Seasonal and Spatial Changes of Microorganism Communities in Constructed Wetlands: A Community Level Physiological Profiling Analysis

In constructed wetlands, microorganisms associated with plants are assumed to play a major role. A one-year survey was conducted in five vertical flow constructed wetland systems that had been operating from 2 months to 8 years in small French villages (100–500 People Equivalent) to provide a better understanding of microbiological activity. The objective of our study was to highlight the most important factor generating variability between microorganisms communities compared to treatment performances. Results of community level physiological profiling using Biolog Ecoplates were analyzed using principal component analysis. The greatest microbial activity was observed in the oldest wetland during summer. Profiles of fed and rest bed were differentiated by the nature of the main carbon source metabolized. Whereas carbohydrates and carboxylic acids appeared to be better assimilated with fed beds, it seemed that phosphate compounds as well as amines allowed better growth in the plates inoculated with samples of rest beds. In all fed beds, the most important parameters affecting the diversity were the season and the age of the wetlands. There were only slight profile differences between surface and subsurface samples and between the first and second stage samples

Two-year performance of single-stage vertical flow treatment wetlands planted with willows under cold-climate conditions

Climate-related issues constitute an important obstacle for the development of treatment wetland (TW) applications in regions with freezing winter temperatures. The aim of the present study was to evaluate the efficiency of a new configuration of TWs based on the vertical flow (VF) configuration. The proposed TWs system is planted with a willow species (Salix miyabeana SX67) and including design adaptations for cold climate operation. Two different flow modes for winter-time operation were proposed: percolated and saturated with continuous artificial aeration. The pilot-scale systems were tested with municipal wastewater, at an organic loading ranging from 5 to 20 g CBOD5 m−2 d−1. The pilot TWs were successfully operated for 22 months despite freezing winter temperatures reaching as low as −32 °C. Willow development was normal, with evapotranspiration ranging from 19 to 23 mm/d in July 2017 for the pilot TWs at an organic loading of 10 g CBOD5 m−2 d−1. Organic matter removal efficiency was high for all pilot TWs, with an average 91% COD and 81% TSS removal. Nitrification was essentially complete during the summer period and remained high for pilot TWs operated under percolating flow mode in winter but was lower for the saturated flow mode, probably due to insufficient air supply. Our study confirms the successful application of a modified version of VF TW in regions with freezing air temperatures

Combination of slag, limestone and sedimentary apatite in columns for phosphorus removal from sludge fish farm effluents

Laboratory scale studies have repeatedly reported high P-retention in slag, a by-product of the steel manufacturing industry. Thus, it has emerged as a potential material to increase P-removal from constructed wetlands (CWs). However, several limitations were highlighted by field experiments, including the high pH of treated water and clogging. We hypothesized that the addition of sedimentary rocks to slag would preserve P-removal properties while reducing the pH of treated water. Four 2.5 L-columns were filled with 100% apatite (column A); a 50% weight each mixture of limestone with apatite (column B); 10% steel slag located at the inlet, plus 45% limestone mixed with 45% apatite (column C); and a mixture of steel slag (10%), limestone (45%) apatite (45%) (column D). A synthetic effluent (26 mg P/L) and a reconstituted sludge fish farm effluent containing 97 mg/L total suspended solids (TSS), 220 mg/L chemical oxygen demand (COD) and 23.5 mg P/L phosphorus (P) were applied sequentially during 373 and 176 days, under saturated flow conditions and 12–24 hours hydraulic residence time (HRT), respectively. Treatment performance, P-removal, pH and calcium (Ca2+) were monitored. Results indicated that columns that contained 10% weight steel slag resulted in a higher P retention capacity than the columns without steel slag. The highest P removal was achieved in column C, containing a layer of slag in the inlet zone, 45% apatite and 45% limestone. Feeding the columns with a reconstituted fish farm effluent led to biofilm development, but this had little effect on the P-removal. A combination of slag and sedimentary rocks represents a promising filtration material that could be useful downstream of CWs to further increase P-removal

Thermal properties of treatment wetlands operated under freezing conditions

ABSTRACT: The use of treatment wetlands (TWs) presents particular challenges in regions with sub-zero winter temperatures, due to reduced biological activity and risk of pipe breakage or clogging due to freezing. We studied the vertical temperature distribution in four pilot-scale TWs exposed to winter temperatures in order to determine the impact of operational system parameters and the role of insulation on heat conservation inside the filtering bed. The overall temperature pattern was similar in all wetlands, with a trend of increasing temperature from the surface toward the bottom during the cold season. No freezing was detected in the wetlands despite average daily temperatures as low as −20 °C. Influent water temperature and hydraulic loading had a stronger influence on TW temperatures in winter than air temperature. The vertical distribution of temperatures in TWs is more sensitive to hydraulic loading variation in the percolating operating condition than in the saturated flow with forced aeration configuration. Our results suggest that TW systems can remain operational under cold winter conditions provided the surface is properly insulated by vegetation, mulch and/or snow

