Influent NO Research Articles

Factors affecting the treatment of reject water by the anammox process

Reject water from a municipal wastewater treatment plant was treated using a stirred tank anammox reactor after being treated by a partial nitrification reactor. The results indicated the variations in the influent NO 2 - -N to NH 4 + -N ratio had a negative effect on reactor performance, especially when the T–N concentrations were high. Influent total organic carbon concentrations greater than 50 mg/L were proven to have a serious effect on the nitrogen removal efficiencies of the anammox reactor. Observations by scanning electron microscope showed that the surface of the anammox granular sludge was covered by some materials, possibly the effluent SS contained in the partial nitrified reject water. Furthermore, the study of the bacterial composition of the anammox granular sludge showed that the anammox bacterium, Planctomycete KSU-1, was dominant, even during the inhibition phase.

Nitrate removal rates in woodchip media of varying age

A variety of low-cost carbonaceous solids have been successfully tested in bioreactors designed for nitrate treatment. In many agricultural and wastewater settings, however, such reactors may be practical only if they are maintenance free for a number of years after installation. Although field installations have demonstrated consistent treatment over multi-year timeframes, the ability to accurately quantify slowly declining reaction rates in field settings is problematic because of variations in reactor flow rates, ambient temperatures and influent chemistry. In this study, laboratory column tests were undertaken on four samples of coarse wood particle media (woodchips), two that were fresh and two that had been in continuous operation in subsurface denitrifying bioreactors for periods of 2 and 7 years respectively. Four experimental runs were undertaken at increasing influent NO 3-N concentrations of from 3.1 to 48.8 mg N L −1. Nitrate mass removal rates remained relatively constant and did not systematically increase in successive runs at higher NO 3 concentrations indicating that NO 3 was not the rate-limiting substrate at these concentrations. Thus, zero-order reaction kinetics were used to model the attenuation reaction (presumably denitrification). The 7-year-old media had a mean NO 3-N removal rate of 9.1 mg N L −1 d −1 (6.4 g N m −3 media d −1), which remained within 75% of the rate for the 2-year-old media (12.1 mg N L −1 d −1 or 8.5 g N m −3 media d −11) and within 40–59% of the rate for the fresh chips (15.4–23.0 mg N L −1 d −1 or 10.8–16.1 g N m −3 media d −1). Results support field experience indicating that woodchips loose about 50% of their reactivity during their first year of operation as soluble organic compounds are leached out, but then relatively stable rates persist for a considerable number of years thereafter.

Competition for Single Carbon Source Between Denitrification and Phosphorus Release in Sludge under Anoxic Condition

In order to investigate the competition for carbon source between denitrification and phosphorus release processes, simultaneous phosphorus release and denitrification in sludge operated in anoxic, aerobic mode are investigated by varying the ratio of influent COD to nitrogenous compound concentration under anoxic condition using a lab-scale sequencing batch reactor (SBR). The results show that the nitrate reduction rate is nearly independent of the ratio of influent COD to nitrate under anoxic condition. More NO − x -N in the influent leads to less PO 3− 4 -P release during the feeding period. However, PO 3− 4 -P release proceeds at a low rate simultaneously with denitrification even when the influent NO − x -N concentration is as large as 20 mg·L −1 and its rate is increased obviously when NO − x -N is denitrified to a concentration lower than 0.5 mg·L −1. The variation of pH during anoxic period gives some information about the biochemical reactions of denitrification and PO 3− 4 -P release. When more nitrate is present in the influent, more acetate uptake in feeding period is used for direct microorganism growth.

Autohydrogenotrophic denitrification of drinking water using a polyvinyl chloride hollow fiber membrane biofilm reactor

A hollow fiber membrane biofilm reactor (MBfR) using polyvinyl chloride (PVC) hollow fiber was evaluated in removing nitrate form contaminated drinking water. During a 279-day operation period, the denitrification rate increased gradually with the increase of influent nitrate loading. The denitrification rate reached a maximum value of 414.72 g N/m 3 d (1.50 g N/m 2 d) at an influent NO 3 −–N concentration of 10 mg/L and a hydraulic residence time of 37.5 min, and the influent nitrate was completely reduced. At the same time, the effluent quality analysis showed the headspace hydrogen content (3.0%) was lower enough to preclude having an explosive air. Under the condition of the influent nitrate surface loading of 1.04 g N/m 2d, over 90% removal efficiencies of the total nitrogen and nitrate were achieved at the hydrogen pressure above 0.04 MPa. The results of denaturing gel gradient electrophoresis (DGGE), 16S rDNA gene sequence analysis, and hierarchical cluster analysis showed that the microbial community structures in MBfR were of low diversity, simple and stable at mature stages; and the beta-Proteobacteria, including Rhodocyclus, Hydrogenophaga, and beta-Proteobacteria HTCC379, probably play an important role in autohydrogenotrophic denitrification.

