Preparation Of Immobilized Mixed Bacteria Carrier And Experimental Study On Organic Wastewater Treatment

The pollution of organic wastewater is harmful to ecological environment and human health.In recent years,immobilized microorganism technology has become a popular method for biological treatment of organic wastewater in various industries,and the development of immobilized carriers with low cost and excellent performance is the core problem in the application of this technology.In this paper,two kinds of agricultural and forestry wastes,pine bark and corn straw,were used as immobilized carriers,and were modified by formaldehyde-sodium alginate method,isopropanol-sodium alginate method and heat treatment-sodium alginate method,respectively.The immobilized carriers were prepared by biofilm.The best bark and straw carrier were selected by Zeta potential,infrared spectrum,biological modulus and pretreatment of organic wastewater.The results showed that the bark and straw carrier had better performance and organic degradation which were modified by formaldehyde-sodium alginate.Then the best carriers were analyzed by optical microscopy,scanning electron microscopy,mass transfer property,mechanical property and water absorption.The results showed that the cut surface structure of bark and straw carriers were all dense polygonal stacking,and there were all kinds of pores and channels.The larger specific surface area,more pores and better biocompatibility were observed after modification.The rate of mass transfer and water absorption were as follows: modified straw > original straw > modified bark > original bark;the mechanical properties were: original bark / straw > modified bark / straw,but the strength of the modified bark and straw was enough to support the experiment.The degradation effect and optimum condition of the best bark / straw carrier treat domestic wastewater,phenol wastewater and carbendazim pesticide wastewater were studied.The experimental results showed that: for the 1400 mg/L domestic wastewater,the large radius straw carrier had the best degradation effect,when the temperature of30 ℃,pH of 7,the dissolved oxygen of 3 mg/L,and the addition ratio of 1:5,the maximum degradation rate was 96.57 % in 96 h;Use the small diameter bark carrier,when the temperature of 30 ℃,pH of 7,the dissolved oxygen of 3 mg/L,and the addition ratio of 1:5,the maximum degradation rate was 95.71 % in 96 h.For the 100 mg/L phenol wastewater,under the same conditions,the best bark and straw carrier can completely degrade phenol in 24 h,and the degradation effect is bark > straw.For the 500 mg/L carbendazim pesticide wastewater,under the same conditions,the maximum degradation rate of straw carrier and bark carrier was 86.87 % and 85.71 % in 96 h,respectively.In this project,the best bark and straw immobilized carriers have the dual function of adsorption flocculation and microbial metabolism degradation with the organics,especially the existence of dominant species such as Proteobacteria,Nitrosomonas,Acinetobacter,Chloroflexi and so on,so that the organics of wastewater are degraded and consumed as carbon and energy,and the nutrients needed by bacteria are provided at the same time,which will open up a way for the treatment of organic wastewater in the future.