Dudnikova Tamara, Wong Ming Hung, Minkina Tatiana, Sushkova Svetlana, Bauer Tatiana, Khroniuk Oleg, Barbashev Andrei, Shuvaev Evgenyi, Nemtseva Anastasiya, Kravchenko Ekaterina
Southern Federal University, Rostov-on-Don, Russian Federation.
Southern Federal University, Rostov-on-Don, Russian Federation; Consortium on Health, Environment, Education, and Research (CHEER), The Education University of Hong Kong, Tai Po, Hong Kong SAR, China.
Environ Res. 2025 Feb 1;266:120444. doi: 10.1016/j.envres.2024.120444. Epub 2024 Nov 29.
Pyrolysis of sewage sludge can significantly reduce industrial waste while producing high-value biochar for soil improvement. This study aimed to evaluate the quality and safety of biochar from sewage sludge under different pyrolysis conditions. Optimal carbonization conditions (700 °C, 60 min, 5 °C/min) were identified by analyzing the physicochemical properties, elemental composition, structural characteristics, and the specific surface area of biochar. Results show that pyrolysis of waste sludge reduces the total content of priority polycyclic aromatic hydrocarbons (PAHs) by 48%, from 6367 ng/g to 3317 ng/g, mainly due to a reduction in low-molecular-weight compounds. The composition of polyarenes in biochars is represented primarily by low-molecular compounds, among which naphthalene and phenanthrene predominate. At the same time, among high-molecular compounds, fluoranthene, pyrene, and chrysene stand out, significantly dominating the overall picture. According to the Incremental Lifetime Cancer Risk model, the carcinogenic risks associated with biochar usage are primarily driven by hazardous compounds such as chrysene, benzo(a)pyrene, and dibenz(a,h)anthracene, evaluated through toxic equivalent concentrations. It was found that with oral or dermal exposure to these pollutants, the likelihood of cancer in children is 1.1-1.4 times higher than in adults. At the same time, with inhalation, this threat increases by 1.5 times for adults compared to children. However, with increased pyrolysis temperature, heating rate, and holding time of sewage sludge, the carcinogenic risks of biochar decrease. Biochar produced under optimal conditions contains PAH levels below toxic threshold standards set by the International Biochar Initiative. The safe application rate for biochar in Haplic Chernozem soils at 0-20 cm depth is up to 26 t/ha.
污水污泥热解可显著减少工业废弃物，同时生产用于土壤改良的高价值生物炭。本研究旨在评估不同热解条件下污水污泥生物炭的质量和安全性。通过分析生物炭的物理化学性质、元素组成、结构特征和比表面积，确定了最佳碳化条件（700℃、60分钟、5℃/分钟）。结果表明，废弃污泥热解使优先多环芳烃（PAHs）的总含量降低了48%，从6367 ng/g降至3317 ng/g，主要是由于低分子量化合物的减少。生物炭中多芳烃的组成主要以低分子化合物为主，其中萘和菲占主导地位。同时，在高分子化合物中，荧蒽、芘和 Chrysene 较为突出，在整体情况中占显著优势。根据增量终身癌症风险模型，通过毒性当量浓度评估，与生物炭使用相关的致癌风险主要由 Chrysene、苯并(a)芘和二苯并(a,h)蒽等有害化合物驱动。研究发现，经口或经皮接触这些污染物时，儿童患癌的可能性比成人高1.1 - 1.4倍。同时，通过吸入接触时，成人面临的这种威胁比儿童增加1.5倍。然而，随着污水污泥热解温度、加热速率和保温时间的增加，生物炭的致癌风险降低。在最佳条件下生产的生物炭所含PAH水平低于国际生物炭倡议组织设定的毒性阈值标准。在0 - 20厘米深度的薄层黑钙土中，生物炭的安全施用量高达26吨/公顷。
