Studies Of Large-scale Duck Farms,wasterwater Treatment And Utilization Of Hydroponic Vegetables

The irrational ways to deal with and utilize the wastewater of large-scale duckfarms result in serious pollution of the environment. My experiment was aimed todiscuss up-to-standard discharge and rational utilization of wastewater dischargefrom large-scale duck farms,and achieve virtuous cycle of ecology of agricultureand stock husbandry. In my experiment,the pollution level of large-scale duck farmswas investigated and the best combinations of vegetables was selected on thepurifying effect of different hydroponic vegetables on wastewater. Production status,waste treatment facilities and the content of COD,BOD₅,NH₃-N and SS in thewastewater from five representative large duck farms in Henan province wasinvestigated Different combinations of vegetables （amaranth, spinach,dropwort） wereused in the hydroponics test of wastewater from duck farms. The effect of differentcombinations of vegetables on wastewater was analysed after the test.Also comparedto the commercially available hydroponic vegetables in nutrient solution,the effect ofwastewater on vegetables growth was analysed.Results suggest that:（1） The average content of COD,BOD₅,NH₃-N,TP suspendedsolids in the wastewater from five dark farms were721.6±54.31mg/L,183±12.34mg/L,169.4±9.17mg/L,13.4±1.42mg/L,679±45.76mg/L,respectively,all theindexes were higher than “Discharge standard of pollutants for livestock and poultrybreeding”. The average content of COD,BOD₅,NH₃-N,TP suspended solids in thewater near the duck farm were47.9±3.14mg/L,14.9±2.71mg/L,10.4±1.15mg/L,1.1±0.1mg/L,respectively,all the indexes were higher than "Environmentalquality standard for surface water".（2）In the hydroponic experiment, the removal rateof COD of amaranth, spinach, dropwort was all higher than40%whenever it wascultured solely or mixedly. The removal rate of COD of solely cultured spinach was93.4%, highest. The removal rate of COD of solely cultured dropwort was45.5%,lowest.The removal rate of BOD₅all reached75％. The removal rate of BOD₅ of solely cultured dropwort was93.6％,highest. The removal rate of BOD₅of solelycultured spinach was77.8％, lowest. The removal rate of NH₃-N was all higher than40%. The removal rate of NH₃-N of three kinds of mixedly cultured vegetables was82.4％,highest. The removal rate of NH₃-N of solely cultured dropwort was66.3％,lowest.The removal rate of TP was all higher than75%. The removal rate of NH₃-Nof three kinds of mixedly cultured vegetables was84.5％, highest. The removal rate ofNH₃-N of solely cultured amaranth was77.8％,lowest.（3）The growth rate of plantheight of spinach and dropwort in the duck farm wastewater were significantly lowerthan in the commercially available culture medium,（P <0.05）. The growth rate ofstem diameter of Amaranth and dropwort in the duck farm wastewater weresignificantly lower than in the commercially available culture medium,（P <0.05）.Conclusion:（1）According to the survey, the wastewater of and around five large-scale duck farmswas all in serious pollution level,the indexes of NH₃-N and SS were most serious inthe wastewater of duck farms. And ammonia nitrogen in the wastewater around duckfarms exceeded most seriously, TP followed.（2） Among different combination of hydroponic culture, the removal rate of COD ofsolely cultured convolvulus in sewage was best. The removal rate of BOD₅of solelycultured dropwort in sewage was best. Overall, when amaranth, spinach, dropwortmixed culture, the removal rate of wastewater pollutant were best.（3）The growth effect of wastewater on amaranth and spinach was of no differencefrom the commercially available culture medium, but, the dropwort was worst.