Study On The Inhibitory Effect Of Biochar On The Ammonia Nitrogen In The Process Of Anaerobic Digestion Of Pig Manure Wastewater

Along with the development of industry,a large amount of fossilfuels is consumed which caused climate change and deficiency of energy,thus human begins to quest for renewable energy sources thatlessen greenhouse gases emission?Therefore,the development of clean energy,such as bioenergy,is one of the important ways to solve the current energy crisis.Ammonia inhibition is ubiquitous in anaerobic fermentation of substrates rich in organic nitrogen.Therefore,this paper takes pig manure wastewater as the research object to study the effect of ammonia nitrogen concentration on anaerobic digestion performance,and alleviates the inhibition of ammonia digestion by adding biochar,investigates the effect of biochar addition on anaerobic digestion,and compares the effects of biochar on anaerobic digestion performance in the presence of ammonia nitrogen inhibition and in the absence of ammonia nitrogen inhibition.The main results of this study are as follows:The effects of ammonia nitrogen concentration of 900 mg/L,1500 mg/L,2500 mg/L and 3500 mg/L on anaerobic digestibility were studied.The results showed that with the increase of ammonia nitrogen concentration,the anaerobic digestibility began to be affected by the following factors.With the increase of ammonia nitrogen concentration,the methane content and methane production decreased the average methane concentration decreased from 52.22%in the control group to 39.93%in 3500 mg/L,and the cumulative methane production decreased from 213 mL to 622 mL.With the increase of ammonia nitrogen concentration,the COD removal rate decreased gradually.The COD removal rate of 1500 mg/L,2500 mg/L group and 900 mg/L group was 75.31%and 73.31%respectively,while that of 3500 mg/L group was only 47%.With the increase of ammonia nitrogen concentration,the accumulation rate of volatile fatty acids increased gradually.The average concentration was 3561 mg/L,4115 mg/L,4890 mg/L and 6260 mg/L.The effect of biochar on anaerobic digestion was investigated under the condition of ammonia nitrogen concentration of 900 mg/L.The results showed that the content of methane under the conditions of adding 2g,5g,lOg and 15g biochar was higher than that of the control without biochar.for.The average concentration of methane increased compared with the control group,and the cumulative production of methane increased from 1213 mL to 1504 mL,1612 mL,1815 mL,and 1922 mL.With the increase of biochar addition,the removal rate of COD gradually increased,and the removal rate of COD of 2g,5g,lOg and 15g increased to 79.69%,85.61%,89.98%and 91.80%.With the increase of biochar addition,the degradation rate of volatile fatty acids became faster,and the average concentration decreased from 3571mg/L to 3525mg/L,2893mg/L,2595mg/L,and 2370mg/L.Experiments have shown that biochar can promote the production of methane by anaerobic digestion.The effect of biochar on gas production characteristics and performance of anaerobic digestion was analyzed under the condition of ammonia nitrogen concentration of 3500 mg/L.In the test,the amount of biochar added was the same as above.The experimental results show that under the condition of high concentration of ammonia nitrogen,biochar has a good effect on shortening the gas production lag period,so that anaerobic fermentation can run stably.At the same time,methanogenesis helps to eliminate ammonia inhibition and improve the stability of the anaerobic digestion system.Finally,the effects of biochar on ammonia nitrogen,pH and COD in 3500 mg/L pig manure wastewater were studied by blank adsorption experiment.The reasons for the removal of ammonia inhibition by biochar were preliminarily discussed by comparing the removal of ammonia nitrogen in anaerobic digestion experiment and adsorption experiment.