Study On The Control Of Inorganic Nitrogen Concentration In Aquarium

Inorganic nitrogen in water mainly includes ammonia, nitrite and nitrate. Ammonia and nitrite were the main influencing factors for fish survival. Nitrate was less toxic to fish, but it was easy to accumulate in water. When it reached a certain concentration, it could also produce toxic effects on aquatic organisms. At present, aquaculture water treatment technology still need to change the water regularly, leading to the high operation cost, waste of water resources seriously.Accordingly, this paper to build an aquarium containing nitrogen control system to focus on, silver doped TiO2 photocatalysts were prepared by using optical deposition method, and by the means of SEM, XRD, XRF, UV Vis and characterization, modified successfully. Firstly, the oxidation of ammonia and nitrite as the main removal target was investigated, and the optimal reaction conditions were studied. Then investigate the reduction, to nitrate nitrogen removal is the main object of study, and to investigate the effect of volume and light source on the degradation performance of ammonia, nitrite and nitrate nitrogen and total removal, and the effect of pH, formic acid, metal doping amount, catalyst dosage. Finally, according to the characteristics of the photocatalytic oxidation and reduction of the modified titanium dioxide, a set of sequencing batch reactor was designed to study the degradation effect of inorganic nitrogen.Experimental results show that:in the experiment of photocatalytic degradation of ammonia nitrogen and nitrite nitrogen and the initial concentration of ammonia nitrogen and nitrite nitrogen is 2mg/L, the study found that at pH= 10, theory of metals doping content is 1.0%, optimal catalyst dosage of 1g/L, light source is 125W UV lamp, full to continued exposure to nitrogen gas, reaction time is 3h, NH4+-N and NO2--N and TN removal rate maximum reached 91.1% and 95.9% and 34.1%.In the experiment of photocatalytic degradation for ammonia, nitrite nitrogen and nitrate nitrogen, ammonia nitrogen and nitrite nitrogen concentration to 2mg/L, nitrate nitrogen concentration is 100mg/L(CNH4+:CNO2-:CNO3-=1:1:50), Ag/TiO2 best metal doping 1.5wt%, the optimal catalyst dosage was 1.5g/l and full continued exposure to nitrogen, at room temperature,125w UV lamp as light source and using formic acid regulation to a pH of 2.5, reaction time is 3h of NH4+-N concentration increased slightly, NO2--N removal rate was 93.4%, nitrate removal rate reached 99.6%, TN removal rate was 96.5%.In subsection sequencing batch photocatalytic reaction, oxidation reaction after prior to benefit to the reduction reaction conditions, segmented catalyst and 3h before adding metal doped 1.0g/L 1% catalyst,3h after adding metal doped 0.5g/L 1.5% catalyst, ammonia nitrogen gas throughout the sustained exposure, a slight increase in reaction after 390min, the nitrate removal rate was 100%, the nitrate removal rate was 83.5%, total nitrogen removal rate was 77.8%; the first is conducive to the oxidation reduction reaction conditions, one-time dosing of metal doped 1.5g/L catalyst 1.5%, total nitrogen is more conducive to the overall Cheng Bao reaction,6h reaction after, NH4+-N increased slightly, NO2--N increased slightly, NO3--N removal rate is 96.5%, the removal rate of TN was 86.8%.