Proceedings of the 14th IWA Specialized Conference on Small Water and Wastewater Systems & the 6th Specialized Conference on Resources Oriented Sanitation (S2Small 2017)

International audienceThe scope of our conference is to go beyond the simple assumption that small water andwastewater systems are technically feasible and working to answer specific needs undermany different configurations. The scope of our conference is to demonstrate that smallwater and wastewater systems represent part of the solution for the future of humanity,from theoretical concepts up to very applied case studies our conference will show thatsmall is smart, small is beautiful, small is efficient, small is affordable, small is generous inother words small is the future!Only small solutions for water and wastewater will enable to meet UN Sustainable DevelopmentGoal 6: « Ensure access to water and sanitation for all ». Only small water and wastewatersolutions will help to increase water re-use, water recycle and resource recoveryfrom wastewater. If you also believe that small water and wastewater systems representtomorrow’s solutions do not hesitate anymore and come to S2Small2017 to share yourknowledge, meet the main actors in the field, strengthen your network in a wonderful city(surrounded by water) and in a region where small water solutions are really developed!On behalf of the organizing Committee,Florent CHAZAREN

REACTIVE MEDIA IN TREATMENT WETLANDS

International audienc

Optimisation des systèmes de traitement des eaux usées domestiques par filtres plantés de macrophytes

Idéal pour l'assainissement des petites communes (<= 1000 habitants), les filtres plantés de roseaux (FPR), offrent une alternative socio-économique au traitement classique des eaux usées. En 2003, en France, il éxiste plus de 200 stations de ce type. Elles ont été créées en réponse à une situation récente, générée à la fois par l'évolution du contexte législatif et par la répartition de la densité démographique. Bien que les installations françaises offrent de bonnes performances, les mécanismes de dégradation sont peu connus et certaines améliorations semblent encore possibles. Cette thèse a eu pour but d'apporter des éléments sur le fonctionnement des FPR. Les résultats ont été présentés en deux chapitres. Le premier a été focalisé sur les performances du flux horizontal, l'incidence de la charge organique et hydraulique sur l'éfficacité d'écoulement. La finalité a été de proposer de éléments de modélisation. Le second chapitre a reposé sur l'analyse du comportement biologique des flux verticaux. Les variations de la composition et de l'activité biologique ont été suivies dans le temps et dans l'espace. Les résultats obtenus ont permis de mettre en évidence, pour le flux horizontal, les limites pour le traitement des eaux usées primaires, qui entraîne des défaillances hydrauliques et biologiques, et le rôle important de l'évapotranspiration, qui augmente l'efficacité hydraulique et le temps de séjour des effluents. Pour le flux vertical, les résultats ont montré l'importance de la couche qui se développe avec l'âge en surface des filtres, aussi bien au niveau hydraulique que biologique, et l'influence de la saison et de la nature du garnissage sur les principaux catabolismes en présence. Ce travail dresse un premier bilan du comportement global et des limites d'utilisation des deux types de flux des FPR. Plusieurs éléments d'optimisation ainsi que des orientations pour mieux comprendre le procédé ont été proposés.Ideal for small communities of up 1000 residents, constructed wetlands (CWs) provide an environmentally sound alternative to traditional methods of wastewater treatment. In France, in response to a recent situation, there are 200 functioning CWs in 2003. Even though FrenchCWs are satisfactorily efficient, degradation mechanisms are still misunderstood. It is still possible to improve the french specific design of CWs. This thesis work has been conducted in this context. The aim was to determine some conceptual and optimisation parameters of the global filter behaviour. Several samples were collected between 2001 and 2003 in both pilot scale ans full scale CWs. Results were presented ans discussed in two chapters. The first focused on hydraulic and organic loading influence on hydraulic residence time distribution (HRT) occuring in horizontal flow. The objectives were to propose models and to quantify the potential dysfunctions. The second chapter presented vertical flow CW microbiology and its relationship with time and space. Results showed taht in horizontal flow constructed wetlands, there were treatment limitations for raw wastewater, causing hydraulic and biological deficiences and the effect of evapotranspiration was significant, increasing the HRT and the hydraulic efficiency. In vertical flow constructed wetlands, results showed that the development of a surface layer with time had an important role for hydraulic repartition, retention and biological diversity and that season and media size had a strong effect on biological catabolism. In winter and with small size media the conditions were more anaerobic that in summer with larger filtration material. To conclude, this thesis draws a first summary of the global behaviour and design limits of both horizontal and vertical CWs. Several optimisation suppositions for future research were recommended.CHAMBERY -BU Bourget (730512101) / SudocSudocFranceF

Comment améliorer les performances des filtres plantés de roseaux par la bio-augmentation

International audienc

Wetland pollutant dynamics and control

International audienceNo abstrac

Treatment of pollution in constructed wetlands: from the fundamental mechanisms to the full-scale applications

WOS:000360311500001International audienceno abstrac