The reuse of domestic greywater for toilet flushing has the potential to reduce both water consumption and wastewater production, but there is a need for low-cost, low-maintenance greywater treatment systems that can meet reclaimed water quality standards. The purpose of this thesis is to develop a horizontal subsurface flow wetland design that can be sited in a greenhouse, to document the initial performance of the design treating real greywater, to determine the effect of plants, and to provide recommendations for design. Pilot wetlands (planted and unplanted replicates) were constructed in a passively heated greenhouse and fed real domestic greywater. Effluent quality was compared to national reclaimed water quality guidelines. After the first five months of the study, operational changes (reduced loading, aeration of influent, fill and drain) were tested to determine their effect on effluent quality. The results show that the original design basis, 7.5 gBOD m-2d-1, is not appropriate for greywater wetland design under the conditions of this study due to insufficient removal of BOD and turbidity (although suspended solids removal was acceptable). Anoxic conditions within the wetlands led to reduction of sulfate to hydrogen sulfide, which demands oxygen and leads to odour and turbidity problems. Plants did not affect treatment during the first five months. Aerating influent and operation in fill and drain mode may improve BOD removal at relatively high hydraulic loading rates, but effluent disinfection is required to completely remove E.coli. Design recommendations were developed, including tentative loading rates and plant species. / Ontario Centres of Excellence, NSERC

Constructed wetlands are one of alternative solution wastewater treatment. Compared to conventional wastewater plants have many advantages. For example it´s technology saving construction, low operating costs, cleavability diluted wastewater and little or no need for electrical power. There are many publications dealing with Natural Ways wastewater treatment or even constructed wetlands. I decided to look for a thesis on one of the key processes – clogging bed media. The thesis is focused on ways to prevent clogging of bed media, mitigate the consequences and technology to increase hydraulic conductivity of constructed wetlands. The main test method is improving drainage parameters using pulsed filling and emptying of the bed media. This method is a very effective way to achieve quality requirements for effluent water from the treatment plant. Another test method is based on the injection of air into the media bed and sludge extraction using a specially modified industrial vacuum cleaner or pump.

Au cours des dernières décennies, une grande variété de pesticides émergents, tels que le chlorantraniliprole (CAP), ont été introduits malgré le manque de connaissance approfondie de leur risque écotoxicologique. Les marais filtrants (TW) sont des technologies écologiques et durables qui ont montré un grand potentiel d’atténuation des polluants agricoles communs, tels que les pesticides dans le ruissellement. L’objectif de cette étude était d’optimiser l’utilisation du marais filtrant sous-surfacique à écoulement horizontal (HSSF) en déterminant: a) l'effet d’un amendement de biochar au substrat et b) la performance de trois espèces de macrophytes (Phragmites australis subsp. americanus, Scirpus cyperinus et Sporobolus michauxianus) dans l'abattement du CAP du ruissellement agricole. L'efficacité d'abattement a été calculée en utilisant la méthode du bilan de masse dans des mésocosmes HSSF matures alimentés avec un ruissellement agricole synthétique contenant du CAP pendant une période d'un mois. Les mésocosmes avec l’ajout de biochar se sont avérés très efficaces dans l’abattement du CAP (90 à 99%) et ils le sont restés tout au long de la période expérimentale. Cette efficacité est probablement due à la grande capacité d’adsorption du biochar, bien que ce mécanisme n’ait pas été directement mesuré. En revanche, l'abattement du CAP dans les mésocosmes plantés sans biochar était faible et limité et il n’y avait pas de différence entre les espèces, bien qu’elles aient eu des différences dans leur biomasse aérienne et leur taux d'évapotranspiration (ET). Cependant, les traitements plantés ont agi comme zone tampon, en atténuant la masse du CAP de l'influent et en la libérant lentement dans l'effluent. Le taux d'ET de Scirpus et Phragmites était plus élevé que celui de Sporobolus, ce qui s’est traduit par un meilleur effet tampon. Cette étude suggère que l'ajout de biochar au substrat HSSF TW est prometteur pour l'atténuation du CAP dans le ruissellement agricole, mais leur efficacité à long terme reste à être étudiée. Malgré tout, les TW devraient être utilisés comme un outil complémentaire, dans le cadre d'actions plus larges visant à réduire la pression des polluants sur les écosystèmes aquatiques. / Over the past decades, a wide variety of emergent pesticides, such as chlorantraniliprole (CAP), have been introduced despite the lack of in-depth knowledge of their ecotoxicological risk. Treatment wetlands (TWs) are environmentally friendly and sustainable technologies that have shown great potential to mitigate common agricultural pollutants, such as pesticides in runoff. The objective of this study was to optimize the use of the horizontal subsurface flow treatment wetlands (HSSF TWs) by determining a) the effect of biochar amendment to the substrate and b) the performance of three species of macrophytes (Phragmites australis subsp. americanus, Scirpus cyperinus and Sporobolus michauxianus) in CAP removal from agricultural runoff. The removal efficiency was calculated using the mass balance method in mature HSSF mesocosms fed with synthetic agricultural runoff containing CAP for a period of one month. Mesocosms with the addition of biochar were very effective in removing CAP (90-99%) and remained so throughout the experimental period. This efficiency is likely due to the high adsorption capacity of biochar, although this mechanism has not been directly measured. In contrast, CAP removal in mesocosms planted without biochar was low and limited and there was no difference between species, although there were differences in their above-ground biomass and their evapotranspiration (ET) rate. However, the planted mesocosms acted as buffer zones, reducing the CAP mass of the influent and slowly releasing it into the discharge. The ET rate of S. cyperinus and P. australis was higher than that of S. michauxianus, resulting in a better buffering effect. This study suggests that adding biochar to the HSSF TW substrate is promising for CAP attenuation in agricultural runoff, but their long-term effectiveness remains to be investigated. Nevertheless, TWs should be used as a complementary tool, as part of wider actions aimed at reducing the pressure of pollutants on aquatic ecosystems.