Struvite pellet crystallization in a high-strength nitrogen and phosphorus stream

2013 ◽  
Vol 68 (6) ◽  
pp. 1300-1305 ◽  
Author(s):  
Yongmei Li ◽  
Mingyan Liu ◽  
Zhiwen Yuan ◽  
Jinte Zou
Keyword(s):  
High Strength ◽  
Ammonia Nitrogen ◽  
Synthetic Wastewater ◽  
Nitrogen And Phosphorus ◽  
Growth Environment ◽  
Ph Values ◽  
Nutrient Removal Efficiency ◽  
Mean Size ◽  
The Mean ◽  
P Removal

Struvite crystallization is a reliable method to recover nutrients from wastewater. Laboratory-scale experiments were conducted to investigate nutrient recovery from synthetic wastewater with high-strength orthophosphate and ammonia-nitrogen by the formation of struvite pellets. Without adjusting pH, struvite crystal growth environment was achieved in ammonia-nitrogen and orthophosphate concentration ranges of 100–1,000 and 221–2,214 mg/L, respectively. The mean size of the harvested struvite pellets was in the range of 3–4 mm. pH is an important factor indicating the process supersaturation. A range of pH 6.2–9.0 was tested in order to enhance nutrient removal efficiency. The results showed although higher N, P and Mg removals were achieved at higher pH values, over 95% N, P and Mg removals were still achieved at pH of 7.6. Recycling ratio of the clarifier supernatant to influent had no significant promotion of N or P removal.

Improvment of nitrogen and phosphorus removal in the anaerobic-oxic-anoxic-OXIC (AOAO) process by stepwise feeding

2000 ◽  
Vol 42 (3-4) ◽  
pp. 89-94 ◽  
Author(s):  
H.Y. Chang ◽  
C.F. Ouyang
Keyword(s):  
Carbon Source ◽  
Phosphorus Removal ◽  
Removal Rate ◽  
Feeding Strategy ◽  
Synthetic Wastewater ◽  
Biological Nutrient Removal ◽  
Nitrogen And Phosphorus ◽  
Nitrogen And Phosphorus Removal ◽  
Kjeldahl Nitrogen ◽  
P Removal

This investigation incorporated a stepwise feeding strategy into the biological process containing anaerobic/oxide/anoxic/oxide (AOAO) stages to enhance nitrogen and phosphorus removal efficiencies. Synthetic wastewater was fed into the experimental reactors during the anaerobic and anoxic stages and the substrates/nutrients were successfully consumed without recycling either nitrified effluent or external carbon source. An intrinsic sufficient carbon source developed during the anoxic stage and caused the NOx (NO2-N+NO3-N) concentration to be reduced from 11.85mg/l to 5.65mg/l. The total Kjeldahl nitrogen (TKN) removal rate was between 81.81%∼93.96% and the PO4-P removal ratio ranged from 93%∼100%. The substrate fed into the anaerobic with a Q1 flow rate and a Q2 into the anoxic reactor. The three difference experiments contained within this study produced Q1/Q2 that varied from 7/3, 8/2, and 9/1. The AOAO process saved nearly one-third of the energy compared with typical biological nutrient removal (BNR) system A2O processes.

A study of NH3-N and P refixation by struvite formation in hybrid anaerobic reactor

2004 ◽  
Vol 49 (5-6) ◽  
pp. 207-214 ◽  
Author(s):  
J.J. Lee ◽  
C.U. Choi ◽  
M.J. Lee ◽  
I.H. Chung ◽  
D.S. Kim
Keyword(s):  
Removal Efficiency ◽  
Ammonia Nitrogen ◽  
Magnesium Ions ◽  
Nitrogen And Phosphorus ◽  
X Ray ◽  
Naked Eye ◽  
N Removal ◽  
Magnesium Salts ◽  
Main Components ◽  
P Removal

This research is concerned with the removal of ammonia nitrogen and phosphorus in foodwaste by crystallization. Reductions have been achieved by struvite formation after the addition of magnesium ions (Mg2+). Magnesium ions used in this study were from magnesium salts of MgCl2. The results of our analysis using scanning electron microscopy and energy dispersive X-ray analysis showed that the amount of struvite in precipitated sludge grew enough to be seen with the naked eye (600-700μm). EDX analysis also showed that the main components of the struvite were magnesium and phosphorus. NH3-N removal efficiency using MgCl2 was 67% while PO4-P removal efficiency was 73%. It was confirmed that nitrogen and phosphorus could be stabilized and removal simultaneously through anaerobic digestion by Mg, NH3 and PO4-P, which were necessary for struvite formation.

