Removal Rate Of NH3-N Research Articles

Conventional bioretention column with Fe-hydrochar for stormwater treatment: Nitrogen removal, nitrogen behaviour and microbial community analysis

An FeCl3-modified rice husk hydrochar (‘Fe-hydrochar’) was used as the filler in a conventional bioretention column to remove nitrogen from synthetic stormwater. When the ammonia nitrogen (NH4-N) and nitrate nitrogen (NO3-N) concentrations of the influent were both 20 mg/L, the average removal rates of NH4-N and total nitrogen (TN) were approximately 97% and 50%, respectively. Nitrogen was mainly removed by microbial nitrification and denitrification, with 25% of NH4-N being adsorbed by the Fe-hydrochar. The remaining NH4-N was converted into NO3-N by nitrification in the upper layer, and NO3-N was mainly converted to nitrogen gas (N2) by denitrification in the lower layer. The organic matter released by the Fe-hydrochar was degraded and used as the carbon source for denitrification. The dominant bacteria were Pseudomonas, Rhizobium, and Flavobacterium at the genus level. Pseudomonas and Rhizobium were responsible for heterotrophic nitrification–aerobic denitrification, while Flavobacterium was related to the degradation of organic matter.

An experimental study on the use of a sequencing-batch membrane bioreactor (SBMBR) for the treatment of mixed municipal wastewater.

Several water treatment techniques have been combined using the sequencing batch reactor with the membrane bioreactor for addressing water pollution. However, cleaning of the membrane is dependent on the approach involved as well as the operating conditions. In the present study, the sequencing-batch membrane bioreactor was used to treat real mixed municipal wastewater. The pollutant removal and membrane filtration performances were examined. The results show that the average removal rates of chemical oxygen demand (COD), total nitrogen, NH3-N, total phosphorus, and turbidity were 90.75, 63.52, 92.85, 87.58, and 99.48%, respectively, when the system was in continuous operation for 95 days. The membrane had a significant effect on COD and turbidity removal and provided stable performances for nitrogen and phosphorus removal. By observing the appearance of the membrane modules before and after the cleaning operation, it was concluded that the deposited sludge and granular sediment on the membrane surface can be effectively removed by hydraulic cleaning. In addition, recovery of membrane filtration performance to 60% of that of a new membrane can be achieved. Furthermore, we found that different sequences and duration of cleaning have different effects on the recovery of membrane filtration performance.

Design of modular constructed wetland and its effect on rural domestic sewage treatment

According to the characteristics of large amount and scattered discharge of domestic sewage in rural residential environment, a rural domestic sewage treatment system based on modular constructed wetland was designed. The wetland is composed of three modules with a treatment scale of 30 m3/d. The plants are Arundo donax and Typha, and three kinds of filter media are selected to fill the substrate. The treatment capacity and treatment effect of the modular constructed wetland were studied through experiments. The results showed that the modular constructed wetland had a good treatment effect on sewage, and the average removal rates of BOD5, COD, SS, NH3-N, TN and TP were 83.3%, 83.5%, 90.5%, 70%, 66.9% and 68.3%, respectively. The treated water quality can meet the first class standard of water pollutants discharge standard for rural domestic sewage treatment and disposal facilities (DB37/3693-2019) of Shandong Province. The modular constructed wetland can be used to treat rural scattered domestic sewage with strong applicability, flexibility and feasibility.

Evaluation of Galdieria sulphuraria for nitrogen removal and biomass production from raw landfill leachate

