Effects Of Zn²⁺ On Formation Of Aerobic Granular Sludge And Related Population Control

Aerobic granulation, a novel environmental biotechnological process,was increasinglydrawing interest in the area of wastewater treatment for its favorable settlingability, highbiomass retetion, withstand high strength organic wasterwater, removal of nitrogen,phosphate, and bioremediation of toxic aromatic pollutants. While, the formationmechanism of aerobic granule is unclear,and a long time running will affect the stability ofgranules. According these viewpoints, we focus on the cultivation, growth and stability ofaerobic granules with the augmentation of Zn²⁺, and the ability to remove nitrogen,phosphate, carbon. The reseach results are list in the following:1.The augmentation of Ca²⁺,Mg²⁺,Zn²⁺promote the granulation. The configuration ofgranular sludge and the removal of nitrogen, phosphate, under10mg/L Zn²⁺have a betterability of removing nitrogen, phosphate, carbon.First,the granules with the augmentationof Mg²⁺,Zn²⁺have a about70%removal of Ammonia nitrogen.Then,their removal ofsoluble phosphate have significant differences.Last, the granules with the augmentation ofZn²⁺have a better removal of TOC.2.Adding1to50mg/L Zn²⁺promote the granulation, while adding100mg/L Zn²⁺affect the granulation. We succeed to cultivate granules. When adding50mg/L Zn²⁺, thegranules show a good physical quanity, such as high sludge concentration, bigsedimentation rate, large moisture content.3.The augmentation of Zn²⁺produce more EPS. Under different concentration of Zn²⁺,the TOC content is increasing, while among all, the granules produce the content of TOC ismaximum, when adding10mg/L Zn²⁺, and adding100mg/L Zn²⁺affect the producing ofEPS.4.Cultivated the granular sludge in experiment has ability of removing carbon,nitrogen and phosphate. The augmentation of10mg/L Zn²⁺have a better removal of COD,NH₄⁺-N, PO₄^3--P than other concentration. There are significant differences in differentoperate phase. From1to32days,the removal abilities enhance,then decrease,increaseafterward,between100to120days,they tend to be stable.In mature period,the granules’sremoval of TOC is better than NH₄⁺-N, PO₄^3--P. The augmentation of10mg/L Zn²⁺show astronger ability of removing PO₄^3--P, COD, NH₄⁺-N,respetively are80%,83%and75%.5.The augmentation of Zn²⁺promote the activitives of dehydrogenase.When adding10mg/L Zn²⁺,the dehydrogenase activitives achieve73ug/mL.As the increasing of Zn²⁺concentration, the activity of dehydrogenase is enhancing and ability of removing TOCincreasing, too. When the Zn²⁺concentration continue to increase, the activity of dehydrogenase decrease quickly, and the concentration of TOC is high.In different operatephase, the activitives of dehydrogenase continue to enhance before16hour,it decreasequickly after36hour.