A state-of-the-art review of geotechnical challenges and opportunities in recycling and reusing sewage sludge as landfill cover material: A review

Abstract

This paper emphasizes the critical significance of sustainable Sewage Sludge (SS) management and its pivotal role in environmental protection. It also strives to identify shortcomings in established practices that warrant additional investigation and examination. The excessive generation of SS, replete with microorganisms and potentially hazardous inorganic and organic substances, is a formidable challenge closely linked to wastewater and biological treatment plants. Moreover, this paper furnishes an extensive survey of advancements in landfill cover systems incorporating SS, elucidating the underlying principles governing their effectiveness. SS could be a cost-effective alternative to traditional landfill covers with proper engineering and management, addressing waste disposal challenges and promoting environmental benefits. However, a comprehensive assessment of geotechnical properties and site conditions is essential to ensure the long-term effectiveness and safety of the landfill cover system. The literature reveals that specific parameters, such as hydraulic conductivity, UCS, and toxic substance leaching, are paramount in designing the cover layer. Nevertheless, some factors, including freezing-thawing, wetting-drying, and long-term behavior, have not received adequate research, suggesting potential future research avenues. In addition, potential environmental risks, such as the leaching of hazardous constituents into groundwater and resultant soil contamination, can be mitigated by integrating engineered barriers, continuous monitoring systems, and adaptive management practices to safeguard ecological integrity.