This study evaluates the potential of thermophilic mixotrophic alga, Galdieria sulphuraria, to efficiently perform on-site treatment of landfill leachate (LL). Nutrient removal and algae growth experiments using various dilutions (20%, 40%, 60%, 80%, 100%) of actual municipal LL were carried out in a 14-day lab scale set-up. The effect of N/P mass ratio (255:1; 100:1; 50:1; 25:1; 10:1; 4.55:1) was also tested. Based on the results, it was evident that the growth reactors with 20% LL outperformed the other growth reactors. The final algal biomass density in 20% LL was 2.16 ± 0.22 g L−1 (twice more than compare to standard media) and the observed growth rate was 159 mg L−1d−1. Fourteen-day removal efficiencies were 99.9% for ammoniacal-nitrogen and 34% for phosphate, with removal rate of 22.78 mg L−1d−1 and 2.91 mg L−1d−1, respectively. Addition of P increased NH4-N removal rate from 16.3 to 23.6 mg L−1 day−1 when N/P mass ratio was changed from 255:1 to 4.55:1. Furthermore, range of N/P mass ratio from 100:1 to 25: 1 has been found to achieve almost 100% removal of both NH4-N and PO4-P from 20% LL in 14 days. Overall, this study showed a promising algal-based treatment system for LL nutrient removal and producing algal-biomass for subsequent value-added product generation.

Electrolysis-enhanced ecological floating bed and its factors influencing nitrogen and phosphorus removal in simulated hyper-eutrophic water.

To enhance ammonia nitrogen (NH3-N) and phosphate (PO43--P) removal in hyper-eutrophic water, electrolysis-enhanced ecological floating bed (EEEFB) was designed with a Mg-Al alloy anode, a Ir-Ta-Ti metal oxide-coated titanium anode, and an Fe anode with the same graphite cathode. The results showed that the Mg-Al alloy anode with graphite cathode had a better ability to enhance NH3-N and PO43--P removal. When the current density was 0.37 mA·cm-2, the electrolysis time was 24 h/d, and the net removal rates of NH3-N and PO43--P were 62% and 99.4%, respectively. In winter, the purification efficiencies of NH3-N and PO43--P were as high as 7388.4 mg·m-2 and 4297.5 mg·m-2, respectively, by EEEFBs which were significantly higher than the traditional ecological floating bed (p < 0.05). Scanning electron microscopy (SEM) and X-ray spectrometry confirmed that the PO43--P was deposited in the sediment of EEEFBs with Mg-Al alloy anode and Fe anode.

Long-term effect of graphene oxide on the aerobic granular sludge wastewater treatment process

This study investigated the bioreactor performance, production of extracellular polymeric substance (EPS), and microbial activity of a granulated sequencing batch reactor (SBR) by increasing the graphene oxide nanoparticle (GO NP) concentration stepwise. The GO NPs reduced the removal of chemical oxygen demand (COD), ammonia, and phosphorus, whereas the nitrite and nitrate contents of the effluent were kept stable during the experiment. The ammonia-nitrogen (NH4-N) and COD removal rates were deceased considerably from 99% and 95–96.2% and 78.6% at 55 mg/L GO NPs; furthermore, at 115 mg/L GO NPs, the NH4-N and COD removal rates further decreased to 88.5% and 59.3%. The removal of phosphorus decreased even at small concentrations of graphene oxide (GO), and the inhibitory effect enhanced with an increase in the GO NP content. The increased amounts of nanoparticles significantly influenced the microbial activity of aerobic granular sludge (AGS). The specific oxygen uptake rate (SOUR) decreased from 42.04 to 33.14 mg O2/g MLVSS*h, specific ammonia oxidation rate (SAOR) declined from 4.84 to 4.12 mg N/g MLVSS*h, specific phosphorus uptake rate (SPUR), and specific phosphorus release rate (SPRR) significantly decreased from 13.1 and 10.05–8.2 and 8.7 mg P/g MLVSS*h after 98 days. However, the specific nitrite and nitrate reduction rate (SNIRR and SNRR), and the specific nitrite oxidation rate (SNOR) remained relatively stable. The EPS content of sludge was initially 5.95 mg/g MLVSS, but the presence of GO up a concentration of 55 mg/L promoted the secretion of EPS and increased to 11.86 mg/g MLVSS. At higher GO concentrations, the secretion of EPS was inhibited. After 14 days, when the influent synthetic wastewater (SWW) did not contain GO NP, the AGS SBR performance showed a remarkable recovery capability.

