When we consider global sanitation from within the framework of sustainable development, we are both failing to meet the needs of the present and are jeopardizing the capacity of future generations to do so. The primary function of sanitation and waste treatment is the protection of public health, but it is urgent that we also consider the long-term sustainability of sanitation and waste treatment systems. Our choice of sanitation and waste treatment systems is intimately connected to the greatest equity and sustainability challenges of our time, and we need something better than the Porcelain Dream (i.e. flush toilets, sewerage, and centralized conventional wastewater treatment). This thesis explores the design of sustainable sanitation systems from three different but complementary perspectives: 1. In a material flow analysis (MFA), I evaluate the positive impact of ecological sanitation (or the reuse of nutrients in excreta for agriculture) as an intervention to mitigate nitrogen pollution and improve stewardship of the global nitrogen cycle. I find that ecological sanitation can substitute 51% of nitrogenous fertilizer use, reduce discharge of nitrogen to waterways by 71%, decrease nitrous oxide (N2O) emissions by 34%, and improve the circularity of the agricultural-sanitation nitrogen cycle by 22%. 2. Through environmental engineering research, I derive fundamental drying characteristics of fresh faeces to support the development of ecological and sustainable sanitation. Based on this characterization, I propose the use of the Guggenheim, Anderson, and de Boer (GAB) model for predicting the relationship between water activity (aw) and equilibrium moisture content, calculating the heat of sorption, and estimating the corresponding energy requirements for drying of fresh faeces. Given an anticipated range of initial moisture contents of 63 to 86%, I estimate an energy requirement of 0.05 to 0.4 kJ/mol to inactivate pathogens in fresh faeces. 3. Via an evaluation of the composting toilet project at the University of Victoria (UVic), I explore factors critical to promoting a paradigm shift from the conventional to more ecological and sustainable systems. I identify the following as factors that facilitated implementation in the Exploration and Adoption/Preparation phases: supportive and self-reinforcing research and outcomes, favorable adopter characteristics, and the technology’s beneficial features. The overall objective of the research is to communicate that the design of sustainable sanitation systems is urgent, with implications both locally and globally, and to provide information to support a shift towards more sustainable sanitation systems. / Graduate / 2020-12-11

Basic oxygen furnace (BOF) slag media were studied through a series of laboratory, modeling and field studies as a potential treatment material for use in on site wastewater disposal systems. Microsphere enumeration methodology was examined in a factorial experiment to evaluate the minimum density and minimum number of microspheres that should be counted to ensure accurate and precise estimations of concentration. The results suggest that to minimize variability at least 350 microspheres should be counted and a microsphere density of 25-40 microspheres field-1 is necessary. A review of existing methodologies for high-titer bacteriophage production was conducted and an amalgamation of existing methodologies was chosen that reliably achieves elevated concentration and ensures a purified suspension. A combination of batch and column studies was conducted to evaluate the removal of the bacteriophage, PRD-1, and virus-sized fluorescent microspheres by BOF media, and to delineate the relative contributions of the two principle attenuation processes, inactivation and attachment. In the batch studies, substantial removal of PRD-1 does not occur in the pH 7.6 and 9.5 suspensions, but at pH 11.4, removal of the virus was 2.1 log C/C0 day-1 for the first two days, followed by 0.124 log C/C0 day-1 over the subsequent 10 days. Two column studies were conducted after 60 and 300 days of saturation with artificial groundwater at a flow rate of 1 pore volume day-1 using two BOF mixtures. After 300 days of column saturation, microsphere concentrations approached input levels, indicating a removal of 0.1-0.2 log C/C0 and suggesting attachment processes were negligible. PRD-1 removal was more pronounced (1.0-1.5 log C/C0). The reduction of PRD-1 is likely the result of a combination of virus inactivation at elevated pH (10.6-11.4), and attachment processes. Geochemical factors controlling microsphere attachment were compared between the two sets of experiments after 60 and 300 days of column saturation. Differences in attachment efficiency may be due to higher influent DOC concentration in the second experiment, conversion of amorphous iron phases to more crystalline forms over time, reductive dissolution of preferable attachment sites on iron phases, or precipitation of calcite. Hydrus-1D, a one-dimensional numerical model, was used to quantify transport processes, inactivation and attachment/detachment, occurring in the column experiments by model inversion. Fitted microsphere breakthrough closely matched observed data, whereas PRD-1 breakthrough with realistic parameter values does not closely match the peaked nature of the observed curves. The model achieved improved fits for microsphere and PRD-1 breakthrough when both strongly- and weakly-binding sites are represented. A unique set of parameter estimates could not be determined because of overparameterization of the inverse modeling for the experimental systems. An alternative latrine incorporating BOF slag media was constructed in a periurban community located near São Paulo, Brazil. Pathogen indicator removal is approximately 4-5 orders of magnitude in less than one meter of vertical transport through the BOF slag media. In a control latrine, constructed with similar hydraulic characteristics and inert materials, comparable reductions in pathogenic indicators were observed over three meters of vertical transport.

