Optimal Conditions and Influencing Factors for Copper Removal by Stenotrophomonas maltophilia
To remove heavy metal copper in wastewater from livestock and poultry farming,a strain of Stenotrophomonas maltophilia that can tolerate heavy metal copper was screened from livestock and poultry manure.The optimal conditions for copper removal by the bacterium were studied from pH,bacterial dosage,initial concentration,removal time and temperature.The effects of major pollut-ants such as nitrogen,phosphorus,and tetracycline on copper removal by Stenotrophomonas malto-philia were also studied.The results showed that at pH of 5,initial concentration of 100 mg/L,dosage of 8 g/L,and removal rate of 76.1%at removal time of 90 min were the best removal conditions.When ammonia nitrogen in livestock sewage was lower than 80 mg/L,Cu2+removal was good,and to-tal phosphorus had no adverse effect on Cu2+removal.When chlortetracycline concentration was 1 mg/L,the removal rate of Cu2+was less than 1%,and the addition of chlortetracycline 0.01 mg/L had an effect on the removal rate of Cu2+.Scanning electron microscopy(SEM)and infrared spectros-copy(FTIR)analysis indicated that the removal mechanism of Cu2+by the bacterium exhibited a clear surface adsorption effect,and functional groups such as hydroxyl,amino,amide,carboxyl,and phosphate on the cell surface were involved in the binding with Cu2+.It is concluded that the treat-ment of heavy metal copper in livestock and poultry sewage by Stenotrophomonas maltophilia can be used as an advanced treatment technology,suitable for processing wastewater with an ammonia nitro-gen concentration of less than 80 mg/L.
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