Designing pit emptying technologies: combining lessons from the field with systems thinking

The ideal pit emptying machine has been envisioned to be safe, hygienic, and economical, while being mobile and lightweight, allowing access to pits located away from main roads. The machine should be robust, should be amenable to easy operation by a few personnel, and can be maintained using local expertise and supplies. Using the insights from a recent workshop and our own field experience, we discuss the challenges of designing such a machine, and broaden the discussion to include the entire system of pit emptying, collection, and transport. We classify pit emptying technologies according to the type of pit (e.g., wet pits with little trash, wet pits with lots of trash, and dry pits with lots of trash), and argue that designing technologies accordingly should be the focus in the future. A systems approach that includes transport optimisation, sustainability of small businesses, and operator safety and training is advocated

Educating sanitation professionals: moving from STEM to specialist training in higher education in Malawi

Achieving the United Nations Sustainable Development Goals (SDGs) requires effective changes in multiple sectors including education, economics, and health. Malawi faces challenges in attaining the SDGs in general, and specifically in the sanitation sector. This paper aims to describe the existing landscape within public universities in Malawi to build a framework for training a cadre of locally trained experts. This is achieved by reviewing science, technology, engineering, and mathematics (STEM) degree programmes and assessing the extent of inclusion of sanitation education. The historical compartmentalization of academic programmes has resulted in few programmes to build on. Deliberate investment is needed to build from the current STEM higher education landscape to an effective framework for training sanitation experts, especially female experts. For low-income countries such as Malawi, a cadre of ~17,600 locally trained sanitation experts may be needed, for which the current higher education landscape is not sufficient. Using the Centre of Excellence in Water and Sanitation at Mzuzu University in Malawi as a case study, this paper provides a model of sanitation education in low-income countries that: 1) provides an effective complementary contribution to delivering sanitation education; 2) links to overall SDGs, national policy, university goals, and localized needs; and 3) engages students, faculty, and communities in local research

Microbial community function and bacterial pathogen composition in pit latrines in peri-urban Malaw

Despite the widespread global reliance on pit latrines as improved sanitation systems, the decomposition of waste within pit latrines is poorly understood. One area needing elucidation is the characterization and function of microbial communities within pit latrines. To address this gap, we characterized the microbial communities of 55 lined pit latrines at three sampling layers from two communities in peri-urban Malawi. The microbial communities of the fecal sludge samples were analyzed for beta diversity, pathogen presence, and functional profiling. Household surveys were conducted and used to compare microbial community patterns to household characteristics and pit latrine use patterns. Compared to activated sludge, anaerobic digestion in municipal wastewater systems, and human gut microbiomes, pit latrines were found to contain unique microbial communities. While the microbial community composition as a whole did not vary by sampling depth, pathogen composition varied by sampling depth, location, and household water source. The inferred microbial function also varied by depth (e.g., increase in methanogens and decrease in aerobes with depth). The richness of lined pit latrines determined from surface samples from eight latrines was found to be representative for a given area. Samples from middle and lower depths collected using a Gulper pump did not provide more information on richness, a result that informs future sampling designs. These findings are important for improving waste-based epidemiology (WBE) approaches to understand community health and waste degradation characterization of lined pit latrines

Microbial community function and bacterial pathogen composition in pit latrines in peri-urban Malawi

Despite the widespread global reliance on pit latrines as improved sanitation systems, the decomposition of waste within pit latrines is poorly understood. One area needing elucidation is the characterization and function of microbial communities within pit latrines. To address this gap, we characterized the microbial communities of 55 lined pit latrines at three sampling layers from two communities in peri-urban Malawi. The microbial communities of the fecal sludge samples were analyzed for beta diversity, pathogen presence, and functional profiling. Household surveys were conducted and used to compare microbial community patterns to household characteristics and pit latrine use patterns. Compared to activated sludge, anaerobic digestion in municipal wastewater systems, and human gut microbiomes, pit latrines were found to contain unique microbial communities. While the microbial community composition as a whole did not vary by sampling depth, pathogen composition varied by sampling depth, location, and household water source. The inferred microbial function also varied by depth (e.g., increase in methanogens and decrease in aerobes with depth). The richness of lined pit latrines determined from surface samples from eight latrines was found to be representative for a given area. Samples from middle and lower depths collected using a Gulper pump did not provide more information on richness, a result that informs future sampling designs. These findings are important for improving waste-based epidemiology (WBE) approaches to understand community health and waste degradation characterization of lined pit latrines

Molecular Methods in Biological Systems

This review summarizes literature demonstrating the application of molecular biology tools in biological systems with specific applications in biological waste treatment, public health, and bioremediation. In addition, this review highlights new methods that were developed in 2001. As molecular tools move from development to applications, environmental engineers and scientists need to use care in interpreting the results of experimental procedures. Molecular biology tools offer powerful approaches for understanding the microbial communities in biological systems, but researchers and practitioners share the responsibility of translating this new knowledge into useful practical outcomes

Quantifying Filamentous Microorganisms in Activated Sludge before, during, and after an Incident of Foaming by Oligonucleotide Probe Hybridizations and Antibody Staining

Quantitative oligonucleotide probe hybridizations, immunostaining, and a simple foaming potential test were used to follow an incident of seasonal filamentous foaming at the Urbana-Champaign Sanitary District, Northeast Wastewater Treatment Plant. A positive correlation was observed between an increase in foaming potential and the appearance of foam on the surfaces of aeration basins and secondary clarifiers. In addition, during the occurrence of foaming, the mass and activity of Gordonia spp. increased as measured by fluorescence in situ hybridization, antibody staining, and quantitative membrane hybridization of RNA extracts. An increase in Gordonia spp. rRNA levels from 0.25 to 1.4% of total rRNA was observed using quantitative membrane hybridizations, whereas during the same period, the fraction of mixed liquor volatile suspended solids attributed to Gordonia spp. increased from 4% to more than 32% of the total mixed liquor volatile suspended solids. These results indicate that both the activity and biomass level of Gordonia spp. in activated sludge increased relative to the activity and the biomass level of the complete microbial community during a seasonal occurrence of filamentous foaming. Thus, Gordonia spp. may represent a numerically dominant but metabolically limited fraction of the total biomass, and the role of Gordonia spp. in filamentous foaming may be linked more tightly to the physical presence of filamentous microorganisms than to the metabolic activity of the cells

Interfacing Phylogenetic Oligonucleotide Probe Hybridizations with Representations of Microbial Populations and Specific Growth Rates in Mathematical Models of Activated Sludge Processes

Accurate estimates of microbial population concentrations and the direct, in situ determination of kinetic parameters could improve the calibration and validation of existing mechanistic mathematical models of biological nutrient removal activated sludge systems. Oligonucleotide probe hybridizations show promise for measuring concentrations and in situ specific growth rates of microbial populations. The most common targets for oligonucleotide probes are the phylogenetically conserved ribosomal RNA molecules. Recent advances in hybridization techniques have improved the quantitative nature of ribosomal RNA based assays. However, correlations between concentrations of \u27theoretical\u27 microbial populations predicted by mechanistic models and quantitative information obtained with oligonucleotide probe hybridizations are not yet developed. Future work should develop such correlations, while addressing the limitations of the molecular assays