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PubMed2004

Effects of seawater salinity on nitrite accumulation in short-range nitrification to nitrite as end product.

The effect of seawater salinity on nitrite accumulation in short-range nitrification to nitrite as the end product was studied by using a SBR. Experimental results indicated that the growth of nitrobacteria was inhibited and very high levels of nitrite accumulation at different salinities were achieved under the conditions of 25-28 degrees C, pH 7.5-8.0, and the influent ammonia nitrogen of 40-70 mg/L when seawater flow used to flush toilet was less than 35% (salinity 12393 mg/L, Cl- 6778 mg/L) of total domestic wastewater flow, which is mainly ascribed to much high chlorine concentration of seawater. Results showed that high seawater salinity is available for short-range nitrification to nitrite as the end product. When the seawater flow used to flush toilet accounting for above 70% of the total domestic wastewater flow, the removal efficiency of ammonia was still above 80% despite the removal of organics declined obviously (less than 60%). It was found that the effect of seawater salinity on the removal of organics was negative rather than positive one as shown for ammonia removal.

Ammonia↗

PubMed2004

Effect of an industrial waste water on the nitrification in fixed-bed biofilm reactors--use of fluorescence in-situ hybridization (FISH).

The influence of an industrial waste water containing partly toxic and poorly biodegradable substances on an autotrophic biocenosis was investigated. Nitrifying bacteria were identified using fluorescently-labeled oligonucleotide probes and epifluorescence microscopy. Industrial waste water was used untreated and after ozonation to simulate the effects of indirect discharge to municipal waste water treatment plants. Results were compared to those obtained with acetate as a non-toxic and easily biodegradable substance and a mixture of acetate and pyruvate. The degradation of ammonium and the formation of nitrite and nitrate were measured and compared with the results obtained by fluorescence in-situ hybridization (FISH). The untreated waste water, containing higher amounts of refractory substances, disturbed nitrification, which was restored after reaching higher elimination of the organic substances. However, it showed only minor effects on the bacterial composition. These findings were similar to those reached by the addition of acetate and pyruvate. On the other hand, the ozonated waste water, showing higher toxicity than the untreated waste water, caused a stabilization in nitrification, but the composition of the population of ammonium-oxidizing bacteria changed significantly. In all cases, nitrite-oxidizing bacteria were only little affected both in activity and abundance.

Biodegradation, Environmental↗

PubMed2004

Nitrogen removal from pharmaceutical manufacturing wastewater with high concentration of ammonia and free ammonia via partial nitrification and denitrification.

In this study, laboratory-scale experiments were conducted applying a Sequencing Batch Reactor (SBR) activated sludge process to a wastewater stream from a pharmaceutical factory. Nitrogen removal can be achieved via partial nitrification and denitrification and the efficiency was above 99% at 23 degrees C+/-1. The experimental results indicated that the nitrite oxidizers were more sensitive than ammonia oxidizers to the free ammonia in the wastewater. The average accumulation rate of nitrite was much higher than that of nitrate. During nitrogen removal via the nitrite pathway, the end of nitrification and denitrification can be exactly decided by monitoring the variation of pH. Consequently, on-line control for nitrogen removal from the pharmaceutical manufacturing wastewater can be achieved and the cost of operation can be reduced.

Ammonia↗

PubMed2004

Wastewater treatment in a hybrid biological reactor (HBR): nitrification characteristics.

OBJECTIVE: To investigate the nitrifying characteristics of both suspended- and attached-biomass in a hybrid bioreactor. METHODS: The hybrid biological reactor was developed by introducing porous ceramic particles into the reactor to provide the surface for biomass attachment. Microorganisms immobilized on the ceramics were observed using scanning electron microscopy (SEM). All chemical analyses were performed in accordance with standard methods. RESULTS: The suspended- and attached-biomass had approximately the same nitrification activity. The nitrifying kinetic was independent of the initial biomass concentration, and the attached-biomass had a stronger ability to resist the nitrification inhibitor. CONCLUSION: The attached biomass is superior to suspended-biomass for nitrifying wastewater, especially that containing toxic organic compounds. The hybrid biological reactor consisting of suspended- and attached-biomass is advantageous in such cases.

Biomass↗

PubMed2005

[Terramycin wastewater treatment with combination hydrolysis-denitrification-nitrification].

