The Primary Study On Main Microorganisms Decomposing Ammonia Nitrogen In Recirculating Aquaculture System

Bacterial bio-film is one of the important methods in aquaculture wastewatertreatment. Main principle of this method is to utilize the bacteria attached on thebio-film to eliminate harmful substances in water body. Ammonia and nitrite are theproducts of aquaculture process. Both of them are harmful to aquatic organisms.Meanwhile， nitrite has strong carcinogenicity， which has potential threaten tohuman health. Therefore， the key point of this study is how to decompose andeliminate of these toxic products in aquaculture process.In this field， studies focus on the use of biological method to purify water inaquaculture wastewater treatment process. In China， the development ofrecirculating aquaculture purification system started late， hence， it is necessary touse foreign production technology for reference to set up new pattern and technologyin mariculture and seedling water treatment. There are fewer studies on the microbialcommunity structure in the bacteria filter of circulating water treatment system.Modern molecular biology technology provides advanced methods to studyenvironmental microbes deeply. Using microbiology to aquaculture engineeringexperiment is a major characteristic of this experiment， hoping to discover newbreakthrough and findings in these interdiscipline subjects. Actually， except forharmful pollutants， there are varies of tiny organisms-plankton protozoa such asciliates and flagellates， phytoplankton such as diatom， bacteria， microalgae etc.We can expand our horizon and focus on the crossing field between wastewatertreatment technology and protozoa， phytoplankton， zooplankton，microorganism. These tiny organisms formerly ignored have potential abilities todisposal special pollutant， and could be ultimate to culture specificity nitritebacteria liquid， which will improve the treatment abilities and get more benefit. This study is funded by national science and technology support project(2011BAD13B04). Preliminary works contain review literatures about recirculatingaquaculture system， water aquaculture monitoring specification， etc. Preliminaryexperiments are carried out. Based on the questions met in preliminary experiment，the design of experiment is revised and improved. In this paper， aquaculturewastewater treatment is studied by the means of microorganism cultureidentification， aiming to get breakthroughs for improving the water treatmentabilities of circulating water purification system and to provide theoretical basis forproduction practice.This paper consists of six chapters. Chapter one is introduction. In this part，the research status quo at home and abroad in the field， the academic ideas of thispaper， the problem aimed to solve， the innovation of the research， theoreticalsignificance and practical application are introduced. Chapter two and chapter threemainly analysis the recirculating aquaculture system and the methods of aquaculturewastewater treatment and summarize the research status of the role nitrifying bacteriaplayed in aquaculture water treatment system. Chapter four is about the study onseparation and identification the microorganism decomposing ammonia nitrogen inaquaculture wastewater. Chapter five is the study on the impact of nitrite bacteria onaquaculture water environment. Chapter six is the summary and prospect of the paper.In chapter two and three， the function of nitrifying bacteria in aquaculturewastewater treatment system is reviewed. The common method of nitrifying bacteriaenrichment， separate， identification and storage are summarized， and thefactors affecting the treatment abilities of nitrifying bacteria are analysis. In thispart， some further works are also suggested， hoping to provide basic data infuture study.In chapter four， marine bacteria are separated from the bio-film of activatedsludge in the well-operated circulating water system to study the ammonia nitrogendecomposing capacity of marine microorganism in bio-filter. By the enrichmentculture， purification， DNA extraction， PCR amplification，16SrRNAsequencing， a light yellow strain fluorescent pseudomonad Pseudomonasfluorescens SS101is got. The result reveals that in addition to nitrifying bacteria，some specific microorganism also would decompose ammonia nitrogen for their growth in cultivation wastewater. This study will provide basic information on furtherstudies about the microorganism community in cultivation wastewater， and lay afoundation to optimize the property of bio-film in wastewater treatment system.In chapter five， aiming to explore efficient ammonia nitrogen decomposingpattern in wastewater， the ammonia nitrogen decomposing abilities of nitritebacteria in fluid medium and in the bacteria filter are studied.In chapter six， the whole paper is summarized， meanwhile， some suggestsand prospect on further work are proposed.