Effect Analysis of Sequential Batch Membrane Bioreactor on Mixed Municipal Sewage Treatment

The removal efficiency of pollutants and the development of membrane fouling were investigated by using sequencing batch membrane bioreactor (SBMBR) to treat mixed municipal wastewater without membrane cleaning. The results showed that under the condition of DO 1.0 ∼ 2.0 mg/L and operating cycle 6h, the system operated continuously for 89d, and the pollutant removal effect was good. The average removal rates of COD, TN, NH3-N, TP and turbidity were 89.4%, 70.6%, 89.9%, 91.1% and 99.4%, respectively. In addition, the enhanced removal of COD and turbidity was significant, and the removal of nitrogen and phosphorus was stable. Moreover, the membrane filtration pressure difference rose slowly, and the membrane filtration performance was relatively stable during the continuous operation of the system.

Enhance biological nitrogen and phosphorus removal in wastewater treatment process by adding food waste fermentation liquid as external carbon source

The problem of poor carbon source is a common technical bottleneck inhibiting the nutrients removal in biological wastewater treatment. This study aimed to investigate the feasibility of using food waste (FW) fermentation liquid (FL) as the external carbon source to enhance biological nitrogen and phosphorus removal (BNPR) in sequencing batch reactors. It was found that the ammonium nitrogen (NH4-N) and phosphate (PO4-P) in FL was not need to be removed before it was added into wastewater treatment system, and the added FL did not cause the external deterioration of NH4-N and PO4-P removal. The effect of volume ratio of FL to wastewater (FL/W) on BNPR process was investigated, and the results suggested the optimum ration of FL/W was 1/90. Compared to the control system with no acetic acid and FWFL as external carbon source, the experimental system with 1/90 of FL/W exhibited higher PO4-P and NH4-N removal efficiencies, which were 92.70 % and 92.38 %. Moreover, the analysis of this study suggested that the high removal rates of PO4-P and NH4-N were mainly attributed to the extra volatile fatty acid in added FWFL and the accumulated intracellular polyhydroxyalkanoates (PHAs) in anaerobic stage, which could be the main energy sources for the denitrification and PO4-P removal.

A three-dimensional and multi-source integrated technology system for controlling rural non-point source pollution in the Three Gorges Reservoir Area, China

Techniques for controlling rural non-point source pollution (RNSP) represent cleaner production techniques that can provide an effective guarantee for regional sustainable development. The majority of studies on RNSP control technologies are mainly aimed at handling only a single pollution source. However, such studies are difficult to perform in rural areas, which have dense populations, complex terrains and extreme climates, such as the Three Gorges Reservoir Area (TGRA), China. Therefore, this paper focuses on the application of the RNSP control technologies based on the following four aspects: crop planting, livestock production, domestic inputs and water-level-fluctuating (WLF) zone. Based on the unique topography, land features and planting patterns of the TGRA, a three-dimensional (3D) and multi-source integrated technology system for controlling RNSP was established according to the principle of source reduction, runoff regulation, and nitrogen (N) and phosphorus (P) loss control. From the results of the long-term observations, the risk of RNSP has been significantly reduced in the study area. The nutrient capacity of the soil increased by 9–15%, while the chemical fertilizer application reduced by 30–50%. The loss of sediment, N and P were reduced by 60–80%, 30–70% and 50–90% in the sloping land at the backslope, respectively, by 30–60%, 70–90%, and 70–90% in the paddy field at the footslope, respectively, and by 75–90%, 30–50%, 65–95% in the WLF zone, respectively. The average removal rates of COD, NH3-N and TN in sewage in the residential area were higher than 82%, 87% and 63.3%, respectively. Overall, more than 90% of RNSP was reduced by using this 3D and multi-source technology system, and it can be widely promoted for controlling RNSP in similar ecological areas with support from local governments by implementing effective measures, such as strengthening environmental protection education and government subsidies.