Successive hydrolysis-denitrification-nitrification process is adopted to treat terramycin wastewater in lab scale for 70 days. Two sludge bed reactors are used respectively for hydrolysis and denitrification, and two biofilm reactors are used for nitrification. When the COD and NH4+ -N concentrations in influent were 2 200 - 3 000mg/L and 400 - 460mg/L, more than 80% COD and TN removals were achieved under a total HRT of 56h. The COD of the effluent was reduced to 293mg/L through coagulation under a polyferric sulfate dose of 48mg/L as Fe.

Biodegradation, Environmental↗

PubMed2005

[Operation performance of membrane nitrification bioreactor for ammonia-containing wastewater].

The operation performance of membrane nitrification bioreactor to treat ammonia-containing wastewater as well as the capabilities of separation and filtration of polypropylene membrane modules were tested. The removal efficiency of ammonia was kept higher than 95% when the hydraulic retention time was set at 1 day, the influent concentration was increased up to 80 mmol (NH4+ -N) x L(-1) and the volume loading rate was increased up to 1.12 kg (NH4+ -N) x m(-3) x d(-1). The biomass in the reactor was accumulated from 5 g x L(-1) to 10 g x L(-1) within 50 days, which indicated that polypropylene membrane modules were efficient in retaining biomass. The biomass attached to the membrane also contributed to the conversion of ammonia and nitrite. When the hydraulic pressure was lower than 80cm, the increase of hydraulic pressure improved the permeation of membrane. However, when the hydraulic pressure was beyond 80cm, the increase of hydraulic pressure did not significantly improve the permeation of membrane. The permeate flux was the highest 2.51 (L x m (-2) x h(-1)) but the resistance was the lowest (2.63 x 10(-5)) m(-1) when the hydraulic pressure was about 20 cm. The results showed that the membrane nitrification bioreactor could be run normally without extra energy input.

Biodegradation, Environmental↗

PubMed2005

Performance of a pilot-scale high rate algal pond system treating abattoir wastewater in rural South Australia: nitrification and denitrification.

As part of a study examining the efficacy of high-rate algal pond treatment of high-strength abattoir wastewater, the impact of pond configuration and loading rate on nitrification was determined. The extent of nitrification in all ponds was consistent with mass balance estimates of oxygen demand and availability. Deeper ponds were more stable nitrifying systems, with shallow ponds displaying greater variation in response to changes in nitrogen loading. In a separate experiment the pond system was modified by covering a part of an in-series HRAP to exclude light, providing conditions suitable for denitrification. Specific denitrification rates were often within the range typical for endogenous carbon sources, with mass balance calculations indicating removals of up to 95%.

Abattoirs↗

PubMed2005

Treatment of nitrogen-rich wastewater using partial nitrification and anammox in the CANON process.

Partial nitrification combined with Anammox in a single reactor (the CANON process) is an energy-efficient N-removal technology that could substantially lower the N-load of a WWTP by separate treatment of nitrogen-rich side streams, preventing the need for extensive expansion and reducing the total energy requirement. This study looks at the enrichment of Anammox from activated sludge and its application in the CANON process on lab-scale. The aim was to identify the critical process control parameters necessary for successful operation of CANON. An Anammox culture capable of removing 0.6 kg N/m3/d was enriched in 14 weeks in a sequencing batch reactor. Nitrifying biomass was inoculated into the Anammox reactor (10% v/v) together with limited oxygen supply (< 8 mL/min) to initiate the CANON process in continuous culture. The small flocs formed by the biomass (< 1000 microm) were sensitive to low O2 concentrations (< 0.1 mg/L) which prevented simultaneous nitrification and Anammox. Operation with 20 min aerobiosis and 30 min anaerobiosis was necessary to achieve sustained, completely autotrophic N-removal for an extended period at a rate of 0.08 kg N/m3/d. Essential process control parameters for stable CANON operation were the nitrite concentration, oxygen concentration, pH and the temperature.

Ammonia↗

PubMed2005

Importance and measurement of decay rate when assessing nitrification kinetics.

Nitrification kinetics are important for process design, optimization and capacity rating of activated sludge wastewater treatment plants. Assessment of nitrification behaviour historically has focused on measuring the nitrifier maximum specific growth rate, micro(AUT). Very little attention has been directed at the of nitrifier organism rate has been assumed negligible. However, incorrect assessment of decay rate leads to errors in the micro(AUT) estimate; the magnitude of the error depends on the micro(AUT) measurement method employed. This paper illustrates why decay rate is important when measuring micro(AUT), and that the decay rate is significant. The paper also explains why measurement methods for nitrifier decay may have underestimated the decay rate. Results from an experiment incorporating improvements to previously suggested methods and data analysis are presented.