Anammox enrichment from different conventional sludges

Three sets of sequencing batch reactor (SBR) were used for Anammox enrichment from conventional sludges including upflow anaerobic sludge blanket, activated sludge, and anaerobic digestion sludge. After four months of operation, the Anammox activity occurred in all reactors allowing continuous removal of ammonium and nitrite. The morphology of the cultivated Anammox sludge was observed using scanning electron microscope. The photographs showed that the obtained culture was mostly spherical in shape, presumably Anammox culture. There were also filamentous-like bacteria co-existing in the system. Fluorescene in situ hybridization (FISH) analysis using 16S rRNA targeting oligonucleotide probes PLA46 and Amx820 showed that the dominant population developed in all SBRs was hybridized with both PLA46 and Amx820 gene probes. It means that the cultivated biomass in all SBRs was classified in the group of Planctomycetales bacteria with respect to the anaerobic ammonium-oxidizing bacteria, Candidatus Brocadia anammoxidans and Candidatus Kuenenia stuttgartiensis. Numerous time sequences were tested in this experiment. The shortest workable reaction time was found in the range from 5 to 7 h. Good quiescence of sludge was obtained at 30 min of settle period followed by a discharge period of 15 min. A long-term performance showed a near perfect removal of nitrite based on the influent NO 2 - – N concentration of 50–70 mg l −1. The maximum ammonia removal efficiency was 80% with the influent NH 4 + – N concentration of 40–60 mg l −1. It is, therefore, concluded that Anammox cultivation from conventional sludges was highly possible under control environment within four months.

Removal of nitrate in aquaria by means of electrochemically generated hydrogen gas as electron donor for biological denitrification

A hydrogenotrophic denitrification reactor was designed for the removal of nitrate from aquaria. An average hydrogen gas transfer up to 130 mg per day from the gas to the water phase was accomplished by recirculating the water from the denitrification reactor over a separate trickling filter column with a volume of 1.3 l. During batch experiments removal rates up to 36 mg N/l reactor per day were recorded at a hydraulic residence time of 12 h. To avoid the need for storage of large volumes of hydrogen gas in aquarium or aquaculture applications, an electrochemical cell was used to generate hydrogen gas. During a 7 day aquarium test, a nitrate removal rate up to 18.5 mg N/l reactor per day was recorded at an influent NO 3 −–N concentration of 20 mg/l.

The characteristics of anaerobic ammonium oxidation (ANAMMOX) by granular sludge from an EGSB reactor

An expanded granular sludge bed (EGSB) reactor was started-up by seeding the anaerobic sludge from a brewery wastewater treatment plant. After 3 months operation, the granular sludge occurred in the reactor and the ammonium nitrogen could be removed continuously. The morphology and inner structure of the granules was observed using scanning electron microscopy (SEM) and the photographs indicated that the anaerobic granular sludge was relatively regular in shape. The outer layer had a rather fluffy and loose structure and was more transparent compared to the centre of the granule. The centre of the granule had a dense structure. The long-term operational results showed that the maximal removal efficiency of NH 4 +–N was 40% when the influent NH 4 +–N concentration was 70–250 mg/L; the NO 2 −–N removal efficiency was more than 98% when the influent NO 2 −–N concentration was 70–250 mg/L; and the COD removal efficiency was 84% at the influent concentration of 500 mg/L. This revealed that the reaction of anaerobic ammonium oxidation (ANAMMOX) probably taken place in the EGSB reactor. In order to validate the existence of ANAMMOX reaction and investigate the performance of nitrogen removal by anaerobic granular sludge, the granular sludge taken from EGSB reactor and the activated sludge taken from partial-nitrification reactor was used to treat synthetic wastewater. The experimental results demonstrated that for the activated sludge, the removal efficiency of total nitrogen (TN), NH 4 +–N and NO 2 −–N was 45.5, 13.4 and 99.9%, respectively; for the anaerobic granular sludge, they were 54.3, 21.7 and 99.9%, respectively. The removal rate of NH 4 +–N was stable, about 3.17 mgN/(L h). At the beginning of the reaction, the ANAMMOX process was performed mainly through the pathway of interaction between NH 4 +–N and NO 2 −–N, as time went on, with the exhaustion of NO 2 −–N, the granular sludge could use NO 3 −–N as electron acceptor to oxidize NH 4 +–N, yielding dinitrogen gas. In this research, the COD removal efficiency was about 90.4%. In the light of estimation of COD consumption, the anaerobic granular sludge could use organic carbon source as electron donor, reduce NO 2 −–N and NO 3–N, to carry out the traditional denitrification. The results obtained in this study reveal that in the anaerobic granular sludge reactor the ANAMMOX reaction took place, accordingly, the existence of an anaerobic ammonium oxidation phenomenon in the EGSB reactor could be deduced.

