Universal Characteristics of Landfill Leachate Generated from Food and Organic Wastes: A Review

The management of municipal solid waste (MSW) containing significant fractions of food and organic matter presents critical challenges, primarily due to the potent and dynamically evolving nature of the resultant landfill leachate. This study addresses the persistent variability observed in leachate composition across diverse geopolitical regions, which often complicates the design and optimization of robust treatment systems, leading to inefficient resource expenditure and environmental non-compliance. Utilizing a comprehensive, comparative meta-analysis of leachate data derived exclusively from anaerobic decomposition phases of high-organic-content landfills globally, this research aimed to delineate the foundational physicochemical parameters that exhibit universal consistency, irrespective of confounding site-specific operational or climatic factors. This methodological approach involved the rigorous standardization and statistical integration of analytical metrics sourced from over fifty operational and closed landfill sites across four continents, focusing specifically on early to intermediate decomposition stages where the high initial organic loading remains the principal driver of chemical composition. The analysis conclusively identified several quantitative and qualitative characteristics intrinsic to high-organic-waste leachate that transcend geographic location or specific waste input details. Notably, a consistently high average BOD/COD ratio (ranging strictly from 0.45 to 0.70) was established as a definitive marker during the early acidogenic and intermediate methanogenic phases, signifying substantial initial biodegradability driven by massive concentrations of short-chain volatile fatty acids (VFAs), primarily acetic and propionic acid. Furthermore, ammonia nitrogen concentrations consistently ranked as the predominant inorganic constituent, often correlating directly with the initial protein input and exhibiting extreme resistance to conventional biological removal due to frequent co-occurrence with inhibitory high salinity levels. These findings collectively underscore the critical need for standardized pre-treatment strategies that specifically target VFA neutralization, recalcitrant ammonia stripping, and management of extremely high organic loading, offering a foundational, universal baseline for engineering design across disparate organic waste disposal scenarios.