Treatment of high-ammonia-nitrogen landfill leachate nanofiltration concentrate using an Fe-loaded Ni-foam-based electro-Fenton cathode

Abstract In order to treat high-ammonia-nitrogen (NH3-N) landfill leachate nanofiltration concentrate (LLNC), an Fe-loaded, activated C-based Ni-foam composite electrode was prepared via ferrous ion impregnation and calcination in a nitrogen atmosphere. The composite electrode was used as a cathode and combined with a dimensionally stable anode (DSA) to form the electro-Fenton system. On the basis of single-factor experiments, a response surface methodology (RSM) was applied to evaluate the influence factors. A second-order polynomial was then obtained, and the optimum treatment conditions for the LLNC were found to include an applied voltage of 10 V, initial pH of 2.81, electrode spacing of 1.53 cm, chemical oxygen demand (COD) removal rate of 77.24 % at 300 min, and an applied voltage of 9.02 V, initial pH of 3.90, electrode spacing of 1.04 cm, and an NH3-N removal rate of 74.62 %. Three-dimensional excitation-emission matrix fluorescence spectroscopy of the LLNC before and after the electro-Fenton reaction revealed that the fluvic and humic acid-like substances, as well as the soluble microbial byproducts, were effectively removed from the LLNC. These results indicate that the electro-Fenton system can both inhibit the consumption of Fe ions and efficiently reduce the pollution indices (e.g., COD, NH3-N, and color) of LLNC without the addition of a Fenton's reagent or the production of Fe-sludge.

Pilot-scale Study on Removal of Pollutants in Tannery Wastewater and Sludge Reduction by Biological Synergist Effect

The characteristics of tannery wastewater are complex composition, high suspended substance (SS) and heavy sludge load. Adding the functional bacteria agent into the Aerobic system and Sludge digestion tank can improve the biological system activity and reduce sludge discharge. The pilot-scale study results show that: The removal of CODcr and NH3-N was improved after biological synergy. The average removal rate of CODcr was 90.1% and the average removal rate of NH3-N was 97.4%, both of which were higher than the control group. The excess sludge reduction of the system could reach 75.16%, and the effect of sludge reduction was obvious in the experimental group. After biological synergy, the number of bacteria in aerobic pool increased significantly, and the microbial flora migrated in a better direction.

The influence of flow rates and water depth gradients on the growth process of submerged macrophytes and the biomass composition of the phytoplankton assemblage in eutrophic water: an analysis based on submerged macrophytes photosynthesis parameters.

Submerged macrophytes and phytoplankton assemblage play significant roles in the functioning of aquatic ecosystems. An experiment was carried out in Beijing in order to further evaluate the environmental factors that affect the growth of submerged macrophytes and phytoplankton assemblage. Submerged macrophytes (i.e., Vallisneria natans, Hydrilla verticillata, and Ceratophyllum demersum) constructed the growth system with some controllable influencing factors (i.e., the flow rate and water depth gradient). The flow rates were set separately as 4L/h (1#), 6L/h (2#), and 12L/h (3#), while the water depth gradient was of 0.5-1.7m in eutrophic water. Generally, all macrophytes could grow normally in the experiment, and the system could maintain and improve the effluent quality. The average removal rates of NH3-N, COD, NO3-N, TN, and TP were about 90%, 33%, 65%, 45%, and 40%, respectively. Seen from the results of the water depth gradient experiments, it is indicated that Vallisneria natans grows better in shallow water (0.5m) and moderate shallow water (0.7m) area, with an average relative growth rate (ARGA) of 57%. Hydrilla verticillata and Ceratophyllum demersum grow better in moderate deep water (1.2m) and deep water (1.7m) area (ARGA of 66% and 64%, respectively). Results of the flow rate experiments showed that the moderate flow rate (6L/h) was the best for those three macrophytes' growth. As the fitting results of the rapid light curves (RLCs) showed that the utilization of light and the tolerance to strong light were different for these macrophytes, if they are ranked in the order of the utilization and the tolerance from strong to weak, they are Hydrilla verticillata, Ceratophyllum demersum, and Vallisneria natans. Microbial analyses indicated that the overall system diversity of the experimental groups have been improved after cultivation of macrophytes. However, the accumulated Cyanobacteria caused by the low flow rate (1#) would lead to the suppression of microbial organics decomposition and nutrient metabolism in the macrophytes. To sum up, the results of this study provided theoretical guidance and technical support for the restoration of submerged macrophytes in eutrophic water.

