Nitrite and nitrate as electron acceptors for biological sulphide oxidation

2015 ◽  
Vol 72 (4) ◽  
pp. 593-599 ◽  
Author(s):  
G. Munz ◽  
A. Mannucci ◽  
J. Arreola-Vargas ◽  
F. Alatriste-Mondragon ◽  
F. Giaccherini ◽  
...  
Keyword(s):  
Steady State ◽  
Electron Acceptor ◽  
Removal Rate ◽  
Nitrate Removal ◽  
Pilot Scale ◽  
Ratio Increase ◽  
Steady State Condition ◽  
Primary Sludge ◽  
Nitrogen Loads ◽  
Solids Retention

Autotrophic denitrification with sulphide using nitrate (R1) and nitrite (R2) as electron acceptor was investigated at bench scale. Different solids retention times (SRT) (5 and 20 d) have been tested in R1 while R2 was operated at SRT = 13 d. The results indicated that the process allows complete sulphide removal to be achieved in all tested conditions. Tested sulphide loads were estimated from the H2S produced in a pilot-scale anaerobic digester treating vegetable tannery primary sludge; nitrogen loads originated from the nitrification of the supernatant. Average nitrogen removal efficiencies higher than 80% were observed in all the tested conditions once steady state was reached. A maximum specific nitrate removal rate equal to 0.35 g N-NO3− g VSS−1 d−1 was reached in R1. Due to sulphide limitation, incomplete denitrification was observed and nitrite and thiosulphate tend to accumulate especially in the presence of variable environmental conditions in both R1 and R2. Lower SRT caused higher NO2accumulated/NO3reduced ratios (0.22 and 0.24, with SRT of 5 d and 20 d, respectively) using nitrate as electron acceptor in steady-state condition. Temperature decrease caused sudden NO2accumulated/NO3reduced ratio increase in R1 and NO2− removal decrease in R2.

Modeling the performance of biodegradation of textile wastewater using polyurethane foam sponge cube as a supporting medium

2010 ◽  
Vol 62 (12) ◽  
pp. 2801-2810 ◽  
Author(s):  
Yen-Hui Lin
Keyword(s):  
Steady State ◽  
Polyurethane Foam ◽  
Textile Wastewater ◽  
Pilot Scale ◽  
Biofilm Reactor ◽  
Column Test ◽  
Steady State Condition ◽  
Suspended Biomass ◽  
The Government ◽  
Carbon Dioxide Co2

A pilot-scale fixed-biofilm reactor (FBR) was established to treat textile wastewater to evaluate the feasibility of replacing conventional treatment processes that involve activated sludge and coagulation units. A kinetic model was developed to describe the biodegradation of textile wastewater by FBR. Batch kinetic tests were performed to evaluate the biokinetic parameters that are used in the model. FBR column test was fed with a mean COD of 692 mg/L of textile wastewater from flow equalization unit. The influent flow rate was maintained at 48.4 L/h for FBR column test. Experimental data and model-predicted data for substrate effluent concentration (as COD), concentration of suspended biomass in effluent and the amount of carbon dioxide (CO2) produced in the effluent agree closely with each other. Microscopic observations demonstrated that the biofilm exhibited a uniform distribution on the surface of polyurethane foam sponge. Under a steady-state condition, the effluent COD from FBR was about 14.7 mg COD/L (0.0213 Sb0), meeting the discharge standard (COD < 100 mg/L) that has been set by the government of Taiwan for textile wastewater effluent. The amount of biofilm and suspended biomass reached a maximal value in the steady state when the substrate flux reached a constant value and remained maximal. Approximately 33% of the substrate concentration (as COD) was converted to CO2 during biodegradation in the FBR test. The experimental and modeling schemes proposed in this study could be employed to design a full-scale FBR to treat textile wastewater.

Denitrification of groundwater using acetic acid as a carbon source

1999 ◽  
Vol 40 (2) ◽  
pp. 53-59 ◽  
Author(s):  
A. Mohseni-Bandpi ◽  
D. J. Elliott ◽  
A. Momeny-Mazdeh
Keyword(s):  
Acetic Acid ◽  
Carbon Source ◽  
Nitrate Nitrogen ◽  
Removal Rate ◽  
Bacterial Species ◽  
Nitrate Removal ◽  
Pilot Scale ◽  
Operating Conditions ◽  
Acid Loading ◽  
Species Being

A pilot scale rotating biological contactor was used to investigate the ability to remove nitrate from groundwater using acetic acid as a carbon source under various operating conditions. The reactor achieved a nitrate removal efficiency of 99 to 83 percent at loading rates of 76 and 490 mg/m2.hr respectively with a flow rate of 2.5 l/min at 20±2°C. The nitrate removal rate was found to be dependent on the influent acetic acid loading rate. The optimum acetic acid to nitrate-nitrogen (A/N) ratio was found to be 4.3:1. Under optimum conditions the effluent nitrate, nitrite-nitrogen and residual acetic acid concentrations were 0.43, 0.03 and 4.4 mg/l. The process generally produced low nitrite intermediate production for up to 100 mg/l influent nitrate-nitrogen. The results of this study show that an anoxic RBC using acetic acid as a carbon source is a convenient and reliable process for the removal of nitrate from water supply. Pseudomonas were found to be the dominant bacterial species with species being Ps. stutzeri and Ps. fluorescence.

