Development of a Novel Hydrodynamic Sequencing Batch Reactor for Landfill Leachate Treatment by Shortcut Biological Nitrogen Removal

Abstract

This study introduced an alternative shortcut biological nitrogen removal (SBNR) process for landfill leachate treatment by developing a novel hydrodynamic sequencing batch reactor (H-SBR). The reactor could enhance the oxygen transfer rate (OTR) and nitrite accumulation ratio (NAR) by modifying internal hydrodynamic turbulence intensity. The average chemical oxygen demand (COD) and total nitrogen (TN) concentrations introduced into the reactor were 660 and 250 mg L−1, respectively, and the average removal efficiencies were 93% (COD) and 96% (TN). The effect of geometric parameters on oxygen transfer was estimated by performing a hydrodynamic model and a nonlinear least square analysis. After correcting the constants (α and β) of mass transfer coefficients (KLa) to values of 0.7361 and 1.2639, the model data fit the experiment well with an R-squared value of 0.99. The OTR improved by up to 30%, and hence, increased the NAR by up to 20% with a reduction of about 0.5 kg N kW−1 for power efficiency. The H-SBR development is innovative because the oxygen transfer efficiency was improved by the hydrodynamic modification of internal turbulence intensity, although not by mechanical equipment or chemical supplements. For the SBNR process, the modification of the reactor configuration for OTR enhancement could significantly improve nitrogen removal efficiency with successful nitrite accumulation. In addition to landfill leachate treatment, the H-SBR process can be employed in the treatment of low C/N ratio wastewaters.

Pretreatment of Landfill Leachate Using Hydrodynamic Cavitation at Basic pH Condition

“…The conventional physical and chemical treatment methods for LL, such as coagulation/flocculation [12], adsorption [13,14], membrane processes (microfiltration, nanofiltration, ultrafiltration, and reverse osmosis) [15,16], can only transfer pollutants from one medium to another and are unable to mineralize pollutants. In the pretreatment process, advanced oxidation processes (AOPs), including O 3 [17], Fenton, and Fenton-like processes [18,19], supercritical water oxidation (SCWO) [20], and electrochemical oxidation processes [21], etc., would modify the structures of pollutants, produce by-products which are biodegradable and less toxic, and enable subsequent biological treatments to be carried out more effectively.…”