In recent years, biochar has attracted considerable attention due to its unique characteristics and wide applications in agricultural and environmental areas. Biochar is recognized for its potential role in carbon sequestration, reduction of greenhouse gas emissions, soil amendment, bioenergy production and waste mitigation. The current review discusses on the utilization of various lignocellulosic and lignin-based feedstocks for the biochar production. However, the quality of biochar varies among different thermo-conversion technologies due to the differences in their key process parameters and the feedstock composition. This article aims to review two production technologies for lignocellulosic and lignin-based biochar, namely, slow pyrolysis and fast pyrolysis. The effects of feedstock composition (cellulose, hemicellulose, lignin) and pyrolysis conditions such as temperature and heating rate on the quality of biochar are compared. The relationship between the feedstocks composition, temperature, heating rate of pyrolysis and the quality of biochar are also discussed. Future work would further correlate the effects of feedstock composition and process parameters on the quality of biochar such as surface area and functionality.

Microplastics pose a significant environmental threat, with potential implications for toxic chemical release, aquatic life endangerment, and human food chain contamination. In Asia, rapid economic growth coupled with inadequate waste management has escalated plastic pollution in rivers, positioning them as focal points for environmental concern. Despite Asia's rivers being considered the most polluted with plastics globally, scholarly attention to microplastics in the region's freshwater environments is a recent development. This study undertakes a systematic review of 228 scholarly articles to map microplastic hotspots in Asian freshwater systems and synthesize current research trends within the continent. Findings reveal a concentration of research in China and Japan, primarily investigating riverine and surface waters through net-based sampling methods. Polyethylene (PE), polypropylene (PP), and polyethylene terephthalate (PET) emerge as the predominant microplastic types, frequently observed as fibers or fragments. However, the diversity of sampling methodologies and reporting metrics complicates data synthesis, underscoring the need for standardized analytical frameworks to facilitate comparative analysis. This paper delineates the distribution of microplastic hotspots and outlines the prevailing challenges and prospects in microplastic research within Asian freshwater contexts.