Nitrite Nitrogen Removal Research Articles

Analysis of the regulation mechanism for salt-tolerant anammox process: process performance and metabolic insights

ABSTRACT : In this study, the start-up and microbial domestication of a salt-tolerant functional anammox system was investigated by gradually increasing the salinity level in a stabilized anammox system in the laboratory. After 44 days of stable operation, the salt-tolerant system was successfully activated, at which time the salinity of the influent water was 3 g/L, and the maximum removal efficiency of ammonia nitrogen and nitrite nitrogen in the system reached 94.18% and 96.66%, respectively, and then the ammonia nitrogen and nitrite nitrogen removal efficiency were stabilized at 88.17% and 96.48% after the enrichment domestication for 89 days. The system was operated in the salinity of 10 g/L, with the concentration of each nitrogen compound measured at the same time. The ammonia nitrogen removal efficiency decreased to 59.93% at a salinity of 10 g/L, which had a significant impact on the system. High-throughput sequencing revealed that the system was enriched with a large number of Chloroflexi, the relative abundance of which increased from 19.46% to 52.33%, and the genus of AnAOB was transformed from Candidatus Brocadia to Candidatus Kuenenia, Candidatus Kuenenia, with a percentage of 4.78%. The system successfully achieved the simultaneous removal of ammonia nitrogen and nitrite nitrogen under salinity stress, which to a certain extent indicated that AnAOB could achieve the initiation and enrichment domestication under salinity conditions, and could provide a basis for the efficient and low-consumption treatment of high salinity nitrogen-containing wastewater.

Nitrogen removal performance and rapid start-up of anammox process in an electrolytic sequencing batch reactor (ESBR)

In this study, the electrolytic sequencing batch reactor (ESBR) with different current densities was constructed to investigate the nitrogen removal performance and rapid start-up of anaerobic ammonia oxidation (anammox) process. The changes of total nitrogen removal rate (TNRR), specific anammox activity (SAA) and nitrogen concentration under different current densities were analyzed, and then the effect of the optimal current density on the start-up of anammox in ESBR was explored. The results showed that ammonium nitrogen removal efficiency (92.7%), nitrite nitrogen removal efficiency (15.5%) and total nitrogen removal efficiency (28.1%) were obtained with the TNRR and SAA were 0.0118 g N L−1 d−1 and 0.0050 g N (g Vss d)−1, respectively under the optimal conditions (i.e., current density = 0.10 mA cm−2, temperature = 36 °C and pH = 7.6). In addition, the stoichiometric ratio indicated that anammox was initiated successfully for 91 days in ESBR with the current density of 0.10 mA cm−2, which was shortened by 10 days compared with the conventional SBR without current density. These results suggest that an array of rapid start-up processes of anammox can be developed through applying current density to stimulate the activity of anammox bacteria (AnAOB).

Nutrient Removal Efficiency and Growth of Watercress (Nasturtium officinale) under Different Harvesting Regimes in Integrated Recirculating Aquaponic Systems for Rearing Common Carp (Cyprinus carpio L.)

The harvesting of plant biomass is usually implemented as an effective tool for plant management and removing the nutrients absorbed in plant tissues. Here, the influence of harvesting different biomasses (50%, 33%, 25%, and 0% (no harvest)) of watercress (Nasturtium officinale) was investigated in integrated recirculating aquaponic systems (IRASs) for rearing common carp (Cyprinus carpio). Twelve independent IRASs were designed (4 × 3); each system consisted of a fish rearing tank, a waste collection tank, and a hydroponic bed. Water quality parameters and the growth of both fish and plants were measured in all the systems, and then the nutrient removal capacities of the hydroponic beds were calculated. The results revealed that increasing the biweekly harvested biomass of the plants decreased the growth of the watercress, while it did not affect the growth of the common carp. Increasing the harvested biomass of the plants also decreased the nitrate nitrogen and orthophosphate removal efficiencies of the aquaponic systems, while it did not affect the ammonia and nitrite nitrogen removal efficiencies. Therefore, a biweekly harvesting of less than 25% of the biomass of the growing watercress is recommended for efficient nutrient removal and the sustainable growth of both watercress and the common carp in aquaponic systems.

