Pathogen destruction and solids decomposition in composting latrines: study of fundamental mechanisms and user operation in rural Panama

Abstract

The relationship between temperature, high pH, desiccation, decomposition, pathogen destruction, and user operation in active double vault urine diverting (DVUD) composting latrines located in the Bocas del Toro region of Panama was assessed. Latrine samples were analyzed for temperature, pH, % moisture, carbon-to-nitrogen (C/N) ratio, and presence of specific pathogens.Surveys and visual inspections were used to verify use and type of dry material desiccant added.Measurements supported findings that compost latrines do not reach temperatures sufficient to destroy all pathogens. pH measurements showed that many latrines were operating within the range for ideal aerobic decomposition, a pH of 7.5-8.5, but only 17% of latrines measured pH 9 or above. Almost 100% of composting latrine users added sawdust and wood ash, to lower moisture level and provide carbon for decomposition. However, the recommended amount of desiccant added was insufficient to reduce moisture to the suggested 25% for pathogen destruction and C/N ratios remained in the range of raw human faeces. Importantly, pathogens, mainly helminths, were still present in compost stored for the 6-month contact time. The latrines have conflicting goals of pathogen destruction and aerobic decomposition. Recommendations are made regarding operation of composting latrines and disposal of composted material.

Sustainable sanitation, improved use of composting latrines through mixing and moisturizing: case study in Paraguay

“…This study confirms and further explains the results and conclusion of Mehl et al (2011) which also found that (1) compost latrines do not always reach the Safe Zone of Pathogen Destruction and (2) compost needed to be composted for more than 6 months due to the existence of pathogens and helminths. This study was performed on a single, typical latrine, with detailed temperature readings, while Mehl et al (2011) measured only one temperature value in multiple latrines.…”

A Method for Determining Ascaris Viability Based on Early-to-Late Stage In-Vitro Ova Development

“…We expect this method to be more applicable in tropical and sub-tropical regions where A. lumbricoides is prevalent and environmental conditions are favorable for ova development [12][13]. further research is needed to determine the usefulness of this method for determining ova viability in applications other than human fecal materials applied onto agricultural soils, such as sewage sludge treatment processes.…”

“…then, the spatula was used to till the top few cm of the soil surface to blend in the ova-biosolid mixture. additional deionized (di) water was added to the biosolid-amended soil to increase the moisture content of each microcosm to approximately 22.25% (less than 25% suggested for pathogen destruction) [12,34]. a total of 48 microcosms were prepared.…”

“…Ascaris spp. are most prevalent in tropical and sub-tropical regions, but occur worldwide in various climates [12][13]. yet, even though developmental time depends on geographic area and climate, there is a lack of understanding of Ascaris spp.…”

“…A. suum ova were used as a model for A. lumbricoides, as the two are morphologically and genetically similar, yet the swine type is less infectious, easier to acquire, and more resistant to environmental stresses [10,12,[30][31]. results obtained by both methods were compared to determine any significant differences between the methods.…”