Microbial effects on phosphorus release in aquatic sediments

2008 ◽  
Vol 58 (6) ◽  
pp. 1285-1289 ◽  
Author(s):  
Ting-Lin Huang ◽  
Xiao-Chun Ma ◽  
Hai-bing Cong ◽  
Bei-Bei Chai
Keyword(s):  
Ion Exchange ◽  
Release Rate ◽  
Phosphorus Release ◽  
Source Water ◽  
Aquatic Sediments ◽  
Iron Respiration ◽  
Microbial Effects

Microbial effects on phosphorus release were studied for the sediments of Tianjin source water by controlling DO and pH. The results show that: (1) In sterilised water, phosphorus began to release when pH = 9.1 and the stable release rate was 9.51 mg/(d·m2). It indicates that microorganisms may utilise anaerobic iron respiration to release Fe-P. (2) With unsterilised water, phosphorus release rate is 2.14 mg/(d·m2) when pH = 6.5, 8.60 mg/(d·m2) when pH is uncontrolled, and gets to 8.51 mg/(d·m2) when pH = 9.1. This indicates that microorganisms can dissolve insoluble phosphates to accelerate the ion exchange of OH− and PO43−, which are derived from iron-bound ortho-P and aluminium-bound ortho-P.

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.

Phosphorus release rate and plant response in some calcareous soils

2009 ◽  
Vol 55 (1) ◽  
pp. 91-103 ◽  
Author(s):  
Farzaneh Sadate Biabanaki ◽  
Alireza R. Hosseinpur
Keyword(s):  
Release Rate ◽  
Calcareous Soils ◽  
Phosphorus Release ◽  
Plant Response

Use of phosphorus release batch tests for modelling an EBPR pilot plant

2002 ◽  
Vol 45 (6) ◽  
pp. 99-106 ◽  
Author(s):  
E. Tykesson ◽  
H. Aspegren ◽  
M. Henze ◽  
P.H. Nielsen ◽  
J. Ia C. Jansen
Keyword(s):  
Release Rate ◽  
Phosphorus Removal ◽  
Pilot Plant ◽  
Phosphorus Content ◽  
Phosphorus Release ◽  
Biological Phosphorus Removal ◽  
Batch Tests ◽  
Initial Release ◽  
Analysis Programme ◽  
Biological Phosphorus

The aim of this study was to evaluate how routinely performed phosphorus release tests could be used when modelling enhanced biological phosphorus removal (EBPR) using activated sludge models such as ASM2d. A pilot plant with an extensive analysis programme was used as basis for the simulations. Without any calibration the prediction of phosphorus removal was poor and the initial release rates from the simulations were not similar to those found from the laboratory tests. A period with low organic loading was chosen as a calibration period. In this period averages of daily influent measurements were used as influent parameters. First, calibration was performed in order to fit effluent COD and MLVSS in the sludge. Next, the phosphorus content in the sludge was decreased to the measured level by decreasing the fermentation rate. Finally, the initial phosphorus release rate was calculated from a simulated batch test and the PHA uptake rate was increased to fit this release rate with the average initial rates from laboratory batch tests performed during the period. The calibrated model was verified with data from the subsequent period where acetate was dosed.

Indomethacin release from ion-exchange microspheres: impregnation with alginate reduces release rate

2004 ◽  
Vol 96 (3) ◽  
pp. 369-378 ◽  
Author(s):  
C. Chretien ◽  
V. Boudy ◽  
P. Allain ◽  
J.C. Chaumeil
Keyword(s):  
Ion Exchange ◽  
Release Rate

Internal Phosphorus Load in an Oligotrophic Precambrian Shield Lake with an Anoxic Hypolimnion

1986 ◽  
Vol 43 (3) ◽  
pp. 574-580 ◽  
Author(s):  
Gertrud K. Nürnberg ◽  
Margo Shaw ◽  
Peter J. Dillon ◽  
Don J. McQueen
Keyword(s):  
Release Rate ◽  
Lake Ontario ◽  
Phosphorus Release ◽  
Phosphorus Load ◽  
Release Rates ◽  
Eutrophic Lakes ◽  
Precambrian Shield ◽  
Anoxic Water ◽  
Internal Sources ◽  
External Loads

