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Low plant available phosphorus limits legume growth and biological nitrogen fixation (BNF). This study examined, under controlled conditions, the relationship between soil phosphorus and alfalfa and soybean BNF on two contrasting low-P soils (Ontario and Nova Scotia) from organic dairy farms. Soluble P was applied up to 135 mg P kg-1. An optimum range of 45 to 90 mg kg-1 applied P increased soybean plant growth, nodulation, N and P uptake and BNF. Significant effects of soil type reflected greater N supplying ability and lower P sorption for the Ontario soil. Alfalfa response to soluble P application was not as apparent. In addition three potentially organically acceptable amendments (MSW compost, Crystal Green® struvite and partially solubilized rock phosphate) were evaluated as alternate sources of plant available P. Compost and struvite, applied at moderate rates, sufficiently supplied P to increase plant growth and BNF comparably to that found for soluble P fertilizer.

Utilizing food and yard waste (FYW) compost for plant production requires determination of application rates that support crop production, improve soil properties and avoid excessive nutrient build-up. An 88 day incubation experiment showed 12 t ha-1 FYW compost to contribute 3.6 kg M3P ha-1 and 0.3 kg mineral N ha-1, 24 t ha-1 supplied 15.1 kg M3P ha-1 and 0.7 kg N ha-1 and 36 t ha-1 gave 39.5 kg M3P ha-1 and 1.2 kg N ha-1 to Pugwash series coarse, loamy soil. A field study showed FYW compost yielded higher P concentrations in grain and stover but lower grain yields than fertilizer. In the residual year, compost treatment yields didn’t decrease and concentrations and amounts of P and N increased. This FYW compost applied to corn at 24 t ha-1 with an N fertilizer can yield similarly to fertilizers only, removing greater amounts of P in grain and stover.

This study explored the use of a biosecure, static composting structure to inactivate MAP. In Experiment #1, it was concluded that composting is unlikely to achieve temperatures necessary to inactivate MAP associated with cattle mortalities and that M. smegamatis is an unlikely surrogate for MAP. This study also used the same system to explore changes in the microbial community in mortality compost after exposure to thermophilic temperatures. As high-throughput sequencing technologies advance, it is possible to characterize microbial communities in environments with a high degree of resolution. In Experiment #2, as members of Clostridia were present at temperatures > 55°C, it appears that anaerobic conditions existed within regions of the compost. Extreme temperatures and non-homogeneous high moisture conditions resulted in spatial distribution of temperature in a biosecure, static composting system, which failed to meet conditions necessary for complete composting and pathogen reduction.

In this thesis, a study was undertaken on the premise that the world population living in urban centers is expected to increase from 3.8 billion to 5.2 billion, from 2005 to 2025, representing 54% and 65% of total world population, respectively. The urban population (UP) growth will produce remarkable amounts of urban food waste (UFW) that will add more pressure on already overloaded municipal solid waste (MSW) management systems of cities. This problem is more serious in countries experiencing major economic growth such as China where UP is expected to increase from 44% to 66% of the total country population, from 1995 to 2025. Asia produces the largest amount of UFW, which is expected to increase from 251 million ton to 418 million ton (45% to 53% of total world UFW) from 1995 to 2025. On site treatment of UFW along with a limited movement of world population from rural to urban areas are suggested to reduce pressure on MS W management system for the upcoming decades. / In this thesis, a project was also undertaken to develop compost recipes for urban center such as downtown Montreal. Monthly (June to August) average residential FW production was found to 0.61 (+/-0.13) kg capita-1 day-1 and that of a restaurant was found to be 0.56 (+/-0.23) kg customer-1 day-1. From trial tests, the best compost recipes mixed 8.9 kg, 8.6 kg and 7.8 kg of UFW for every kg of wheat straw, hay and wood shaving, on a wet mass basis. However, quantity and characteristics of FW vary from one month to another; therefore, regular adjustment of compost recipe is recommended. When using wood shavings as bulking agent, it is strongly recommended to correct the acid pH.

