Abstract
ABSTRACTThe increasing threat to human health and aquatic life caused by nitrogen pollution in surface waters requires critical attention. The membrane-aerated biofilm reactor (MABR) is a promising alternative compared to conventional technologies. In this work, a pilot-scale MABR system was employed to treat polluted surface water in continuous-flow mode. The nitrogen removal performances with the variations of the aeration parameters, hydraulic loading and C/N ratio were explored. The results showed that intra-membrane pressure plays a dominant role in improving the denitrification rate. The nitrification dynamics of the MABR system were favoured in conditions of low influent C/N ratios and hydraulic loading, but limit the denitrification process due to insufficient carbon source. A counter optimal hydraulic loading of 0.016 m3/(m2 day) (hydraulic retention time of 36 h), and a corresponding increase in the influent C/N ratio was beneficial for nitrogen removal. When the influent C/N ratio was raised to a factor of 8, the total organic carbon (TOC), ammonium and total nitrogen (TN) removal efficiency could reach 80.0%, 92.2% and 60.3%, respectively. This indicated that the MABR has a potential to remove TN by simultaneous nitrification and denitrification (SND) in polluted surface water treatment.
Highlights
Surface water is considered to be one of the most severely polluted water sources around the world [1,2]
The synthetic surface water was continuously supplied at a carbon/nitrogen ratio (C/N) ratio of 8 and HRT of 16 h during the initial phase operation
The effects of aeration parameters including intra-membrane air flow velocity and intra-membrane air pressure, hydraulic loading and C/N ratio on nitrogen removal were investigated at experimental phases
Summary
Surface water is considered to be one of the most severely polluted water sources around the world [1,2]. Increasing discharge of unregulated sewage and municipal wastewater, industrial wastewater and over-usage of agricultural fertilizers and pesticides are major sources responsible for surface water nitrogen contamination [3]. These nitrogenous pollutants (ammonia, nitrite and nitrate) in water bodies can cause eutrophication, which is responsible for the deterioration of water quality and the alteration of the ecological structure in freshwater, and pose great potential hazards to human and animal health [4]. Bioreactor techniques are a matured technology widely used in wastewater treatment and have great potential in surface-water nitrogen removal [10,12]. Promotion of practical and cost-effective treatment technologies is urgent for surface water total nitrogen (TN) removal and water quality protection
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