Bioprocess of nitrite accumulation in water - a review / 生物工程学报

Nitrite is a by-product of the nitrogen cycle. The excessive nitrite not only constrains growth and metabolism of bacteria, but also impairs health of humans and aquatic organisms. On the other hand, the continuous maintaining of nitrite accumulation could achieve the shortcut nitrification process, and reduce energy consumption of biological nitrogen removal to save cost. This article reviews the biological processes and causes of nitrite accumulation in the water environment, and summarizes the factors that affect the accumulation of nitrite, to provide reference for wastewater treatments, including improving the nitrogen removal efficiency, reducing operating costs, decreasing discharge of sewage and nitrite nitrogen in natural water.

Comparação de métodos para quantificação de bactérias nitrificantes / Comparison of methods for quantification of nitrifying bacteria

RESUMO A quantificação de bactérias nitrificantes é de extrema importância para o monitoramento de sistemas biológicos de tratamento que promovam a nitrificação. Neste trabalho, 15 amostras de efluentes coletadas em sistema de tratamento por lodos ativados (LA) foram analisadas de modo a quantificar bactérias nitrificantes por meio de duas técnicas: tubos múltiplos ou técnica do número mais provável (NMP); e hibridação in situ fluorescente (FISH). Os resultados sugerem que houve uma tendência de se obter valores diferentes para bactérias oxidadoras de amônia por meio da NMP em comparação com a FISH. Não obstante, a análise estatística revelou que a diferença de quantificação encontrada entre as técnicas não foi significativa, indicando que ambas podem ser usadas. Para as oxidadoras de nitrito, não foi possível realizar comparação, uma vez que os gêneros que estavam sendo determinados em cada uma das técnicas provavelmente eram diferentes. Sendo assim, as técnicas NMP e FISH se mostraram métodos relativamente simples e adequados para quantificação de microrganismos nitrificantes, com vantagens e limitações inerentes a cada uma.

ABSTRACT The quantification of nitrifying bacteria is of utmost importance for monitoring biological treatment systems designed to promote nitrification. In this study, 15 activated sludge samples were analyzed in order to quantify nitrifying bacteria by two different methods: the most-probable number (MPN); and the fluorescence in situ hybridization (FISH). The results suggest that there was a tendency to obtain different values for ammonia-oxidizing bacteria by MPN compared to FISH. However, statistical analysis of these data revealed that the difference found between the two techniques was not significant, indicating that both can be used for quantification of ammonia-oxidizing bacteria. For nitrite-oxidizing bacteria it was not possible to make this comparison, since the bacterial genera that were being determined in each technique were likely different. Thus, MPN and FISH techniques proved to be relatively simple and suitable for quantification of nitrifying microorganisms in sludge samples, each of them with advantages and limitations.

Seasonal variations in abundance of nitrifying bacteria in fish pond ecosystem.

Seasonal changes in abundance of nitrifiers (ammonia-oxidizing and nitrite-oxidizing bacteria) in surface and bottom water of freshwater ponds were examined with respect to temperature, DO, pH as well as concentration of ammonia and nitrite. The most probable number (MPN) of ammonia-oxidizers in different ponds varied from 1297±3.6 to 1673.23±0.36 ml-l in bottom and 720.5±8.1 to 955.3±10.8 ml-l in surface water during the rainy season while the MPN ranged from 1074±1.07 to 1372.17±4.6 ml-l in bottom and 515±10.1 to 678±11.8 ml-l in surface water in winter. However, the MPN were greatly reduced in summer and ranged from 435.05±15.7 to 547.54±2.12 ml-l in bottom and 218.7±7.3 to 368.4±9.32 ml-l in surface water. Similar seasonal trends were also observed in MPN of nitrite-oxidizers. Among all the physico-chemical parameters, abundance of nitrifiers was more positively correlated with ammonia and nitrite concentration in all the seasons. The abundance of nitrifiers in surface and bottom water was highest in rainy season followed by winter and modest in summer. The potential nitrification activities and oxidation rates were shown to be linear and activity of ammonia-oxidizing and nitriteoxidizing bacteria was highest during rainy season.

Study on the Conservative Property and Decay Kinetic of Nitrite Oxidizing Bacteria / 中国生物工程杂志

One factor at a time design and first order exponential model were applied to investigate the effects of the four major factors(temperature,ionic strength,pH and osmo-regulator) in the preservation process of nitrite oxidization bacteria(NOB),and a first order decay kinetics was introduced.The result showed that the anoxic decay rate of nitrifying bacteria reduced from 0.25 to 0.015,the half life was extend to 53d at 4℃,pH7.60,ionic strength 0.035mol/kg.The protecting effect of glycerin showed obviously better than that of other cryoprotectants at 4℃.

Analysis of Microbial Flora in Full Autotrophic Ammonium Removal System / 微生物学通报

The microbial flora of fungi,bacterial and actinomycetes in full autotrophic ammonium removal reactor and activated sludge was analyzed,and the amount of nitrite-oxidizing bacteria and ammonia-oxidizing bacteria was also compared.The result showed that the population,species,species number and dominates of microorganisms in full autotrophic ammonium removal reactor were different from that in activated sludge.In full autotrophic ammonium removal reactor,the amount of ammonia-oxidizing bacteria was increased remarkably which indicated that the accumulation of ammonia-oxidizing bacteria was a remarkable feature of full autotrophic ammonium removal system.

Studies on the Culture and Applicayion of a Nitrite-oxidizing Bacterium with High Nitrification Activity / 微生物学通报

As to a nitrite-oxidizing bacterium screened in our laborator y, the effect of pH, nitrogen sources, carbon sources and sodium chloride on its g rowth was studied in order to obtain high cell density. It showed that the cult ure conditions of nitrite- oxidizing bacterium were 4500mg/L sodium nitrite, 1 .5g/L sodium carbonate, 0~0.5% sodium chloride and 0~0.1% glucose at 28℃~30 ℃, 110 r/min and pH 8.0~8.5. After cultivation for 9 days, the bacteria conc entration reached 4.6?109 MPN/mL and all NO-_2-N in the medium w as converted to NO-_3-N. But the transformation of nitrogen sources was inhibited while the sodium chloride concentration exceeded 0.5% or glucose con centration exceeded 0.1%. According to the test of NO-_2-N conversion with nitrite-oxidizing bacteria in a freshwater aquaculture pond, NO-_2 -N began to decrease on the third day of the moculation of this bacterium and t he concentration dropped from 1.47mol/L to 0.49mol/L after 18 days at 25℃ and pH 8.6.