Phosphorus removal by apatite in horizontal flow constructed wetlands for small communities: pilot and full-scale evidence

Phosphorus (P) removals in constructed wetlands (CWs) have received particular attention in recent decades by using specific materials which promote adsorption/precipitation mechanisms. Recent studies have shown interest in using apatite materials to promote P precipitation onto the particle surface. As previous trials were mainly done by lab experiments, this present study aims to evaluate the real potential of apatites to remove P from wastewater in pilot units and a full-scale plant over a 2 year period. P retention kinetics of two qualities of apatites are presented and discussed. In this work apatite appears to have high retention capacity (>80% of P removal) and is still an interesting way for P removal in CWs for limiting the risk of eutrophication downstream of small communities. Nevertheless, the apatite quality appears to be of great importance for a reliable and long term P removal. The use of materials with low content of apatite mineral (40–50%) seems to be not economically relevant.

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Phosphorus removal by the use of apatite in constructed wetlands: Design recommendations

Water Practice & Technology ◽

10.2166/wpt.2011.046 ◽

2011 ◽

Vol 6 (3) ◽

Cited By ~ 9

Author(s):

P. Molle ◽

S. Martin ◽

D. Esser ◽

S. Besnault ◽

C. Morlay ◽

...

Keyword(s):

Constructed Wetlands ◽

Phosphorus Removal ◽

Saturation Degree ◽

Design Recommendations ◽

Phosphate Mineral ◽

Apatite Mineral ◽

Precipitation Phenomena ◽

Filter Area ◽

P Removal

Phosphorus (P) removal in constructed wetlands (CWs) has received particular attention during the last decades by using specific materials which promote P adsorption/precipitation phenomena. Recent studies have shown an interest in using apatite materials to promote P precipitation onto their surface. About ten years of experiments at different scales (laboratory, pilot, full scale) have passed. The process is now open in France. This paper presents the first design recommendations according to the apatite mineral quality and treatment outlet requirements. Kinetics and their evolution with the material saturation degree are presented based on the k-C* model. The process can achieve 1 mgP.l−1 for long term while using surface P removal filter area of 0.5 m2.p.e.−1. With a low land footprint and high P removal efficiency, the interest of the process also result in the orthophosphates accumulation on a phosphate mineral which makes easier to reuse phosphorus from wastewater once saturated

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Phosphorus removal in constructed wetlands: can suitable alternative media be identified?

Water Science & Technology ◽

10.2166/wst.2005.0335 ◽

2005 ◽

Vol 51 (9) ◽

pp. 267-273 ◽

Cited By ~ 40

Author(s):

C.A. Arias ◽

H. Brix

Keyword(s):

Constructed Wetlands ◽

Binding Capacity ◽

Chemical Properties ◽

Full Scale ◽

Suitable Alternative ◽

Limited Application ◽

The Media ◽

Full Scale Tests ◽

Physical And Chemical ◽

P Removal

Removal of phosphorous in constructed wetlands is limited by the capacity of the media to adsorb, bind or precipitate the incoming P. To enhance P removal and the life span of constructed wetlands the approach might be to use natural sands rich in calcium or iron, to use an alternative ‘artificial’ medium with high P-binding capacity, or to establish external P-binding filters after the wetland. Our studies focused on the evaluation of calcium-rich materials potentially useful as P-binding media. The materials tested included calcite products, natural sands and seashells. Tests included assessment of physical and chemical properties of the materials, extractions in P-spiked water at different P concentrations to determine P-binding equilibrium isotherms, and column experiments. In addition, full-scale tests were performed with calcite in an external filter. The result showed that equilibrium isotherm is an indicator of the potential P-sorption capacity of the media, although the value is of limited application for the determination of the binding capacity in full-scale systems. The columns showed that the materials do bind phosphorus. However, the binding capacities are still insufficient for the establishment of external P-removal filter; the volumes of the filters would be too large to be of practical use.