Hydrogenotrophic denitrification of drinking water using a hollow fibre membrane bioreactor

Research Article| May 01 2001 Hydrogenotrophic denitrification of drinking water using a hollow fibre membrane bioreactor Sarina J. Ergas; Sarina J. Ergas 1Department of Civil and Environmental Engineering, University of Massachusetts, 18 Marston Hall, Amherst, MA 01003, USATel: 413-545-3424; Fax: 413-545-2202; E-mail: ergas@ecs.umass.edu, http://www.ecs.umass.edu/cee/faculty/ergas.htmlgradient E-mail: ergas@ecs.umass.edu Search for other works by this author on: This Site PubMed Google Scholar Andreas F. Reuss Andreas F. Reuss 2Procter & Gamble GmbH & Co. Manufacturing, OHG Industriepark Am Silberberg 53877, Euskirchen, Germany, 2251-121030 E-mail: reuss.a@pg.com Search for other works by this author on: This Site PubMed Google Scholar Journal of Water Supply: Research and Technology-Aqua (2001) 50 (3): 161–171. https://doi.org/10.2166/aqua.2001.0015 Views Icon Views Article contents Figures & tables Video Audio Supplementary Data Share Icon Share Twitter LinkedIn Tools Icon Tools Cite Icon Cite Permissions Search Site Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentAll JournalsThis Journal Search Advanced Search Citation Sarina J. Ergas, Andreas F. Reuss; Hydrogenotrophic denitrification of drinking water using a hollow fibre membrane bioreactor. Journal of Water Supply: Research and Technology-Aqua 1 May 2001; 50 (3): 161–171. doi: https://doi.org/10.2166/aqua.2001.0015 Download citation file: Ris (Zotero) Reference Manager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex The objective of this research was to investigate the performance of a hollow fibre membrane bioreactor (HFMB) for hydrogenotrophic denitrification of contaminated drinking water. In the HFMB, H2 flows through the lumen of the hydrophobic hollow fibres and diffuses to an attached H2 oxidizing biofilm. Nitrate in the contaminated water serves as an electron acceptor. A hydrogenotrophic denitrifying culture was enriched from a wastewater seed. Batch culture experiments were conducted to compare heterotrophic (methanol as electron donor) and hydrogenotrophic denitrification rates and to investigate the conditions required for the HFMB studies. The batch cultures demonstrated mixotrophy, with denitrification rates of 30 g NO−3-N m−3 d−1 for heterotrophic and 18 g NO−3-N m−3 d−1 for hydrogenotrophic conditions. A laboratory-scale HFMB was constructed that utilized 2,400 polypropylene hollow fibres with an inner diameter of 200 µm, an outer diameter of 250 µm and a 0.05 µm pore size. After a 70-day start-up period, the NO−3 loading rate was gradually increased over a three-month period. The NO−3 utilization rate reached a maximum of 770 g NO−3-N m−3 d−1 at an influent NO−3 concentration of 145 mg NO−3-N l−1 and a hydraulic residence time of 4.1 hours. Influent NO−3 concentrations of up to 200 mg NO−3-N l−1 were almost completely denitrified. Tests with contaminated water from the Cape Cod aquifer resulted in an increase in product water turbidity and dissolved organic carbon (DOC) concentrations. biological denitrification, bioreactor, drinking water, hydrogen, membranes, nitrate This content is only available as a PDF. © IWA Publishing 2001 You do not currently have access to this content.

