碱解预处理改善污泥与煤共成浆特性的研究

王睿坤 刘建忠 胡友瑞 周俊虎 岑可法

摘 要：将污水污泥与煤粉掺混制备成浆体燃料是一种经济有效的污泥资源化方法。由于污泥中含有丰富的胞外聚合物和极强的持水性能，由其制备的污泥水煤浆往往具有很高的粘度，不利于工业应用。该文研究了CaO对污泥有机物、持水性能、絮体结构等的影响，以及CaO改性污泥与煤共成浆性能。研究发现，CaO有促进污泥絮体有机物破解的作用。上清液中分子量大于5000 Da （Mn>5000 Da）的有机物含量下降，而Mn<5000 Da的含量升高。污泥颗粒的可溶性化学需氧量SCOD增加，挥发分含量VSSC降低。原污泥SCOD为16.2 mg O2/g DS，VSSC为58.19%。当加入20 wt.%CaO处理24 h后，SCOD增加至153.6 mg O2/g DS，VSSC降为45.61%。CaO对污泥有机物的水解作用和改性作用降低了污泥的持水性能，原污泥具有较强的持水性能，饱和持水率SMC为84.71%，当加入20%的CaO处理24 h后，SMC降为79.10%。这都是有利于成浆的。与原污泥水煤浆相比，改性污泥水煤浆具有较低的特征粘度。原污泥水煤浆的特征粘度为1 635.3 mPa·s，当加入20%的CaO调理24 h后，特征粘度降为1 082.2 mPa·s。

关键词：污泥处理 污泥碱解 成浆性能 胞外有机物 浆体燃料

Abstract：Municipal wastewater sludge （denoted as sludge hereafter） can be economically and effectively utilized by mixing it with coal to prepare slurry fuels.However，the abundant extracellular polymeric substances （EPSs） and strong water-holding capacity of raw sludge causes the viscosity of slurry fuel to increase remarkably， which is disadvantageous for industrial applications.The slurrying properties of sludge can be improved by alkaline hydrolysis. This study examined the effects of calcium oxide （CaO） on EPSs，water-holding capacity，floc structure of sludge， and co-slurrying properties of sludge with coal.Results showed that after CaO modification，the relative amount of EPSs with a number-average molecular weight（Mn） >5000 Da noticeably decreased， whereas the relative amount of EPSs with Mn< 5000 Da increased. Moreover， the soluble chemical oxygen demand （SCOD） of sludge increased， and its volatile suspended solid （VSS） content decreased. Raw sludge had an SCOD of 16.2 mg O2/g dry sludge （DS） and VSS of 58.19%. After treatment with 0.2 g CaO/g DS for 24 h，SCOD increased to 153.6 mg O2/g DS，VSS decreased to 45.61%，the water-holding capacity of the sludge decreased，and the saturated water content of raw sludge decreased from 84.71% to 79.10%.The characteristic viscosity ηc of raw sludge–coal slurry was 1 635.3 mPa·s， which decreased to 1 082.2 mPa·s after treatment with 0.2 g CaO/g DS for 24 h.These findings strongly suggested that sludge solubilization can help improve slurrying.

Key Words：Municipal Wastewater Sludge；Alkaline Hydrolysis；Slurrying；Extracellular Polymeric Substances （EPS）；Slurry Fuels

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