Thesis (M.Eng.(Engineering and Technology Management))-University of Pretoria, 2007. / Abstract in English. Includes bibliographical references.

L’activité érosive des badlands marneux des Alpes du Sud présente des conséquences négatives pour l’homme qui a ainsi cherché à restaurer ces terrains dès le XIXème siècle. Depuis une dizaine d’années, une stratégie d’ingénierie écologique y est développée et se concentre sur les lits de ravines, pierres angulaires de leur restauration. La question appliquée à la base de ce travail de thèse est d’identifier comment l’implantation d’ouvrages de génie écologique dans lelit de ravines marneuses érodées favorise leur restauration écologique sur le long terme.L’objectif de recherche associé à cette question est de mieux comprendre comment des communautés végétales interagissent avec la restauration des sols de lits de ravines érodées sur le long terme. Nous avons fait l’hypothèse que les traits végétaux des plantes à l’échelle de communautés constituent un point d’entrée pertinent pour étudier ces interactions. Dans la première partie, nous avons utilisé les traits comme un outil de compréhension de l’effet mécanique des plantes sur les dynamiques géomorphologiques des lits de ravines en cours de restauration. Nous avons notamment montré que les traits permettent d’expliquer la capacité de communautés végétales implantées à favoriser la formation d’amas sédimentaires dans le lit des ravines durant la première décennie post-travaux. Dans la deuxième partie, nous nous sommes intéressés à l’évolution potentielle sur le long terme (centaine d’années) des propriétés de ces amas, constituant des sols en devenir. Nous avons montré que la diversité ainsi que les valeurs dominantes des traits végétaux influencent les propriétés de ces sols, notamment la stabilité des agrégats et la fertilité des sols. En plus d’être un outil de compréhension, nous montrons que cette utilisation des traits constitue un outil pour guider les actions de restauration de badlands via l’implantation d’ouvrages de génie écologique, en apportant des éléments sur le devenir géomorphologique et écologique post-travaux des systèmes sol-plante de lits de ravines. / In the French Southern Alps, severe erosion in marly badlands shows negative consequencesfor human populations, who worked to restore these terrains since the XIXth century. For adecade, an ecological engineering strategy is developed and focuses on gully beds, cornerstonesof their restoration. The operational question at the root of this PhD project is to identify towhat extent ecological engineering structures implanted in marly gully beds can foster theirlong-term ecological restoration. The scientific objective related to this question is to betterunderstand how plant communities interact in the long-term with the restoration of soils ingully beds. We hypothesized that plant traits at the community scale is a relevant entry point tostudy these interactions. In the first part, we used traits as a tool to study the mechanical effectof plants on geomorphological dynamics in gully beds under restoration. In particular, weshowed that traits enable us to explain the capacity of plant communities to favor theaccumulation of sediment mounds in gully beds during the first decade after ecologicalengineering works. In the second part, we concentrated on the potential long-term (century)evolution of the properties of these sediment mounds, in the process of becoming real soils. Weshowed that both trait diversity and dominant values of traits interacted with the properties ofthese soils, such as soil aggregate stability and soil fertility. With a strong multidisciplinaryapproach, this work provides results and insights on the interactions between plant traits andecosystem functioning in the specific case of highly eroded semi-natural ecosystems. It alsocontribute to set tools to restore badlands via ecological engineering works, by providinginformation about the long-term geomorphological and ecological evolution of soil-plantsystems in restored gully beds.

No description available.

In recent years, the treatment of phosphorus in Nyland's water treatment plant (located in Åre municipality) has been substandard. The problem has persisted despite attempts to lower the concentration to meet the emission requirements. A desire to find alternative, more environmentally friendly treatment methods has therefore been expressed from the municipality.Aside from the requirements, there is a desire to keep nutrient levels in the recipient (Indalsälven) low to preserve its natural state. A recognized method for treating wastewater is the use of constructed wetlands, where the characteristics of a natural wetland are enhanced and taken advantage of.The assessment of which type of constructed wetland that would be most beneficial to apply, was done by rating and weighting a number of characteristics of importance for lowering the phosphorus concentration. A first-order area-based model was used to estimate the size of the wetland.This report found that there is a suitable site to build a free water surface wetland in the vicinity of the water treatment plant. The wetland would act as a polishing step in the treatment train. As there is an element of uncertainty in treatment performance when a living ecosystem as wetlandis used, it is advised to enlarge this study and include more design aspects to refine the layout and configuration. / <p>2023-06-02</p>

