Comparative assessment of different scenarios for upgrading activated sludge wastewater treatment plants in developing countries

Hamdy Awad; Mohamed Mossad; Hani Mahanna; Moharram Foad; Mohamed Gar Alalm

doi:10.1016/j.scitotenv.2023.168022

Comparative assessment of different scenarios for upgrading activated sludge wastewater treatment plants in developing countries

Sci Total Environ. 2024 Jan 10:907:168022. doi: 10.1016/j.scitotenv.2023.168022. Epub 2023 Oct 28.

Authors

Hamdy Awad¹, Mohamed Mossad², Hani Mahanna², Moharram Foad², Mohamed Gar Alalm³

Affiliations

¹ Public Works Engineering Department, Faculty of Engineering, Mansoura University, Mansoura 35516, Egypt; Civil Engineering Dept., Delta University for Science and Technology, International Coastal Road, Gamasa City, Egypt.
² Public Works Engineering Department, Faculty of Engineering, Mansoura University, Mansoura 35516, Egypt.
³ Public Works Engineering Department, Faculty of Engineering, Mansoura University, Mansoura 35516, Egypt. Electronic address: m_gar_alalm@mans.edu.eg.

PMID: 37898189
DOI: 10.1016/j.scitotenv.2023.168022

Abstract

Improvement of current wastewater treatment plants (WWTPs) to accommodate the growing influent flow rate and cope with the increasingly stringent regulations is hindered by the allowed space and the difficulty of changing the design parameters. Mathematical modeling is a useful tool for assessing the performance of WWTPs in light of broadening objectives. We herein explore the utilization of mathematical modeling to improve effluent quality in conventional activated sludge systems. BioWin was used to model Mansoura WWTP, one of the largest WWTPs in Egypt. Lab records, design reports, and additional analyses were conducted through site visits and a comprehensive sampling campaign. The wastewater was characterized, and the plant-wide model was calibrated following the protocol of the Dutch Foundation for Applied Water Research STOWA. Important kinetic and stoichiometric parameters were identified and adjusted during the calibration process. The model validity was assessed using different validation periods considering average relative deviation (ARD) values below 20 % as acceptable. The optimized nitrification and denitrification processes involved 16 scenarios with different operational conditions. By changing some zones in the aeration basin from aerobic to anoxic and increasing the return activated sludge, the average ammonia and nitrate concentrations were significantly reduced from 23.06 and 0.5 mg/L to 4.64 and 0.07 mg/L respectively. Furthermore, phosphorus removal optimization was carried out through biological and chemical processes. Chemical phosphorus removal was 85.76 % by using a coagulant dosage of 25 mg/L, resulting in an effluent concentration of 1.04 mg P/L. Biological phosphorus removal was increased to 85.43 % by modifying the volume of anaerobic and aerobic zones with lower power consumption. Overall, this study demonstrates the effectiveness of mathematical modeling in enhancing effluent quality and reducing energy consumption to meet stringent wastewater treatment regulations.

Keywords: BioWin; Optimization; WWTP modeling; Wastewater treatment.

MeSH terms

Bioreactors
Developing Countries
Nitrogen / analysis
Phosphorus
Sewage* / analysis
Waste Disposal, Fluid / methods
Wastewater
Water Purification*

Substances

Sewage
Nitrogen
Wastewater
Phosphorus