This study explored the use of a biosecure, static composting structure to inactivate MAP. In Experiment #1, it was concluded that composting is unlikely to achieve temperatures necessary to inactivate MAP associated with cattle mortalities and that M. smegamatis is an unlikely surrogate for MAP. This study also used the same system to explore changes in the microbial community in mortality compost after exposure to thermophilic temperatures. As high-throughput sequencing technologies advance, it is possible to characterize microbial communities in environments with a high degree of resolution. In Experiment #2, as members of Clostridia were present at temperatures > 55°C, it appears that anaerobic conditions existed within regions of the compost. Extreme temperatures and non-homogeneous high moisture conditions resulted in spatial distribution of temperature in a biosecure, static composting system, which failed to meet conditions necessary for complete composting and pathogen reduction.

Passive treatment systems for mine water pollution remediation require no chemical or energy inputs, and should only incur limited maintenance costs if properly constructed. This thesis investigates two such passive treatment systems that have been installed at sites in County Durham, UK. The overall objectives of the investigation were to improve understanding of the operation of passive systems in order to produce more accurate design guidelines, and to develop a new passive treatment option to complement existing technologies. To put the research into context the causes, impacts and extent of mine water pollution in the UK and overseas are outlined. In addition a detailed and up-to-date review of passive treatment research and development is provided, which highlights areas in which further research is required. At Quaking Houses, County Durham, a full-scale compost wetland has been constructed to treat an acidic and metal-rich discharge from the spoil heap of an abandoned coal mine. Over the 27 month study period the discharge had pH >_ 4, and mean iron, manganese and aluminium concentrations of 5.4 mg/L, 3.6 mg/L and 6.2 mg/L respectively. The unique design and construction of the 440 m2 wetland is described. An examination of the performance of the wetland illustrates that it has yielded significant improvements in water quality since its construction. Mean reductions in acidity, iron and aluminium concentrations are all around 50%. Bacterial sulphate reduction may be an important contaminant removal mechanism, but its proportional significance is unclear. Comparison of the system at Quaking Houses with other wetlands reveals that the mean reduction in acidity in terms of mass removal per unit area (5.01 g/m2/d) is comparatively low. However, it is shown that comparing wetland performance on this basis may be misleading where influent contaminant concentrations are relatively low, because contaminant removal is demonstrably influent concentrationdependent. A first-order removal assessment method of performance may be more appropriate, and on this basis the Quaking Houses wetland performs well when compared to systems in the USA. An algorithm for predicting wetland effluent iron concentrations is derived using a linear multiple regression technique. Time series analysis strongly suggests that some effluent water quality variables (and therefore wetland performance measures) are significantly affected by seasonal climate changes. In particular aluminium and acidity removal rates rise with increasing air temperature. This implies that to meet the same effluent water quality targets passive treatment systems in cold climate locations may need to be larger than equivalent systems in warmer climates. At Kimblesworth, also in County Durham, a pilot-scale passive treatment system has been operated for 4 months. The Kimblesworth discharge is a net-alkaline pumped mine water containing up to 2 mg/L iron and up to 1 mg/L manganese. The novel system at this site was designed to rapidly remove iron by oxidation and accretion of iron to high surface area media. The monitoring programme has revealed the system to be very efficient. Iron concentrations are consistently reduced to < 0.5 mg/L, and removal rates are an order of magnitude greater than in wetland systems. Furthermore, lithium tracer tests reveal that the residence time of water in the reactors is just 5- 10 minutes. The results of this research suggest that the technology could be applied at full-scale. The compost wetland at Quaking Houses and the new reactor at Kimblesworth may well complement each other. The Quaking Houses system generates alkalinity and removes metal contaminants, but effluent water still contains marginally elevated concentrations of iron (mean 2.4 mg/L). The Kimblesworth system is shown to be very effective at rapidly removing low concentrations of iron, and thus could conceivably be used as a polishing unit following a compost wetland such as that at Quaking Houses. Alternatively high surface area media reactors such as those at Kimblesworth could be used to treat discharges in topographically difficult locations, where the installation of a wetland is not feasible.

