| Anaerobic technology plays an important role in the treatment of high concentration and refractory organic wastewater.The anaerobic sludge granulation is the key to the efficient and stable operation of the anaerobic reactor,but the anaerobic sludge granulation is slow,and the resources of mature anaerobic granular sludge are rare resulting a high price.With its large-scale application,it is of great practical and theoretical value to study the economical and effective technology of cultivating anaerobic granular sludge.Based on using granular dewatered sludge as final seed sludge,this paper mainly studied influences of the kind of intial seed sludge and the agentia addition before the seed sludge dewatering on stability and activity of the granules in the process of cultivating anaerobic granular sludge.In addition,the degrading ability of the cultivated granular sludge was tested by pharmaceutical wastewater.It should be noted that in this paper,anaerobic granular sludge was not formed from flocculent sludge including the flocculent sludge from the broken granular dewatered sludge,but directly transformed from the granular dewatered sludge.The effects of seed sludge characteristics on cultivating anaerobic granular sludge were studied at first.In the three kinds of seed sludge,the protein(PN)/ polysaccharide(PS)ratio of the extracellular polymer(EPS)was in the order of anaerobic sludge> aerobic sludge>concentrated sludge,and there had better stability under higher PN/PS value.The granules activity was in the order of anaerobic sludge>concentrated sludge>aerobic sludge,especially the granules contained anaerobic sludge having much better performance on COD removal rate,biogas yield and CH4 content.While the activity tended to be same after 27 cultivation,which proved the possibility of using aerobic sludge to cultivate anaerobic granular sludge.Secondly,the effects of adding different substances before sludge dewatering on the cultivation of anaerobic granular sludge were studied.About the improvement of stability,without the 30 min drying under 35?,inorganic coagulants and PAM with high iondegree(50%)can significantly improve the stability of granules,and the enhancement of polyaluminum chloride(PAC)was better than polyferric sulfate(PFS)and poly aluminium ferrous chloride(PAFC).While with the 30 min drying under 35?,PAC had no effect,but the PAM can make significant improvement with higher molecular weight instead of higher iondegree.About the activity,zero-valent iron(Fe0)can improve COD removal rate,CH4 content and secretion of EPS,although the granules stability was not improved by single addition of Fe0,it made a significant improvement by adding Fe0 and PAC together,which also better than single addition of PAC.The addition of carbon sources can improve the activity of granules,but the loss amount of granules increased accordingly.With the additive amount of 100mgCOD/gMLSS and 200mgCOD/gMLSS,sodium acetate make bad effect on stability,while starch can improve the stability with 100mgCOD/gMLSS and had more loss of granules than sodium acetate with 200mgCOD/gMLSS.When cultivating anaerobic granular sludge with granular dewatered sludge,the EPS inside the granules undergone a process of descending and increasing which helped to build porous structure.The hydraulic shear force can not be too low during the cultivation,and the activity and stability of granules obtained at 150 r / min are not as good as 165 r / min.And when the amount of granules was too much in anaerobic reactor,there will be more loss of granules.In addition,the storability of cultivated granular sludge was good,it still had well activity and stability after a storage about 90 d. |
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