Keywords

1 Introduction

Ensuring sanitation is essential for human health and dignity. Unfortunately, 2.0 billion people still do not have access to basic sanitation services (WHO and UNICEF 2020). Although the Sustainable Development Goals set a target to ensure sanitation access for all by 2030 (United Nations 2015), no ideal solution is currently available to ensure global sanitation.

Given the critical issues facing the world in the future, sanitation solutions must be compatible with solutions to global challenges such as water scarcity and food insecurity. These conditions justify sanitation approaches that utilize dry sanitation with agricultural use of human excreta. Furthermore, agricultural use of human excreta adds value to sanitation based on the resource value of human excreta. This value can potentially speed up the slow pace of sanitation adoption worldwide. There are many approaches to sanitation that employ agricultural use in a dry manner. One such approach is urine-diverting dry toilets (UDDTs), aiming at the sanitization of human excreta and agricultural use. UDDTs typically used in low- and middle-income countries are waterless toilets that separate urine and feces at the source at the time of excretion, thereby efficiently sanitizing the feces without liquid by separating the urine. Based on the concept of ecological sanitation (Ecosan), UDDTs have been used in many countries (e.g., Harada and Fujii 2020; Jackson 2005; Werner et al. 2009; Winblad and Simpson-Hébert 2004).

On the other hand, in practice, some people have an aversion to agricultural use of human excreta; such an attitude is called fecophobia (Winblad and Simpson-Hébert 2004). Establishment of latrines employing excreta use is, therefore, sometimes difficult because of fecophobic attitudes; for example, some face challenges in the initial acceptance of UDDT installation and ongoing management after installation (Drangert 2004; Jackson 2005; Uddin et al. 2014). Regardless of whether the type of latrine employs human excreta for agriculture or not, there are two essential requirements for latrines: to provide a comfortable defecation space that can be used continuously and to improve human health through their use. Although the type of latrines that take advantage of the resource value of human excreta and use it for agriculture can potentially drive the spread of sanitation, it is essential that the agricultural use of human excreta and latrines employing mechanisms to use excreta are socio-culturally acceptable and established in the field for the long term.

This chapter focuses on UDDTs in rural areas to examine the socio-cultural acceptability of sanitation employing excreta use for agriculture. Based on three cases of UDDT introduced in rural areas of Vietnam, Malawi, and Bangladesh, and used for some years, we examined the factors that influenced the establishment of UDDTs, and the impact of the fertilizer value of feces and urine on the socio-cultural establishment of UDDTs on a long-term basis. Furthermore, we discuss the relationship between long-term establishment of sanitation and the fertilizer value of human excreta.

2 Methodology

2.1 Case A: UDDT Introduction in Rural Vietnam

Vietnam is a country in South East Asia, surrounded by China, Laos, Thailand, Cambodia, and the East China Sea. The project site was in a hamlet of the Dan Phuong Commune, located in Lam Dong Province in the central highlands of Vietnam (Fig. 12.1). The total population of the project site was 491. At the time of project implementation, most households did not own any toilets in the project site, although some households had unsanitary simple pit latrines without slabs, meaning unimproved sanitation. Most households earned their livelihoods from agriculture. Although some areas of Vietnam have traditions of using human excreta for agriculture, people in the target areas had no such tradition.

Fig. 12.1
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Area of the UDDT project in Vietnam

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In this project, 85 UDDTs with double fecal chambers were installed in each household by an international NGO (Nippon International Cooperation for Community Development) in 2012–2013. Figures 12.2 and 12.3 show the appearance and interior view of the UDDT. The design of the toilet is a partial modification of the UDDTs previously designed in Vietnam (Nha Trang Pasteur Institute VinaSanres Project 2002). This UDDT has a squatting pan with two covered holes at each end, leading to two separated fecal chambers under the slab, and a urinal in the center of the pan for draining and collecting urine. The urine is stored in a urine container behind the toilet building and can be used as a liquid fertilizer for agriculture after dilution. Ashes fall into the fecal chamber, where they are held for at least 10 months. The fecal matter mixed with ash is then removed through a small door behind the toilet building and can be used for agriculture.