Eutrophication is one of the most serious environmental problems in the Baltic Sea due to factors such as nutrient discharges from different sources and long residence time. Eutrophication gives rise to increased primary production, often followed by oxygen depletion and disruption of important ecosystems. An action plan has been created by the Helsinki Commission (HELCOM) in order to achieve good ecological status of the Baltic Sea in the year of 2021. According to the action plan, 21 000 tonnes of nitrogen and 290 tonnes of phosphorus shall be decreased of the annual discharge from Sweden. The aim of methods within ecological engineering is to solve environmental problems, and the applications ranging from the harvesting of existing ecosystems to the construction of new ecosystems. This study evaluates if harvest of algae, reed, and mussels can help meeting the goals of the action plan considerably, in accordance with areas and biomass amounts that need to be harvested, and to assess the efficiency of the three biomasses with regards to nutrient reduction. The potential of harvested biomasses as substrates in biogas production and as fertilizers is investigated, and how much fossil CO2 that can be saved from being released to the atmosphere if net energy benefits, calculated from energy budgets in the biogas process, replaces fossil fuels. Life cycle inventories which extend from the harvest (i.e. from the Baltic coast of Sweden) to the production of biogas have been made in order to investigate the biogas potential of algal, reed, and mussel biomass. Suitability of the three biomasses as fertilizers has been assessed through comparison between nutrient sufficiency of crops and nutrient contents of the three biomasses (i.e. based on quotients of nitrogen). The quantity of biomass in the areas that can be harvested can help meeting the goals of the action plan drawn up by HELCOM, and mussels show to be most efficient with regards to nutrient reduction efficiency. Reed has the highest net energy benefit followed by algae, and both biomasses show potential of further investigation as substrates in the biogas production process. Mussels have low net energy benefit and thus are not a suitable substrate in biogas production. The three biomasses are suitable as fertilizers with respect to contents of nitrogen but the content of phosphorus occurs under the sufficiency levels for the crops (i.e. peas, grain, and sugar beets). For algae and reed, the potassium contents occur above the sufficiency level for peas and grain but under the level for sugar beets, mussels contain lower levels of potassium than the need of the investigated crops. / Eutrofiering är ett av de största miljöhoten i Östersjön och orsakas av faktorer som utsläpp av näringsämnen från olika källor samt lång uppehållstid. Eutrofiering ger upphov till ökad primärproduktion där syrebrist och störning av viktiga ekosystem är vanliga påföljder. En aktionsplan har utformats av HELCOM som fastställer att Sverige ska reducera 21 000 ton kväve och 290 ton fosfor av de årliga utsläppen till Östersjön, med syftet att uppnå god ekologisk status år 2021. Metoder inom ecological engineering innefattar sund skörd av existerande ekosystem med syftet att lösa miljöproblem. I den här studien undersöks om skörd av alger, vass och musslor kan hjälpa till att möta miljömålen med påtaglig effekt, samt mängder och ytor som måste skördas av de tre biomassorna. Effektiviteten med avseende på näringsreducering hos de tre biomassorna jämförs. Potentialen för användning av de skördade biomassorna som substrat i biogasproduktion samt som gödningsmedel undersöks, samt hur mycket CO2 som kan besparas att släppas ut till atmosfären om nettoenergi från energibudgetar i biogasprocessen ersätter fossila bränslen. Energibudgetar som sträcker sig från skörd till biogasproduktion har utformats samt näringsinnehåll av de tre biomassorna jämfördes med näringsbehov hos vissa grödor för att ta reda på biomassornas eventuella potential som gödningsmedel. Beträffande biomassor och areor som finns att skörda visade det sig att metoderna kan möta miljömålen utformade av HELCOM. Musslor visade sig vara den mest effektiva biomassan att skörda med avseende på näringsämnesreducering. Vass erhöll högst nettoenergiutbyte (i.e. baserat på energibudgetarna) följt av alger, därmed finns potential för vidare undersökning av de båda biomassorna som substrat i biogasprocesser. Nettoenergiutbytet i biogasprocessen hos musslor var lågt vilket visar att musslorna inte är lämpligt som substrat. De tre biomassorna uppvisar lämplighet som gödningsmedel med avseende på kväveinnehåll men innehållet av fosfor ligger under näringsbehovet hos de grödor som undersöktes. Alger och vass uppfyller kaliumbehovet hos ärter och spannmål, men inte hos sockerbetor. Musslornas kaliuminnehåll är lägre än näringsbehovet hos samtliga grödor.

