Effect Of Water Quality On The Culture Of Biofilm

More advanced natural science and technology and water treatment equipmentsare applied to the model of recirculating seawater aquaculture (RAS). It is the basis ofproviding high-quality products and protecting ecological environment, andrecirculating seawater aquaculture is an inevitable choice for the development of thefactory sustainable aquaculture. The key system to circulating water efficient farmingis the water treatment system. As a core part of the water treatment system, biologicalfilter keeping efficient and stable operation is very important. Biological carrier filerand the operating conditions play a key role on the function of the biological filter toremove pollutants. In this paper, as a core of water purification technology incirculating water treatment system, the efficient of the biological filter purificationand the working conditions were studied. In order to determine the suitable conditions,the experiments and conclusions provide the data to maintenance and management ofthe optimal designing of the biofilter in the factory recirculating aquaculture system.The main contents and conclusions are as following:1. Ammonium chloride and glucose are added to the sea water, explosion cotton(PP) as a biological carrier, microbial ecological agent were used as strain forbiofilm cultivation, and biological filter pure this water, and then the process of theformation of biofilms of microorganisms in biological carrier were explored, cyclingand variation. By counting the number of the total heterotrophic bacteria,ammonia-oxidizing bacteria and nitrifying bacteria, and measuring the concentrationof ammonia, nitrite, and nitrate in the start-up of the biological filter. Then influentammonia concentration of the biofilm maturation and water purification efficiency isexplored. And after that, the appropriate influent ammonia concentration to culture isdetermined. The results showed that, the higher concentration of the influent ammoniais better to the growth and the formation of biofilms. The cycle of the biofilm matureis shorten, and it is faster into the stable operation of the biological filter; biofilmmicrobial community is gradually formed, eventually reached a relatively stable state.The number of all types of bacteria and biological filter (hydraulic loading, wastewater characteristics, temperature, strain and biological carrier) are closely to the startof the biological filter cycle biofilm. Under the present experimental conditions, the biological filter needs30-60d to start-up under different influent ammoniaconcentration.2. The situation of biofilm on the three stuffings of Corallite+the explosioncotton and Volcanic and Bio-filter balls in the treatment of simulated mariculturewastewater were compared in the laboratory simulation test. After the biofilmmaturation, each stuffing was under five different C/N (0,0.5,1,2and5) of thesimulated mariculture wastewater was tested and fitting out of the degradation kineticequation of ammonia nitrogen. The results show that biofilm maturation time ofcorallite+the explosion cotton and volcanic filter was significantly shorter than thebio-filter balls. Under the same initial concentration of ammonia nitrogen, with theC/N increasing, nitrification rate is increasing. When C/N ratio is5, each group filterhas a maximum rate of nitrification, Corallite+the explosion cotton> Volcanic>Bio-filter balls. Nitrification rate of each group of filter at the initial ammonianitrogen concentration of2.5mg/L is faster than ammonia nitrogen concentration of5.0mg/L. Under the same initial concentration of ammonia nitrogen, with theincreasing of C/N, the accumulation of nitrite is decreasing. Under the same C/N, withthe initial ammonia nitrogen concentration increasing, the accumulation of nitriteincrease.3. Using microbial ecological agent as strain for biofilm cultivation, simulateartificial aquaculture waste water as a processed object, then exploring the ammoniaremoval capacity of the biofilter under the different influent ammonia concentrationand under different gas-water ratio. After that, it can conclude the appropriategas-water ratio for the operation of the biological aerated filter. The experimentalresults show that, with the air-water ratio gradually increased, the TAN averageremoval efficiency of the biofilter increases are more than80%. And the nitriteconcentration level of accumulation is reducing. The average removal rate of thebiofilter under different gas-water ratio is analyzed by SPSS software, when gas-waterratio are4:1,5:1,6:1,8:1,10:1,12:1,they have gradient significant difference withgas-water ratio of3:1. Gas-water ratio of4:1has gradient significant difference withgas-water ratio of10:1, but the other five gas-water ratio have no statisticallysignificant difference between the average removal rate of TAN(p<0.05). Under thecondition of this experiment, taking the conditions such as running costs into account,under gas-water ratio of5:1can keep biofilter has higher average removal rate ofTAN.