scholarly journals Optimization and Modeling of Ammonia Nitrogen Removal from High Strength Synthetic Wastewater Using Vacuum Thermal Stripping

Processes ◽  
2021 ◽  
Vol 9 (11) ◽  
pp. 2059
Author(s):  
Arif Reza ◽  
Lide Chen
Keyword(s):  
High Strength ◽  
Ammonia Nitrogen ◽  
Operating Conditions ◽  
Synthetic Wastewater ◽  
Optimal Conditions ◽  
Waste Streams ◽  
N Removal ◽  
Ann Models ◽  
Artificial Neural Network Ann ◽  
Good Agreement

Waste streams with high ammonia nitrogen (NH3-N) concentrations are very commonly produced due to human intervention and often end up in waterbodies with effluent discharge. The removal of NH3-N from wastewater is therefore of utmost importance to alleviate water quality issues including eutrophication and fouling. In the present study, vacuum thermal stripping of NH3-N from high strength synthetic wastewater was conducted using a rotary evaporator and the process was optimized and modeled using response surface methodology (RSM) and RSM–artificial neural network (ANN) approaches. RSM was first employed to evaluate the process performance using three independent variables, namely pH, temperature (°C) and stripping time (min), and the optimal conditions for NH3-N removal (response) were determined. Later, the obtained data from the designed experiments of RSM were used to train the ANN for predicting the responses. NH3-N removal was found to be 97.84 ± 1.86% under the optimal conditions (pH: 9.6, temperature: 65.5 °C, and stripping time: 59.6 min) and was in good agreement with the values predicted by RSM and RSM–ANN models. A statistical comparison between the models revealed the better predictability of RSM–ANN than that of the RSM. To the best of our knowledge, this is the first attempt comparing the RSM and RSM–ANN in vacuum thermal stripping of NH3-N from wastewater. The findings of this study can therefore be useful in designing and carrying out the vacuum thermal stripping process for efficient removal of NH3-N from wastewater under different operating conditions.

scholarly journals Size and Strength of Tropical Cyclones as Inferred from QuikSCAT Data

2012 ◽  
Vol 140 (3) ◽  
pp. 811-824 ◽  
Author(s):  
Kelvin T. F. Chan ◽  
Johnny C. L. Chan
Keyword(s):  
Tropical Cyclones ◽  
High Strength ◽  
Outer Core ◽  
The North ◽  
Large Size ◽  
Tangential Wind ◽  
Ocean Surface Winds ◽  
Mean Size ◽  
The Mean ◽  
Potential Factors

A comprehensive statistical climatology of the size and strength of the tropical cyclones (TCs) occurring over the western North Pacific (WNP; including the South China Sea) and the North Atlantic (NA; including the Gulf of Mexico and the Caribbean Sea) between 1999 and 2009 is constructed based on Quick Scatterometer (QuikSCAT) data. The size and strength of a TC are defined, respectively, as the azimuthally averaged radius of 17 m s−1 of ocean-surface winds (R17) and the azimuthally averaged tangential wind within 1°–2.5°-latitude radius from the TC center (outer-core wind strength, OCS). The mean TC size and strength are found to be 2.13° latitude and 19.6 m s−1, respectively, in the WNP, and 1.83° latitude and 18.7 m s−1 in the NA. While the correlation between size and strength is strong (r ≈ 0.9), that between intensity and either size or strength is weak. Seasonally, midsummer (July) and late-season (October) TCs are significantly larger in the WNP, while the mean size is largest in September in the NA. The percentage frequency of TCs having large size or high strength is also found to vary spatially and seasonally. In addition, the interannual variation of TC size and strength in the WNP correlate significantly with the TC lifetimes and the effect of El Niño over the WNP. TC lifetime and seasonal subtropical ridge activities are shown to be potential factors that affect TC size and strength.

scholarly journals Energy consumption and performance of a rotating biological contactor treating high-strength wastewater

2021 ◽  
Author(s):  
Rakesh Desai
Keyword(s):  
Energy Consumption ◽  
Angular Velocity ◽  
Oxygen Demand ◽  
High Strength ◽  
Ammonia Nitrogen ◽  
Aeration Rate ◽  
Synthetic Wastewater ◽  
Rotating Biological Contactor ◽  
Unit Energy ◽  
Unit Energy Consumption

