The BioChemical Clogging of Landfill Leachate Collection System: Based on Laboratory Studies.

Yili Liu,Jianguo Liu

doi:10.3390/ijerph17072299

Abstract

Leachate collection system (LCS) clogging is a common operational problem in municipal solid waste (MSW) landfills in China, which can result in high leachate levels that threaten the safety of landfill operations and subsequently increase the leachate leakage risk. In our previous research, a filtration test was conducted and the physical clogging effect was evaluated. To fully analyze the LCS failure, in this study, a set of column experiments were carried out to investigate the biochemical clogging development and mechanisms. Results showed that the biofilm and deposited CaCO3 composed the primary clogging materials. During the experimental period, the hydraulic conductivities in simulated gravel and nonwoven geotextile drainage layers were observed (91.7% and five orders of magnitude reduction), and decreased to 10−4 and 10−8 m s−1, respectively. Therefore, the significance of the geotextile layer in LCS designing needs to be reconsidered. The biochemical clogging was positively correlated with volatile fatty acids (VFAs), and Ca2+ loading and the Ca2+ played the dominant role. Meanwhile, an improved method for analyzing biochemical clogging development was proposed.

Highlights

In 2018, 1.2 billion tons of municipal solid waste (MSW) was disposed in 663 landfill sites in China.To ensure operational safety and minimize leachate leakage, the leachate collection system (LCS) was designed and installed at the bottom of the modern sanitary landfills
The biochemical clogging was positively correlated with volatile fatty acids (VFAs), and Ca2+ loading and the Ca2+
The pH value was measured measured by a Fe20 pH electrode (Mettle, Switzerland); the total organic carbon (TOC) and TIC were by a Fe20 pH electrode (Mettle, Switzerland); the total organic carbon (TOC) and TIC were tested tested using a TOC-VCPH instrument (Shimadzu, Japan); ; the VFAs were obtained by gas using a TOC-VCPH instrument (Shimadzu, Japan); the VFAs were obtained by gas chromatography chromatography (GC, Shimadzu, Japan) with flame ionization detectors, and the Ca2+ and Mg2+

Summary

Introduction

In 2018, 1.2 billion tons of municipal solid waste (MSW) was disposed in 663 landfill sites in China. To ensure operational safety and minimize leachate leakage, the leachate collection system (LCS) was designed and installed at the bottom of the modern sanitary landfills. A field test showed that the LCS hydraulic conductivity was as low as 10−8 m s−1 at the Laohukeng sanitary landfill in Shenzhen city [1]. The leachate level ranged from several to dozens meters in MSW landfills and had caused several landslides events in China [2,3]. The saturated waste could block landfill gas (LFG) transport channels and prevent the directional diffusing to the gas collection system [4,5]

Methods

Results

Conclusion