Study On Purification Of Aquaculture Wastewater By Immobilized Algae-bacteria

Aquaculture Wastewater broke aquaculture and the surrounding natural water bodies,as well as natural ecosystems and human health were threatened.Study on the treatment of aquaculture wastewater is hot topics for aquatic biology research experts and professors.In this thesis,the investigation on purification of aquaculture wastewater by immobilized algae-bacteria was carried out.Purchase and cultivation of Chlorella pyrenoidosa Chick and Photosynthetic Bacteria?PSB?,immobilization of algae-bacteria the characteristics and behavior of immobilized algae-bacteria were studied respectively.The results were expected to supply useful references for nitrogen and phosphorus biological treatment methods,the waters of the ecological restoration and algae-bacteria synergy.The main research conclusions are reported as follows:1. Chlorella pyrenoidosa are cultivated and determined of growth analysis.It has strong fouling resistance and removal capacity,at the same time the stationary phase about 10 days.Photosynthetic Bacteria?PSB?are cultivated and determined of growth analysis.It is easy culture and grows well.2.Sodium alignate is the carrier material of Chlorella pyrenoidosa Chick and PSB.It is reference index removal rate of PO₄^3--P,NH⁺₄-N and NO₂^--N.The conditions of its immobilization were studied by orthogonal experiments.The results showed that the optimum conditions for the immobilization were as follows:sodium alignate concentration 2%,calcium chloride concentration 6%,cross-linked time 24 h.The comparative study which different volume of Chlorella pyrenoidosa Chick and PSB purify PO₄^3--P,NH⁺₄-N and NO₂^--N of wastewater find optimum algae/bacteria volume 2:1.Under the condition of the above,The radius of immobilized algae-bacterium balls is about 2 mm,its'density is about 1 g cm^-3.3.Analysis of TN,TP removal test which immobilized algae-bacterium balls and algae-bacterium's free are in aquaculture wastewater showed that the purification capacity of immobilized will be better.4.Influence on algae and bacterium growth and nitrogen and phosphorus removal under various conditions of temperature and illumination was investigated.The results showed that algae and bacterium were capable of removing nitrogen and phosphorus under different temperature or illumination coditions.Under different temperature coditions,the optimizing conditions in term of removal efficiency was initial p H value at 7.0,intensity of illumination at about3000Lx,light from the darkness than for 12:12,culture time at 8 d,with the removal rate of PO₄^3--P and NH⁺₄-N by immobilized algae-bacterium balls being 84%and 95%.Under different illumination coditions,the optimizing conditions in term of removal efficiency was initial p H value at 7.0,intensity of illumination at about3000Lx,culture temperature at 25±1?,culture time at 8 d,with the removal rate of PO₄^3--P and NH⁺₄-N by immobilized algae-bacterium balls being 88%and 90%.5.Different dosage of immobilized algae-bacterium balls were added to the aquaculture wastewater.The effects of different dosage on water quality index(p H,DO,COD,PO₄^3--P,NH⁺₄-N and NO₂^--N)were studied.The results showed that,The optimal immobilized algae-bacterium balls dosage were 160-200 granule per litre.6.The relationship of Chlorella pyrenoidosa Chick and PSB which were immobilized was studied.The results showed that,microalgae and bacterium had synergistic effect.