Wang Lin, Liu Jiayi, Li Huan
Tsinghua Shenzhen International Graduate School, Tsinghua University, Shenzhen, 518055, China.
Tsinghua Shenzhen International Graduate School, Tsinghua University, Shenzhen, 518055, China.
Environ Pollut. 2023 Oct 15;335:122348. doi: 10.1016/j.envpol.2023.122348. Epub 2023 Aug 8.
Microplastics (MPs) generated from daily life are commonly collected by urban sewage pipe networks and then transfer to sludge in wastewater treatment plants. Conventional biochemical treatment processes cannot degrade MPs effectively, causing an ecological risk via sludge land use. Wet air oxidation (WAO) is a promising sludge treatment technology with a strong ability to decompose complex organic matter, but its potential for the removal of MPs in sludge was unclear. In this study, three common MPs (polyethylene, polystyrene, and polyethylene terephthalate, which are called PEMPs, PSMPs, and PETMPs) were added into the sludge samples (1 g MP in 180 mL sludge), to test the effects of WAO on sludge and MPs. The results showed that WAO simultaneously degraded sludge and the PEMPs, and the two degradation processes were relatively independent when oxygen was supplied adequately. The dissolution of PSMPs and organic matter in sludge was not affected by each other, but the degradation rate was slowed down due to the interaction of ketones and benzene compounds. The hydrolysis of sludge and PETMPs was accelerated, while the hydrolyzed products such as terephthalic acid were oxidized without interfering with each other. No obvious MPs remained in the effluent, and volatile fatty acids (VFAs) were the main components, among which acetic acid accounted for 90%. When the sludge was treated with PEMPs, PSMPs, or PETMPs, the concentration of acetic acid finally accounted for 45%, 21%, and 18% of DOC. Overall, MPs can be degraded or even mineralized during sludge WAO, and humic acid derivatives, acetate, and other small molecules of alcohols, ketones, or aldehydes were the typical intermediates.
日常生活产生的微塑料通常由城市污水管网收集，然后转移到污水处理厂的污泥中。传统的生化处理工艺无法有效降解微塑料，通过污泥土地利用会带来生态风险。湿式空气氧化（WAO）是一种很有前景的污泥处理技术，具有很强的分解复杂有机物的能力，但其去除污泥中微塑料的潜力尚不清楚。在本研究中，将三种常见的微塑料（聚乙烯、聚苯乙烯和聚对苯二甲酸乙二酯，分别称为PEMPs、PSMPs和PETMPs）添加到污泥样品中（180 mL污泥中加入1 g微塑料），以测试WAO对污泥和微塑料的影响。结果表明，WAO同时降解污泥和PEMPs，在氧气供应充足时，这两个降解过程相对独立。PSMPs与污泥中有机物的溶解互不影响，但由于酮类和苯类化合物的相互作用，降解速率减慢。污泥和PETMPs的水解加速，而水解产物如对苯二甲酸被氧化且互不干扰。出水无明显微塑料残留，挥发性脂肪酸（VFAs）是主要成分，其中乙酸占90%。当污泥用PEMPs、PSMPs或PETMPs处理时，乙酸浓度最终分别占DOC的45%、21%和18%。总体而言，微塑料在污泥WAO过程中可被降解甚至矿化，腐殖酸衍生物、乙酸以及其他醇类、酮类或醛类小分子是典型的中间产物。
