Mathematical model of phosphate release rate from sediments considering the effect of dissolved oxygen in overlying water

1989 ◽  
Vol 23 (3) ◽  
pp. 351-359 ◽  
Author(s):  
M ISHIKAWA ◽  
H NISHIMURA
Keyword(s):  
Mathematical Model ◽  
Dissolved Oxygen ◽  
Release Rate ◽  
Overlying Water ◽  
Phosphate Release

Non-steady variations of SOD and phosphate release rate due to changes in the quality of the overlying water

2000 ◽  
Vol 42 (3-4) ◽  
pp. 265-272 ◽  
Author(s):  
T. Inoue ◽  
Y. Nakamura ◽  
Y. Adachi
Keyword(s):  
Release Rate ◽  
Oxygen Demand ◽  
Phosphate Concentration ◽  
Sediment Oxygen Demand ◽  
Biochemical Reactions ◽  
Overlying Water ◽  
Phosphate Release ◽  
Do Concentration ◽  
The Difference

A dynamic model, which predicts non-steady variations in the sediment oxygen demand (SOD) and phosphate release rate, has been designed. This theoretical model consists of three diffusion equations with biochemical reactions for dissolved oxygen (DO), phosphate and ferrous iron. According to this model, step changes in the DO concentration and flow velocity produce drastic changes in the SOD and phosphate release rate within 10 minutes. The vigorous response of the SOD and phosphate release rate is caused by the difference in the time scale of diffusion in the water boundary layer and that of the biochemical reactions in the sediment. Secondly, a negative phosphate transfer from water to sediment can even occur under aerobic conditions. This is caused by the decrease in phosphate concentration in the aerobic layer due to adsorption.

Discussion of “Mathematical Model for Dissolved Oxygen”

1964 ◽  
Vol 90 (6) ◽  
pp. 117-125
Author(s):  
Donald J. O'Connor ◽  
Dominic Di Toro ◽  
Robert V. Thomann
Keyword(s):  
Mathematical Model ◽  
Dissolved Oxygen

Prediction of dissolved oxygen concentration along sanitary sewers

1996 ◽  
Vol 34 (5-6) ◽  
pp. 525-532 ◽  
Author(s):  
J. Saldanha Matos ◽  
E. Ribeiro de Sousa
Keyword(s):  
Mathematical Model ◽  
Dissolved Oxygen ◽  
Oxygen Concentration ◽  
Oxygen Transfer ◽  
Oxygen Balance ◽  
Dissolved Oxygen Concentration ◽  
Empirical Expression ◽  
Slime Layer ◽  
Sanitary Sewers ◽  
The Mathematical Model

The oxygen balance in wastewater collection systems is important in respect to the degree of biological oxidation that occurs within the stream and in respect to the control of septicity and its effects. In this paper, a simple mathematical model is presented, in order to predict dissolved oxygen concentration profiles along sanitary sewers. The mathematical model was developed based on an analytical solution of the simple differential equation of dissolved oxygen balance in sewers, and includes an empirical expression for prediction of dissolved oxygen transfer to the slime layer on the pipe walls. Because the factors controlling dissolved oxygen balance in sewers are so complex, it would be unrealistic to expect, that with this rather simple model, dissolved oxygen concentrations can be accurately predicted. Nevertheless, it is reasonable to suppose that the predictions may be adequate for some design and operation purposes.

scholarly journals Distribution and Release Characteristics of Phosphorus in a Reservoir in Southwest China

2019 ◽  
Vol 16 (3) ◽  
pp. 303 ◽  
Author(s):  
Yuanming Wang ◽  
Kefeng Li ◽  
Ruifeng Liang ◽  
Shiqing Han ◽  
Yong Li
Keyword(s):  
Water Temperature ◽  
Release Rate ◽  
Surface Sediments ◽  
Southwest China ◽  
Particulate Phosphorus ◽  
Limiting Factor ◽  
Dam Construction ◽  
Overlying Water ◽  
Reservoir Water ◽  
Main Form

