Leachate treatment using sequential microwave and algal photo-bioreactor: Effect of pretreatment on reactor performance and biomass productivity

Development and challenges of emerging biological technologies for algal-bacterial symbiosis systems: A review

The algal-bacterial symbiosis system (ABSS) is considered as a sustainable wastewater treatment process. This review provides a comprehensive overview of the mechanisms of ABSS for the removal of common pollutant, heavy metals, and especially for emerging pollutants. For the macroscopical level, this review not only describes in detail the reactor types, influencing factors, and the development of the algal-bacterial process, but also innovatively proposes an emerging process that combines an ABSS with other processes, which enhances the efficiency of removing difficult-to-biodegrade pollutants. Further for the microscopic level, interactions between algae and bacteria, including nutrient exchange, signaling transmission and gene transfer, have been deeply discussed the symbiotic relationship with nutrient removal and biomass production. Finally, recommendations are given for the future development of the ABSS. This review comprehensively examines ABSS principles, development, algal-bacterial interactions, and application in wastewater treatment, aiming to deepen theoretical and practical understanding and advance ABSS technology.

Technological solutions to landfill management: Towards recovery of biomethane and carbon neutrality

Inadequate landfill management poses risks to the environment and human health, necessitating action. Poorly designed and operated landfills release harmful gases, contaminate water, and deplete resources. Aligning landfill management with the Sustainable Development Goals (SDGs) reveals its crucial role in achieving various targets. Urgent transformation of landfill practices is necessary to address challenges like climate change, carbon neutrality, food security, and resource recovery. The scientific community recognizes landfill management's impact on climate change, evidenced by in over 191 published articles (1998-2023). This article presents emerging solutions for sustainable landfill management, including physico-chemical, oxidation, and biological treatments. Each technology is evaluated for practical applications. The article emphasizes landfill management's global significance in pursuing carbon neutrality, prioritizing resource recovery over end-of-pipe treatments. It is important to note that minimizing water, chemical, and energy inputs in nutrient recovery is crucial for achieving carbon neutrality by 2050. Water reuse, energy recovery, and material selection during manufacturing are vital. The potential of water technologies for recovering macro-nutrients from landfill leachate is explored, considering feasibility factors. Integrated waste management approaches, such as recycling and composting, reduce waste and minimize environmental impact. It is conclusively evident that the water technologies not only facilitate the purification of leachate but also enable the recovery of valuable substances such as ammonium, heavy metals, nutrients, and salts. This recovery process holds economic benefits, while the conversion of CH4 and hydrogen into bioenergy and power generation through microbial fuel cells further enhances its potential. Future research should focus on sustainable and cost-effective treatment technologies for landfill leachate. Improving landfill management can mitigate the adverse environmental and health effects of inadequate waste disposal.

Critical review with science mapping on the latest pre-treatment technologies of landfill leachate

The most frequent strategy for solid waste management, adopted across the globe is landfill. Through microbial decomposition municipal solid waste degrades, producing end products such as carbon dioxide, methane, volatile organic compounds, and leachate. High levels of organic waste and heavy metals content in leachate can cause pervasive damage to the ecosystem and contaminate groundwater. Leachate requires extensive treatment before being released into the environment because of its complex chemical composition and identifying the appropriate technologies for leachate treatment remains a key problem for municipal landfill operations. Given the possible harm caused by substantially contaminated leachate, it should adhere to stricter quality criteria for direct disposal of leachate and one treatment method cannot efficiently tackle all the pollutants. In order to reduce the landfill leachates high fouling power, pre-treatment of landfill leachate is necessary. The study provides a comprehensive review of pre-treatment technologies, as well as a critical assessment of strengths and limitations. Current review-based analysis was undertaken based on the filtered 395 papers published for science mapping and to evaluate the qualitative studies in the area of pre-treatment of Landfill Leachate till 2022. A three-step process was employed to conduct bibliometric analysis, qualitative valuation, and identification of influential and productive journals, countries, researchers and articles, emerging technology, and outlining some of the major research gaps in the research field.