Stormwater runoff from developed land is a source of pollution and excessive flow to waterways. The most commonly employed practices for flow and volume control are stormwater ponds and basins (also referred to as detention and retention ponds). These structures can be effective at controlling peak discharge to water bodies by managing flow timing but are often ineffective at removing nutrients, particularly in dissolved forms. Pond morphology coupled with place-specific characteristics (like soil type and drainage area characteristics) may influence plant community composition in these water bodies. The interaction of physical, chemical, and biological elements in stormwater ponds may affect their water quality performance in more significant ways than previously understood. Floating treatment wetlands (FTW) are floating rafts of vegetation that can be constructed using a variety of materials and are an emerging technology aimed at improving the pollutant removal and temperature control functions of stormwater ponds. Previous studies with field research in subtropical and semiarid climatic regions found incremental nutrient removal improvement correlated with FTW coverage of pond surface area. However, data on their performance in cold climates is lacking from the literature. This dissertation presents data from a three-year study examining the performance of FTW on stormwater pond treatment potential in cold climate conditions and optimal vegetation selection based on biomass production, phosphorus (P) uptake, and root architectural characteristics that enhance entrapment functionality. To put the FTW pond performance data into context, results from a survey of seven permitted stormwater ponds in Chittenden County, Vermont and the ponds' associated variability in influential internal and external dynamics are also discussed. Pond morphology, drainage area land use, soil types, and biological communities are analyzed for correlative relationships to identify design factors that affect pond performance but are not controlled factors in stormwater system permitting.

Agricultural runoff is one of largest contributors of phosphorus (P), nitrogen (N), and sediment affecting freshwater systems in watersheds across the Northeastern U.S., including the Lake Champlain Basin in Vermont. Agricultural cropping systems, such as corn silage and haylands, used for dairy feed production have been shown to impact watershed hydrology and water quality. Agricultural best management practices (BMPs) have the potential to decrease runoff volumes and flow rates and the associated export of nutrients and sediment from agricultural fields. Many states in the Northeastern U.S., including Vermont, are beginning to require farmers to implement water quality BMPs and further improve risk evaluation of export of P in runoff using evolving P site assessment tools, such as the Phosphorus Index (P-Index). Quantifying the effects of BMPs on hydrologic and nutrient exports from fields is critical for informing site assessment tools that aid in the development of nutrient management plans and to help design agroecosystems that do not degrade water quality. However, there is a lack of data on the effects of BMPs on edge-of-field hydrologic and nutrient fluxes, especially in cold-climate regions with snow-melt induced runoff events. This thesis consists of four chapters, Chapter 1 is a comprehensive literature review on agricultural hydrology and water quality, BMP effectiveness, and P site assessment tools. Chapters 2 and 3 address research objectives related to the evaluation of BMP and P site assessment tool effectiveness. Chapter 4 is a summary of the conclusions drawn from the work done in Chapters 2 and 3, and suggestions for future work. Chapter 2 evaluates the effects of soil aeration prior to manure application on edge-of-field hydrology, water quality, and P fluxes in haylands with clay soils during both precipitation and snow-melt induced runoff events. Edge-of-field water quality monitoring techniques and passive-capillary lysimeter systems were used to continuously measure the losses of surface runoff, subsurface leachate, and the associated export of nutrients (total phosphorus, total dissolved phosphorus, total nitrogen, and total dissolved nitrogen) and total suspended solids resulting from runoff events year-round from 2012 to 2018. Annual P fluxes in the form of vegetative uptake and removal, manure additions, and soil test P were also recorded. Results from this study indicated that soil aeration had the potential to reduce nutrient and sediment exports from haylands with poorly-drained, high runoff producing soils in the Northeastern U.S. where winter freeze-thaw conditions exist. However, potential increases in surface and subsurface hydrologic flows can accompany these reductions; these implications should be considered before implementation. Chapter 3 identifies potential P-Index improvements through the representation of topographic controls on phosphorus (P) transport by comparing results from the Vermont P-Index (VT P-Index) and a more complex process-based model, TopoSWAT, across topographic regions in a small agricultural watershed (360 ha) in the Lake Champlain Basin. Scenarios of varying P management strategies were modeled for corn silage production fields with poorly-drained soils and rolling topography. Modeled outputs of P risk assessments and edge-of-field dissolved and particulate P losses were compared. Results from this study suggest that the VT P-Index could improve its ability to support farm nutrient management planning and other P-based management decisions by incorporating topographic controls of runoff production into its estimation of P transport.

