Evaluation Of Microalgae Isolated From Landfill Leachate For Ammonia Nitrogen Removal Efficiency

At present the problem of landfill leachate treatment in China is very serious,the landfill leachate as a kind of wastewater whose treatment is difficult,in the case of improper disposal will seriously affect the surrounding water,air and soil environment.The paper based on landfill surrounding environment for the sampling points,obtaining local algal strains through separation and purification,and obtaining dominant algal strains after screening,exploring the nitrogen and phosphorus ratio on the influence of ammonia nitrogen treatment in landfill leachate with dominant algal strains and algal strain in FACHB-Collections as experiment materials,as well as investigating the effect of ammonia nitrogen treatment in landfill leachate under different nutrient model and nitrogen abundance conversion.The following conclusions were mainly drawn:Study on separation,screening and identification of dominate algal strains in landfill leachate: The 57 dominate algal strains obtained from in the collected water samples after enrichment activation and separation and purification were numbered: NCU1-NCU57,which was observed the morphology under the optical microscope,mainly were Chlorella and Chlamydia.From the results of the anti-fouling performance test and the screening of dominate algal strains could be seen that not all the algal strains obtained from the water samples had the anti-fouling properties.It was determined that the 12 strains of microalgae were tolerant to leachate,and then the NCU9,NCU12 and NCU39 had strong anti-fouling properties by the fine screening process based on biomass.The results of the identification of the dominant species showed that these species are all Chlorella sp..Study on the effect of microalgae on the removal of ammonia nitrogen in landfill leachate: The growth of four microalgae in landfill leachate was good.The growth of four microalgae in the unsterilized leachate was better than that in BG11 medium,and Chlorella 2714 in the l later period was gradually slowed down and the biomass was lower than the biomass in BG11.In the sterilizing leachate,Chlorella 2714 showed a similar growth with local screening.algal strains.In the unsterilized landfill leachate,the treatment effect of the local algae NCU9 on ammonia nitrogen was significantly better than that of Chlorella 2714,the theory removal efficiency are 36.41% and 29.75% respectively,but it was not obvious in the unsterilized leachate the theory removal efficiency are 44.91% and 43.41% respectively.When the ratio of nitrogen and phosphorus was 30:1,the growth of NCU9 was best,and the effect of NCU9 for ammonia nitrogen removal was significantly better than the original leachate than under the ration,removal rate is 1.35 times of the original,ratio of nitrogen and phosphorus was below or beyond 30:1,the ability of microalgae for ammonia nitrogen removal in leachate would decreased,but all were better than the original landfill leachate.Study of ammonia nitrogen removal in landfill leachate using nutrient model and nitrogen abundance transformation showed that the biomass of NCU9 in different nutrition modes was from large to small,which was in order of the mixotrophic,heterotrophic and autotrophic.When NCU9 was converted from nitrogen-enriched to nitrogen starvation,the growth was limited.The growth results of NCU9 from sufficient nitrogen mixotrophic and deficient nitrogen heterotrophic converted to landfill leachate showed no stagnation in the deficient nitrogen group and the sufficient nitrogen group.The ammonia nitrogen removal effect of deficient nitrogen group was much better than sufficient nitrogen group,and the advantage was most obvious in the earlier stage,the removal rate in the latter period slowed down slightly,but the ammonia nitrogen removal efficiency was superior to sufficient nitrogen group in the whole process,for removal rate,compared with sufficient nitrogen,average daily ammonia nitrogen treatment capacity in deficient nitrogen groups was 1 mg/L/d higher,up to 9.6 mg/L/d.Group deficient nitrogen heterotrophic theory removal rate of ammonia nitrogen in landfill leachate is as high as 68.22%,compared with the spake in fourth chapter 58.51% increased by nearly 10%,compared with the sufficient nitrogen heterotrophic group of 59.33% also have great advantages,deficient nitrogen heterotrophic group's overall ammonia nitrogen removal rate as high as 91%.