The Selection Of Biological Filter Material In Industrialized Fish Culture And The Application Of Denitrifying Bacteria

As a modern and intensive fish culture, industrialized fish culture can improve the culture efficiency, reduces culture risk and can help us find a new way to solve the problems of growing aquaculture water and depleting water resources. Water treatment technology has been seen as the limitation in the industrialized fish culture, so many experts and scholars at home and abroad all have focused on water treatment technology. In recent years, biological methods processing culture sewage have been widely recognized for its small size, stable performance and efficiency. This experiment shall provide some useful data for production practices as well as promote the development of fishery.This experiment is divided into three parts:the first part is the selection of different biological filter materials. We selected five kinds of filter materials, including ceramic ring, bio ball, biochemical ring, and brush as well as vine cotton. Every kind of filter material forms a group with three parallel tests. Sewage used in experiment is artificially mixed with NO2-concentration of2.5mg/L, NH4+concentration of5mg/L and COD of10mg/L.During the experiment, every aquarium contains100L culture sewage;32L filter material by a ratio of100:32. The experiment ran for24days, and we tested water quality every three days. The experimental results show that:ceramic ring works better in degrading NO2-, Nh4, and COD than any other filter materials, followed by biochemical ring. Preliminary study shows that the ceramic ring and biochemical ring have application value. The second part of experiment mainly analyzes and compares the degrading effects of different filter materials with different hydraulic retention time. We chose biochemical ring and brush in this experiment. During the experiment, the culture sewage in the aquarium of200L circulates for every20minutes, every40minutes and every60minutes with three parallel experiments respectively. Same with the first part experiment, the second part culture sewage is also compounded with chemical reagents. We put32L filter and100L culture sewage in the aquarium in which sewage circulates for every40minutes and60minutes and put64L filter and200L sewage in the aquarium, in which sewage circulates for every20minutes so as to keep the ratio of32:100. This experiment ran for33days and we tested water quality every three days. The preliminary result shows that sewage degradation works best in the aquarium where sewage circulates for every20minutes. The third part of the experiment is to test the effects of denitrifying bacteria in degrading sewage. During the experiment, we used three kinds of filter materials, including ceramic ring, biochemical ring and brush and we used commercial denitrifying bacteria and cultured denitrifying bacteria. At the beginning of the experiment,45ml denitrifying bacteria from different sources with same density were added in the aquariums. Ten days later, we added10ml denitrifying bacteria from different sources with same density. This experiment ran for30days with every three days water quality testing. The final result of the experiment shows that the cultured denitrifying bacteria works better than the commercial denitrifying bacteria in degrading sewage; filter materials adding denitrifying bacteria in degrading sewage works better than those not.