Fig. 12.2
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A UDDT in the case of Vietnam: (left) outside views of a UDDT; (right) inner view of a UDDT. (Adapted from Harada and Fujii 2020)

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Fig. 12.3
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Area of the UDDT project in Malawi. (Adapted from Harada and Fujii 2020)

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The UDDTs were built by local contractors trained and supervised by the NGO after orientation and lectures on the significance of UDDTs. The beneficiaries contributed to the construction in part by providing labor. Once in use, a local female health worker, who was one of the beneficiaries, visited each household every 2–3 weeks for 4 months. See Harada et al. (2004) and Harada and Fujii (2020) for more information on the project.

After the UDDTs were installed, door-to-door monitoring on the use of UDDTs was repeated for 4 months by using a checklist composed of 17 items (Harada et al. 2004). No monitoring or intervention activities were conducted for political reasons from 7 to 38 months after the installation. Approximately 3 years later, specifically, 39 months after installation, a postintervention monitoring survey, consisting of structured interviews and observations of construction conditions, toilet management, and usage, was conducted (Harada et al. 2009).

2.2 Case B: UDDT Introduction in Rural Malawi

Malawi is located in southeastern Africa and is separated from Tanzania and Mozambique by Lake Malawi (Fig. 12.3). As of 2017, 65.9% of Malawi’s rural population did not have at least basic sanitation services (WHO and UNICEF 2020). The abovementioned NGO that introduced UDDTs in Vietnam implemented a comprehensive rural development project in three districts in Malawi (Nkhotakota, Dowa, and Lilongwe, Fig. 12.3) between 2007 and 2014. A total of 1052 UDDTs with double fecal chambers, including public units, were introduced as part of the project, with a slightly modified design of the UDDTs introduced in Vietnam (Fig. 12.4). The total number of beneficiaries reported by the NGO was 26,100, most of which did not have access to basic sanitation facilities before the project and had no experience with the use of human excreta for agriculture. UDDTs were built by local contractors trained and supervised by the NGO, and beneficiaries contributed to the construction in part by collecting bricks and providing labor. Workshops were held on the usage of UDDTs, their cleaning, and use of the collected feces and urine for agriculture.

Fig. 12.4
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A UDDT in Malawi: (left) outside views of a UDDT; (right) inner view of a UDDT. (The left figure was adapted from Harada and Fujii 2020)

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In 2017, a postintervention monitoring survey consisting of structured interviews and observations of construction status, toilet management, and usage was conducted on 277 UDDTs over 5 years after their introduction. In conjunction, an investigation was conducted on demographic status, perceptions of the effect of UDDT use on diarrhea reduction, and perceptions of the effect of feces and urine use on yield increase, as briefly summarized in Harada et al. (2018) and Harada and Fujii (2020).

2.3 Case C: UDDT Introduction in Rural Bangladesh

The project site was a rural area, located at Keshabpur Upazila and Sharsha Upazila in Jessore district, Khulna division, Bangladesh (Upazila is an administrative unit under a district) (Fig. 12.5). Of the populations in Keshabpur and Sharsha, 98% and 96% used well water at the time of the survey, respectively. Sanitary latrines with water sealing, sanitary latrines without water sealing, nonsanitary latrines, and others were, respectively, used by 29%, 29%, 37%, and 5% in Keshabpur, and 27%, 33%, 33%, and 7% in Sharsha.

Since 2004, the introduction of UDDTs with double fecal chambers and an anal cleaning space has been attempted in Bangladesh (Fig. 12.6). A postintervention monitoring study of 300 UDDTs introduced in Keshabpur and Sharsha between 2007 and 2016 by an international NGO (Japan Association of Drainage and Environment) different from that in cases A and B was conducted in 2018. In this study, structured interviews and observations were used to investigate, similarly to case B. In addition, structured interviews were conducted on the main reasons for continued use and cessation of UDDTs, and of feces and urine for agriculture.

Fig. 12.5
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Area of the UDDT project in Bangladesh

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Fig. 12.6
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A UDDT with double fecal chambers and anal cleaning space in Bangladesh. The fecal hole cover can be observed in the upper middle, and the urinal is in its lower-right part. The anal cleaning space is located at the leftmost middle in this picture

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3 Results and Discussion

3.1 The Case of Rural Vietnam

3.1.1 Use of UDDTs

At 39 months after the introduction of UDDTs, 65.8% of the UDDTs were in use. More than 80% of UDDTs without serious physical damage were used. Considering the 3-year nonintervention period, these percentages were evaluated as high, and the use of UDDTs can be assessed as having a certain degree of long-term acceptance. The main reason for lack of use was physical damage caused by strong winds at the highland. For continued use, robust construction and active self-repair by the users remain major challenges to achieving sustainable use of UDDTs.