Biotrickling Filtration of Nitric Oxide

ABSTRACT A biotrickling filter with blast-furnace slag packings (sizes = 20-40 mm and specific surface area = 120 m2/m3) was utilized to treat NO in an air stream. The operational stability, as well as the effects of gas empty-bed retention time (EBRT) and nutrient addition on the removal ability of NO, were tested. Approximately six weeks were required for the development of a biofilm for NO degradation, and a two-week organic carbon deficiency resulted in the detachment of biofilms from the packing surfaces. A steady removal rate of 80% was attained at specified influent NO concentrations of 892 to 1237 ppm and an EBRT of 118 sec. The effluent NO concentration diminished exponentially with enlarging EBRT, with influent NO concentrations of 203-898 ppm, and EBRTs of 25 to 118 sec. Nutrient addition is essential for efficient removal of the influent NO. Mass ratios of C: P: N = 7: 1: 30 and NaHCO3: NO-N = 6.3 could be used for practical applications.

Nitrate removal in riparian wetland soils: Effects of flow rate, temperature, nitrate concentration and soil depth

Riparian zones, located adjacent to intensely managed agricultural fields, are thought to play an important role in removal of nutrient contaminants including NO − 3 from groundwater. We studied the effect of flow rate, NO − 3 concentration and temperature on NO − 3 removal in soil columns under saturated-flow conditions. Bibb (coarse-loamy, siliceous, acid thermic Typic Fluvaquent) sandy loam soil was collected from a riparian forest located in Nomini Creek Watershed, Virginia. Soils included in the study were a permanently inundated surface horizon, a seasonally saturated surface horizon, a shallow subsurface horizon and a deep subsurface horizon. Soil columns were infiltrated with NO − 3 amended groundwater at concentrations from 14 to 36 mg NO − 3-N L −1. Column operating temperatures varied between 8 and 20°C and flow rates between 0.01 and 0.09 mL min −1. Following a 48 h equilibrium period, effluent NO − 3 and N 2O concentrations were determined. Denitrification was the primary mechanism of NO − 3 removal, with higher denitrification capacities found in the surface horizons. Effluent NO − 3 concentrations could be described by a linear combination of temperature, flow rate and influent NO − 3 concentrations. Low temperatures and increased flow rates reduced the denitrification capacity in all soils. Our results showed that the NO − 3 removal capacity present in the Bibb soil should theoretically be sufficient to remove most, if not all, NO − 3 from the groundwater at the Nomini Creek study site. However, on-site measurements of NO − 3 concentration in receiving streams indicated that this capacity is not fully realized in the field, suggesting the importance of other factors such as local hydrology and groundwater flow patterns.

High-rate seawater denitrification utilizing a macro-porous cellulose carrier

Continuous denitrification experiments were undertaken using marine denitrifying bacteria immobilized in a macro-porous cellulose carrier. The denitrifying capacity of this immobilized system was examined using an ejector-type bioreactor at pH 8.0, 30°C, under anaerobic conditions. In addition, the immobilized denitrifying bacteria were isolated and characterized. The results showed that complete denitrification will not occur unless (i) a phosphorus (g) per NO 3-N (g) ratio ( P NO 3-N ) of 0.029, (ii) 0.01% trace element solution (containing Fe, Mn, Mo, etc.) at 280 g/m 3 NO 3-N concentration and (iii) a methanol concentration at 30% more than the theoretical carbon concentration requirement are maintained. Copper enhanced nitrite reduction at an influent Cu (g) per influent NO 3-N (g) ratio ( Cu NO 3-N ) of 0.002. Based on these results, a feeding medium was formulated which not only reduced costs but, more importanly, allowed the maximum NO 3-N loading rate of 24.8 kg-N/m 3-carrier/d (at a NO 3-N influent concentration and hydraulic retention time of 500 g/m 3 and 5 h, respectively). This value is comparable to that of freshwater in which a macro-porous cellulose carrier was also employed, indicating the insensitivity of the immobilized denitrifying bacteria to salinity. The morphological and physiological characterisitics of the immobilized denitrifying bacteria showed similarities to Hyphomicrobium spp.