Substrate Inhibition and Kinetic Characteristics of Marine Anaerobic Ammonium Oxidizing Bacteria Treating Saline Wastewater

An anaerobic sequencing batch reactor (ASBR) was used to study substrate inhibition and kinetic characteristics of marine anaerobic ammonium oxidizing bacteria (MAAOB) treating saline wastewater. The results indicated that when ammonia increased to 1200 mg·L-1, the MAAOB still maintained good nitrogen removal capability, though there was a slight inhibitory effect. At the same time, nitrite nitrogen removal efficiency was stable at about 80.70%. When nitrite increased to 265.6 mg·L-1, the MAAOB were inhibited obviously, and ammonia nitrogen removal efficiency decreased to about 63.01%. When influent nitrite concentration increased to 305.6 mg·L-1, the removal rate of ammonia nitrogen further decreased to 43.93%. The kinetic characteristics resulting from inhibition of the MAAOB were simulated by the Haldane model and Aiba model. Three parameters, TNRRmax, KS, and Ki, and the relationship between effluent substrate concentration and total nitrogen loading (TNRR) were evaluated. Based on further analysis, the Haldane model was more suitable for describing dynamic characteristics resulting from NH4+-N inhibition, while the Aiba model was more suitable for describing the dynamic characteristics resulting from NO2--N inhibition. The predicted effluent inhibitory concentrations of NH4+-N and NO2--N were 3893.625 mg·L-1 and 287.208 mg·L-1, respectively. The results could provide a theoretical basis for saline wastewater treatment by MAAOB.

Ammonia and nitrite nitrogen removal in shrimp culture by Vibrio alginolyticus VZ5 immobilized in SA beads

The toxicity of nitrogen in the shrimp culture water has been well established. In this study, SA beads composed of Vibrio alginolyticus VZ5, sodium alginate (SA) and sugarcane bagasse were used for ammonia nitrogen (NH4-N) and nitrite nitrogen (NO2-N) removal. A 50-day cultivation experiment was carried out in aquaria to evaluate the activity of the SA beads in shrimp culture. The results indicate that SA beads have a maximum capacity of 1.06 × 108 colony-forming units (cfu)/bead. However, the optimal initial density of the bacteria embedded in the SA beads is 104–105 cfu/bead. The maximum NO2-N degradation rate achieved for the SA beads was 8.44 mg/L/day, and the average NO2-N degradation per bead was 0.06 mg. The addition of a carbon source accelerated the degradation of NH4-N and NO2-N by the SA beads. The NH4-N and NO2-N concentrations after treatment with SA beads were below 1.55 and 1.62 mg/L, respectively, at later time points, and these concentrations were significantly lower than in the group without any treatment (P 0.05, df = 29), and the yield resulting from water treatment with SA beads reached approximately 70 % of the yield with water exchange treatment. Moreover, the particulate organic carbon and dissolved organic carbon concentrations in the water were enhanced by the addition of SA beads. At later time points, some of the SA beads had broken down, and the sugarcane bagasse from the SA beads may have served as a carbon source for forming bioflocs. The new approach proved effective for NH4-N and NO2-N removal in shrimp culture.

Study on the Salinity Domestication and Mechanism of Nitrite Nitrogen Removal of <i>Acinetobacter lwoffii</i>

In this paper, the salinity domestication and mechanism of nitrite nitrogen removal ofAcinetobacter lwoffiiwere studied.The results showed that the optimum domestication salinityof the bacteria was 0.5% NaCl. It was speculated that the bacteria might have both oxidase andreductase, transform the nitrite nitrogen into ammonium nitrogen and nitrate nitrogen, and then usethem to synthesis the body protein. It also found that high concentrations of sodium nitrite hadinhibition effect on the bacteria growth.

