Islam; Manish Kumar; Sunita Varjani; A A Kazmi; Vinay Kumar Tyagi

doi:10.1016/j.chemosphere.2023.137945

Resolution of conflict of reduced sludge production with EBPR by coupling OSA to A²/O process in a pilot scale SBR

Chemosphere. 2023 Mar:318:137945. doi: 10.1016/j.chemosphere.2023.137945. Epub 2023 Jan 23.

Affiliations

¹ Department of Civil Engineering, College of Engineering, KSU, Riyadh, 11421, Saudi Arabia; Department of Civil Engineering, Z.H. College of Engineering, AMU, Aligarh, India. Electronic address: aahmad4@ksu.edu.sa.
² Department of Civil Engineering, College of Engineering, KSU, Riyadh, 11421, Saudi Arabia.
³ Department of Biochemical Engineering and Biotechnology, Indian Institute of Technology, Delhi, India.
⁴ Discipline of Earth Sciences, Indian Institute of Technology, Gandhinagar, 382355, India; Escuela de Ingeniería y Ciencias, Tecnologico de Monterrey, Campus Monterey, Monterrey, 64849, Nuevo Leon, Mexico.
⁵ Gujarat Pollution Control Board, Gandhinagar, 382 010, Gujarat, India.
⁶ Department of Civil Engineering, Indian Institute of Technology, Roorkee, 247667, India.
⁷ Environmental Hydrology Division, National Institute of Hydrology Roorkee, Roorkee, Uttarakhand, 247667, India. Electronic address: vinayiitrp@gmail.com.

PMID: 36702406
DOI: 10.1016/j.chemosphere.2023.137945

Abstract

The pinnacle of all the efforts of nutrient removal is practically put-down the moment biological cells are lysed, hydrolyzed or digested causing subsequent reappearance of assimilated nitrogen and phosphorus in any biological process. While sludge reduction requires high SRT, the enhanced phosphorus assimilative uptake demands low SRT. A novel reactor configuration for enhanced sludge and phosphorus removal was put to test by incorporating a side stream anaerobic reactor to an Anaerobic-Anoxic-Aerobic (A²O) SBR with a pre-anoxic chamber and an influent receiving inlet anaerobic reactor. The reactor was operated at the average and lowest range of prevailing carbon/phosphorus (C/P) ratio of 50 and 15 in the sewage. The phosphorus enrichment was 0.0469-0.135 mgTP/mgVSS resulting in 1.76-5.05-fold increase from cellular content by virtue of maintaining sludge recycle from SBR aeration tank to side stream anaerobic reactor from 3.78 to 9.78 (average 4.4-8.2) gVSS/gVSS present in the reactor. However, the sludge was also reduced from 3% to 51% on an average basis during the same recirculation regime. This novel configuration consists of an inlet anaerobic reactor, one pre-anoxic chamber and one intermittent oxic anoxic reaction SBR and a side stream anaerobic reactor. The first anaerobic reactor at inlet followed by pre-anoxic chamber was provided for increased ortho-p released and nitrification respectively and a side stream anaerobic reactor for sludge reduction through sludge fasting mechanism. The EBPR and lesser sludge growth were two conflicting parameters reconciled to the extent that if sludge recycled up to 6.41 gVSS/gVSS the sludge growth would be reduced by 25% and phosphorus enrichment could be attained up to 3.46 times the stoichiometric value. Any further recirculation would reduce the sludge further but at the expense of enhanced phosphorus uptake as released phosphorus from side stream anaerobic reactor also recycled back to main SBR causing looping and at more than 6.41gVSSrecycled/gVSS it nullified the enhanced effect.

Keywords: EBPR; Oxic-settling-anaerobic process; SBR; Sludge reduction.

MeSH terms

Bioreactors*
Nitrification
Nitrogen
Phosphorus
Sewage*
Waste Disposal, Fluid

Substances

Sewage
Phosphorus
Nitrogen