Removal of nitrogen and organic matter in a submerged-membrane bioreactor operating in a condition of simultaneous nitrification and denitrification

Abstract

This study evaluated the removal of nitrogen and organic matter in a membrane bioreactor system operating in a condition of simultaneous nitrification and denitrification controlled by intermittent aeration. A submerged-membrane system in a bioreactor was used in a pilot scale to treat domestic wastewater. The dissolved oxygen concentration was maintained between 0.5 and 0.8 mg L-1. The concentration of the mixed liquor suspended solids (MLSS) in the system ranged from 1 to 6 g L-1. The system efficiency was evaluated by the removal efficiency of organic matter, quantified by Chemical Oxygen Demand (COD), Biochemical Oxygen Demand (BOD5) and Total Organic Carbon (TOC). Nitrogen removal was assessed by quantifying Total Kjeldahl Nitrogen (TKN) and ammonia nitrogen. During the system start-up, the removal efficiencies of COD and NTK were around 90% and 80%, respectively. After the simultaneous nitrification and denitrification (SND) conditions were established, the removal efficiencies of COD and NTK were 70% and 99%, respectively. These results showed that sewage treatment with the membrane bioreactor (MBR) system, operating with simultaneous nitrification and denitrification conditions, was able to remove organic matter and promote nitrification and denitrification in a single reactor, producing a high-quality permeate.

Membrane bioreactor for mall wastewater treatment

“…The concentration of phosphorus in the raw sewage was 25.3 mg L -1 ± 17.6 mg L -1 and the permeate 12.85 ± 8.12 mg L -1 (removal of 49.22%). This removal is higher than the result of Barbosa et al (2016), which obtained an efficiency of 33% for phosphorus. In addition, Rodríguez-Hernández et al (2014) showed a removal in a range of 37% and 42% of phosphorus, for municipal wastewater treated by an MBR, and the removal was attributed to the nutritional need of the microorganisms, disregarding the removal by the phosphorus-accumulating organisms (OAPs) due to the low organic load applied and the high age of the sludge.…”

“…The removal of nitrogen remained in the range of 80% to 90% for nearly the entire period of MBR operation, but this value can oscillate over a wide range. For example, Barbosa et al (2016) performed experiments under constant aeration and a sludge age of 3 days, and a removal efficiency of 81% was achieved. Capodici et al (2015) observed removal of nitrogen similar to our work (55% to 76%).…”

“…C) Anoxic cycle: Belli et al (2014) reported the removal of ammonia of 99% and total nitrogen of 82% when an MBR was operated in a sequential batch. Barbosa et al (2016) established nitrification and simultaneous denitrification (NDS) conditions, removing both COD and total nitrogen in a single reactor. However, we kept the age of the sludge at 30 days and the dissolved oxygen above 2 mg L -1 .…”

“…They are flexible and compact systems that require little area for installation, and they have been applied on a large scale worldwide and have been constantly optimized and adapted to new configurations that seek to improve their performance (Huang and Lee, 2015). Membrane bioreactors can be easily adapted to different operating cycles, with the incorporation of anaerobic / anoxic periods, which can operate with high efficiency in the removal of organic matter and nutrients with simultaneous nitrification and denitrification conditions (Barbosa et al, 2016;Belli et al, 2014;Capodici et al, 2015).…”