Search for: All records

Abstract The treatment of landfill leachate and sewage is crucial for mitigating the environmental impacts of dissolved organic nitrogen (DON) effluent in aquatic ecosystems. This study used three sequencing batch reactors (SBRs) to treat sewage mixed with landfill leachates of varying organic carbon content. While the SBRs significantly removed dissolved inorganic nitrogen (DIN), the effluents were enriched with landfill leachate-induced DON. These landfill leachate-induced DON effluents (R1, R2, and R3) were then photodegraded under simulated summer sunlight conditions based on Greensboro, NC, USA weather data. The study utilized visible light (400–780 nm, 9340 μW/cm²), UVA (365 nm, 1442 μW/cm²), UVB (285 nm, 76 μW/cm²), UVC (254 nm, 315 μW/cm²), and dark controls. Effluents were mixed with Neuse River Estuary water, serving as a natural algal source, and exposed for 90 days under these light conditions. Samples were analyzed every 10 days for DON degradation and algal growth, with molecular changes assessed using FTICR-MS, FTIR, and EEM-PARAFAC. Results showed substantial DON degradation across all light treatments, with UVA achieving the highest reduction (up to 99.07%), followed by UVC (88.85%), visible light (86.19%), and UVB (75.11%), while no degradation occurred under dark conditions. Initial DON levels of 2.69–2.7 mg/L were reduced to as low as 0.025 mg/L under UVA in R3 effluent. UVC treatment led to increased NO3-N concentrations due to the oxidation of DON to NH4-N and its subsequent conversion to NO3-N, reaching 2.66, 2.59, and 2.63 mg/L in R1, R2, and R3, respectively. UVC inhibited algal growth, resulting in no NH4-N uptake and subsequent oxidation to stable, elevated NO3-N levels in the samples. Algal growth responses varied by light treatment, with visible light and UVB promoting the highest algae growth, minimal algae growth observed under UVA, and no growth under UVC or dark conditions. These findings demonstrate the evidence of rDON degradation during the long-term retention in the receiving water bodies and potential impact on the algal growth. 

ABSTRACT Landfill leachate management is a critical challenge for the municipal solid waste (MSW) industry due to its significant environmental impact and high operational costs. In the United States, sanitary landfilling remains the primary MSW disposal method, with more than half of generated waste landfilled as of 2022. The U.S. generates between 7.1 and 11.3 billion gallons of landfill leachate annually, with up to one-third of landfill operational costs dedicated to leachate management. Leachate production can persist for decades after landfill closure, necessitating long-term management strategies. Around 61% of landfill leachate is disposed of at publicly owned treatment works (POTWs). These facilities face challenges in treating hazardous leachate components, including high Total Nitrogen levels, UV quenching substances (UVQS), refractory dissolved organic nitrogen (rDON), elevated temperature landfill (ETLF) leachate, micro- and nanoplastics (MP/NP), and per- and polyfluoroalkyl substances (PFAS). This presentation will explore the historical context of landfill leachate management and the challenges of co-treating leachate at POTWs. It will also identify emerging solutions and technologies aimed at improving treatment processes, enhancing environmental protection, and reducing costs. Addressing these challenges is crucial for minimizing the environmental footprint of landfill operations and ensuring compliance with regulatory standards. 

This study evaluated the performance of sequencing batch reactors (SBR) in the fate and transport of dissolved organic nitrogen (DON) using a blend of wastewater and landfill leachate. Most nitrogen removal methods concentrate on inorganic nitrogen, whereas some biological processes add DON to the effluent. Two reactors were introduced with wastewater and landfill leachate of high and low organic carbon and compared them to a reactor without leachate. DON transformation, characterization, and microbial community dispersion were examined to understand the effects of leachate-induced effluent DON on the biological nitrogen removal process. The ammonium removal efficiencies were found 96, 97, and 98%; COD removal efficiencies were 75, 59, and 63%; and total nitrogen (TN) removal efficiencies were 83, 86, and 88%, for R1, R2, and R3, respectively. The effluent nitrate concentrations were found 1.67 ± 0.89 (R1), 3.05 ± 2.08 (R2), and 1.31 ± 1.30 (R3) mg/L and DON went down from 9.67 ± 2.5 to 6.02 ± 2.8 mg/L (R1), 9.29 ± 3.4 to 7.49 ± 3.6 mg/L (R2), and 3.59 ± 1.6 to 2.08 ± 1.1 mg/L (R3). Fourier transform ion cyclotron resonance mass spectrometry (FTICR-MS) and excitation-emission matrices (EEMs) with parallel factor (PARAFAC) analysis were used to characterize DON. Microbial community analysis was also conducted. Leachate-induced DON discharge's environmental effects were assessed using in-situ aquatic ecosystem algal bioassay. SBR system removed most inorganic nitrogen species and a small amount of leachate-induced DON. The study emphasizes the need for independent investigations to assess their effects on receiving water bodies. 

Landfill leachate contains high levels of dissolved organic nitrogen (DON) that can be detrimental to aquatic life and water quality because it promotes the growth of harmful algal blooms (HABs). This study used physicochemical treatment technologies such as Fenton treatment and Granular Activated Carbon (GAC) adsorption to assess the breakdown and removal of landfill leachate-induced DON. The physicochemical treatments were applied to effluents of two bioreactors treating blended wastewater and landfill leachate. Bioreactor-1 (R1) was fed with high organic landfill leachate, and bioreactor-2 (R2) was fed with low organic landfill leachate. For R1 effluent, the Fenton treatment removed 66±9.2% COD and 52.4±8.7% DON at an optimum dosage of 200mg/L H2O2 and 1000mg/L FeSO4.7H2O. On the other hand, GAC removed 94.4±4.9% COD and 85.9±4.6% DON at an optimum dosage of 10g/L GAC. For R2 effluent, the Fenton treatment removed 75.8±6.6% COD and 60.3±3.2% DON at an optimum dosage of 200mg/L H2O2 and 1000mg/L FeSO4.7H2O. On the contrary, GAC treatment removed 92.2±4.3% COD and 92.3±3.7% DON at an optimum dosage of 10g/L GAC. Moreover, fluorescence spectrophotometry combined with parallel factor analysis (PARAFAC) was employed to provide insight into the DON degradation mechanisms. The study found that Fenton treatment and GAC adsorption both can effectively reduce DON in landfill leachate. However, GAC treatment was superior to Fenton treatment in eliminating DON from landfill leachate, while Fenton treatment may convert DON into inorganic nitrogen. The study emphasizes properly handling landfill leachate to avoid nitrogen contamination and harmful algal blooms in aquatic ecosystems.