Impact of Silica Nanoparticles on the Heterotrophic Denitrification

Silica nanoparticles (Si NPs) have a wide range of uses in semiconductors, battery cathode material, and high power laser source materials. However, Si NPs would flow into the wastewater treatment inevitably, and then potentially harmful interactions can occur between nanoparticles and wastewater systems, especially in denitrification process. The present study was aimed to investigate the effects of Si NPs on nitrate nitrogen removal under anaerobic conditions by employing activated sludge. Our data demonstrates that Si NPs had positive effects on denitrification at the beginning and did not display any measurable effect on nitrite nitrogen removal at the concentration of 100 mg/L and below. The denitrification process was elucidated by using the first-order reaction kinetics equation. This study provided useful data for understanding the effects of Si NPs on wastewater treatment.

Inhibition of biomass activity in the via nitrite nitrogen removal processes by veterinary pharmaceuticals

The inhibitory effect of two veterinary pharmaceuticals was studied for different types of biomass involved in via nitrite nitrogen removal processes. Batch tests were conducted to determine the inhibition level of acetaminophen (PAR) and doxycycline (DOX) on the activity of short-cut nitrifying, denitrifying and anoxic ammonium oxidation (anammox) biomass and phosphorus accumulating organisms (PAOs). All biomass types were affected by PAR and DOX, with anammox being the most sensitive bacteria. DOX inhibited more the biomass treating high strength nitrogenous effluents (HSNE) than low strength nitrogenous effluents (LSNE). The phosphorus uptake inhibition under anoxic conditions was lower than 25% in the presence of PAR up to 400 mg L(-1). The same DOX concentration inhibited anoxic phosphorus uptake more than 65% for biomass treating LSNE and HSNE. Heterotrophic denitrifying bacteria seem to be more robust at high DOX and PAR concentrations than anammox. Both veterinary products inactivated ammonium oxidizing, Accumulibacter phosphatis and denitrifying bacteria.

Chemical Treatment for Nitrite Nitrogen Removal From Stainless Steel Pickling Liquor Wastewater

Chemical Treatment for Nitrite Nitrogen Removal From Stainless Steel Pickling Liquor Wastewater

Nitrogen removal from polluted river by enhanced floating bed grown canna

Floating beds of canna can remove nitrogen from polluted river water, but the removal efficiency is not very high in a short time, so some enhanced methods must be used to improve nitrogen removal efficiency by the system. Immobilized denitrifying bacteria and aeration were added into the canna floating bed. The experimental results showed that these enhancements substantially improved the nitrogen removal efficiency of the floating beds. With the enhancements, total nitrogen removal was 72.1%, ammonia nitrogen oxidation was 100%, nitrate nitrogen removal was 75.8%, nitrite nitrogen removal was 95.9%, and COD removal was 94.6% in 5 days. Without the enhancements, the canna floating bed system removed only 50.4% of the total nitrogen, 22.4% of the nitrate nitrogen, 5.3% of the nitrite nitrogen and 39.9% of the COD, respectively, in 5 days, but did accomplish 100% oxidation of the ammonia nitrogen. The experimental results provide an improved method for the treatment of polluted river water.

Nitrogen and Phosphorus Discharge during Spring Regeneration of Constructed Wetlands at a Commercial Nursery

Mitigation of offsite movement of nutrients in nursery runoff is a serious concern for commercial nurseries with container-grown plants. Wight Nurseries, Cairo, Ga. has operated 3.77 ha of planted constructed wetlands since 1996 to remediate nutrients from runoff. The wetlands receive drainage from a 48.6 ha nursery production area. Monitoring by nursery staff had suggested net export of nitrogen and phosphorus may occur during spring regeneration. Intensive monitoring was conducted between early March and mid-May 2003. There was no net export of nitrogen during the study. Nitrite nitrogen removal remained at 100% in the 1st stage wetland throughout March but declined in April to 89.6% as loading increased 5-fold. However, the 2nd stage wetland removed 100% of the remaining nitrite. Nitrate removal in the 1st stage wetland was high through early April (97.6%) but low in 2nd stage wetlands (16%) until loading increased 10-fold when efficiency rose to 94.9%. Nitrate removal by the 1st stage declined during mid-April but 2nd stage efficiency remained above 95%. For phosphorus, there was net export during March from both stages. However, during April, the wetlands removed phosphorus although loading tripled during the month. In May, net export of phosphorus from the wetlands recommenced with peak 1st stage export of 130% and 2nd stage uptake declining until mid-May when export began again. Neither water temperature nor rainfall appeared correlated with wetland efficiency. While phosphorus was exported by the wetlands during parts of the study, neither nitrate nor nitrite was exported as spring progressed and decomposition of last year's growth accelerated.

