Effects Of Sulfamethoxazole And Copper On Anaerobic Digestion Of Livestock Wastewater

The application of anaerobic biological technology to treat livestock wastewater hasattracted more and more attention due to its low energy consumption,low sludge yield,good results,low demand for nutrient substances,and the advantage of recoverable energy gas?biogas?.However,higher antibiotics and heavy metal residues may have toxic effects on the anaerobic treatment of livestock wastewater,eventually leading to the deterioration of the anaerobic digestion process and the collapse of the system.Therefore,the influence of antibiotics and heavy metals on the anaerobic digestion process has received more and more attention.In this study,the Batch test method was used to study the effects of SMX and Cu²⁺alone,and their combined effects on anaerobic digestion of livestock wastewater.SMX and Cu²⁺were used to investigate the characteristics of anaerobic digestion of livestock wastewater and organic matter degradation,as well as their solid and liquid properties and provides a theoretical basis for the engineering application of anaerobic digestion of livestock wastewater.The main results are as follows:?1?SMX was 5-1000 mg/L,the inhibition rate of cumulative methane productionincreased with the increase of SMX concentration,and the removal rate of SCOD decreased,and the residual amount of solid phase is greater than the residual amount of liquid phase.The order of use of methanogens for each VFAs was:acetic acid>propionic acid>isobutyric acid.SMX was positively correlated with VFAs and SCOD and negatively correlated with cumulative methane production and methane content.?2?Cu²⁺in the range of 10⁵0 mg/L was beneficial to the methanation of VFAs,butin 50⁴00 mg/L,it slightly inhibited the cumulative methane production.RDA analysis showed that Cu²⁺was positively correlated with VFAs and negatively correlated with cumulative methane production and methane content.After anaerobic digestion,the soluble Cu²⁺in the liquid phase was greatly reduced,which may be due to adsorption,or Cu²⁺gradually transforms from an unstable state to a relatively stable organic state and residual state copper that making it more stable.?3?When SMX was 5mg/L and Cu²⁺was 10⁴00mg/L,Cu²⁺promotes anaerobic microorganisms to convert SMX to VFAs;SMX was 10⁵0mg/L,and Cu²⁺was 10⁴00mg/L,both showed antagonistic effect.With the increasing of Cu²⁺,the antagonistic effect was weakened;when SMX was 100²00mg/L and Cu²⁺was 10⁴00mg/L,Cu²⁺and SMX showed synergistic inhibition of anaerobic digestion process.After the anaerobic digestion,soluble Cu²⁺was not detected in the liquid phase in all treatment groups;SMX was 5¹0 mg/L,and Cu²⁺was 10⁴00 mg/L.No SMX was detected in the solid phase but SMX When?50mg/L and Cu²⁺were 10-400mg/L,about 60%-80%of SMX remained in the liquid phase,but no residue was observed in the solid phase.