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

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.