Key Takeaways & Executive Findings
- •• • Optimized laboratory-scale activated carbon achieved a particle strength of 91.3% and specific surface area of 571.44 m2·g−1, with iodine adsorption value of 526 mg·g−1, phenol adsorption value of 125.6 mg·g−1, and CTC adsorption rate of 34.1%, indicating high mechanical robustness and adsorption capacity suitable for industrial applications. • • Engineering-scale production line (5 t/day) yielded activated carbon with a strength of 94.3% and specific surface area of 471.42 m2·g−1, confirming that the optimized process is scalable and maintains product quality under continuous operation. • • Process yields were 47.5% for biochar after carbonization and 45.3% for activated carbon after activation, translating to a daily output of approximately 1.18 t of activated carbon from 5 t of feedstock, demonstrating efficient conversion. • • Production cost was 3,595.65 CNY per ton of activated carbon, with energy consumption and equipment depreciation being the largest cost components; further cost reduction is possible through energy management optimization and scale expansion, indicating economic viability.
Abstract
The production of activated carbon from waste biomass such as cyanobacteria from Lake Taihu represents a promising resource utilization route. However, existing studies are mostly confined to laboratory scale, and the gap between laboratory processes and industrial production hinders the evaluation of technical feasibility and economic viability. This study optimized the process for producing cyanobacteria-based columnar activated carbon by co-processing cyanobacteria with garden waste (sawdust), and validated the process on an engineering-scale production line with a daily capacity of 5 t of raw materials. Economic feasibility was also assessed. Results showed that the optimized activated carbon exhibited a particle strength of 91.3% and a specific surface area of 571.44 m2·g−1. The engineering-scale line processed 5 t of raw materials daily, yielding approximately 1.18 t of activated carbon with stable quality: strength of 94.3% and specific surface area of 471.42 m2·g−1, featuring a microporous-dominant structure with coexisting micropores and mesopores. Cost analysis indicated a production cost of 3,595.65 CNY per ton of activated carbon, demonstrating favorable economic benefits. This work provides a basis for larger-scale production and application of cyanobacteria-based activated carbon.
1. Introduction
The frequent outbreak of cyanobacterial blooms in Lake Taihu poses severe threats to aquatic ecosystems and human health. Mechanical salvage of cyanobacteria has been a primary control measure, generating approximately 9.2×10^6 t (99% moisture) of cyanobacteria from 2013 to 2020 in the Wuxi area alone. Conventional disposal methods such as incineration and composting suffer from high energy consumption, low resource efficiency, and limited product marketability. Converting cyanobacteria into high-value activated carbon has emerged as a promising resource utilization strategy, but existing research has been confined to laboratory scales, leaving a critical gap in validating process feasibility and economic performance under industrial conditions.
This study addresses this bottleneck by optimizing the co-processing of cyanobacteria with sawdust—a garden waste—to produce columnar activated carbon. The co-feed mitigates seasonal fluctuations in cyanobacteria availability and improves the adsorption performance and mechanical strength of the final product. The optimized process was scaled up to a 5 t/day engineering line, and the resulting activated carbon was characterized for its physical and adsorption properties. A cost analysis was performed to evaluate economic viability. The findings provide essential data for the industrial deployment of cyanobacteria-based activated carbon production, offering a dual solution for waste management and value-added product generation.
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WU Jing, HUANG Dongxu, WU Nan, PU Tian, ZHU Ge, ZHENG Jinxing, ZHENG Zhiyong, LIU He (2026). Preparation and Engineering Scale-Up of Cyanobacteria-Based Columnar Activated Carbon. Chinese Journal of Environmental Engineering. https://doi.org/10.12030/j.cjee.202506031
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Frequently Asked Questions
What is the mechanical strength and specific surface area of the activated carbon produced on the engineering scale, and how do these compare to laboratory-scale products?
The engineering-scale activated carbon exhibited a strength of 94.3% and a specific surface area of 471.42 m2·g−1, compared to laboratory-scale values of 91.3% and 571.44 m2·g−1, respectively. The slight decrease in surface area is likely due to scale-up effects, but the strength improved, indicating robust mechanical integrity suitable for industrial applications.
What are the yields of biochar and activated carbon in the engineering-scale process, and what is the daily output?
The biochar yield after carbonization was 47.5%, and the activated carbon yield after activation was 45.3%. With a daily feedstock of 5 t, the production line yielded approximately 1.18 t of activated carbon per day.
What is the production cost per ton of activated carbon, and what are the major cost components?
The production cost was 3,595.65 CNY per ton of activated carbon. Energy consumption and equipment depreciation were the largest cost components, together accounting for a significant portion. Optimization of energy use and further scale-up could reduce costs.
How does the adsorption performance of the engineering-scale activated carbon compare to commercial activated carbons?
The engineering-scale activated carbon had an iodine adsorption value of 526 mg·g−1 (laboratory) and a specific surface area of 471.42 m2·g−1 (engineering). While commercial activated carbons often have higher surface areas (e.g., >800 m2/g), the cyanobacteria-based product offers a cost-effective alternative with adequate performance for many applications, particularly given its low production cost.
What are the key process parameters for the engineering-scale production, and how were they optimized?
Key parameters include carbonization temperature (400°C), activation temperature (800°C), water flow rate (200 kg/h), and residence times controlled by rotary kiln speeds (1.2 rpm for carbonization, 1.6 rpm for activation). These were optimized via single-factor experiments on laboratory scale, then validated on the engineering line.
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