The world’s sanitation systems must be up to the challenge of addressing the global crises of water shortages and food insecurity in the face of a growing population. To help address these problems, ecological sanitation (Ecosan), which typically involve the use of urine-diverting dry toilets (UDDTs) and the application of excreta in agriculture, can be employed. This paper discusses the challenges and potentials of the Ecosan approach in terms of 3 essential requirements—continuous defecation use, reduction of health risk, and use of excreta—by examining 3 cases of Ecosan use in Vietnam and Malawi. The experience with traditional Ecosan in rural Vietnam suggests that dry sanitation practices that apply Ecosan are effective at reducing fecal contamination in the surrounding water environment, thereby reducing the health risk from unavoidable accidental ingestion of contaminants. However, current sanitization processes involving the application of manure to agricultural products represent a significant health risk challenge. The experience with modern UDDTs in rural Vietnam suggests that they can be continuously used for defecation for long periods of time without intervention, while there remain major challenges to continuous use from physical damage to the UDDT structures. The proper management of fecal chambers can successfully control the offensive odors that are a source of wide concern. In rural Malawi, the introduction of modern UDDTs successfully fostered a demand for the use of feces by raising the perception of its value in agriculture and through an integration of the Ecosan project into an agricultural technology transfer program. Urine use, by contrast, did not gain a wide acceptance, suggesting that raising an awareness of the effects of urine on agriculture is a key challenge. Thus, although some challenges still need to be overcome, 3 cases of Ecosan showed bright potentials of the Ecosan approach from the 3 essential requirement.

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There is a huge problem with the reuse of dairy slurry (i.e., liquid fraction of dairy manure) which has a high potential as a fertilizer in Japan. The dairy farmer applies too much dairy slurry to their farm for pasture and meadow, because they have a huge amount of slurry production, resulting in over-fertilizing and also causing a bad odor problem. To overcome these problems, the nutrients should be used for other crops managed by other farmers. This is, however, costly due to transportation and a special machine needed for its application. Furthermore, nutrient salt concentrations of slurry as such is improper. Therefore, the solid fertilizers production process (SFPP) from dairy slurry is proposed to produce ammonium sulfate and potassium chloride as fertilizers, and sodium hydrogen carbonate as a by-product. The objectives of this research are 1) to investigate the effect of temperature on sodium hydrogen carbonate precipitation and 2) to confirm the principle of separated precipitation of sodium and potassium. As a result, precipitation of sodium hydrogen carbonate was observed in the temperature range from 25°C to 50°C. The sodium concentration in precipitation was high at 25°C among the experiments. Then, the sodium removal and potassium recovery processes produced sodium hydrogen carbonate and potassium chloride precipitations separately, without ammonia in the precipitations. The element analysis and XRD analysis supported the existence of the crystals. Finally, the possibility of separate production of potassium fertilizer and sodium salt was confirmed.

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Forward osmosis (FO) is a promising technology for urine volume reduction to ease the recovery of nutrients. Its efficiency is highly dependent on the draw solution. Hence, functionalization of novel draw solutions for forward osmosis (FO) has become a subject of intense investigation. Coated magnetic nanoparticles (MNPs) based solutions offer great potentials for their ability to generate osmotic pressure as well as their easy recovery. Since concentrated urine features high osmotic pressure, we aim to synthesize a high osmotic pressure generating draw solution. Polyethylene glycol (PEG), is an attractive coating agent as aqueous Polyethylene Glycol solutions are known to generate high osmotic Pressure. Moreover, PEG are hydrophilic and expected to have physical aggregation suppression. In this study, we adopted coprecipitation method to synthesize PEG 4000 coated MNPs as draw solution, and studied the influence of the initial coating agent amount and sonication effect on the coating ratio and the osmotic pressure generation of solutions made of the synthesized particles. We found that initial PEG to MNP ratio affects the coating ratio. Indeed, higher coating ratio is obtained with higher initial PEG to MNP ratio. A PEG to MNP ratio of 1 to 4 led to 31% coating ratio. This coating ratio can be slightly increased if the synthesized draw solution is treated with ultrasound for 30 minutes. Water flux data collected from forward osmosis experiment revealed that this novel draw solution generates osmotic pressure. The osmotic pressure obtained from a draw solution containing a given amount of PEG 4000, is larger than the osmotic pressure if the same amount of PEG 4000 is used alone. Fate of the osmotic pressure of the novel draw solution following recycling of the synthesized MNPs is also evaluated. It was found that the drop in osmotic pressure of the regenerated draw solution is insignificant, proving possibility to reuse this draw solution for many cycles.

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Disease burden due to unsafe water, lack of sanitation, and poor hygiene behavior requires attention. In developing countries, poor school hygiene behavior remains high-risk and causes infectious disease among students. Safe hygiene behavior such as hand washing with soap can protect children from infectious disease. However, a cross-sectional study found the correct rate of hand washing of Chinese people was only 4%. Our research evaluated the knowledge, attitudes, and practices (KAP) of sanitation and hygiene among school children in the rural area of Northeast China. Participants were 333 groups of students and their parents. A questionnaire was used in the participants who reported the score of KAP level of sanitation and hygiene. Hand washing skill was checked following a checklist. Observation of sanitation facilities at school was also conducted. The questionnaires included participant characteristic, household socioeconomic status, and KAP questionnaire. The results of the questionnaires survey showed more than 80% of students had adequate knowledge of proper hygiene. Although students have sufficient knowledge about hygiene, lack of facilities may negatively affect their practice. There was no soap available in 2 schools, 53% of students reported it affects their hand washing performance at school. The results indicated the impact of gender, facilities and knowledge level on behavior. Our findings underscore the need for more hygiene education and the improvement of sanitation and hygiene facilities in the area.

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