城市污泥和浒苔共水热碳化参数响应面优化

Response surface optimization of co-hydrothermal carbonation parameters of municipal sludge and enteromorpha

日益增多的城市污泥对环境造成了严重的危害,传统处理处置方法在实现无害化和资源化方面仍存在各种挑战。水热碳化技术被认为一种有效处理处置城市污泥的方式,但由于污泥的低碳、高灰特性,限制了水热炭作为燃料的应用。利用高碳、低灰的浒苔和污泥进行共水热碳化有利于解决这一问题。开展了不同水热反应条件下(温度160~280℃,时间30~150 min,污泥占比0~100%)污泥和浒苔的共水热碳化实验,探究了过程参数对于能量回收效率和电能消耗指数的影响规律,并利用响应面法对3个主要因素(温度、时间、污泥占比)进行了优化设计。结果表明,利用Central Composite Design设计建立的响应面模型,拟合程度良好(模型P<0.05,相应的失拟项P>0.05),预测值和实际值偏差较小。污泥占比对于能量回收效率有显著影响(P<0.05),时间是对于电能消耗指数影响极其显著的因素(P<0.0001),温度对于电能消耗指数的影响达到显著水平(P<0.05)。通过数学模型的优化,得出了达到最佳能量回收效率(0.470)和最低电能消耗(165.61)的最佳条件,分别是反应温度216℃、反应时间83 min、污泥占比为64%和反应温度200℃、反应时间60 min、污泥占比为50%。此外,在反应温度208℃、反应时间62 min、污泥占比52%的条件下,可以同时获得较高的能量回收效率(0.463)和较小的电能消耗指数(171.60)。通过3次重复实验验证,实验值与预测值偏差小于5%。研究结果可为城市污泥和浒苔的资源化和高值化利用提供科学依据。

The increasing amount of municipal sludge poses a serious threat to the environment.Traditional treatment methods still face various challenges in terms of harmlessness and resource utilization.Hydrothermal carbonization is considered an effective method for treating municipal sludge,but its low carbon and high ash characteristics limit the application of hydrochar as a fuel.To address this issue,the co-hydrothermal carbonization of municipal sludge and enteromorpha(a high-carbon and low-ash waste biomass)is proposed as a potential solution.In this study,co-hydrothermal carbonization experiments of municipal sludge and enteromorpha were conducted under various reaction conditions,including temperatures ranging from 160 to 280℃,residence times ranging from 30 to 150 minutes,and municipal sludge proportions ranging from 0 to 100%.The impacts of these process parameters on energy recovery efficiency(ERE)and electricity consumption index(ECI)were investigated.The response surface method was adopted to optimize the three main factors(temperature,time,and municipal sludge proportion)affecting ERE and ECI.The results indicated that the response surface models established by Central Composite Design exhibited a good fit(model P<0.05,corresponding lack-of-fit P>0.05),with minimal deviation between predicted values and actual values.Municipal sludge proportion had a significant impact on ERE(P<0.05),while time exerted an extremely significant influence on ECI(P<0.0001).Temperature also had a significant impact on ECI(P<0.05).Through mathematical model optimization,the optimal conditions for achieving the highest ERE(0.470)and the lowest ECI(165.61)were determined to be 216℃,83 minutes,and a 64%municipal sludge proportion,respectively.Additionally,a higher ERE(0.463)and lower ECI(171.60)could be obtained simultaneously at 208℃,62 minutes,and a 52%municipal sludge proportion.To validate the results,three repeated experiments were conducted,and the errors between the experimental values and predicted values were found to be less than 5%.The findings of this study provide a scientific basis for the resource utilization and high-value utilization of municipal sludge and enteromorpha.By optimizing the co-hydrothermal carbonization process,it is possible to enhance energy recovery efficiency and reduce electricity consumption,contributing to the sustainable management of municipal sludge and the preservation of the environment.