Clean water availability, energy costs and the environmental impact of energy usage are major concerns all over the world. At the same time, the Rotating Biological Contactor (RBC) has emerged as a low energy-consuming technology used in wastewater treatment which compares favorably with other treatment methods. RBC is a fixed-film bioreactor employing rotating discs to provide support medium for the microbial growth and to supply dissolved oxygen. RBCs, when applied in the treatment of high strength wastewater, demand some modifications such as the addition of aeration systems or change the flow configuration. Aeration systems certainly reduce the footprint but at the cost of energy consumption. Therefore, the optimization of energy consumption in a modified RBC is a very relevant research objective. This thesis is an investigation on energy optimization in a commercial scale RBC modified with an aeration system and treating high strength synthetic wastewater. The coarse bubble diffuser was replaced by fine bubble air diffusers. To study energy consumption a mono-block main drive system and the central compressed air supply were replaced by a three phase motor with variable frequency drive and an aeration blower respectively. Removal performance and unit energy consumption were studied at various combinations of rotating speed (2.5-5 RPM) and rate of aeration (0-15 SCFM). Constant hydraulic (0.017 m³/m²-day), organic (86.1 gCOD/m²-day) and ammonia (3.444 gNH₃-N/m²-day) loadings were maintained throughout the study. The modified RBC was able to remove 34 to 96% COD and 21 to 68% ammonia depending on the aeration rate and angular velocity. The suspended growth section of the modified RBC contributed 47 to 85% and 38 to 87% of the total removal of COD and ammonia respectively. Conversion of ammonia-nitrogen to nitrate-nitrogen was observed very negligible at 0.26 to 1.59%. The angular velocity, 3.66 RPM and the rate of aeration 8.13 SCFM, were found to be the optimum parameters to achieve minimum unit energy consumption of 1.31 KWH/kg CODr. A mathematical model correlating energy consumption per unit oxygen demand with the rate of aeration and the angular velocity was developed.

scholarly journals Energy consumption and performance of a rotating biological contactor treating high-strength wastewater

2021 ◽  
Author(s):  
Rakesh Desai
Keyword(s):  
Energy Consumption ◽  
Angular Velocity ◽  
Oxygen Demand ◽  
High Strength ◽  
Ammonia Nitrogen ◽  
Aeration Rate ◽  
Synthetic Wastewater ◽  
Rotating Biological Contactor ◽  
Unit Energy ◽  
Unit Energy Consumption

Clean water availability, energy costs and the environmental impact of energy usage are major concerns all over the world. At the same time, the Rotating Biological Contactor (RBC) has emerged as a low energy-consuming technology used in wastewater treatment which compares favorably with other treatment methods. RBC is a fixed-film bioreactor employing rotating discs to provide support medium for the microbial growth and to supply dissolved oxygen. RBCs, when applied in the treatment of high strength wastewater, demand some modifications such as the addition of aeration systems or change the flow configuration. Aeration systems certainly reduce the footprint but at the cost of energy consumption. Therefore, the optimization of energy consumption in a modified RBC is a very relevant research objective. This thesis is an investigation on energy optimization in a commercial scale RBC modified with an aeration system and treating high strength synthetic wastewater. The coarse bubble diffuser was replaced by fine bubble air diffusers. To study energy consumption a mono-block main drive system and the central compressed air supply were replaced by a three phase motor with variable frequency drive and an aeration blower respectively. Removal performance and unit energy consumption were studied at various combinations of rotating speed (2.5-5 RPM) and rate of aeration (0-15 SCFM). Constant hydraulic (0.017 m³/m²-day), organic (86.1 gCOD/m²-day) and ammonia (3.444 gNH₃-N/m²-day) loadings were maintained throughout the study. The modified RBC was able to remove 34 to 96% COD and 21 to 68% ammonia depending on the aeration rate and angular velocity. The suspended growth section of the modified RBC contributed 47 to 85% and 38 to 87% of the total removal of COD and ammonia respectively. Conversion of ammonia-nitrogen to nitrate-nitrogen was observed very negligible at 0.26 to 1.59%. The angular velocity, 3.66 RPM and the rate of aeration 8.13 SCFM, were found to be the optimum parameters to achieve minimum unit energy consumption of 1.31 KWH/kg CODr. A mathematical model correlating energy consumption per unit oxygen demand with the rate of aeration and the angular velocity was developed.