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Natural and Constructed Wetlands for Wastewater Treatment: Potentials and Problems

Water Science & Technology ◽

10.2166/wst.1999.0130 ◽

1999 ◽

Vol 40 (3) ◽

pp. 27-35 ◽

Cited By ~ 27

Author(s):

Brij Gopal

Keyword(s):

Wastewater Treatment ◽

Constructed Wetlands ◽

Native Species ◽

Point Sources ◽

Toxic Substances ◽

Small Communities ◽

Wastewater Disposal ◽

River Floodplains ◽

Wetland Processes

Wetlands are being considered increasingly important for wastewater treatment because of the ability of many wetland plants to absorb large amounts of nutrient and a variety of toxic substances. The paper highlights the physical, chemical and biological processes which contribute to the improvement of water quality, and the distinction between natural and constructed wetlands. The impacts of long-term wastewater disposal on the biotic changes, reduction in treatment efficiency, and wetland processes such as production of trace gases, are pointed out. Constraints in using wetlands, for wastewater treatment, such as poor understanding of the natural wetland functions and responses of native plants and animals to wastewater, particularly in developing countries, are briefly discussed. It is suggested that while the possibilities for using constructed wetlands based on native species for small communities are explored, greater emphasis should be laid on the restoration of lost and degraded wetlands, especially the river floodplains, lake littorals and coastal wetlands, which can help check pollution from non-point sources.

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Study of aggregation in surface sludge deposits from 14 full-scale French constructed wetlands using particle size distribution and dynamic vapor sorption analyses

Water Science & Technology ◽

10.2166/wst.2017.523 ◽

2017 ◽

Vol 77 (1) ◽

pp. 79-90 ◽

Cited By ~ 6

Author(s):

M. Kania ◽

M. Gautier ◽

P. Michel ◽

R. Gourdon

Keyword(s):

Particle Size ◽

Constructed Wetlands ◽

Full Scale ◽

Aggregation Process ◽

Vapor Sorption ◽

Dynamic Vapor Sorption ◽

Small Communities ◽

Fresh Organic Matter ◽

Factors Of Influence ◽

Representative Samples

Abstract French vertical flow constructed wetlands (French VFCWs) are widely used for the treatment of wastewaters from small communities. In the system, unsettled wastewater is percolated through two successive stages of filter-cells planted with reeds. This causes the formation of a surface sludge layer. This layer plays positive roles in the treatment performance, but also leads to clogging. The objective of this study was to contribute to the description of the sludge deposits characteristics and their dynamics of evolution, which may control the development of clogging. Representative samples of sludge deposits were taken from 14 French VFCWs full-scale plants and analyzed for particle size, dynamic vapor sorption and other parameters of composition to compare their structure and evaluate the factors of influence. Results showed that ageing of the surface deposits layer over the years of operation in each plant induced the formation and integration of microaggregates within the initial macrostructure of fresh organic matter (OM). The humification process of the OM was found to play a key role in the aggregation process. The injection of FeCl3 operated to precipitate phosphates before filtration was found to accelerate the aggregation process in the early phase (<1 year) of operation of the sludge.

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Removing filterable reactive phosphorus from highly coloured stormwater using constructed wetlands

Water Science & Technology ◽

10.2166/wst.2001.0813 ◽

2001 ◽

Vol 44 (11-12) ◽

pp. 85-92 ◽

Cited By ~ 2

Author(s):

M.A. Lund ◽

P.S. Lavery ◽

R.F. Froend

Keyword(s):

Constructed Wetlands ◽

Plant Biomass ◽

Central Zone ◽

Benthic Flux ◽

Removal Capacity ◽

Removal Processes ◽

Reactive Phosphorus ◽

Total P ◽

P Removal

A constructed wetland design, consisting of 16 repeating cells was proposed for Henley Brook (Perth, Western Australia) to optimise the removal of FRP from urban stormwater. Three replicate experimental ponds (15×5 m), were constructed to represent at a 1:1 scale a single cell from this design. Three 5 m zones of each pond were sampled: shallow (0.3 m) vegetated (Schoenoplectus validus) inflow and outflow zones and a deeper (1 m), V-shaped central zone. In 1998/99, inflows and outflow waters were intensively sampled and analysed for FRP and Total P. In addition, all major pools of P (plants, sediment) within the ponds, and important P removal processes (benthic flux, uptake by biofilm and S. validus) were quantified. A removal efficiency of 5% (1998) and 10% (1999) was obtained for FRP. Initial uptake was mainly in plant biomass, although the sediment became an increasingly important sink. Benthic flux experiments showed that anoxia did not cause release of P from sediments, indicating that most of the P was bound as apatite rather than associated with Fe or Mn. The highly coloured waters were believed responsible for the very low biofilm biomass recorded (<1 g.m-2). We have demonstrated that constructed wetlands can be effective for removing FRP immediately after construction, although their long-term removal capacity needs further research.

