Treatment of Nitrate-contaminated Water Using Sulfur-based Autotrophic Denitrification Combined with Bac (Biological Activated Carbon) System
|School||Shanghai Jiaotong University|
|Keywords||Sulfur autotrophic denitrification Biological activated carbon Nitrate nitrogen Heterotrophic denitrification|
Eutrophication and groundwater nitrate nitrogen pollution worldwide more and more serious, denitrification has become an important step to improve water quality, and denitrification as the final step of denitrification, but also of great significance. Relative to the traditional differences denitrification possible shortcomings of secondary pollution caused by sulfur autotrophic denitrification advantage of no external carbon source to become a research focus in recent years. However, the sulfur autotrophic denitrifying bacteria growth cycle and sensitive to changes in the external environment, resulting in lower efficiency of denitrification. In order to improve the sulfur autotrophic denitrification rate in this paper using UASB reactor, activated carbon as sulfur autotrophic anti nitrifying bacteria growth and reproduction carrier, the formation of biological activated carbon (BAC) system for the removal of NO 3 the the sub> - sup>-N made the following conclusions and results: The system in the influent NO 3 - sup>-N concentration of 10 1 sup> 00mg / L, hydraulic retention time (HRT, hydraulic retention time) 0.67 4 sup> h the range, you can get the the above NO 90% 3 - sup>-N removal rate and more than 80% of the TN removal rate, the maximum influent NO 3 - sup>-N load (NLR , nitrogen loading rate) for 1.12kgN / m 3 sup> · d minimum HRT of 0.67h, the best denitrification concentration 40 mg / L, the water basically no the of NO 2 - sup>-N accumulation. 76 days of operating results contrast the BAC system 148 days of running with the ordinary anaerobic sludge BAC higher nitrogen removal system, the shorter residence time, more secure and stable operation effect. Processing organic matter containing low concentrations of NO 3 - sup>-N wastewater feasibility BAC system, add a low concentration of COD in the influent to simulate the actual water quality test results found that, the low COD add nitrogen removal of the whole system basically no impact, and promote the growth of some heterotrophic denitrifying bacteria sulfur autotrophic denitrification denitrification load sharing to some extent. Experiments show that the influent S / N is reduced to 0.7, affects neither the denitrification effect, but also reduce the concentration of sulphate in water, indicating that the BAC system combined with sulfur autotrophic denitrification applicable to the actual body of water. Reaction at all stages of the process of mud-like SEM observation and analysis of molecular biology experiments, cultured in this experiment the sulfur autotrophic denitrifying bacteria as a Brevibacterium mass adsorbed on the activated carbon surface is not yet found in the gene pool its similarity greater than 60% of the known bacterial gene fragment and lower traditional Thiobacillus denitrificans affinity. Using real-time quantitative PCR to examine the growth of denitrifying bacteria in the running of the whole culture and the outside world for its impact, the results show: denitrifiers sludge concentration declined by domestication, then gradually increased in the run. Domesticated eliminated most different denitrifying bacteria, sulfur autotrophic denitrifying bacteria in the running process of gradual growth, and to play a leading role in the system. BAC system, granular activated carbon (GAC) has played the role of bioconcentration and biological carrier, sulfur autotrophic denitrifying bacteria with a small number of heterotrophic denitrifying bacteria complementary, and eventually the system to achieve high efficiency and low consumption of nitrogen removal.