Elia Nabil1, Fikry Ghobrial2, and Mahmoud Roushdi3
1Environment and Climate changes Research Institute, National Water Research Center, Egypt, (ORCID: 0000-0001-6998-0260) 2Faculty of Engineering, Ain Shams University, Cairo 11517, Egypt 3Environment and Climate change Research Institute, National Water Research Center, Egypt, (ORCID: 0000-0003-2018-0224)
Received: November 10, 2022 Accepted: February 14, 2023 Publication Date: May 2, 2023
Copyright The Author(s). This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are cited.
The presence of nutrients in surface water can result in environmental problems that negatively impact ecosystems. This research aimed to purify nitrogen from municipal wastewater using cascade technology. A pilot plant for an activated sludge system was established using a two-step cascade with step feeding, incorporating both oxic and anoxic regions in each step. The reactor had a total volume of 111 liters and an operating condition of a 35% ratio between anoxic and oxic zone volumes. The experiment utilized synthetic wastewater, with a total influent flow rate of 6.4 l/h discharged to the reactor through the first and second anoxic zones with different flow rates. Results showed nitrogen and organic matter removal efficiencies of 93% for Total Kjeldahl Nitrogen (TKN), 97% for Biological Oxygen Demand (BOD), and 96% for Chemical Oxygen Demand (COD) through the nitrification/denitrification process. The highest removal efficiency was achieved when the influent flow rate was distributed 75%: 25% between the first and second anoxic zones. This study found that two-step cascades were effective in removing carbon and nitrogen from municipal wastewater, and this technology can be used in wastewater treatment plants by dividing the activated sludge reactor into three parts with a 75:25 Q1: Q2 ratio and a 35% Vanoxic/Voxic ratio.
Keywords: Municipal wastewater treatment, two-step cascade, carbon and nitrogen removal.
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