深度脱水污泥好氧堆肥中多环芳烃的含量与风险削减研究

多环芳烃(polycyclic aromatic hydrocarbons, PAHs)是影响污泥安全资源化的重要因素.以无机药剂调理的深度脱水污泥有利于污泥的好氧堆肥处置，但对于该处置过程中深度脱水污泥PAHs的降解和风险削减尚缺乏认识.主要以复合铝镁盐调理的深度脱水污泥为对象，分析不同好氧堆肥条件下污泥中PAHs的含量、来源和风险，以明确好氧堆肥工艺过程对风险有机物的削减效果及潜在影响因素.通过气相色谱-质谱仪、特征比值法和风险熵法分析污泥中美国EPA优先控制的16种PAHs的含量、来源和风险，重点考察了深度脱水污泥在好氧堆肥前后PAHs含量和风险变化.结果表明：(1)16种PAHs在6组污泥中均有检出，其总量范围为777.78～1 878.38 ng/g，组成以中高环芳烃为主，主要来源为石油污染和燃烧的混合源.(2)堆肥28 d后6组污泥中PAHs的去除率分别为37.66%、54.29%、12.38%、15.40%、56.78%和34.25%，表明添加颗粒大的返混料或辅料更有利于PAHs的降解.(3)污泥中的PAHs整体处于中低风险，好氧堆肥后除组1的苯并[a]芘和组2的芴由低风...

Content and Risk Reduction of Polycyclic Aromatic Hydrocarbons in Deep Dewatered Sludge Aerobic Composting

Polycyclic aromatic hydrocarbons (PAHs) are important factors affecting the safety of sludge application. Deep dewatered sludge conditioned with inorganic chemicals is beneficial to the disposal of aerobic composting of sludge, but the degradation and risk reduction of PAHs in deep dewatered sludge during its aerobic composting remains unclear. Focusing on the deep dewatered sludge conditioned by aluminum magnesium salt, this study investigated the content, source and risk of PAHs in the sludge during the aerobic composting process under different conditions, to elucidate the risk reduction of organic pollutants and potentially influencing factors. By using gas chromatography-mass spectrometry, characteristic ratio and risk quotient method, the contents, potential sources and risk of 16 PAHs prioritized by the US EPA were analyzed. Especially, the changes of risk of PAHs in deep dewatered sludge before and after aerobic composting were investigated. The results showed that: (1) 16 PAHs were detected in all sludge, their total content ranged from 777.78 to 1878.38 ng/g. The detected PAHs were mainly medium and high cyclic PAHs and were mainly from mixed sources of petroleum pollution and combustion. (2) After 28 days of aerobic composting, the degradation rates of PAHs in 6 groups were 37.66%, 54.29%, 12.38%, 15.40%, 56.78% and 34.25%, respectively. It showed that the addition of back mixing and auxiliary materials with large particle sizes were conducive to the degradation of PAHs. (3) The overall risk of PAHs before composting was medium to low. Except that the risk of BaP in group 1 and Flu in group 2 increased from low level to medium level, the risk of PAHs in all other groups did not change or decreased after aerobic composting. This study proposed that the air permeability was an key impact factor for aerobic composting, and the addition of back mixing and auxiliary materials with large particles could effectively improve the air permeability to promote the degradation efficiency and risk reduction of PAHs during aerobic composting of deep dewatered sludge. Moreover, PAHs in sludge composting and the compost products should be monitored as important indicators to avoid cumulative ecological risks caused by long-term exposure.