Study On The Establishment And Efficency Of Nitrogen Removal System In Marine Aquarium

Ammonia, nitrite and nitrate are the main contamination in the marine aquarium and aquaculture systems. Biological methods are used to be used in the removal process. Nitrifying bacteria and denitrobacteria, which can convert the ammonia to nitrite and nitrate and N₂, play a crucial role.Since Aquaculture water is oxygen-rich environment, and the C/N is low, studying of direct application of denitrification technology is difficult. Therefore, it is meaningful to use denitrification technology in farming water purification.In this paper, the physical and chemical properties of denitrobacteria agent were studied. The effect of carbon source and carbon nitrogen ratio to nitrogen removal system and the establishment and running of nitrogen removal system was determined in marine aquarium. Also the establishment of nitrification function was determined in marine aquarium. The results of the investigation were as follows:1. The Mlss, Mlvss, cell density, size distribution, zeta potential, toxicity, TKN and protein content of marine denitrobacteria were determined respectively. Compared to the normal- temperature preservation, the results showed that he biological activity of agents can be maintained under low-temperature preservation.2. When 5 kinds of carbon sources were used for denitrification of the marine denitrobacteria, their optimum carbon and nitrogen ratios were:Ethanol (2.5), sodium acetate (3), sodium citrate (3.5), sodium pyruvate (3.5) and glucose (4).The denitrification rates were 2.54mg/gMLSS·h,2.51mg/gMLSS·h, 2.36 mg/gMLSS·h,2.35 mg/gMLSS·h and 2.24 mg/gMLSS·h.3.The the nitrogen removal system can quickly start after inoculation of denitrifying bacteria.Compared to the control group, of which the nitrogen removal system is still unable to establish after 45 days, but 100mg/L of nitrate nitrogen in 20L marine aquarium can be degraded completely by the experimental group.4. Effect of four kinds of carbon sources on nitrogen removal in marine aquarium was investigated,and the results showed that sodium acetate is a relatively good carbon source for higher efficiency of nitrogen removal and no accumulation of nitrite.5. The best HRT of the nitrogen removal system of the marine aquarium is 6h; the best inoculation volume of denitrobacteria is 50mL; It took the nitrogen removal system 108 hours to complete degradation of nitrite nitrogen of 5mg/L in marine aquarium. The nitrogen can be completely removed by the nitrogen removal system of the seawater aquarium by Adding external carbon source to the marine aquarium.