Inhibitory effect of high concentration ammonia nitrogen on anaerobic membrane bioreactor treating swine wastewater and the associated biochar regulation performances
To investigate the ammonia inhibition during anaerobic digestion of swine wastewater,the effects of ammonia loading rates on anaerobic membrane bioreactor(AnMBR)treating swine wastewater,and the regulatory benefits of biochar addition were studied.The results showed that when the ammonia load rate was 0,3 000 and 4 500 mg·L-1,the methane yields of conventional AnMBR were 85.2％,73.2％and 51.7％,respectively,which could increase to 93.2％,83.7％and 63.7％by adding biochar.With the increase of ammonia loading rate,the pollutant removal ability of AnMBR decreased.As the ammonia loading rate increased from 0 to 4 500 mg·L-1,the removal rates of chemical oxygen demand(COD),polysaccharide and protein in swine wastewater by conventional AnMBR decreased from 94.0％,95.7％and 86.8％to 92.4％,90.2％and 80.2％,respectively,while they maintained at 92.7％、91.6％、84.3％after biochar addition,respectively.Further study showed that the existence of high concentration of free ammonia(FAN)was the main reason for the decline of fermentation efficiency of AnMBR.When the ammonia loading rate increased from 3 000 mg·L-1 to 4 500 mg·L-1,the contents of soluble microbial products(SMP)and extracellular polymeric substances(EPS)in conventional AnMBR sludge increased by 84.1％and 62.6％,respectively,of which aromatic proteins were the main substances of microbial metabolites.Addition of biochar reduced SMP content by 17.9％～27.1％and EPS content by 2.6％～9.3％.The experimental results of methane fermentation activity of volatile fatty acids(VFA)showed that high concentration of ammonia nitrogen mainly inhibited the specific methanogenic activity of acetic acid-degrading microorganisms,while biochar addition was conducive to maintain the ability of sludge to degrade acetate and produce methane at high concentration of ammonia nitrogen.The results of this study provide some suggestions for the operation of AnMBR treating swine wastewater with high ammonia nitrogen contents.
万方数据
维普