Dam construction changes the nutrient transport of a river system. Phosphorus is an important fundamental material in the global biochemical cycle and is always a limiting factor in the primary productivity of reservoirs. Extending the study of phosphorus in reservoirs is necessary given the dam construction in southwest China. Zipingpu Reservoir was chosen as the research site in this study. The form and distribution of phosphorus in the reservoir’s surface sediments and overlying water were analyzed. The results showed that overall, the total phosphorus (TP) content of surface sediments in the Zipingpu Reservoir decreased from the tail to the front of the dam. The TP content ranged from 682.39 to 1609.06 mg/kg, with an average value of 1121.08 mg/kg. The TP content at some sampling points was affected by exogenous input. Inorganic phosphorus (IP) was the main form of phosphorus in surface sediments and had a proportion of 89.38%. Among the forms of IP, the content of Ca-P was larger than that of O-P; Ex-P, Fe-P, and Al-P had the lowest contents. Particulate phosphorus (PP) was the main form of phosphorus in the overlying water of the Zipingpu Reservoir and was strongly affected by hydrodynamic conditions. The content of total dissolved phosphorus (TDP) in the overlying water was relatively low. To further understand the risk of phosphorus release in the surface sediments in the reservoir, the rate and flux of phosphorus exchange at the sediment-overlying water interface were investigated through laboratory experiments. The results showed that both water temperature and pH significantly affected the sediment release rate, but the influence of water temperature was more significant. Acidic and alkaline conditions were conducive to the release of phosphorus from sediment, while a neutral environment was not. The release rate significantly increased with increasing water temperature, and a positive linear relationship was found between these two parameters. The sediment exhibited absorption characteristics when the water temperature was extremely low and exhibited releasing characteristics at a high temperature. These results could provide a theoretical basis for the management and protection of reservoir water environments.

Numerical Simulation of Plug Discharge with Dissolved Oxygen Convection and Diffusion

2012 ◽  
Vol 433-440 ◽  
pp. 1920-1925
Author(s):  
Ze Gao Yin ◽  
Le Wang ◽  
Jin Xiong Zhang ◽  
Xian Wei Cao
Keyword(s):  
Mathematical Model ◽  
Dissolved Oxygen ◽  
Oxygen Concentration ◽  
Dissipation Rate ◽  
Concentration Distribution ◽  
Coupled Model ◽  
Computational Results ◽  
Dissolved Oxygen Concentration ◽  
Velocity Pressure ◽  
And Diffusion

In Fluent, the 3-D RNG k- ξ mathematical model is employed to compute the plug discharge, and dissolved oxygen convection and diffusion model is established to simulate the concentration distribution of dissolved oxygen with user defined scalar method. Velocity, pressure, turbulence kinetic energy, turbulence dissipation rate and dissolved oxygen concentration are computed. Then, velocity, pressure and dissolved oxygen concentration are compared with the data of physical model, and they agree with each other approximately, showing it is valid and reliable to compute the plug discharge and dissolved oxygen concentration with the coupled model. Furthermore, the characteristics of hydraulic factors including dissolved oxygen concentration are analyzed and generalized based on the computational results.

Phosphate release from waste stabilisation pond sludge: significance and fate of polyphosphate

2011 ◽  
Vol 63 (8) ◽  
pp. 1689-1694 ◽  
Author(s):  
N. Powell ◽  
A. Shilton ◽  
S. Pratt ◽  
Y. Chisti
Keyword(s):  
Release Rate ◽  
Phosphorus Removal ◽  
Algal Bloom ◽  
Chemical Precipitation ◽  
Phosphorus Release ◽  
Common View ◽  
Phosphate Release ◽  
Initial Release ◽  
Polyphosphate Accumulation ◽  
The Common

Net phosphorus removal from waste stabilisation pond (WSP) systems is governed by the rate of phosphorus incorporation into the sludge layer and the rate of phosphorus release from this sludge back to the overlying wastewater. Luxury uptake of phosphorus by microalgae has been shown to occur under WSP conditions in the laboratory; however, the significance of this mechanism and the fate of polyphosphate contained in the settled solids have not previously been investigated. In this work the analysis of sludge samples from three WSP showed that up to 71% of the total phosphorus in the sludge was in the form of polyphosphate. This indicates that polyphosphate accumulation could potentially be an important mechanism for phosphorus sequestration in WSP and challenges the common view that chemical precipitation is the predominant phosphorus removal mechanism in these systems. The release of phosphate from WSP sludge samples was monitored in the laboratory. The samples from two different pond systems had release rates in the order of 4.3 μgP/gTSS.d. However, the third sample which was collected during an algal bloom had a release rate of 12.4 μgP/gTSS.d. Phosphate release from fresh microalgal sludge grown under laboratory conditions was also studied and was shown to have a release rate of 160 μgP/gTSS.d. Analysis of polyphosphate during the experiments on laboratory grown microalgal sludge showed that polyphosphate was indeed degraded resulting in phosphate release. Interestingly, after the initial release phase phosphorus was assimilated by the biomass and some polyphosphate was reformed. It is likely that this is due to bacterial growth in the sludge.

Sign in / Sign up

Export Citation Format

Share Document