Hidenori Harada

Dewatering of faecal sludge (FS) is indispensable for adequate FS management. However, comprehensive knowledge is lacking on FS dewatering performance. This study compared the dewatering performance of FS from different countries and onsite sanitation technologies, to assess influential characteristics on dewatering, and to compare dewatering performance of FS with wastewater sludge. We collected 73 FS samples from septic tanks, lined pit latrines, unlined pit latrines and johkasou tanks in Ugan

Septic systems are potentially a significant source of greenhouse gases (GHGs). The present study investigated GHGs from the blackwater septic systems that are widely used especially in low- and middle-income countries. Ten blackwater septic tanks in Hanoi, Vietnam, were investigated using the floating chamber method. The average methane and carbon dioxide emission rates measured at the first compartment (65% of total capacity) of the septic tanks were 11.92 and 20.24 g/cap/day, respectively, wh

Interest in phosphorus recovery from urine diverted from faeces has been growing recently. Phosphorus in urine can be precipitated out as struvite (MgNH4PO4 x 6H2O) with addition of magnesium salt under alkaline conditions. Struvite formation, however, should be more well understood for its practical application. We predicted the struvite formation with a development of a new equilibrium model. The model considered the formation of eight different kinds of precipitates, including struvite, with

Although many cities have planed to develop sewerages in developing countries, sewerage establishment still requires huge investment and engineering efforts. Improvement of existing sanitation facilities may contribute the betterment of urban sanitation before sewerage establishment. The purpose of this study is to propose a measure to improve urban sanitation in areas where a sewerage development plan is proposed but has not been yet established, based on a case study in Hanoi, Vietnam. We foun

Infectious disease transmission is frequently mediated by the environment, where people's movements through and interactions with the environment dictate risks of infection and/or illness. Capturing these interactions, and quantifying their importance, offers important insights into effective interventions. In this study, we capture high time-resolution activity data for twenty-five Vietnamese farmers during collection and land application of human excreta for agriculture. Although human excreta

Septic tanks in low- and middle-income countries are often not emptied for a long time, potentially resulting in poor pollutant removal efficiency and increased greenhouse gas emissions, including methane (CH₄). We examined the impact of long emptying intervals (4.0-23 years) on the biochemical oxygen demand (BOD) removal efficiency of 15 blackwater septic tanks and the CH₄ emission rates of 23 blackwater septic tanks in Hanoi. The average BOD removal efficiency was 37% (-2

Sanitary wastewater from an urban slum was heavily contaminated with pathogenic Escherichia coli. It is worth noting a great health risk of accidental exposure to pathogenically contaminated wastewater improperly discharged in and around urban slums. The distinct difference in pathotypes between wastewater and drinking water and the significantly smaller positive proportion of the human-specific E. coli genetic biomarker (H8) in drinking water indicate that drinking water contamination could be

Sewage generated in Southeast Asia is typically characterized by small per-capita flow and low concentration. This study investigated the impacts of exfiltration (leaking-out) and infiltration (leaking-in) on sewage flow and quality in Hue, Vietnam. Sewage flow and quality were continuously monitored at the sewer outlet of a residential drainage area for 68 and 82 days during dry and rainy seasons, respectively. Infiltration was estimated based on the least sewage flow before morning. Lithium tr

Fecal contamination with a poor water, sanitation and hygiene environment in urban informal settlements poses diarrhea risks. Little information is available on the contamination of environmental media with enteric pathogens in such settlements. We investigated the contamination of Escherichia coli, rotavirus, and Cryptosporidium spp. in water, on kitchenware, and on flies in urban informal settlements of Chawama and Kanyama, Lusaka, Zambia. These environmental media were examined by XM-G agar c

Urban sanitation issues should be tackled strategically, and may be addressed effectively when sewage development is pursued in conjunction with complementary sanitation measures. Five sanitation improvement scenarios employing sewage, night-soil collection-and-treatment (NSCT) system, and/or septic-tank improvement by annual dislodging were analyzed from the perspective of COD loads, total nitrogen loads, and cost under the conditions found in Hanoi, Vietnam. Compared to the development of sewa

Northern Vietnam has a history of using urine diversion (i.e., UD) toilets with agricultural use of excreta. This study tried to identify the current practices of UD toilets in suburban Hanoi, Vietnam. An interview survey to 120 households showed that UD toilets were used by 26.7% of households, of which most were double-vault UD toilets. Human wastes were used by 73.0% of vault toilets. It was interpreted that they are still recognized as not wastes but fertilizers especially by farming househo

The purpose of this study is to find the strategy to handle human excreta properly in rural areas of developing countries. In this study, 85 Ecological Sanitation (EcoSan) toilets, based on an improved version of the Vietnamese Double-Vautlt toilet were introducedin a minority hamlet of Vietnam, which was located at highlands. Using these toilets, feces and urine are collected separately. Urine is used as fertilizer after dilution. Feces are stored in the toilet for a certain period. It is then

Human urine can be diverted from faeces by urine diversion toilets. Nutrient recovery from diverted urine has been a growing concern recently, because urine contains many nutrients. Phosphorus in urine can be recovered as a precipitate of MAP (i.e., struvite, MgNH4PO4·6H2O) by adding magnesium salt under alkaline conditions. In this study, we (1) developed a plant for struvite recovery from urine using a urine diversion toilet, (2) investigated the characteristics of the plant's urine collection

Phosphorus recovery from wastewater has been a growing concern. Since human urine is one of the main sources of phosphorus in the environment, several studies have been undertaken to recover phosphorus from human urine diverted from feces. Phosphorus in human urine can be recovered as a precipitate of MAP (i.e., struvite, MgNH4PO4·6H2O) by adding magnesium salt under alkaline conditions. However, little is known about the chemical reaction of MAP formation in human urine, which is essential for