Effects of Nitrifying Bacteria on Construction of Nitrification Function in Marine Aquarium and Analysis of Related Factors
|School||Qingdao Technological University|
|Keywords||Ammonia nitrogen Nitrite nitrogen Nitrifying bacteria Nitrification function Nitrification kinetics|
In recent years, marine aquaculture and aquarium developed very fast in our country. Species of cultured organisms have been changed from common varieties to high quality varieties. Way of mariculture has been transformed from extensive into intensive. So, the requirement of water quality becomes stricter.Ammonia and nitrite nitrogen are the major pollutant in culture system, and both are virulent to cultured organisms. If they are exposed in water with high concentration of ammonia and nitrite nitrogen, they’ll have a descent of immunity and high risk of infecting pathogenic microorganism. So the removal of ammonia and nitrite nitrogen is the key point of culture water purification. Biological methods are mostly used in the removal process for its safety and efficient effects. Nitrifying bacteria play a very important role in biological removal process, they can transform ammonia into nitrite, and then transform nitrite into nitrate which is non-toxic to cultured organisms.Because of long generation time, sensitiveness to changes of environment and low quantity in culture system, it is very difficult for marine nitrifying bacteria to form dominant microflora in a marine culture system. To increase concentration of nitrifying bacteria and optimize process of nitrification construction is very necessary and meaningful. In this paper, the effects of nitrifying bacteria on construction of nitrification function in marine aquarium and analysis of related factors were studied. The results of the investigation are as follows:(1) Both ammonia-oxidizing bacteria and nitrite-oxidizing bacteria perform a good adaptability in artificial seawater system and natural seawater system during the construction period of nitrification function. Nitrite-oxidizing bacteria has a higher activity in artificial seawater system than in natural seawater system.(2) 3 methods of construction of nitrification function in marine aquarium were compared. During the period of ammonia oxidation, method of adding nitrifying bacteria needed the shortest time(7d), methods of substrates and rotten meat needed 12d、30d, respectively. During the period of nitrite oxidation, method of adding substrates needed the shortest time(25d), methods of nitrifying bacteria、rotten meat needed 31d、59d, respectively. The blank needed 61d.(3) In this study, 5 kinds of substrates, i.e. haydite, white sand, Philippines sand, coral sand and fiber ball were chosen as substrates in marine aquarium and their effects on nitrification construction were determined. The results showed that there were obvious differences among marine aquariums with different substrates during the construction of nitrification function. The one with Philippines sand as substrate constructed nitrification function fastest, within a period of 20d, and the one with coral sand, white sand, haydite, fiber ball as substrate needs 31d, 34d, 41d and 141d, respectively. The differences among marine aquariums with different substrates in ammonia-oxidizing bacteria maturation process are insignificant, but the differences are obvious in nitrite-oxidizing bacteria maturation process. (4) The biodegradation of ammonia nitrogen on the film of haydite, white sand, Philippines sand, coral sand followed the first-order dynamics and the biodegradation rates were 0.198、0.191、0.141、0.206h-1, respectively. The biodegradation of nitrite nitrogen on the film of haydite, white sand, Philippines sand, coral sand also followed the fisrt-order dynamics and the biodegradation rates were 0.269、0.183、0.199、0.291h-1, respectively. Because of different physical and chemical properties, the rates of forming biofilm on the 4 substrates are not positively correlated with the rate of biodegradation of ammonia nitrogen or nitrite nitrogen.