Study On Nitrifying Bacteria Adsorbed By Different Carriers On Nitrogen Conservation Of Swine Manure Aerobic Composting

Aerobic composting can realize the harmless and resource utilization of manure brought by the rapid development of swine breeding in our country.Usually,there is a large amount of NH₃ volatilization during this process,which not only causes the loss of nitrogen,reduces fertilizer utilization of compost products,but also will cause secondary pollution of the environment.Such problems can be alleviated through external additives,in order to find economical and readily available additives,to promote the development of engineered production of organic fertilizer for swine manure.Therefore,this study uses swine manure and rice husk as composting materials,take the nitrifying bacteria that are self-bred and enriched under simulated wastewater conditions as microbial inoculants,and use biochar,activated carbon,and swine manure decomposed particles to adsorb and fix them as composite additives,and perform intermittent forced ventilation aerobic composting.Study its effect on the decomposing process of swine manure aerobic composting and the effect of nitrogen retention,and explore more economical and efficient nitrogen retention agents.The main research conclusions are as follows:（1）Under the conditions of room temperature and pH control at 7.3～7.7,by controlling the dissolved oxygen at 1.5mg/L and C/N of 2.5,the nitrifying bacterial sludge is domesticated by simulating wastewater.In the initial stage of domestication,the ammonia nitrogen concentration in the incoming water solution is controlled at100 mg/L.When the removal rate of ammonia nitrogen reaches more than 90%,the ammonia nitrogen concentration is increased by 50 mg/L.After 4 times of increase,the final ammonia nitrogen concentration in the incoming water solution is increased to 300 mg/L.On the 32nd day,the removal rate of ammonia nitrogen was 94.76%,and the removal rate of ammonia nitrogen was as high as 99.22%after the domestication for one day.The removal rate of ammonia nitrogen in the reactor was basically maintained at more than 90%.The domestication of nitrifying bacteria was completed.Under the SEM,it can be observed that the nitrifying bacteria gather together into clusters.Add nitrifying bacteria that have been adsorbed by three different carriers in 100 mg/L ammonia nitrogen solution,after 6 hours,activated carbon used as an adsorption carrier to adsorb and immobilize nitrifying bacteria has the fastest removal rate of histamine nitrogen,which is as high as 93.02%,next is biochar,followed by decomposed particles,and the slowest is without any carrier.It shows that different adsorption-type carriers can adsorb and fix domesticated nitrifying bacteria well,among them,the adsorption effect of activated carbon>the adsorption effect of biochar>the adsorption effect of decomposed particles.Although the effect of decomposed swine manure particles as an adsorption carrier to adsorb nitrifying bacteria is slightly worse than that of activated carbon and biochar,from the perspective of economic benefits,its effect is much better than the control group.The adsorption effect of decomposed particles and biochar is not obvious.From an economic point of view,decomposed particles can be used as a new and easily available adsorption carrier into engineering application practice.（2）Nitrifying bacteria adsorbed by different carriers are added as a compound additive to swine manure and rice husk aerobic compost.After 35 days of fermentation,they have reached the standards of harmless and decomposed compost.After composting,the organic matter content of the four treatments of CK,CNSAC,ACNSAC and CPNSAC was respectively reduced by 22.17%,25.21%,25.89%and24.81%,compared with the initial state,indicating that the addition of nitrifying bacteria adsorbed by different carriers can promote the degradation of organic matter in the heap.Speed up the decomposing process and shorten the composting cycle.Among them,the effect of nitrifying bacteria adsorbed by activated carbon is the most obvious.（3）The addition of nitrifying bacteria adsorbed by different carriers can promote the conversion of nitrogen from NH₄⁺-N to NO₃^--N in the heap,and increase the relative concentration of organic nitrogen and total nitrogen.The total nitrogen concentration increased by 20.84%,28.39%and 18.99%respectively compared with the initial stage of composting.Compared with the CK group,the three treatments of CNSAC,CNSAC and CPNSAC respectively reduced the cumulative release of NH₃by 37.94%,51.87%,and 29.97%,which reduced the loss of nitrogen in aerobic composting of swine manure and played a role in maintaining nitrogen.Adding activated carbon to adsorb the nitrifying bacteria has a better effect.Activated carbon not only has a high specific surface area and rich porosity,but also has a large number of active functional groups,which can adsorb NH₄⁺and NH₃and provide good growth and metabolism for microorganisms in composting,it has the best effect in reducing the loss of nitrogen.The research results of this paper can provide some parameters for the engineering production and practical application of nitrifying bacteria and the engineering practice of aerobic composting process of swine manure.There are 35figures,9 tables and 122 references in this paper.