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Evaluation of Pollutant Removal Efficiency in Environmentally Friendly Full-scale Constructed Wetlands for Treating Domestic Sewage during Long-term Monitoring

Korean Journal of Environmental Agriculture ◽

10.5338/kjea.2009.28.2.097 ◽

2009 ◽

Vol 28 (2) ◽

pp. 97-105 ◽

Cited By ~ 2

Author(s):

Dong-Cheol Seo ◽

In-Seong Jo ◽

Seok-Cheon Lim ◽

Byeong-Ju Lee ◽

Seong-Kyu Park ◽

...

Keyword(s):

Removal Efficiency ◽

Constructed Wetlands ◽

Environmentally Friendly ◽

Domestic Sewage ◽

Full Scale ◽

Pollutant Removal ◽

Long Term Monitoring ◽

Term Monitoring ◽

Pollutant Removal Efficiency

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Comparative Labelling and Biokinetic Studies of 99mTc-EDTA(Sn) and 99mTc-DTPA(Sn)

Nuklearmedizin ◽

10.1055/s-0037-1620603 ◽

1977 ◽

Vol 16 (01) ◽

pp. 30-35 ◽

Cited By ~ 1

Author(s):

N. Agha ◽

R. B. R. Persson

Keyword(s):

Complex Formation ◽

Significant Influence ◽

Room Temperature ◽

Ph Value ◽

Maximum Activity ◽

Reduction Step ◽

Labelling Yield ◽

Different Temperatures ◽

Kinetics Of

SummaryGelchromatography column scanning has been used to study the fractions of 99mTc-pertechnetate, 99mTcchelate and reduced hydrolyzed 99mTc in preparations of 99mTc-EDTA(Sn) and 99mTc-DTPA(Sn). The labelling yield of 99mTc-EDTA(Sn) chelate was as high as 90—95% when 100 μmol EDTA · H4 and 0.5 (Amol SnCl2 was incubated with 10 ml 99mTceluate for 30—60 min at room temperature. The study of the influence of the pH-value on the fraction of 99mTc-EDTA shows that pH 2.8—2.9 gave the best labelling yield. In a comparative study of the labelling kinetics of 99mTc-EDTA(Sn) and 99mTc- DTPA(Sn) at different temperatures (7, 22 and 37°C), no significant influence on the reduction step was found. The rate constant for complex formation, however, increased more rapidly with increased temperature for 99mTc-DTPA(Sn). At room temperature only a few minutes was required to achieve a high labelling yield with 99mTc-DTPA(Sn) whereas about 60 min was required for 99mTc-EDTA(Sn). Comparative biokinetic studies in rabbits showed that the maximum activity in kidneys is achieved after 12 min with 99mTc-EDTA(Sn) but already after 6 min with 99mTc-DTPA(Sn). The long-term disappearance of 99mTc-DTPA(Sn) from the kidneys is about five times faster than that for 99mTc-EDTA(Sn).

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Full Scale Investigations on Enhanced Biological Phosphorus Removal – P-Release in the Anaerobic Reactor

Water Science & Technology ◽

10.2166/wst.1994.0331 ◽

1994 ◽

Vol 29 (7) ◽

pp. 153-156 ◽

Cited By ~ 1

Author(s):

D. Wedi ◽

P. A. Wilderer

Keyword(s):

Phosphorus Removal ◽

Full Scale ◽

Process Conditions ◽

Enhanced Biological Phosphorus Removal ◽

Biological Phosphorus Removal ◽

Anaerobic Reactor ◽

P Release ◽

Acinetobacter Sp ◽

Biological Phosphorus ◽

P Removal

Most of the fundamental processes responsible for enhanced biological phosphorus removal (EBPR) were obtained through laboratory tests under defined conditions with pure or enriched cultures. Acinetobacter sp. was identified as the most important group of bacteria responsible for bio-P removal. Full scale data showed, however, that laboratory results do not match full scale results well enough. There is a lack of data on the effects of sub-optimal process conditions such as inadequate availability of volatile fatty acids (VFA), high nitrate recycle, storm water inflow or low temperatures. In this paper the results of full scale experiments on P-release are presented and compared with theoretical values. Measurements at a full scale Phoredox-system showed a surprisingly low P-release in the anaerobic reactor. Only 4 to 10% of the phosphorus in the activated sludge was released in the bulk liquid. With laboratory batch-tests, a maximum of 20% of the P in the sludge could be released. It is assumed that under the prevailing process conditions either the fraction of Acinetobacter sp. was very small, or bacteria other than Acinetobacter sp. were responsible for the P-removal, or most of the phosphorus was bound chemically but mediated by biological processes.

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