Denitrification with external carbon source utilizing adsorption and desorption capability of activated carbon

The adsorption-desorption capability of activated carbon was incorporated into biological denitrification process with the addition of external carbon source for nitrogen removal in water and wastewater treatment. Laboratory scale column packed with granular activated carbon (GAC) was fed with nitrate and sucrose in various modes. Other than continuous organic carbon addition (continuous mode), two different dynamic feeding modes, namely intermittent and injection modes were investigated. Under intermittent mode, organic carbon source was added in accordance with cycles consisting of two stages: an organic carbon feeding stage and an organic carbon starvation stage. Three cycle schedules in terms of duration of feeding stage and starvation period were examined. In injection mode, concentrated organic substrate was fed into the columns for 10 min at frequencies of 1, 2 or 3 times per day. With substrate C:N ratio of 1.88, influent NO 3N level of 20 mgl −1 and empty bed contact time (EBCT) of 80 min, intermittent mode produced high overall N removal efficiencies ranging from 89 to 95% which are comparable with levels attainable under continuous mode. Injection mode achieved slightly lower but reasonably high denitrification efficiencies. Under the conditions employed, once per day organic substrate injection was sufficient to remove 87% of the influent NO 3N. The performance of anthracite media was also compared with GAC under both continuous and intermittent modes using identical set of conditions. Anthracite performed equally well under continuous mode where organic carbon source was always available. However, under intermittent mode, anthracite gave a poor N removal efficiency of 29% during the starvation period due to the lack of adsorption and desorption capability in comparison with 90% obtained in GAC media. The adsorption and desorption property of activated carbon was also applied in denitrification process for the treatment of water or wastewater with fluctuating influent NO − 3 concentration levels. Two cases of NO − 3 fluctuation were examined and in both cases, overall N removal efficiencies of more than 93% were achieved.

High loading denitrification by biological activated carbon process

High loading denitrification was studied using granular activated carbon (Calgon Filtrasorb 400, size: 0.8–1.4 mm) column with injecting carbon source (sucrose) only once a day. Under the condition of EBCT (empty bed contact time) = 80 min, C:N ratio = 1.88, once per day injection mode of organic supply was able to sustain an average denitrification efficiency of 84 to 89% even with influent NO 3N concentration of 80 mgl −1. With an influent NO 3N of 20 mgl −1 and C:N ratio of 1.88, however, reduction of EBCT to 20 min resulted in very poor denitrification. In the latter case, 46% of the added carbon was lost in the effluent immediately after the injection. Short EBCT critically affected the process mainly due to insufficient adsorption rate. Microbial denitrification capability and fermentation might also limit the process. Extended organic injection is a possible option to improve the process efficiency. Occurrence of the sulfate reduction was limited in early phase of the cycle.

Optimization of Denitrification Process

A denitrification system composed of a completely stirred tank reactor (CSTR) followed in series with a plug flow reactor (PFR) was tested in order to minimize the disadvantages of each process when used separately. High efficiency of NO 3 -N removal and good process control can be achieved with the series treatment system using 25% of the volume required with a single CSTR reactor. Most influent NO 3 -N concentrations were greater than 1000 mg/l, and these usually result in effluent concentrations less than 50 mg/l. The effluent NO 3 -N concentration was reduced to less than 0.5 mg/l with a total hydraulic detention time of 1.7 hr when the influent NO 3 -N concentration was 80 mg/l. Design conditions which would minimize treatment volume requirements would include microbial mass loadings (g NO 3 -N g VSS/ day in the CSTR and PFR of 2.0 day - ¹, and 0.2 day - ¹, respectively, resulting in a 40% removal efficiency in the CSTR reactor and greater than 95% NO 3 -N removal efficiency in the total system. The microbial yield averaged 0.11 g VSS synthesized per g of COD removed.

Disappearance of nitrate under transient conditions in columns of soil

Previously a rapid reduction of NO 3 − was obtained in soil columns with continuous flow, before the establishment of steady state conditions. This initial behavior was not a function of flow rates. In order to determine what influence NO 3 − concentrations might have on transient and steady state rates, of NO 3 − loss, small soil columns (2·5 cm i.diam × 10 cm length) were infiltrated with 0, 100 and 1000 μg ml −1 NO 3 −N and the effluents were analyzed daily for NO 3 − and NO 2 −. Several days after an apparent steady state had been obtained, as determined by the effluent NO 3 − concentration, the influent NO 3 − concentrations were changed to 100 μg ml −1 NO −N in some of the columns. All columns showed transitions to new and identical steady state of NO 3 − loss from flowing solutions. Evidently the initial transient kinetics are primarily determined by some solubilization of organic matter during rewetting of air dry soil and subsequent steady states are dependent on lesser available organic matter.