The release of phosphorus from sediments into the anoxic water of oligotrophic Chub Lake, Ontario, determined with three different methods, showed that the average release rate of 2.2 mg∙m−2∙d−1 is much smaller than release rates of more eutrophic lakes (14 mg∙m−2∙d−1). Our hypothesis that anoxic release rates depend on lake trophy was confirmed by the significant positive regression of release rates on lake phosphorus concentrations for 56 lakes from the literature. Despite a comparably small phosphorus release rate, the sediments play an important role in Chub Lake as a source of phosphorus because phosphorus from internal sources is in a highly available form and external loads are small.

Nutrient release from inundated land of a tropical reservoir (nanhua reservoir, Taiwan)

1998 ◽  
Vol 37 (2) ◽  
pp. 325-332 ◽  
Author(s):  
Shui-Ping Chang ◽  
Ching-Gung Wen
Keyword(s):  
Release Rate ◽  
Release Kinetics ◽  
Nutrient Release ◽  
Phosphorus Release ◽  
Nutrient Loads ◽  
Terrestrial Vegetation ◽  
Nitrogen And Phosphorus ◽  
Tropical Reservoir ◽  
Aerobic Conditions ◽  
Actual Operation

Nutrient release from land inundated by creation of a tropical reservoir (Nanhua Reservoir, Taiwan) is investigated. Both the magnitudes of nitrogen and phosphorus which might be released from inundated land are determined on the basis of measurements of biomass and nutrients content of terrestrial vegetation and the nutrients content of topsoil. The fresh biomass of the terrestrial vegetation was estimated at 48600 kg/ha, with an equivalent dry biomass of 15500 kg/ha. After complete decay following submergence, the terrestrial vegetation could potentially contribute 242 kg of nitrogen and 37 kg of phosphorus per hectare. The kinetics of nutrient release from topsoil is determined on a laboratory scale for 80 days, which showed that the phosphorus release rate is averaged at 5.25 mg TP/m2/day in anaerobic conditions and 1.34 mg TP/m2/day in aerobic conditions, also the nitrogen release rate is averaged at 78.31 mg TKN/m2/day in anaerobic condition and 35.71 mg TKN/m2/day in aerobic conditions. Based on the actual operation status of Nanhua Reservoir during the initial operation period of 21 months after construction (from August, 1993 to April, 19950 and nutrient release kinetics, the accumulated nutrient loads originating from the topsoil of the inundated land are about 81342 kg of nitrogen and 4701 kg of phosphorus.

scholarly journals 14C Exposure from Disposal of Radioactive Waste Compared to14C Exposure from Cosmogenic Origin

Radiocarbon ◽  
2018 ◽  
Vol 60 (6) ◽  
pp. 1911-1923
Author(s):  
Erika A C Neeft
Keyword(s):  
Ion Exchange ◽  
Radioactive Waste ◽  
Metal Oxide ◽  
Release Rate ◽  
Cementitious Materials ◽  
Release Mechanism ◽  
Management Technique ◽  
Chemical Corrosion ◽  
Carbon 14 ◽  
Exchange Resins

ABSTRACTThe potential14C (carbon-14, radiocarbon) flux from disposal of14C containing waste into air is compared with the natural14C emanation rate from soil in order to put the14C hazard potential from disposal of this waste in perspective with the14C exposure from cosmogenic origin. Chemical corrosion of neutron irradiated metals, steel and Zircaloy, is bounded by diffusion of water through a thermodynamically stable metal-oxide layer and dissolution of this metal-oxide in a nuclear plant. Many countries process radioactive waste for disposal using cementitious materials, an acknowledged end-point management technique for this waste. The metal-oxides are also stable when these waste forms are embedded in cementitious materials. The14C release rate from this Zircaloy at these alkaline and reducing conditions is comparable to the natural14C emanation rate from soil into air. Neutron irradiated graphite and spent ion exchange resins are chemically inert and therefore other release mechanisms need to be assumed. Radiolytic corrosion is used to determine the14C release rate from this graphite. Moreover, ion exchange—with ingressing anionic species that have a higher affinity than contained anionic14C—is proposed as a release mechanism for these resins.

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