Study on the treatment of livestock farm wastewater by falling water aeration constructed wetland

The livestock farms produce wastewater with high concentration of nitrogen and phosphorus through water rinsing, which is treated by building constructed wetlands. In order to improve the removal efficiency of nitrogen, the author set up a water tank, through falling water aeration to obtain a higher concentration of oxygen to promote nitrification and denitrification reaction. Experiments showed that the removal rates of BOD, NH3-N, TN and TP were 88%, 79.9%, 90.8% and 91.1% respectively. The results show that the experimental removal effect is good, and the results have practical significance for the treatment of aquaculture wastewater.

Partial nitritation and anaerobic ammonium oxidation in biofilter reactors treating low ammonium strength wastewater

Partial nitritation (PN) and anaerobic ammonium oxidation (ANAMMOX) were applied in biofilter reactors to treat low ammonium strength wastewater. The removal efficiency and contribution of PN-ANAMMOX process to CODcr, BOD5, NH3-N, TN and TP were investigated. The results showed that the average removal rates of CODcr, BOD5, NH3-N, TN and TP via PN-ANAMMOX process were 91.9%, 96.7%, 98.9%, 92.8% and 93.3% respectively when hydraulic load was 1.0 m/d. The effluent CODcr, BOD5, NH3-N, TN and TP concentrations were lower than 13.8, 4.8, 0.76, 4.4 and 0.28 mg/L, respectively. The PN-ANAMMOX process showed high efficiency and stability in removing C, N and P pollutants from wastewater. PN reactor played a major role in the removal of CODcr, BOD5, NH3-N and TP. ANAMMOX reactor played a leading role in TN removal.

Practical application of domestic sewage in a new compound biological filter

The application of a new composite biofilter with a batch-type mud membrane composite biofilter (CSBF) series deep treatment filter (EBF) combination in urban domestic sewage was studied. The results of 20-day operation data show that the new filter process has good removal effect on COD, NH3-N, TN and TP. The average removal rate of COD during operation is 94.63%, the average removal rate of NH3-N is 99.02%, and the average removal rate of TN is 77.89%. The average removal rate of TP is 97.99%, and each index is stable to the first-class A standard of GB8978-1996, in which COD, NH3-N and TP can reach the surface water class IV standard.

Magnetic field intervention on growth of the filamentous microalgae Tribonema sp. in starch wastewater for algal biomass production and nutrients removal: Influence of ambient temperature and operational strategy

This paper investigated the effects of temperature and cultivation methods (batch or semi-continuous culture) on the filamentous microalgae Tribonema sp. biomass production and nutrients removal in starch wastewater under low intensity magnetic field (MF) intervention. The MF significantly promoted algal growth in the late logarithmic-phase of batch cultivation, and the effect was even more obvious at lower temperatures. The MF treated group at 30 °C accumulated the highest biomass of 4.44 g/L of batch culture, an increase of 15.0% compared with the control group. The oil content of Tribonema sp. was enhanced with the MF intervention, especially for the batch culture. In the semi-continuous culture under MF intervention, Tribonema sp. reached the high biomass of 18.45 g/L after 25 days. When gradually reducing hydraulic retention time (HRT) to 1 day, the average removal rates for COD, TN, NH3-N and TP were all more than 90% in the semi-continuous cultivation.