Pesticide removal by GAC preloaded with natural organic matter

2002 ◽  
Vol 2 (1) ◽  
pp. 147-154 ◽  
Author(s):  
Y. Matsui ◽  
K. Iwaki ◽  
M. Uematsu ◽  
A. Yuasa
Keyword(s):  
Organic Matter ◽  
Steady State ◽  
Natural Organic Matter ◽  
Membrane Filtration ◽  
Removal Rate ◽  
Free Water ◽  
Pilot Scale ◽  
Order Kinetic ◽  
Pesticide Concentration ◽  
Pesticide Removal

The removal of hydrophobic and hydrophilic pesticides (simazine and asulum) by granular activated carbon (GAC) adsorbers preloaded with natural organic matter (NOM) was studied through experiments using pilot scale columns and microcolumns. The pesticide concentration increased with time after the pesticide application, and it reached a pseudo-steady-state plateau. Less than 8% of the adsorbed simazine desorbed back into the column effluent by 15 days after the influent was switched to simazine-free water. The simazine desorbed from the upper part of the bed was re-adsorbed in the lower part, keeping the effluent concentration at a low level. In the pseudo-steady-state, the removal rate was described by a first order kinetic reaction for the pesticide concentration. The evaluation of removal rate modulus value revealed the profile of loaded pesticide-competitive NOM with depth. The pesticide-competitive NOMs were different for each pesticide. The percentage of the simazine-competitive NOM to the whole NOM increased after UF membrane filtration (molecular weight cutoff 1K), but not for the asulum-competitive NOM.

Advances of External Carbon Source in Denitrification

2012 ◽  
Vol 518-523 ◽  
pp. 2319-2323 ◽  
Author(s):  
Guang Ying Liu ◽  
Huan Zhen Zhang ◽  
Wei Li ◽  
Xin Zhang
Keyword(s):  
Carbon Source ◽  
Slow Release ◽  
Removal Rate ◽  
Nitrate Removal ◽  
Carbon Sources ◽  
Electron Donors ◽  
Primary Sludge ◽  
External Carbon Source ◽  
The Media ◽  
Available Carbon

Carbon source used as electron donors is critical to heterotrophic denitrification. Addition of external carbon source is necessary when internal organics are deficient. A review was conducted on the use of external carbon source in denitrification. Traditional carbon sources such as methanol and ethanol, alternative carbon sources such as cellulose-rich materials, biodegradable polymers and primary sludge are included in external carbon sources. Present situation and problems of its biodegradability and effects in denitrification are summarized. Focus in external carbon source includes further study on the biodegradation mechanism of the media, slow release performance and nitrate removal rate of available carbon source and continuous research on new kinds of substrates. Recommendations on further study of carbon source are put forward.

Hydrolysis of organic wastewater particles in laboratory scale and pilot scale biofilm reactors under anoxic and aerobic conditions

1998 ◽  
Vol 38 (8-9) ◽  
pp. 179-188 ◽  
Author(s):  
K. F. Janning ◽  
X. Le Tallec ◽  
P. Harremoës
Keyword(s):  
Organic Matter ◽  
Mass Balance ◽  
Particulate Organic Matter ◽  
Removal Rate ◽  
Pilot Scale ◽  
Laboratory Scale ◽  
Synthetic Wastewater ◽  
Aerobic Conditions ◽  
Biofilm Reactors ◽  
Hydrolysis Of

Hydrolysis and degradation of particulate organic matter has been isolated and investigated in laboratory scale and pilot scale biofilters. Wastewater was supplied to biofilm reactors in order to accumulate particulates from wastewater in the filter. When synthetic wastewater with no organic matter was supplied to the reactors, hydrolysis of the particulates was the only process occurring. Results from the laboratory scale experiments under aerobic conditions with pre-settled wastewater show that the initial removal rate is high: rV, O2 = 2.1 kg O2/(m3 d) though fast declining towards a much slower rate. A mass balance of carbon (TOC/TIC) shows that only 10% of the accumulated TOC was transformed to TIC during the 12 hour long experiment. The pilot scale hydrolysis experiment was performed in a new type of biofilm reactor - the B2A® biofilter that is characterised by a series of decreasing sized granular media (80-2.5 mm). When hydrolysis experiments were performed on the anoxic pilot biofilter with pre-screened wastewater particulates as carbon source, a rapid (rV, NO3=0.7 kg NO3-N/(m3 d)) and a slowler (rV, NO3 = 0.3 kg NO3-N/(m3 d)) removal rate were observed at an oxygen concentration of 3.5 mg O2/l. It was found that the pilot biofilter could retain significant amounts of particulate organic matter, reducing the porosity of the filter media of an average from 0.35 to 0.11. A mass balance of carbon shows that up to 40% of the total incoming TOC accumulates in the filter at high flow rates. Only up to 15% of the accumulated TOC was transformed to TIC during the 24 hour long experiment.