Ammonia↗

PubMed2006

[Inhibitory effect of pyrazole compound DL-1 on soil nitrification: a preliminary study].

The study with soil incubation test under constant temperature and humidity showed that compared with DCD, DL-1 could significantly inhibit the oxidation of soil ammonium. In the first 3 weeks of incubation, DL-1 had an inhibitory effect of >70% on soil nitrification, with the best effect during 14-28 d of incubation. On the 14, 21, and 28 d of incubation, DL-1 with its dosage being 1.0 % of (NH4)2SO4-N decreased the soil NO3- -N content by 26.23%, 33.27% and 23.31%, respectively, compared with the same dosage of DCD, and by 71.12%, 69.10% and 55.14%, respectively, compared with no inhibitors applied. When the dosage of DL-1 accounted for 2.0% of applied N, soil nitrification was strongly inhibited, and soil NO3- -N content remained at a lower level till to the end (90 d) of incubation.

Ammonia↗

PubMed2006

[Effects of nitrification inhibitors on nitrate content in soil and pakchoi and on pakchoi yield].

A field experiment was conducted on two soil types in the Changsha suburb of Hunan Province to study the effects of hydroquinone (HQ), dicyandiamide (DCD) and thiourea (TU) on the nitrate content in soil and pakchoi and on the yield of pakchoi. The results showed that all the test nitrification inhibitors could significantly decrease the nitrate content in soil and pakchoi during whole growth stage, among which, DCD had the best effect, but the effect was differed on different soil types. Nitrification inhibitors could increase pakchoi yield, DCD was also the best one, and the effect was significantly better on vegetable garden red soil than on vegetable garden alluvial soil. The nitrate content in soil and pakchoi was the highest about 40 days after pakchoi transplanting.

Guanidines↗

PubMed1977

The influence of some herbicides on selected groups of microorganisms in loess and sandy soils. II. The effect of nitrification.

Studies on the effect of herbicides on nitrification in field and laboratory conditions have shown that steady use of these substances in the same field does not exert a significant effect on this process in the soil. The herbicides caused only shortlasting disturbances. Nitrification usually returned to a relative equilibrium in several days after the herbicide application.

2,4-Dichlorophenoxyacetic Acid↗

PubMed1978

Nitrification of industrial wastewaters with high nitrogen concentration.

Industrial wastes from the production of nitrogen fertilizers, containing about 900 mg N/1, (450 mg NH4-N, 300 mg urea-N and 150 mg NO3-N), showed high activity of I stage nitrifying bacteria. The addition of phosphorus to the wastes increases the intensity of nitrification two-fold and also increase the rate of urea hydrolysis. An attempt was made to obtain a nitrifying activated sludge. CaCO3 and Fe(OH)3 were used as carriers and the culture was aerated with air enriched with CO2. After 90 days an activated sludge was obtained which nitrified an average of 80% NH4-N and urea-N with 4-day aeration time of the wastes. In contrast to the activated sludge, the presence of nitrification phase I and II in biological bed was observed, but the efficiency of the process was considerably low (about 38%).

Bacteria↗

PubMed2026

Boosting domestic wastewater treatment with quorum signal-augmented heterotrophic nitrification-aerobic denitrification bacterial-algal aerobic granular sludge.

The aerobic bacterial-algal granular sludge (ABGS) enhanced with heterotrophic nitrification-aerobic denitrification (HN-AD) bacteria, as a novel symbiotic technology, exhibits fluctuating treatment efficiency and unstable performance primarily due to the unstable symbiotic relationship. This study proposes an innovative approach to strengthening the bacteria-algae symbiosis by introducing exogenous signaling molecules. Concurrently, high-throughput, correlation analysis of environmental factors and metagenomic sequencing techniques are employed to elucidate the enhancement mechanisms of the signaling molecules. The results demonstrate that signaling molecule enhancement boosted total nitrogen (TN) removal efficiency by 24.51 % in the bacteria-algae symbiotic system (X1). Scanning electron microscopy (SEM) characterization revealed that the addition of signaling molecules resulted in more compact aerobic granular sludge (AGS) and markedly improved stability. High-throughput sequencing showed signaling molecules enriched denitrifying bacteria (Hydrogenophaga, Pseudoxanthomonas, Thauera, Zoogloea) and organic-degrading Desulfomicrobium, optimizing microbial diversity and enhancing nitrogen/organic removal. Correlation analysis of environmental factors indicate that the addition of C8-HSL facilitates the enrichment and functional activation of specific genera. Metagenomic analysis revealed that signaling molecules enhanced the system's denitrification performance by modulating gene expression and associated metabolic pathways. Quantitative polymerase chain reaction (qPCR) analysis further confirmed that the signaling molecules upregulated the expression of the napA, nirK, and nirS genes. An increased abundance of the napA gene facilitated aerobic denitrification (NO₃⁻-N→NO₂⁻-N), while upregulated abundance of the nirK and nirS genes accelerated nitrite reduction (NO₂⁻-N→N₂). This study aims to provide theoretical and practical foundations for implementing advanced bacteria-algae symbiotic technologies.

