Comparative life cycle assessment of excreta management systems through composting and biomethanization: Case of a low-income tropical country.

Low-income tropical regions, such as Haiti, grapple with environmental issues stemming from inadequate sanitation infrastructure for fecal sludge management. This study scrutinizes on-site sanitation systems in these regions, evaluating their environmental impacts and pinpointing improvement opportunities. The focus is specifically on systems integrating excreta valorization through composting and/or anaerobic digestion. Each system encompasses toilet access, evacuation, and sludge treatment. A comparative life cycle assessment was undertaken, with the functional unit managing one ton of excreta in Haiti over a year. Six scenarios representing autonomous sanitation systems were devised by combining three toilet types (container-based toilets (CBTs), ventilated improved pit (VIP) latrines, and flush toilets (WC)) with two sludge treatment processes (composting and biomethanization). Biodigester-based systems exhibited 1.05 times higher sanitary impacts and 1.03 times higher ecosystem impacts than those with composters. Among toilet types, CBTs had the lowest impacts, followed by VIP latrines, with WCs having the highest impacts. On average, WC scenarios were 3.85 times more impactful than VIP latrines and 4.04 times more impactful than those with CBTs regarding human health impact. Critical variables identified include the use of toilet paper, wood shavings, greenhouse gas emissions, and construction materials.

Quantitative microbial risk assessment (QMRA) of the work of manual pit emptiers, commonly known as bayakous.

In Haiti, manual pit emptiers, known as bayakous, face significant health risks. They work by descending naked into latrine pits, exposing themselves to pathogens and contributing to environmental contamination. This study employs the quantitative microbial risk assessment (QMRA) method to evaluate the microbial risks associated with this practice, considering nine prevalent pathogens in Haiti. Three ingestion scenarios were developed: hand-to-mouth contact, ingestion while immersed in excreta, and a combination of both. A sensitivity analysis assessed the impact of input data on study outcomes. The results indicate a high probability of infection and illness during pit emptying operations annually for all scenarios and pathogens. Recommendations include adopting personal protective equipment (PPE) and using a manual Gulper waste pump to eliminate the need to descend directly into the pits, thereby reducing the risk of injury from sharp objects. The study proposes the establishment of intermediate disposal points approximately 5 km from collection sites to deter illegal dumping. National regulations and professionalization of the bayakou profession are suggested, along with awareness campaigns to promote PPE and Gulper pump usage. Addressing these issues is crucial for safeguarding the health of bayakou and public health in Haiti.

Quantitative microbial risk assessment associated with the use of container-based toilets in Haiti.

A container-based toilet (CBT) is a type of ecological toilet that allows users to compost their feces. During emptying, bucket washing, and composting operations, operators are exposed to microbial risks. This paper aims to evaluate these risks using the Quantitative Microbial Risk Assessment (QMRA) method. Nine pathogens prevalent in Haiti were targeted: Ascaris lumbricoides, Campylobacter spp., Cryptosporidium parvum, Escherichia coli O157:H7, Giardia intestinalis, poliovirus, Salmonella spp., Shigella spp., and Vibrio cholerae. Information regarding pathogens' concentration in feces came from scientific literature data. The exposure scenarios considered were those in which operators accidentally ingested a low dose of feces during the aforementioned operations. A Monte Carlo simulation was conducted to address uncertainties. The results showed that the probability of infection is highly elevated, while the probability of illness is generally moderate or minor, except for poliovirus and Ascaris. Preventive measures can be implemented to reduce these risks during various operations, such as wearing gloves, disposable protective masks, and appropriate clothing. It is up to the political authorities to develop guidelines in this regard and to organize awareness-raising activities with the help of local organizations mandated by the relevant authorities to ensure the safer use of technology by households.