Landfill Leachate Treatment

The escalating loads of municipal solid waste (MSW) end up in open dumps and landfills, producing continuous flows of landfill leachate. Landfill leachate is created by liquid that drains or leaches from the landfill, and it is also generated as a result of percolating excess rainwater through the waste layers of a landfill. Landfill leachate is a highly polluted liquid which contains large amounts of dissolved organic matter (DOM), salts, inorganic ions, heavy metal ions, and other organic compounds (e.g., chlorinated aliphatics, and pesticides), presenting potential threats to the surrounding environment, ecosystems and human ^[1]. Therefore, it is imperative to develop effective treatment technologies for landfill leachate. Alfa Chemistry has been deeply engaged in environmental governance for many years, and has rich experience and strong ability in landfill leachate treatment. We will provide a landfill leachate treatment technology specifically designed for you.

Fig. 1. Conceptual model for landfill leachate generation.

Landfill Leachate Composition

Constituents in landfill leachate can be broadly categorized into four major groups: dissolved organic matter (DOM), inorganic components, heavy metals and xenobiotic organic components (XOCs).

• Dissolved organic matter: DOM is the fraction of organic matter which can be passed through a 0.45 µm filtration membrane in a wide range of molecular weights and sizes, including amino acids, VFA, hydrophilic acids, fulvic-like and humic-like compounds, which is a major component in landfill leachate.
• Inorganic components: Inorganic compounds generally show higher concentrations in landfill leachate. NH_4⁺, NO_3^-, NO_2^-, SO_4^2-, Cl^-, PO_4^3-, sodium (Na⁺), potassium (K⁺), calcium (Ca²⁺), magnesium (Mg²⁺), iron (Fe²⁺) and hydrogen carbonate (HCO_3^-) are among the most predominant inorganic compounds.
• Heavy metals: Typical heavy metals present in landfill leachate include Zn, Ni, Pb, Cu, Cr, and Cd metals and metalloids such as As, Se, Hg and Co, present only in very low concentrations.
• Xenobiotic organic components: XOCs are presented in low concentrations and examples for XOCs are benzene, toluene, phenols, chlorinated aliphatics, phthalates and halogenated hydrocarbons (tetrachloroethylene and trichloroethylene).

Fig. 2. Short-term and long-term hazardous impacts of landfill leachate components.

Our Service

Alfa Chemistry can provide landfill leachate characterization service and customized solutions service of landfill leachate treatment.

1. Landfill leachate characterization methods

The composition and parameter characterization of landfill leachate will directly reflect the characteristics of leachate water quality and the difference between different leachate water quality, which is the key and basis of the subsequent process treatment. Alfa Chemistry takes a variety of advanced characterization methods for the comprehensive characterization of landfill leachate, which lays a good foundation for your landfill leachate treatment. Some of our characterization methods are listed below.

• Basic measurement: Alfa Chemistry can provide the characterization methods for COD, BOD, BOD/COD ratio, TOC, pH, suspended solids, NH_4⁺-N, total Kjeldahl nitrogen and heavy metal concentrations. These parameters are the basic parameters of landfill leachate.
• Molecular weight associated techniques: The distribution of molecular weight is a key parameter reflecting the compositions of leachate DOM. The characterization methods include membrane filtration with different molecular weight cutoffs and size exclusion chromatography (SEC).
• Structural analytical approaches: Structural analysis can provide a wealth of information about the composition and structural formulae of landfill leachate. The characterization methods include elemental analysis, fourier transform ion cyclotron resonance mass spectrometry coupled with electrospray ionization (ESI-FT-ICR-MS), nuclear magnetic resonance spectroscopy (NMR) (¹H-NMR, ¹³C-NMR, ¹⁵N-NMR) and etc.
• Spectroscopic approaches: Spectroscopic techniques can rapidly identify the chemical composition and relative content of substances in leachate samples. The characterization methods include UV-Vis absorption spectroscopy, fluorescence spectroscopy, fourier transform infrared (FTIR) spectroscopy, 2DCOS spectroscopy and etc.

2. Landfill leachate treatment technology

Landfill leachate composition is very complex and the characteristics of landfill leachate exhibit considerable differences due to variations in refuse composition and moisture content, as well as seasonal factors such as temperature and precipitation ^[2]. Therefore, the general treatment of landfill leachate needs to choose different treatment processes according to the actual water quality. The following describes our company's landfill leachate treatment methods and some typical treatment processes.

• Treatment methods: Biological and chemical methods are frequently used by Alfa Chemistry. The details are as follows.

• Typical treatment processes:

①Raw water → leachate storage tank → filtration system → primary reverse osmosis system → secondary reverse osmosis system → degassing tower → clear pool

②Regulating reservoir → collecting tank → anaerobic reactor → catalytic reactor → efficient biochemical pool → desilter → coagulation tank → clarification tank → effluent

③Anaerobic system → MBR → RO

Landfill Leachate Treatment Process

Alfa Chemistry has been committed to solving environmental pollution problems through various means for many years, which can be targeted to solve different types of water pollution. Alfa Chemistry will take into account the pollution degree of waterbody and external environmental factors to choose reasonable treatment technology to fundamentally solve the problem of black-odorous waterbody. We will provide a comprehensive package of solutions, and operational and engineering recommendations. Please feel free to contact us if necessary.

References

• Wijekoon W., et al. Progress and prospects in mitigation of landfill leachate pollution: risk, pollution potential, treatment and challenges[J]. Journal of Hazardous Materials, 2021, 421:126627.
• Teng C., et al. Characterization and treatment of landfill leachate: A review[J]. Water Research, 2021, 203, 117525.