The long-term acceptability of UDDTs may be related to the condition of the fecal chamber. Table 12.1 summarizes the use of UDDTs by fecal chamber conditions after their introduction. The percentages of UDDTs with a foul odor, maggots, and more than ten flies in the fecal chamber were 14.0%, 12.0%, and 0.0%, respectively. Prior to the installation, users were particularly concerned about the fecal odor of UDDTs, but minimal odor or no fly problems were observed in most of the UDDTs. Furthermore, as shown in Fig. 12.7, there was a significant difference in the ratio of UDDTs with foul odor depending on the inside condition of the fecal chambers, and the ratio was significantly lower in fecal chambers in good condition. The absence of foul odor and fly problems could be prerequisites for long-term acceptance of latrines, including UDDTs, and most of the UDDTs introduced in this case were in good condition and met these prerequisites even after a 3-year period with no intervention.

Table 12.1 Proportion of UDDTs with improperly operated fecal chambers
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Fig. 12.7
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Proportion of UDDTs with offensive fecal smell by conditions. Significant differences were tested by the Mann–Whitney U-test. (Adapted from Harada and Fujii 2020)

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One of the reasons why the proper operation of UDDTs was sustained in the long term would be continuous guidance on UDDT management through household visits by a local health worker who herself used a UDDT. As reported by Harada et al. (2004), a typical error in the use of UDDTs in the early stages of their introduction was lack of dispersion of ashes in the fecal chamber; ash is essential in keeping the inside of the chamber in good condition. The conditions of most UDDTs were improved through regular visits by the health worker for the first 5 months. The household visit by the health worker was continued on an irregular basis from month 6 when the project team withdrawal occurred to month 39 when this survey was conducted. Regular visits at the early stage and irregular visits afterward would have contributed to the relatively good condition of the fecal chamber at month 39.

3.1.2 Use of Fecal Matter and Urine

At 39 months after the introduction of UDDTs, 27.1% and 17.3% of the UDDTs were using fecal matter and urine, respectively, for agriculture. As mentioned above, 65.8% of households continued to use the UDDTs in the long term, while many households did not use feces (27.1% in use) or urine (17.3% in use). In the project, acceptability of agricultural use of feces and urine seems to be low, and a major part of the agricultural resource value of human excreta was not effectively utilized. Although some ethnic groups, including the majority of Vietnam, the Kinh, have a history of agricultural use of human excreta, the K’ho, who are the main ethnic group in the study area, had no tradition of using human excreta for agriculture before the UDDT project. This cultural background of the beneficiaries might have affected the acceptance of human excreta use. Although use of UDDTs themselves was accepted to some degree on a long-term basis, the use of human feces and urine as resources is a major unresolved issue in this case.

3.2 The Case of Rural Malawi

3.2.1 Use of UDDTs

The period after the introduction of UDDTs in rural Malawi varied between 5 and 9 years when the survey was implemented. Of the UDDTs introduced, 79.7% were in use at the timing of the survey. Physical damage to the toilets due to heavy rains and strong winds was identified as the main reason for discontinuing their use, similar to the case of Vietnam. This ratio of UDDTs in continuous use was higher than the 65.8% usage ratio of UDDTs in Vietnam (p = 0.014). Furthermore, considering that the case of Vietnam was based on the results of UDDTs 39 months after their introduction and that the results in Malawi were based on the results more than 5 years after their introduction, the long-term acceptability of the use of UDDTs in Malawi was estimated to be higher than that in Vietnam. The factors contributing to this long-term use are discussed in the following sections.