Basic oxygen furnace (BOF) slag media were studied through a series of laboratory, modeling and field studies as a potential treatment material for use in on site wastewater disposal systems. Microsphere enumeration methodology was examined in a factorial experiment to evaluate the minimum density and minimum number of microspheres that should be counted to ensure accurate and precise estimations of concentration. The results suggest that to minimize variability at least 350 microspheres should be counted and a microsphere density of 25-40 microspheres field-1 is necessary. A review of existing methodologies for high-titer bacteriophage production was conducted and an amalgamation of existing methodologies was chosen that reliably achieves elevated concentration and ensures a purified suspension. A combination of batch and column studies was conducted to evaluate the removal of the bacteriophage, PRD-1, and virus-sized fluorescent microspheres by BOF media, and to delineate the relative contributions of the two principle attenuation processes, inactivation and attachment. In the batch studies, substantial removal of PRD-1 does not occur in the pH 7.6 and 9.5 suspensions, but at pH 11.4, removal of the virus was 2.1 log C/C0 day-1 for the first two days, followed by 0.124 log C/C0 day-1 over the subsequent 10 days. Two column studies were conducted after 60 and 300 days of saturation with artificial groundwater at a flow rate of 1 pore volume day-1 using two BOF mixtures. After 300 days of column saturation, microsphere concentrations approached input levels, indicating a removal of 0.1-0.2 log C/C0 and suggesting attachment processes were negligible. PRD-1 removal was more pronounced (1.0-1.5 log C/C0). The reduction of PRD-1 is likely the result of a combination of virus inactivation at elevated pH (10.6-11.4), and attachment processes. Geochemical factors controlling microsphere attachment were compared between the two sets of experiments after 60 and 300 days of column saturation. Differences in attachment efficiency may be due to higher influent DOC concentration in the second experiment, conversion of amorphous iron phases to more crystalline forms over time, reductive dissolution of preferable attachment sites on iron phases, or precipitation of calcite. Hydrus-1D, a one-dimensional numerical model, was used to quantify transport processes, inactivation and attachment/detachment, occurring in the column experiments by model inversion. Fitted microsphere breakthrough closely matched observed data, whereas PRD-1 breakthrough with realistic parameter values does not closely match the peaked nature of the observed curves. The model achieved improved fits for microsphere and PRD-1 breakthrough when both strongly- and weakly-binding sites are represented. A unique set of parameter estimates could not be determined because of overparameterization of the inverse modeling for the experimental systems. An alternative latrine incorporating BOF slag media was constructed in a periurban community located near São Paulo, Brazil. Pathogen indicator removal is approximately 4-5 orders of magnitude in less than one meter of vertical transport through the BOF slag media. In a control latrine, constructed with similar hydraulic characteristics and inert materials, comparable reductions in pathogenic indicators were observed over three meters of vertical transport.

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