Contaminated sites in low prioritized regions demand remediation technologies that are cost- and energy-effective and locally adapted. Parameters such as the time frame during which bioremediation degradation needs to occur may not be as restraining as in urban environments. This licentiate project aims to explore opportunities and constraints for appropriate soil remediation based on organic by-products in tropical developing countries and sparsely populated areas in industrial countries. Ecological Engineering and the Framework for Strategic Sustainable Development were explored as planning tools to steer bioremediation methods towards sustainability. The use of the five concepts of Ecological Engineering within the Framework for Strategic Sustainable Development can steer bioremediation in low prioritized regions towards sustainability. Pilot-scale and laboratory experiments were undertaken to evaluate the feasibility of such bioremediation methods. Experiments carried out at the experiment station in Chontales, Nicaragua showed some promising results, but also revealed problems associated with the clay rich soils, which are typical for tropical regions. Treatment of diesel contaminated ultisol with 6 mL whey kg-1 dw in a pilot-scale experiment considerably increased the degradation rate of diesel constituents, but no effects on the degradation rates were observed after treatment with compost tea or pyroligneous acid.The soil columns study suggests that despite a favorable particle size distribution for microbial transport, the sandy loam retained a greater fraction of the microorganisms present in the ACT in the top 10 cm than the clay loam, presumably because the lower bulk density and higher SOM in the clay loam aided transport and growth of microorganisms.

Thesis (Ph. D.)--Delft University of Technology, 2004. / Includes bibliographical references and abstracts in English and Dutch.

L'objet de cette recherche-action - dont les terrains d'analyse s'inscrivent dans l'agglomération Lyonnaise - a trait à la question de la nature et de l'habitabilité urbaine. La particularité et l'enjeu du sujet résident dans la confrontation entre vision urbanistique de l'espace public, approche physique de la matérialité urbaine et prise en compte de la perception de l'environnement naturel et construit. À ce titre, cette recherche mobilise plus largement des savoirs réunis autour des écologies urbaines. En premier lieu, nous procédons à une analyse de la composante naturelle et matérielle des milieux urbains sélectionnés, de leurs usages ainsi que de leurs fonctions par l'intermédiaire d'une grille évaluative (1). Toute la complexité d'une telle démarche réside dans les critères de choix des indicateurs, notamment lorsque l'objet d'étude se révèle mouvant spatialement et temporellement. Cet examen nous permet de distinguer des modes d'agencements spécifiques contenus dans chaque configuration spatiale examinée. Puis, nous portons un vif intérêt à la dimension idéelle et subjective, deuxième versant de l'habitabilité (2). Nous nous inscrivons dans une problématique de l'expérience à travers laquelle le corps et les sens des acteurs de l'urbain trouvent droit de cité. Des parcours sur sites nous offrent l'opportunité de croiser les regards d'acteurs multiples de la production urbaine afin de recueillir leurs représentations. Ainsi, en croisant les données empiriques de ces deux protocoles d'investigation, il nous est possible d'esquisser des figures plurielles de nature constitutives de l'habitabilité des milieux de vie. / The purpose of this research-action – which fields of analysis are located in the greater Lyons - relates to the question of nature and urban habitability. The particularity of the subject and its stake lie in the confrontation between the urban vision of public space, the physical approach to urban materiality and the consideration of the perception of natural and built environment. In this respect, this research involves more widely knowledge gathered around urban ecologies. First, we conduct an analysis about the natural and physical component of selected urban areas, their uses and their functions through an evaluation grid (1). The complexity of such an approach lies in the criteria used for the selection of indicators, especially when the object of the study reveals unstable spatially and temporally. This examination allows us to distinguish patterns of specific arrangements contained in each spatial configuration subject of the study. Then we take a keen interest in the ideational and subjective dimension, which appears to be the second side of habitability (2). We fall within the issue of experience through which the body and the senses of urban actors become part of the picture. Routes on sites offer us the opportunity to confront the vision of many stakeholders of urban production in order to collect their representations. Thus, by crosschecking empirical data from these two protocols of investigation, we are able to sketch plural figures of nature that constitute the habitability of living environments.