scholarly journals Computational Performance of Disparate Lattice Boltzmann Scenarios under Unsteady Thermal Convection Flow and Heat Transfer Simulation

Computation ◽  
2021 ◽  
Vol 9 (6) ◽  
pp. 65
Author(s):  
Aditya Dewanto Hartono ◽  
Kyuro Sasaki ◽  
Yuichi Sugai ◽  
Ronald Nguele
Keyword(s):  
Heat Transfer ◽  
Steady State ◽  
Natural Convection ◽  
Lattice Boltzmann ◽  
Numerical Results ◽  
Convection And Heat Transfer ◽  
Steady State Condition ◽  
Physical Systems ◽  
Flow And Heat Transfer ◽  
Computational Performance

The present work highlights the capacity of disparate lattice Boltzmann strategies in simulating natural convection and heat transfer phenomena during the unsteady period of the flow. Within the framework of Bhatnagar-Gross-Krook collision operator, diverse lattice Boltzmann schemes emerged from two different embodiments of discrete Boltzmann expression and three distinct forcing models. Subsequently, computational performance of disparate lattice Boltzmann strategies was tested upon two different thermo-hydrodynamics configurations, namely the natural convection in a differentially-heated cavity and the Rayleigh-Bènard convection. For the purposes of exhibition and validation, the steady-state conditions of both physical systems were compared with the established numerical results from the classical computational techniques. Excellent agreements were observed for both thermo-hydrodynamics cases. Numerical results of both physical systems demonstrate the existence of considerable discrepancy in the computational characteristics of different lattice Boltzmann strategies during the unsteady period of the simulation. The corresponding disparity diminished gradually as the simulation proceeded towards a steady-state condition, where the computational profiles became almost equivalent. Variation in the discrete lattice Boltzmann expressions was identified as the primary factor that engenders the prevailed heterogeneity in the computational behaviour. Meanwhile, the contribution of distinct forcing models to the emergence of such diversity was found to be inconsequential. The findings of the present study contribute to the ventures to alleviate contemporary issues regarding proper selection of lattice Boltzmann schemes in modelling fluid flow and heat transfer phenomena.

Continuous determination of the volume of a space in a non steady state condition

1974 ◽  
Vol 36 (1) ◽  
pp. 59-66
Author(s):  
Oscar A. Gómez-Poviña ◽  
Carmen Sainz de Calatroni ◽  
Susana Orden de Puhl ◽  
Mariano J. Guerrero
Keyword(s):  
Steady State ◽  
State Condition ◽  
Steady State Condition ◽  
Continuous Determination

An Approach for Snaky Well Productivity under Steady-State Condition

2006 ◽  
Author(s):  
Zhilin Qi ◽  
Zhimin Du ◽  
Baosheng Liang ◽  
Yong Tang ◽  
Shouping Wang ◽  
...  
Keyword(s):  
Steady State ◽  
State Condition ◽  
Well Productivity ◽  
Steady State Condition

Grinding Process Size Effect and Kinematics Numerical Analysis

1999 ◽  
Vol 122 (1) ◽  
pp. 59-69 ◽  
Author(s):  
William L. Cooper ◽  
Adrienne S. Lavine
Keyword(s):  
Steady State ◽  
Removal Rate ◽  
Empirical Relationship ◽  
Three Dimensional ◽  
Depth Of Cut ◽  
Grinding Process ◽  
Zone Length ◽  
Abrasive Grains ◽  
Three Dimensional Modeling ◽  
Stock Removal

The present work developed numerical codes that simulate steady-state grinding process kinematics. The three-dimensional modeling procedure entails the following: specifying the sizes, shapes, and positions of individual abrasive grains on the wheel surface; geometrically calculating the abrasive grains’ depth of cut distributions along the grinding zone as they pass through the grinding zone (neglecting wheel, abrasive grain, and workpiece deflections); using an empirical relationship to relate the abrasive grains’ geometric depths of cut to the grains’ actual depths of cut; and updating the workpiece surface to account for material removal. The resulting data include the abrasive grains’ average depth of cut distribution along the grinding zone, stock removal depth, stock removal rate, grinding zone shape, grinding zone length, percentage of grains impacting the workpiece, grain-workpiece impact frequency, etc. The calculated grinding zone lengths compare favorably with experimental data. This article examines a number of steady-state grinding processes. [S1087-1357(00)00101-5]

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