| Heavy metals and antibiotics are abundant in livestock and poultry breeding wastewater,of which zinc ion and aureomycin have a high detection rate in breeding wastewater.As an essential trace element for animal growth,zinc ion is often used as feed additive to promote animal growth.Aureomycin is one of the most widely used tetracycline antibiotics.It is often used as veterinary antibiotics to prevent various diseases.Due to the abuse of zinc ion and aureomycin,livestock and poultry wastewater generally contains zinc ion and aureomycin residues,and the concentration varies greatly.Different concentrations of zinc ion and aureomycin have different effects on livestock and poultry wastewater treatment.At present,most studies focus on the single toxicity of heavy metals or antibiotics,while the joint toxicity research is scarce.Therefore,the experiment designed different concentration gradient zinc ions,aureomycin and their mixtures,and designed three binary mixtures of zinc ions and aureomycin with different concentration ratios（ratio1,ratio2 and ratio3）by Equ Ray.The effects of zinc ion,aureomycin and their mixtures on the biological denitrification of livestock and poultry wastewater were studied.Effects of zinc ions,chlortetracycline and their mixtures on denitrogenase activity;The Concentration Addition（CA）and Independent Action（IA）on Isobologram were used to judge the effect of zinc ions and chlortetracycline on nitrification performance and denitrifying enzyme activity on the equivalent diagram..The main conclusions are as follows:（1）Zinc ion,aureomycin and their binary mixtures have significant effects on ammonia nitrogen and COD in the effluent of the reactor.Under the action of low concentration zinc ion and aureomycin,ammonia nitrogen and COD in effluent increased less;Under the action of high concentration zinc ion and aureomycin,ammonia nitrogen and COD in effluent increased greatly.Chlortetracycline had the greatest impact on the COD of effluent,and the COD concentration of effluent increased to 418.31 mg/L;The influence of zinc ion is small,and the effluent COD concentration rises to 380.25 mg/L.the inhibition degree of effluent COD of the three mixture ratios gradually increases with the increase of the proportion of aureomycin.High concentration of zinc ion,aureomycin and their mixture significantly inhibited the removal of ammonia nitrogen with the increase of action time.（2）Zinc ion,aureomycin and their three binary mixtures showed different effects on nitrifying microorganisms.Single zinc ion,ratio1 and ratio2 showed a double dose effect of low concentration promotion and high concentration inhibition on nitrifying microorganisms.The optimum concentration promotion points of single zinc ion,ratio1 and ratio2 are 5 mg/L,2.8 mg/L and 1.9 mg/L.With the increase of concentration,the promoting effect on nitrifying microorganisms gradually changed into inhibition,and the inhibition increased with the increase of action time.Aureomycin and ratio3 showed similar inhibitory effects on nitrifying microorganisms,that is,at the same concentration,the inhibitory effect gradually increased with the increase of reaction time,with a time-dependent effect.At the same time,the inhibitory effect increases with the increase of pollutant concentration.（3）Zinc ion,aureomycin and their three binary mixtures showed similar effects on the activities of ammonia monooxygenase and nitrite reductase.Low concentration has little effect on enzyme activity,while high concentration has great effect on enzyme activity.At the same concentration,the inhibition of enzyme activity gradually increased with the increase of reaction time,with a time-dependent effect.At the same time,the inhibitory effect on enzyme activity gradually increased with the increase of pollutant concentration.（4）Zinc ion,aureomycin and their three binary mixtures showed different effects on the activities of nitrite oxidase and nitrate reductase.Single zinc ion,ratio1 and rattio 2showed a double dose effect of low concentration promotion and high concentration inhibition on nitrite oxidase activity,and the maximum concentration promotion points were 5 mg/L,2.8 mg/L and 1.9 mg/L respectively.Aureomycin and ratio 3 showed similar inhibitory effects on nitrite oxidase activity;Single zinc ion and ratio1 also showed low promotion and high inhibition on nitrate reductase activity,and the maximum concentration promotion points were 5 mg/L and 2.8 mg/L respectively.Aureomycin,ratio2 and ratio3 showed inhibitory effect on nitrate reductase activity.（5）The combined toxic interactions of binary mixtures on nitrifying microorganisms,ammonia monooxygenase,nitrite oxidase,nitrate reductase and nitrite reductase were qualitatively evaluated by Concentration Addition and Independent Action on Isobologram.Basically,the whole concentration region shows a synergistic effect,that is,the effect of the binary mixture of zinc ion and aureomycin is greater than the sum of the effects of zinc ion and aureomycin on microbial enzyme activity,and has a strong concentration dependence and time dependence.In this experiment,the effects of single zinc ion,chlortetracycline and their binary mixtures with three concentrations on comprehensive biological denitrification performance and denitrification enzyme activity of aquaculture wastewater were studied.At the same time,The Concentration Addition and Independent Action are applied to reveal the interaction relationship between nitrification performance and denitrification activity of binary mixtures with different concentration ratios on Equ Ray,and comprehensively and scientifically judged the interaction relationship between zinc ions and chlortetracycline on nitrification performance and denitrification activity.Provide data and reference for scientific evaluation of biological impact of mixed pollutants.Figure [39] Table [6] Reference [111]... |
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