Study On The Removal Of Ammonia Nitrogen In Aquaculture Water By Embedded Fixed Microorganisms

Aquaculture has always occupied a very important position in human production and life,and freshwater aquaculture is an important part of the whole aquaculture industry.With the rapid development,the pollution problems of freshwater aquaculture are becoming more and more serious.Ammonia nitrogen is one of the most dangerous pollutants in aquaculture,especially the molecular ammonia,which has a great toxic effect on the cultured objects.The treatment of ammonia nitrogen in aquaculture water has always been a key issue,but it is also a difficult problem.Therefore,it is of great significance to study how to effectively remove ammonia nitrogen from aquaculture water to promote the healthy development of aquaculture.In this paper,the degradation of ammonia nitrogen in water by Embedded fixed microorganisms was studied.The research contents and results are as follows:Sodium carboxymethyl cellulose?CMC?was used as carrier matrix,and three kinds of inorganic materials such as diatomite,SiO₂ and nano-Fe₃O₄ were composited respectively to prepare the immobilized nitrobacteria.The single-factor experiment and orthogonal test were used to determine the optimal preparation conditions of composite pellets.The optimum preparation conditions of CMC-diatomite composite pellets were determined as follows:the radio of CMC,diatomite,nitrifying bacteria were 2.5%,3%,2.5%respectively,the concentration of crosslinker was 1.5%,crosslinking 4 hours.The optimum preparation conditions of CMC-SiO₂ composite pellets were determined as follows:the radio of CMC,diatomite,nitrifying bacteria were 2.5%,2.5%,2%respectively,the concentration of crosslinker was 1.5%,crosslinking 5 hours.The optimum preparation conditions of CMC-nano Fe₃O₄ composite pellets were determined as follows:the radio of CMC,diatomite,nitrifying bacteria were 2.5%,1.5%,2%respectively,the concentration of crosslinker was 2.5%,crosslinking 3 hours.The three types of immobilized microbeads have a good degradation effect on ammonia in simulated aquaculture water.When pH=7-8,temperature is 30?,initial ammonia nitrogen concentration is 10mg/L,and solid-liquid ratio is 2%,the remo'val rate of ammonia nitrogen by the CMC-SiO₂ pellets was about 90%in 12h,and the removal rate of ammonia nitrogen by the CMC-diatomite pellets and the CMC-nano Fe₃O₄ pellets was about 95%in 12h.Immobilized nitrifying bacteria are more tolerant of undesirable environments than free bacteria,and also have better reusability.At the same time,the high organic content is not conducive to the degradation of ammonia nitrogen by immobilized microbeads.The immobilized microorganism pellets were applied to the treatment of simulated culture water with different initial ammonia nitrogen concentrations.It was found that the immobilized microorganism pellets had a good effect on the treatment of low concentration ammonia nitrogen,when the solid-liquid ratio was 2,the initial ammonia nitrogen concentration was not more than 10 mg/L,and the temperature was 30?.The ammonia nitrogen in simulated culture water can be reduced below 1mg/L in 12h to meet the water quality requirement of surface water environment quality standard.It was found that the low temperature drying had little effect on the activity of the pellets,and the lost activity could be partially recovered after repeated use.The immobilized microbe pellets have certain strength and stability,and can be reused many times.When three kinds of immobilized pellets were applied to the treatment of ammonia nitrogen in real water,the removal rate of ammonia nitrogen was basically above 80%,and the effect was remarkable.