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

2017 ◽  
Vol 77 (1) ◽  
pp. 79-90 ◽  
Author(s):  
M. Kania ◽  
M. Gautier ◽  
P. Michel ◽  
R. Gourdon

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.

2011 ◽  
Vol 63 (8) ◽  
pp. 1629-1637 ◽  
Author(s):  
N. Harouiya ◽  
S. Martin Rue ◽  
S. Prost-Boucle ◽  
A. Liénar ◽  
D. Esser ◽  
...  

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.


Author(s):  
N.A. Sabri ◽  
H. Schmitt ◽  
B.M. van der Zaan ◽  
H.W. Gerritsen ◽  
H.H.M. Rijnaarts ◽  
...  

2015 ◽  
Vol 71 (9) ◽  
pp. 1333-1339 ◽  
Author(s):  
A. Morvannou ◽  
N. Forquet ◽  
S. Michel ◽  
S. Troesch ◽  
P. Molle

Approximately 3,500 constructed wetlands (CWs) provide raw wastewater treatment in France for small communities (<5,000 people equivalent). Built during the past 30 years, most consist of two vertical flow constructed wetlands (VFCWs) in series (stages). Many configurations exist, with systems associated with horizontal flow filters or waste stabilization ponds, vertical flow with recirculation, partially saturated systems, etc. A database analyzed 10 years earlier on the classical French system summarized the global performances data. This paper provides a similar analysis of performance data from 415 full-scale two-stage VFCWs from an improved database expanded by monitoring data available from Irstea and the French technical department. Trends presented in the first study are confirmed, exhibiting high chemical oxygen demand (COD), total suspended solids (TSS) and total Kjeldahl nitrogen (TKN) removal rates (87%, 93% and 84%, respectively). Typical concentrations at the second-stage outlet are 74 mgCOD L−1, 17 mgTSS L−1 and 11 mgTKN L−1. Pollutant removal performances are summarized in relation to the loads applied at the first treatment stage. While COD and TSS removal rates remain stable over the range of applied loads, the spreading of TKN removal rates increases as applied loads increase.


Water ◽  
2016 ◽  
Vol 8 (9) ◽  
pp. 365 ◽  
Author(s):  
Eleanor Butterworth ◽  
Andrew Richards ◽  
Mark Jones ◽  
Gabriella Mansi ◽  
Ezio Ranieri ◽  
...  

Cellulose ◽  
2018 ◽  
Vol 25 (12) ◽  
pp. 6923-6934 ◽  
Author(s):  
Saija Väisänen ◽  
Raili Pönni ◽  
Anna Hämäläinen ◽  
Tapani Vuorinen

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