3.2.2 Use of Fecal Matter and Urine

At 5–9 years after the introduction of UDDTs, the utilization ratios of fecal matter and urine were 78.0% and 28.5%, respectively, in the case of Malawi. In particular, the ratio of fecal matter was significantly higher than that in Vietnam (27.1%, p < 0.001). Only for the UDDTs in use the utilization ratio of fecal matter reached up to 97.7%. Despite the lack of customary use of human excreta for agriculture in Malawi, those who continued to use UDDTs used their fecal matter almost entirely for agricultural purposes. On the other hand, the utilization ratio of urine was much lower than that of feces (p < 0.001); and only for UDDTs in use the ratio of urine use was 35.7%; urine was not used in many households. Underlying this difference in the ratios between fecal matter and urine was that feces was perceived to have a stronger fertilizer effect than urine. When asked about their perceptions of the fertilizer effect of fecal matter and urine at the time of the survey, 98% of UDDT users perceived an increase in yield due to the use of fecal matter in agriculture, whereas only 44% perceived an increase in yield due to urine use (p < 0.001, unpublished data). In this region, there was no custom of using human excreta for agriculture, but UDDT users were highly aware of the value of fecal matter for agriculture. This higher perception of the material value of fecal matter possibly contributed to the long-term acceptance of not only the agricultural use of fecal matter but also the use of UDDTs themselves.

Although the agricultural use of feces is effective, a large proportion of nitrogen, phosphorus, and potassium, which are the three major elements of fertilizer, are contained in urine rather than feces; human urine is reported to have a good fertilizing effect when used properly (Jönsson et al. 2004). Accordingly, use of urine is desirable, and from the viewpoint of the material cycle of nutrients, it is rather preferable than the use of fecal matter. In fact, the utilization ratio of urine was as low as 28.5%, although the agricultural value of urine was explained to the local people during the UDDT introduction, according to an interview with a representative of the NGO implementing the project. One of the reasons for this low acceptability of use of urine is that urine was perceived to have a much lower fertilizer effect than fecal matter, as mentioned above. Yet another possible reason is that there is a tradition of agricultural use of animal manure, which is in the form of solids. Similar to animal manure to some degree, fecal matter treated in the fecal chambers of UDDTs was in the form of solids containing ash. It has a suppressed odor and is dry and less unpleasant. These conditions of fecal matter itself and the familiarity of solid animal manure may give users a positive attitude to using fecal matter. In contrast, urine does not change significantly in morphology from the time of excretion through UDDT use. Users may consider using urine in its liquid and foul-smelling state to be a significant psychological barrier, and it may be one of the reasons for its low utilization ratio.

In addition to these perceptions of feces and urine, another possible reason for the marked difference in fecal matter use between Malawi and Vietnam is the way the project to introduce UDDTs was structured in these two cases. In Vietnam, the UDDT introduction project was implemented on its own, whereas the Malawi UDDT introduction project was implemented as a component of an integrated community development program with seven other components (Table 12.2). In this integrated configuration, the installation of UDDTs was not conducted as a stand-alone practice but was directly linked to agricultural technology transfer efforts to promote effective use of human excreta in agriculture. For example, a demonstration farm was used to instruct UDDT users in the use of fecal matter and urine in agriculture for them to recognize the benefits of their use. Although the effectiveness of these efforts was limited with respect to urine, these efforts may have increased awareness of the agricultural value of fecal matter, potentially associated with the experiences of the use of animal manure, contributing to its higher utilization ratio. Other agricultural, health, and human resource components of the integrated community development program may have also been indirectly linked to UDDTs. Thus, integration of UDDTs with other related components may have contributed to the increased acceptability of agricultural use of fecal matter, as well as the acceptability of UDDT use itself.

Table 12.2 Eight components of the integrated community development program in Malawi
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3.3 The Case of Rural Bangladesh

3.3.1 The Use of UDDTs

The period after the introduction of UDDTs in rural Bangladesh varied by households between 2 and 11 years. Of the UDDTs introduced, 45.3% were in use at the timing of the survey. This utilization ratio was significantly lower than the 79.7% utilization ratio in Malawi (p < 0.001). Based on the results of the structured interview survey of households with UDDTs in use, the three most frequent answers to the primary reasons for continuously using UDDTs were, in order of percentage, robustness against flooding and rain compared to pit latrines (21.3%), ease of use compared to pit latrines (19.1%), and longer physical life than pit latrines (15.4%). These reasons were related to the physical characteristics of their construction as toilets. It is notable that neighbors’ use of UDDTs (13.2%) and health improvement effect of UDDTs (13.2%) were other major reasons for using them, implying that health aspects and social relations in the community also contributed to their use. On the other hand, only 5.1% of households indicated the fertilizer effect of human excreta as the primary reason for using UDDTs. The agricultural value of human excreta was not the main reason for most households to use UDDTs, although 88.7% of the surveyed households had farmland.

