鸡粪接种污泥联合厌氧发酵过程中的流变特性研究

Rheological Study on Anaerobic Co-digestion of Chicken Manure and Sludges

厌氧发酵是目前禽畜粪便等有机废物处理、同时获取能源的一种重要处理技术。发酵反应器中物料的流动与混合状况直接影响底物的转化效率,物料的流态类型是决定反应进行的重要工程因素。为探讨鸡粪和污泥联合厌氧发酵过程中的流态特征,以鸡粪为底物开展了流变特性的研究。通过测定鸡粪和接种污泥混合液粘度系数,并进行数值模拟,研究厌氧发酵过程中鸡粪和污泥联合底物的流变参数及其在发酵过程中各阶段的变化情况,探讨流变参数与物化参数之间的潜在联系。试验结果表明:含固率是影响鸡粪污泥料液流态的主要因素。在TS=5%~12%范围内,鸡粪料液含固率对于稠度系数的影响符合幂率方程,拟合度大于0.992。温度对鸡粪流变特性影响显著。随着温度的增加,表观黏度、稠度系数随之降低。厌氧发酵过程中,鸡粪混合液的流变特性变化剧烈,水解反应对物料流变特性的影响极为显著。可溶性化学需氧量(SCOD)和总有机碳(TOC)的变化与稠度系数之间符合线性关系,相关系数分别为0.92和0.88。由结果可以看出,水解阶段是鸡粪污泥联合发酵液粘度变化的主要阶段,针对推流式的厌氧反应器,在反应器前端采取加密的搅拌装置,后端搅拌装置逐渐减少,从而使反应器搅拌设计与颗粒态物料厌氧降解的基本规律相适宜,可以在保证物料充分混合的基础上,进一步降低设备运行能耗。

Anaerobic digestion is a very promising technology to treat the organic waste such as livestock and poultry manure which can be used to generate the methan.And rheological characteristics and mixing of the substrate directly influence the reaction.Rheological type is a very important index for anaerobic digestion design.In this paper,the rheological characteristics of chicken manure were studied before and after anaerobic digestion in order to provide foundational information for the design and operation of the anaerobic digestion process.The apparent viscosity was tested and consistency coefficient was calculated based on simulation.The effects of total solid(TS),temperature and the inoculum amount on the rheological characteristics of chicken manure were investigated.Changes of rheological properties during anaerobic fermentation were studied.The dependence between rheological characteristics and physical-chemical parameters was also explored.The results showed as follows:TS is a dominate factor to affect the flow pattern of the chicken manure.When the TS changed from 5%to 12%,the correlation between TS and consistency coefficient could be described by using exponential equation with R2>0.992.Temperature is another important factor.The higher the temperature is,the lower the value of apparent viscosity and consistency coefficient is observed.The inoculum of the sludge could also affect the rheological characteristics of chicken manure.During the tests,the viscosity coefficient increased with the increasing of the inoculum,which is fitted to liner relationship.During the anaerobic fermentation of chicken manure,its rheological characteristics changed dramatically.Hydrolysis reactions had a significant effect on the rheological characteristics of chicken manure.And the changes of the soluble SCOD and TOC appeared to be liner while the viscosity coefficient with R2=0.92 and 0.88,respectively.Thus hydrolysis and acidification are the main phases of substrate rheological change.In order to decrease energy consumption,the mixier could be mainly allocated to hydrolysis process.