Monitoring Wetland Mitigation of Nutrient Contaminants from Container Nursery Offsite Drainage

Container-grown plants from commercial nurseries require large amounts of water and nutrients during their production cycle resulting in substantial runoff contaminated with nitrogen and phosphorus. Thus, mitigation of nutrients from exiting runoff water is a serious concern for horticultural concerns. Wight Nurseries of Monrovia Growers, Cairo, Ga., has installed 3.77 ha of planted wetlands to receive direct runoff in excess of recapture needs from a 48.6 ha drainage basin and excess water diverted from adjacent watersheds. Water flows though trench drains between wetland cells and eventually into stilling ponds before it is allowed to exit the property. Water flow through the wetlands ranges from 1.6 million to 2.2 million liters per day. Two years of monitoring data indicates strong seasonal differences in nitrate and nitrite nitrogen removal efficiencies. Nitrogen removal between April and November averaged 93.3% while removal during winter months averaged 44.1%. Nitrite was not found in wetland discharge water samples. Nitrogen as nitrate in discharge water varied from 0.05 ppm to 4.3 ppm, well below drinking water quality standards, and was below 0.6 ppm between June and November except in September during construction activity. Orthophosphate phosphorus removal was highly variable with highest removal during late spring, averaging 33.6%, and some removal during early fall, averaging 13.8%. However, there was a significant net export of phosphorus from the wetlands during winter months and during periods of low vegetative growth. Phosphorus levels ranged between 0.9 and 1.9 ppm. While there is currently no legal water quality standard, these levels are above the generally accepted level of 0.01 ppm for preventing downstream eutrophication.

ANAMMOX and partial denitritation in anaerobic nitrogen removal from piggery waste

The anaerobic ammonium removal from a piggery waste with high strength (56 g COD/L and 5 g T-N/L) was investigated using a lab-scale upflow anaerobic sludge bed reactor at a mesophilic condition. Based on the nitrogen and carbon balance in the process, the contribution of autotrophic and heterotrophic organisms was also evaluated in terms of the influent NO2-N/NH4-N ratio (1:0.8 and 1:1.2 for Phase 1 and Phase 2, respectively). The result of this research demonstrates that the anaerobic ammonium removal from the piggery waste, using the UASB reactor, can be performed successfully. Furthermore, it appears that by using granular sludge as the seed biomass, the ANAMMOX reaction can start more quickly. Average nitrogen conversion was 0.59 kg T-N/m3 reactor-day (0.06 kg T-N/kg VSS/day) and 0.66 kg T-N/m3 reactor-day (0.08 kg T-N/kg VSS/day) for Phase 1 and Phase 2. The NO2-N/NH4-N removal ratio by the ANAMMOX was 1.48 and 1.79 for Phase 1 and Phase 2. The higher nitrite contents (about 50%) in the substrate resulted in higher nitrite nitrogen removal by the partial denitritation, as well as the ANAMMOX reaction, implying higher potential of partial denitritation. However, the result reveals that the ANAMMOX reaction was influenced less by the degree of partial denitritation, and the ANAMMOX bacteria did not compete with denitritation bacteria. The colour of the biomass at the bottom of the reactor changed from dark gray to dark red, which was accompanied by an increase in cytochrome content. At the end of the experiment, red-coloured granular sludge with diameter of 1-2 mm at the lower part of the reactor was also observed.