Effect of Mechanical Aeration on Nitrogen and Microbial Activity in Sediment-Water Interface from Urban Lake

Abstract

Aeration was one of the common techniques which were focused in environmental engineering research. In this study, experiments were carried out to investigate the effect of aeration on nitrogen (N) fractions and its transformation in the sediment-water interface from urban lake. In addition, we measured the dehydrogenase (DHA) and Chla content in surface sediment to detect the changes of the microbial activity. The aim is to explore the regulation of N migration and transformation in the water-sediment interface during the treatment work of lake pollution. By mechanical aeration, we control the DO content of the overlying water at the range of 1.2-1.5 kg/L, 2.5-4.5 mg/L and 6.1-6.2 mg/L. Results showed that DO in overlying water play a role to the variation of N in water-sediment interface. NH4+-N was the mainly N fraction released from sediment, the lower DO concentration (1.2-1.5 mg/L) in overlying water is favorable to the release of NH4+-N from sediment. Whether under aerobic or anaerobic condition, the releasing of NH4+-N from sediment were both higher than its consumption in the overlying water. The benthic microbial activity of the surface sediment (0-2 cm) was higher than that from bottom (6-8 cm). And the microbial activity in surface sediment was in optimum range when the overlying water DO content was about 2.5-4.5 mg/L.

Nutrient Dynamics and Ecosystem Metabolism of Megacity Rivers: Influence of Elevated Nutrient Concentrations in Beijing’s Waterways

“…The uptake and/or regeneration of nutrients by sediments depend on a variety of influencing factors, making river ecological protection more challenging. Nitrate (NO 3 − ) and ammonium (NH 4 + ) are the main forms of nitrogen in sediments [31,32], and their fluxes are primarily controlled by equilibrium concentration at the sediment-water interface and nitrogen form transformation within the N-cycle [29,33,34], including nitrification, denitrification, dissimilatory nitrate reduction to ammonium (DNRA), mineralization and anammox. These processes are mainly performed by microorganisms such as nitrifying bacteria and denitrifying bacteria, which are affected by a range of factors including water temperature, dissolved oxygen (DO) and associated microbial activity [35,36].…”

Nutrient Dynamics at the Sediment-Water Interface: Influence of Wastewater Effluents

“…Nitrogen in sediments can be measured in terms of total nitrogen (TN), and NH 4 + and NO 3 − are the greatest components of TN (Chen and Tang 2005). For NO 3 − and NH 4 + , fluxes are primarily controlled by concentration changes and nitrogen form transformation within the N-cycle (Chen et al 2012). These processes includes denitrification, nitrification, dissimilatory nitrate reduction to ammonium (DNRA), mineralization, and biological nitrogen fixation, which are mainly performed by microorganisms such as nitrifying bacteria, denitrifying bacteria, and mineralized bacteria associated with the decomposition of organic matter (Fear 2003;Mulholland et al 2008;Meghdadi 2018).…”