Landfill leachate treatment with a novel process: Anaerobic ammonium oxidation (Anammox) combined with soil infiltration system

Abstract

A novel combined process was proposed to treat municipal landfill leachate with high concentrations of ammonium and organics. This process consisted of a partial nitritation reactor (PNR), an anaerobic ammonium oxidation (Anammox) reactor (AR) and two underground soil infiltration systems (USIS-1 and USIS-2). Based on the optimum operating conditions obtained from batch tests of individual unit, the combined process was continuously operated on a bench scale for 166 days. Partial nitritation was performed in a fixed bio-film reactor (PNR, working volume = 12 L). Ammonium nitrogen-loading rate (Nv) and DO were combined to monitor partial nitritation, and at T = 30 ± 1• C, Nv = 0.27-1.2 kg/(m 3 ·d), The test results indicated that the combined system could work stably over a long period under the operating conditions, and that the process was feasible for the leachate treatment. AR should be the key to the performance of the combined process.

Decomposition and mineralization of aquatic humic substances (AHS) in treating landfill leachate using the Anammox process

“…Therefore, the strongly weakened absorbances at 1616 and 1637 cm À1 were weighty evidences to confirm that the contents of color-producing groups such as aromatic and ketonic were reduced remarkably in the AR (Stevenson, 1982;Smidt and Meissl, 2007), in consistent with the decolorizing results. Additionally, the changes of inorganic functional groups such as the reduced absorbances at 1370 and 3238 cm À1 indicated the reduced condensation degrees of nitrite and ammonium in the effluent, respectively (Stevenson, 1982), further proving the occurrence of the autotrophic nitrogen removal (Liang and Liu, 2008). Moreover, the disappearing vibration at 617 cm À1 could reveal the complete reduction of sulfate (Smidt and Meissl, 2007), combined with the detected H 2 S in the exhaust gas from the AR (data not shown here).…”

“…Recent studies have noticed the absence of SRB in the microbial communities responsible for sulfate reduction (Rajasekar et al, 2005). In this study, it should be impossible for SRB to live in the habitats with high ORP (generally more than +100 mV), caused by the high strength nitrite in the influent (Liang and Liu, 2008). Therefore, it might be other heterotrophic organisms to reduce sulfate with suitable organic compounds as electron donors in the same way as SRB.…”

“…Detailed characteristics of the raw leachate and operative scheme of AR could be seen in the previous report (Liang and Liu, 2008). During the 166 d continuous running, raw leachate with high-concentrations of NH þ 4 -N (1430-2720 mg L À1 ) and chemical oxygen demand (COD) (1170-2600 mg L À1 ) was firstly fed to the PNR for the removal of VFA and acquirement of mixture with proper nitrite/ammonium ratio.…”

“…In our study, the landfill leachate, from a 6 yr old municipal solid waste sanitation landfill site in Beijing of China, is continuously treated to acquire the removal of ammonium (NH þ 4 ) and DOM by a combined process, consisting of a partial nitritation reactor (PNR), an anaerobic ammonium oxidation (Anammox) reactor (AR) and underground soil infiltration systems (USIS) (Liang and Liu, 2008). AR mainly functions as an inorganic nitrogen remover with autotrophic Anammox microorganisms, and however, parts of AHS and dissolved organic carbon (DOC) are removed simultaneously in the reactor.…”

“…AR mainly functions as an inorganic nitrogen remover with autotrophic Anammox microorganisms, and however, parts of AHS and dissolved organic carbon (DOC) are removed simultaneously in the reactor. Steady-state removal during a long period (166 d) and total nitrogen analyses have excluded the possibilities of microorganism adsorption and heterotrophic denitrification (Liang and Liu, 2008). In this work, we conducted a number of analyses of these refractory organics using carbon (AHS and DOC) analyses, gel permeation chromatogram (GPC), UV/Vis spectroscopy, infrared spectroscopy, and isolation of microorganisms, making it possible to study the conversion and chemical characterization of AHS and to investigate the reasons for the AHS removal from the leachate in the AR.…”