Based on the structured interview survey of the households with UDDTs not in use, the three most frequent answers to the primary reasons to stop using UDDTs were, in order of percentage, discomfort compared to pit latrines (32.3%), no use of fecal matter and urine for agriculture (25.8%), and difficulty in using UDDTs compared to pit latrines (21.9%). Discomfort and difficulty in use, summarized as usability, accounted for more than 50% of the primary reasons for stopping using UDDTs. In contrast, easiness (19.1%), comfort (12.5%), and positive usability were the primary reasons for the continuous use of UDDTs. This discrepancy implies that there was significant variability in usability even when the same technology was introduced.

3.3.2 Use of Fecal Matter and Urine

At 2–11 years after the introduction of UDDTs, agricultural use of fecal matter and urine was 37.0% and 7.3%, respectively, in Bangladesh. Similar to the case of Vietnam, the utilization ratio of fecal matter was significantly lower than that of Malawi (78.0%, p < 0.001), and the utilization ratio of urine was significantly lower than that of feces (p < 0.001). For UDDTs in use only, the utilization ratio of feces was 81.6%; most UDDT users used fecal matter. Of the three cases, the utilization ratio of urine was the lowest, at 16.2%.

Based on the structured interview survey of UDDT users, the two most frequent answers to the primary reasons for using fecal matter were increased yield (65.9%) and improvement in quality of harvest (24.7%). On the other hand, the primary reasons for stopping using fecal matter were religious impurity (33.3%) and lack of collected amount of ash (29.4%). All the respondents in the case of Bangladesh were Muslim, and the religious characteristics of the survey area potentially affected the acceptability of using fecal matter.

It should be noted that the lack of ash was the main reason for stopping using UDDTs. Although the use of UDDTs itself is possible without spreading ashes in sufficient quantities, as shown in the case of Vietnam, the proper spreading of ash in the fecal chamber after defecation keeps it in good condition and prevents foul odor and flies, increasing usability (Winblad and Simpson-Hébert 2004). The main reason for stopping using the UDDTs mentioned above was poor usability. Our results imply that inability to obtain sufficient ashes worsened the condition of the fecal chamber, possibly resulting in unpleasant fecal matter under inappropriate treatment and hindering its agricultural use, as well as the use of UDDTs themselves in this case.

As for urine, the two most frequent answers to the primary reasons to use urine were increase in yield (81.8%) and improvement in quality of harvest (13.6%), while the three most frequent answers to the primary reason for not using urine were religious impurity (44%), bothersomeness in collecting, transporting, and using urine (28.1%), and foul odor (10.1%). Similar to fecal matter, religious characteristics had a major impact on use of urine. On the other hand, labor and odor at the time of urine use were also reasons for not using it to some extent.

In the Bangladeshi case, religious impurity was the main reason for stopping the use of both feces and urine. Difficulties in using human excreta in the Muslim community have been reported (Nawab et al. 2006). Interestingly, the degree of religious impurity was associated with conditions of UDDTs as well as social relations in the community in the case of Bangladesh. Focusing on the use of urine, which had a particularly low utilization ratio, the degree of religious impurity was found to be significantly and positively correlated with the occurrence of insects (mainly cockroaches) in the fecal chamber (R = 0.17, p = 0.004), while the degree was found to be significantly and negatively correlated with the frequency of participation in community-based organization (CBO) activities (R = −0.25, p < 0.001), frequency of monitoring UDDTs (R = −0.25, p < 0.001), and frequency of cleaning UDDTs (R = −0.15, p = 0.015). Although the correlations were weak, they imply that improving the condition of the fecal chamber and strengthening social relations could have some effect in overcoming religious impurity issues, which are the biggest challenge in the case of Bangladesh.

3.4 Comparison of Three Cases

3.4.1 Overall Use of UDDTs, Fecal Matter, and Urine in the Three Cases

The use of UDDTs, fecal matter, and urine in the three projects is summarized in Table 12.3. The proportion of households using UDDTs at the time of the survey ranged from 45.3 to 79.7%, while the use of fecal matter and urine ranged from 27.1 to 78.0% and 7.3% to 28.5%, respectively. Fecal matter was widely used in the case of Malawi by 78.0% of surveyed UDDTs, corresponding to 97.7% of the UDDTs in use. Compared with fecal matter, urine was used in limited proportions in all three cases. In the case of Bangladesh, it was used by only 7.3% of the surveyed UDDTs, corresponding to 16.2% of UDDTs in use.

