carbon
carbon
Overview
Carbon is a chemical element and a foundational component of organic and inorganic matter. In biological systems, carbon forms the structural backbone of carbohydrates, lipids, proteins, and nucleic acids, and it also serves as a central currency in microbial metabolism and environmental biogeochemical cycling. Because of this, carbon is not only a material element but also a key determinant of energy flow, biomass formation, and nutrient transformation in living systems.
In applied environmental and biomedical research, carbon is often discussed in relation to carbon sources, carbon allocation, and carbon recovery rather than as a therapeutic target in the pharmaceutical sense. Its availability and partitioning can strongly influence microbial processes such as denitrification, fermentation, and nutrient removal. In the studies summarized here, carbon was examined in the context of wastewater and sludge treatment systems, where its movement through microbial and physicochemical pathways affected nitrogen removal, volatile fatty acid production, and electron distribution during treatment.
Focus of Latest Publications
Recent studies treated carbon as a central process variable in engineered biological treatment systems rather than as a standalone substance. Across the provided publications, the common theme was how carbon was supplied, recovered, or redistributed to support microbial metabolism and improve treatment performance.
In a duckweed-based stabilization tank study, the authors evaluated nitrogen removal with and without aerobic zones and an intermediate feeding strategy. The reported finding was that intermediate feeding did not significantly improve overall nitrogen removal. The interpretation given was that supplemental carbon must be more precisely synchronized with active redox zones and microbial activity. This suggests that carbon addition alone is not sufficient; its timing and spatial delivery relative to microbial electron-accepting conditions are critical for effective denitrification. The mention of Spirodela polyrhiza in the broader methodological context indicates that duckweed-based systems were part of the experimental framework.
A second study focused on integrated sludge resource recovery using sludge residues-based biochar in pilot-scale liquid-state anaerobic fermentation. Here, the goal was to enhance volatile fatty acid (VFA) production and maximize recovery of carbon and nutrient resources from sludge. The reported conclusion was that the hierarchical recovery strategy substantially improved VFA production, indicating that carbon embedded in sludge could be redirected into more valuable soluble products through fermentation. In this context, biochar appears to have been used as part of the resource recovery strategy, likely supporting the fermentation environment and improving the conversion of sludge-derived carbon into VFAs.
The third study examined microbially induced hydroxyapatite in aerobic granular sludge systems and its effect on simultaneous nitrogen and phosphorus removal. The reported result was that mineral accumulation was accompanied by shifts in carbon and electron allocation patterns, with increased electron flux toward denitrification pathways and improved nitrogen removal performance. This indicates that carbon metabolism was closely linked to electron distribution within the granular sludge community, and that changes in mineral accumulation could alter how carbon-derived electrons were routed through microbial pathways. The study also referenced biologically induced phosphorus precipitation, emphasizing the coupling of carbon and electron allocation with nutrient removal processes.
Taken together, these studies show carbon as a functional driver in environmental biotechnology: it influenced nitrogen removal efficiency, supported fermentation-based recovery of sludge resources, and participated in electron allocation during simultaneous nutrient removal. Rather than acting as a direct drug target, carbon was investigated as a metabolic and process-level determinant in engineered microbial systems.
Key Publications
- Jun Nitrogen removal mechanisms in duckweed-based stabilization tanks with and without aerobic zones and intermediate feeding stream. (Journal of environmental management, 2026, PMID 42296756): "Interestingly, the intermediate feeding strategy did not significantly enhance overall nitrogen removal, suggesting that supplemental carbon must be more precisely synchronized with active redox zones and microbial activity."
- Jun Integrated sludge resources hierarchical recovery: enhancing VFAs production through pilot scale liquid-state anaerobic fermentation by sludge residues-based biochar. (Bioresource technology, 2026, PMID 42219128): "Overall, the proposed hierarchical resource recovery strategy substantially improved VFAs production, maximizing the recovery of carbon and nutrient resources from sludge and representing a highly promising novel sludge resource utilization process."
- Jun Microbially induced hydroxyapatite improves simultaneous nitrogen and phosphorus removal in aerobic granular sludge. (Bioresource technology, 2026, PMID 42225155): "Notably, mineral accumulation in both operational modes was accompanied by shifts in carbon and electron allocation patterns, characterized by increased electron flux toward denitrification pathways and concurrent improvement in nitrogen removal performance in the AGS systems."