Treatment of Wastewater with a Low Concentration of Organics Using an Anaerobic Fluidized Bed Reactor

1992 ◽  
Vol 25 (7) ◽  
pp. 179-191 ◽  
Author(s):  
A. L. F. C. Maragno ◽  
J. R. Campos
Keyword(s):  
Fluidized Bed ◽  
Bovine Liver ◽  
Fluidized Bed Reactor ◽  
Synthetic Wastewater ◽  
Second Phase ◽  
Nitrogen And Phosphorus ◽  
Hydraulic Residence Time ◽  
The Mean ◽  
Anaerobic Fluidized Bed Reactor ◽  
Phase Phase

In this work performed in the Laboratory of Sanitation of São Carlos Engineering School- University of São Paulo, the results obtained from the operation of a laboratory scale anaerobic fluidized bed reactor are presented for the treatment of a synthetic wastewater with a mean COD of 557 and 700 mg/l during the two phases in which the reactor was studied. In the first phase (Phase A) the mean hydraulic residence time () was maintained at 1.0 h and in the second phase (Phase B), 1.5 h. The duration of each phase, counted from the initial startup period, was 197 days and 108 days, respectively. The reactor was constructed using an acrylic tube of 1.50 m height and a total volume of 10.5 1. The support material consisted of sand with the grains retained between sieves with openings of 0.210 mm and 0.149 mm. The total height of the fluidized bed was maintained at 1.40 m throughout the experiment. The reactor was operated at ambient temperature (13°C to 31°C), and was fed with synthetic wastewater composed mainly of bovine liver extract, glucose, sodium bicarbonate and ammonium acetate. The results of physical and chemical analyses: pH, alkalinity, temperature, volatile acids, COD, nitrogen and phosphorus are presented. An evaluation was also made during the experiment of the thickness of the biofilm gathered on the sand grains collected over the whole height of the reactor. The mean efficiency of COD removal attained was 62% for the first phase and 71% for the second phase.

Cheese whey and cheese factory wastewater treatment with a biological anaerobic–aerobic process

1995 ◽  
Vol 32 (12) ◽  
pp. 59-72 ◽  
Author(s):  
F. Malaspina ◽  
L. Stante ◽  
C. M. Cellamare ◽  
A. Tilche
Keyword(s):  
Cheese Whey ◽  
Batch Reactor ◽  
High Strength ◽  
Anaerobic Treatment ◽  
Ammonia Nitrogen ◽  
Post Treatment ◽  
Hybrid Reactor ◽  
Medium Size ◽  
Nitrogen And Phosphorus ◽  
High Investment

Research on the anaerobic treatment of raw cheese whey started in 1990 with the objective of developing a technology suitable for medium size cheese factories that have growing disposal problems and cannot afford high investment costs for whey valorisation technologies (such as whey protein and lactose recovery, spray drying, etc.). In order to couple process stability and high loads, a new downflow-upflow hybrid reactor (DUHR) has been designed. The reactor was able to reach Bv values around 10 g COD·1−1·d−1, with 98% COD converted to gas and effluent soluble COD values close to 1,000 ppm; no external addition of alkalinity is required to maintain a stable pH that was constantly around 6.5-6.7 in the downflow pre-acidification chamber and around 7.5 in the bio-methanation upflow chamber. The high strength of the cheese whey treated gives an effluent that still contains high amounts of COD, ammonia nitrogen and phosphorus and therefore a post treatment is required in order to meet standard limits. Tests of post treatment were carried out during two years with a Sequencing Batch Reactor (SBR). The SBR was tested at various F/M values with different durations of anoxic-anaerobic-oxic cycles, obtaining, under certain conditions, more than 90% removal of COD, nitrogen and phosphorus.

Batch Precipitation of Lead Iodide

1994 ◽  
Vol 59 (6) ◽  
pp. 1301-1304
Author(s):  
Jaroslav Nývlt ◽  
Stanislav Žáček
Keyword(s):  
Aqueous Solution ◽  
Particle Size ◽  
Particle Size Distribution ◽  
Size Distribution ◽  
Crystal Size ◽  
Lead Nitrate ◽  
Lead Iodide ◽  
Constant Rate ◽  
Mean Size ◽  
The Mean

Lead iodide was precipitated by a procedure in which an aqueous solution of potassium iodide at a concentration of 0.03, 0.10 or 0.20 mol l-1 was stirred while an aqueous solution of lead nitrate at one-half concentration was added at a constant rate. The mean size of the PbI2 crystals was determined by evaluating the particle size distribution, which was measured sedimentometrically. The dependence of the mean crystal size on the duration of the experiment exhibited a minimum for any of the concentrations applied. The reason for this is discussed.

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