Study On The Treatment Of Swine Wastewater And Coupled To Cultivate Energy Chlo Ella

Cultivating energy microalgae for biodiesel with pig-breeding wastewater can not only reduce the production cost of biodiesel and ease energy shortage,but also fulfill the purpose of wastewater purification by making use of N and P from the wastewater.This paper aims at exploring the growth adaptability of algal and the possibility of taking pig-breeding wastewater as the culture medium of algae,then sorting out the algae species with advantageous growth and great oil-producing potential in local water environment.It conduct further researches on the optimization of coupled process system which is of high efficiency of pig biogas slurry treatment.The specific research is as follows:Employing factor analysis of SPSS software,the researcher conducted a comprehensive evaluation of the growth adaptability of local algae?Chlorella?and nonlocal algae?Scenedesmue quadricauda,Microcystis?in pig-breeding wastewater,and the possibility of wastewater in different treatment process as culture medium for algae,as well as different algae's adaptability to surrounding temperature changes.The results showe that,first,COD?4500mg/L?,NH₃-N?250mg/L?,TN?210²70mg/L?and TP?36mg/L?in the original pig-breeding wastewater for experimental use were favorable for algae growth.Second,with high cell reproduction rate,vigorous growth conditions and good adaptability,the local algae used in the experiment,Chlorella,was considered as an advantageous species.The research employed some liquid for experimental use from local water environment,then observed and identified 6 kinds of algae including Chlorella.With further separation,purification and enlarged culture,mixture of different algae species and a single algae species were cultured in pig biogas slurry in the Erlenmeyer flasks.Then,biomass observation was conducted.Employing Slogistic2of origin8.5,non-linear simulation of different algae species were completed,and the results showed that the?_max and B_f of Chlorella reached the maximum among the 6kinds of algae in both mixture and single condition.This indicates that Chlorella had good growth adaptability,fast growth rate,and great growth potential,thus led to advantageous growth.The results of comparative analysis of contents level of algal oil and oil-producing potential of the 6 kinds of algae indicates that Chlorella owned the highest oil content p%,total lipid yield and oil-producing rate among the 6 kinds of algae which means Chlorella had the greatest oil-producing potential.With the comparison of water quality index of biogas slurry collected from the flasks cultured the 6 kinds algae,it was found that the biogas slurry from the Chlorella culture flask had the lowest concentration of COD,NH₃-N,and TP,and the highest removal rate.Thus,Chlorella was considered as the target algal species with advantageous growth and high oil-producing ability,meanwhile it was the most adaptable to pig-breeding wastewater.The separated and purified Chlorellaceae sp.strains IS117 and IS118were carried out 18S rRNA genes sequences.The two sequences were uploaded to the gene database?GenBank?of the National Center for Biotechnology Information?NCBI?where two GenBank accession numbers KP201572 and KP201573 for their nucleotide sequences were given respectively.The neighbor-joining?NJ?method and the Maximum Parsimony?MP?method were used to construct phylogenetic trees.Above all,the sorted-out Chlorellaceae sp strains IS117 and IS118 can be identified as Eukaryota,Viridiplantae,Chlorophyta,Trebouxiophyceae,Chlorellales,Chlorellaceae,Chlorella.The research designed and made a coupled process for pig biogas slurry treatment based on Chlorella culturing,then observed,compared and analyzed different process systems'ability in treating biogas slurry,as well as the growth and oil-producing potential of different algae species.The results indicates that,judging from treatment result,the BCO-SBBR-APBR system for co-culture algal and fungi owned the highest removal rate in CODcr,NH₃-N,and TP,which is 74.8%,91%,85.4%and meant the best treatment effect.Judging from the performance index of algae in stationary phase,algae in the BCO-SBBR-APBR process grew best,moreover,the algae cell density,total lipid yield,and oil-producing rate of it reached highest,which is 15.61×10⁶cells/mL,0.495g·L^-1and 0.062g·L^-1·d^-1respectively.All these indicate that the environment of the BCO-SBBR-APBR process was the best for algal growth and could further promote algae's oil-producing potential.In the BCO-SBBR-APBR system for co-culture algal and fungi,the index about the algae cell density,total lipid yield and oil-producing rate is 11.06×10⁶cells/mL,0.368g·L^-1and 0.037g·L^-1·d^-1 respectively and rank the second.Which meant the system is better for algal growth and could further promote algae's oil-producing potential.Take together,the BCO-SBBR-APBR process system for co-culture algal and fungi was the best coupled process system for culturing algae of energy use in pig biogas slurry.The Chlorella cultured in it grew well and can produce much oil.Furthermore,the system may promote efficient purification and treatment of pig-breeding wastewater.Making use of the mixing effect of aeration produced by CFD with the reaction vessel of BCO-SBBR-APBR in simulation analysis,the simulation diagram of flow field showed that with a vessel of stabilized aeration,the algae and biogas could mix well,and the region of very small flow velocity occupied low percentage.This also indicated that the internal flow field of vessel simulated by CFD could explain and confirm the last experiment result that the vessel with better internally mixed condition worked better.Based on the BBD design principle of response surface methods,the experiment used Design-Expert.V8.0.6 to simulate and optimize immobilized particles of Chlorella and activated sludge and got the result.Composited immobilized carrier with the best mix proportion of PVA=5.06%,SA=0.80%,CaCl₂=3.11%.Meanwhile,composited carrier,algae and sludge with the best volume proportion:Chlorella volume fraction was 1.03;activated sludge volume fraction was 2.14;carrier volume fraction was 2.03.According to results of the research of optimizing preparation of immobilized particles,prepared immobilized particles of Chlorella,Chlorella-sludge with Chlorella volume fraction 1.0,activated sludge volume fraction 2.1,and carrier volume fraction 2.0.Then put the immobilized particles into biogas slurry getting from the BCO-SBBR-APB process system in batches and compared the treatment results.It was found that the BCO-SBBR-APBR process system for co-culture fixed algal and fungi had a better removal effect in CODcr?TP?NH₃-N than the BCO-SBBR-APBR process system for culture fixed algal.To conclude:compared the biogas slurry treatment results under all the technological conditions tested in the paper,considering the removal effect of CODcr?TP?NH₃-N in pig-breeding wastewater,the BCO-SBBR-APBR process system for co-culture fixed algal and fungi performed best,the BCO-SBBR-APBR process system for co-culture algal and fungi ranked the second,and then the BCO-SBBR-APBR process system for culture fixed algal was the third.