Urban stormwater runoff is recognised as a substantial source of heavy metal contamination, which adversely impacts on water quality of regional receiving waterways. Conventional treatment of urban runoff mostly involves a filtration system using sand to retain particulate matters. Sand provides limited sorption of dissolved metals and the inclusion of commercial sorbents to these treatment systems is not cost effective due to the concentration of dissolved metals in the runoff. Recycled organic materials are by-products or waste from industrial or agricultural operations, and could be alternative low cost sorbents for stormwater treatment systems. The use of recycled sorbents also provides added value to the waste materials and reduces landfill disposal. The research explores the application of compost, zeolite, ash, and recyclable waste in urban runoff treatment, especially for dissolved metal removal. The research combines the two aspects of experimental studies and management analysis to develop a holistic approach to heavy metal control in urban stormwater systems. Experimental results of batch sorption test show that compost is suitable for removing dissolve copper in stormwater treatment. The comparison of the different mixing ratios between compost and glass beads in column test evaluates the optimum mixing sorbent and performance over a long period for copper removal. Substance Flow Analysis (SFA) of copper has been performed in the Upper Parramatta River Catchment, Sydney to identify the sources of copper associated with runoff, effect of using waste material such as compost in urban stormwater treatment and the copper load in urban stormwater runoff. This case study shows the relationship between copper input, copper stock, sorbent type and urban stormwater quality control in the system boundary of the catchment. Different scenarios of source control are evaluated to control copper load from the different sources. Source control focusing on roads and vehicles is the most effective copper control strategy. The combination of source control and stormwater treatment reduces copper in stormwater and receiving water. The thesis applies the analysis from SFA and experimental results to derive both a regional system-wide solution with source control, and an improved design of stormwater treatment for heavy metal removal using recycled organics.

Use of bauxite refining residue to reduce the mobility of heavy metals in municipal waste compost. Due to the adverse environmental impact of landfills and the lack of space for nearby population centres an unprecedented interest has developed in waste recycling with the objective to reduce the volume of waste disposed. Generally organic matter represents the largest fraction in the domestic waste stream including food, garden and paper waste. In the past efforts have been made to process this organic fraction into muniapal compost.However contamination of the compost with heavy metals has in many cases resulted in the lack of suitable markets and subsequent closure of compost facilities. A study was undertaken and aimed at reducing the concentration and mobility of heavy metals in municipal compost. Bauxite refining residue ha; a high capacity to immobilise metals in soils through precipitation, cation exchange and chemisorption (Fe- and Al- oxides). The first step in the study was to assess the metal adsorption capacity of red mud by equilibrating red mud with metal solutions. Metal removal from solution proved very high. Subsequently, the effect of red mud addition to municipal compost was studied in relation to metal mobility. In particular the interaction of metals with the mobile soluble organic fraction, the humic and fulvic acids, was investigated. It was found that most metals remained in the insoluble humin fraction and the metals in solution remained complexed to the soluble organic fraction. Red mud appeared to be able to adsorp fulvic and humic acids and thus indirectly immobilise the metals in solution. Red mud did not appear to be able to transfer metals from the organic fraction to the mineral red mud fraction. ft was kypothesised that, in order for the metals to be adsorped to red mud, the red mud needed to be present in the organic waste prior to composting. Metal adsorption to red mud is a rapid chemical reaction while metal complexation to the organic fraction takes a number of weeks, since it must be sufficiently oxidised to contain functional groups. In order to verify this hypothesis, an installation with seven incubators was developed which allowed composting to be undertaken under computer controlled conditions and monitored for temperature, airflow and carbon dioxide respiration. The incubators were filled with 10 kg of a mixture of grass clippings and sawdust. The first incubator functioned as a control. The contents of the rest of the incubators were spiked with the following metals: Cd, Cr, Cu, Ni, Pb and Zn. In addition the contents of the 3rd - 7th incubators were amended with an increasing percentage of red mud, respectively 10,20,25,30 and 40 % by weight. After the mixture was composted, the metal mobility was reduced by approx. 80 - 99 %, depending on the metal. The mobility was assessed as leachable and plant available in relation to the total metal content. Red mud did not affect the composting process if < 40% red mud was added. The next step was to compost municipal organic waste in a pilot plant (capacity 5 m3) using batches with and without red mud. Mixed waste was collected from 150 households and the glass, metal and plastic fractions were removed bx- manual sorting. The rest was composted. The red mud - compost had a relatively lower metal content and a reduced metal mobility compared to compost without red mud. The red mud - compost also had a 300 times higher pH buffer capacity and 90%less soluble organic matter. The addition of red mud prior to composting was found to reduce the concentration and mobility of metals in compost, improve the quality of compost as a soil conditioner, increased the resistance of the organic fraction against further breakdown and this process thus adds value to both red mud and organic waste.

Thèse (M.Sc.)--Université Laval, 2008. / Bibliogr.: f. 69-73. Publié aussi en version électronique dans la Collection Mémoires et thèses électroniques.