Denitrification↗

PubMedDate not supplied

Simultaneous biological nutrient removal: evaluation of autotrophic denitrification, heterotrophic nitrification, and biological phosphorus removal in full-scale systems.

Simultaneous biological nutrient removal (SBNR) is the biological removal of nitrogen and phosphorus in excess of that required for biomass synthesis in a biological wastewater treatment system without defined anaerobic or anoxic zones. Evidence is growing that significant SBNR can occur in many systems, including the aerobic zone of systems already configured for biological nutrient removal. Although SBNR systems offer several potential advantages, they cannot be fully realized until the mechanisms responsible for SBNR are better understood. Consequently, a research program was initiated with the basic hypothesis that three mechanisms might be responsible for SBNR: the reactor macroenvironment, the floc microenvironment, and novel microorganisms. Previously, the nutrient removal capabilities of seven full-scale, staged, closed-loop bioreactors known as Orbal oxidation ditches were evaluated. Chemical analysis and microbiological observations suggested that SBNR occurred in these systems. Three of these plants were further examined in this research to evaluate the importance of novel microorganisms, especially for nitrogen removal. A screening tool was developed to determine the relative significance of the activities of microorganisms capable of autotrophic denitrification and heterotrophic nitrification-aerobic denitrification in biological nutrient removal systems. The results indicated that novel microorganisms were not substantial contributors to SBNR in the plants studied. Phosphorus metabolism (anaerobic release, aerobic uptake) was also tested in one of the plants. Activity within the mixed liquor that was consistent with current theories for phosphorus-accumulating organisms (PAOs) was observed. Along with other observations, this suggests the presence of PAOs in the facilities studied.

Bioreactors↗

PubMed1990

The catabolism and heterotrophic nitrification of the siderophore deferrioxamine B.

Three bacteria, two of which were previously noted as active heterotrophic nitrifiers, were examined for their ability to grow and nitrify with the siderophore deferrioxamine B as the carbon source. Pseudomonas aureofaciens displayed limited growth and nitrification while a heterotrophic nitrifying Alcaligenes sp. was without action concerning its metabolism of deferrioxamine B. The third bacterium, a unique Gram-negative soil isolate, was unable to nitrify deferrioxamine B but grew well when the siderophore was employed as the sole C source. The Gram-negative bacterium removed deferrioxamine B from the medium and left only residual amounts of the compound in solution at the termination of its growth. The organism was without action when the ferrated analogue of deferrioxamine B, ferrioxamine B, served as either the C source for growth, for metabolism by resting cells, or as the substrate for cell-free extracts. Deferrioxamine B, by contrast, was rapidly metabolized by resting cells. Cell-free extracts of the bacterium synthesized a monohydroxamate(s) when deferrioxamine B was the substrate. The catabolism of deferrioxamine B, which is synthesized by soil microbes, suggests that soil microflora have the ability to return deferrioxamine B, and perhaps other, siderophores to the C cycle.

Alcaligenes↗

PubMed1976

Rate constants for nitrification and denitrification in soils.

Rate constants for reactions in flowing solutions in soil can be calculated from extents of reactions as functions of depth, rates of flow, effective biomass of microbes and independent measurements of hydrodynamic dispersion. Constants have been calculated from data in the literature and are shown to be arbitrary unless all of these quantities have been evaluated. Good agreement of constants obtained in laboratory columns and in the field have been obtained for nitrification and denitrification in a few cases.

Bacteria↗

PubMed1980

Effect of temperature on nitrification intensity in soil.

The temperature dependence of nitrification can be expressed by the Arrhenius equation while the time course of nitrate production can be expressed by the Gomperz function. These two findings served as a basis for a mathematical model which makes it possible to calculate nitrate production in the soil even when the temperature changes once or more times during the incubation.

Ecology↗