Resource utilization of landfill leachate gasification in supercritical water

In this paper, original landfill leachate gasification in supercritical water was studied in high heating rate batch reactor. The experiments were carried out in the temperature range of 500–650 °C, residence time range of 0–30 min, and pressure range of 22.5–26.0 MPa. The effects of temperature, pressure, residence time, catalysts and oxidant on gasification, chemical oxygen demand (COD) and NH3-N removal rate were examined. As a result, high heating rate could promote landfill leachate gasification in supercritical water better. High temperature and long residence time could improve gasification efficiency. The highest carbon gasification efficiency (CE) reached 99.2% and hydrogen yield reached 26 mol/kg with KOH at 650 °C, 30 min. KOH could also improve COD and NH3-N conversion significantly. The highest COD and NH3-N removal rate was 94.6% and 51.0%, respectively. The addition of oxidant had the same effect on NH3-N elimination obtained with KOH. The results of experiments might predicate that the combination of catalytic and partial oxidation might be an effective method to remove NH3-N for landfill leachate gasification in supercritical water.

Study on Treatment of Domestic Wastewater by Biological Aerated Filter

Biological aerated filter (BAF) is a simple and efficient low-consumption urban wastewater treatment technology in line with China’s national conditions, with the characteristics of land area, high treatment efficiency and convenient operation and management. In this paper, the experimental research and theoretical analysis of BAF treatment of domestic sewage are carried out. The results show that the time required to start the hanging film of BAF is short, and the removal rate of COD and NH4-N is stable at about 75% and 60% respectively after about 24 days. When the aeration 0.25m3/h was maintained, the average removal rate of COD reached 88.73%, the average removal rate of NH4-N reached 65.49%, and the average removal rate of TP was 89.98%.

Predicting removal kinetics of biochemical oxygen demand (BOD) and nutrients in a pilot scale fed-batch algal wastewater treatment system

Our previous reports have presented single-step treatment of primary-settled urban wastewater by a mixotrophic alga, Galdieria sulphuraria. Here, we present an approach to predict the operational cycle time, t*, required to meet the discharge standards for ammoniacal-nitrogen (NH3-N), phosphate (PO4) and biochemical oxygen demand (BOD) in fed-batch mode, under varying influent concentrations. First order removal rates of NH3-N, PO4 and BOD, determined using data from 10 fed-batch cycles in a pilot scale system (700 L), were used to predict their temporal fate and t* in 30 other cycles. Predicted concentrations of NH3-N, PO4, and BOD and t* over a wide range of influent concentrations agreed well with the measured ones, with root mean square errors, respectively, of 2.06 mg/L, 0.23 mg/L, 2.88 mg/L and 0.30 days. The coefficient of determination between the measured and the predicted values were as follows: for NH3-N: r2 = 0.82, n = 90; for PO4: r2 = 0.87, n = 90; for BOD: r2 = 0.70, n = 30; and for t*: r2 = 0.61, n = 30. The validity of the model in predicting temporal concentration profiles of NH3-N, PO4 and BOD reflected by Janus quotient (respectively of 0.85, 0.87 and 0.61) is comparable to or better than those reported in the literature. Sensitivity analysis procedures identified the influent concentration of PO4 as the most sensitive parameter in predicting t*.

Simultaneous removal of NH3-N and COD from shale gas distillate via an integration of adsorption and photo-catalysis: A hybrid approach

In view of the circulation cooling water (CCW) quality for refining and petrochemical enterprises, distillates obtained from shale gas produced water after alkali precipitation, filtration and multi-effect evaporation required further purification to remove NH3-N and COD. Illumination, adsorption, photocatalysis after adsorption equilibrium (AP) and integration of adsorption and photocatalysis (IOAP) were carried out to optimize the distillates treatment. AP and IOAP treatments were feasible for the simultaneous removal of NH3-N and COD from the target distillate, while IOAP treatment had much better adaptability and practicability due to its economic cost and easy operation. In IOAP, the removal rate of COD and NH3-N was high up to 59.0% and 88.9%, respectively, under Xenon lamp illumination (25 A) for 60 min with 10 g/L zeolite. The residual concentration of COD and NH3-N were 73.9 mg/L and 23.0 mg/L, respectively, which could well meet the CCW quality. Furthermore, the results of zeolites characterization (SEM-EDX, BET and FTIR) and kinetics analysis showed that the removal of COD in IOAP process mainly depended on the effect of photocatalysis excited by zeolite, while the removal of NH3-N was in virtue of the synergistic effect of photocatalysis and adsorption.