Table 12.3 Summary of the conditions of UDDTs and the use of fecal matter and urine in the three cases
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3.4.2 Acceptability of UDDTs

The resource value of feces and urine from UDDTs has been confirmed (Andersson et al. 2011; Hu et al. 2016; Winker et al. 2009). Across the three cases in Vietnam, Malawi, and Bangladesh in the present study, the proportion of UDDTs continuously used was 65.8%, 79.7%, and 45.3%, respectively, which varied from case to case. Commonly, the main reason for discontinuation of the UDDTs was severe physical damage to their structure. As the quality of building material was reported as one of the main concerns regarding their use (Mkhize et al. 2017), it can be suggested that one of the main issues for the long-term acceptability of UDDTs is sustainability of the buildings. On the other hand, in Bangladesh, the physical characteristics and usability of UDDTs, such as their robustness to floods and storms, ease of use, and usable life, were the main reasons for their continued use. Primarily, the sustainability and usability of the buildings are the most important reasons for their long-term acceptability. It would be essential to construct robust buildings with high usability as well as to have a mechanism to repair broken buildings by local users.

In Vietnam, where the condition of the fecal chambers was investigated after long-term use, most of the fecal chambers of continuously used UDDTs showed a less unpleasant odor and fewer maggots and flies. In addition, poor fecal chamber management conditions were shown to have a significant impact on odor and fly outbreaks. Interestingly, in Bangladesh, the usability of UDDTs was not only the main reason for continued use, but also the main reason for cessation of use. The case of Vietnam implies that poor fecal chamber management conditions may have contributed to poor usability in Bangladesh. As suggested by the main reason for the cessation of use of UDDTs in Bangladesh, the comfort of the UDDTs as a place of defecation would be a prerequisite for long-term acceptability. In Vietnam, regular household visits by a local health worker during the first 4 months after the introduction of UDDTs and irregular household visits thereafter likely contributed to good fecal chamber management for the establishment of the comfort of the UDDTs. The need for community involvement in the maintenance of UDDTs was also pointed out by Mkhize et al. (2017). A certain level of continuous intervention may play an important role in the comfort of UDDTs and their long-term acceptability, especially as the way that UDDTs are used differs from the widely used pit latrines and flush toilets, requiring behavior change by users.

3.4.3 Acceptability of Fecal Matter Use

Utilization of fecal matter differed greatly in the three cases, and urine use was rarely realized in any of them. Among the continuous users of UDDTs in Vietnam, the utilization ratios of feces and urine were 41.2% and 34.6%, respectively. Although UDDTs were introduced with the objectives of promoting resource recovery from human excreta along with improving sanitary conditions, both feces and urine were not fully utilized, meaning that the objectives could not be fully achieved. The continued use of UDDTs despite the lack of widespread use of human excreta suggests that the resource value of human excreta was not the main motivation for the continued use of UDDTs. In fact, in Bangladesh, where the main reason for continuing to use UDDTs was investigated, the physical characteristics of the UDDTs’ structure and usability were the main reasons for their continuing use, whereas agricultural use of human excreta was not the main reason for most of the UDDT users. Moreover, some households (25.8%) stopped using UDDTs because of the lack of fecal matter and urine use for agriculture.

On the other hand, in Malawi, most of the continuously used UDDTs also used fecal matter for agricultural purposes, and utilization of fecal matter was widely accepted and practiced by most UDDT users. This demonstrates that agricultural use of feces can be accepted and established at a high level in the long term. It has been pointed out that awareness of the fertilizer value of human excreta does not always result in actual use (e.g., Ignacio et al. 2018; Sharda et al. 2020; Mariwah and Drangert 2011). In Malawi, most of the continuous users of UDDTs perceived the fertilizer value of feces to be high and, in fact, used it. One of the enabling conditions for this successful acceptance of feces use is that UDDTs in Malawi were introduced as part of an integrated community development effort, especially in conjunction with organic farming promotion. Although it is not clear whether use of UDDTs was motivated as a result of the perceived value of fecal matter, organic farming promotion may have contributed to its perceived high value, resulting in its continued use. Furthermore, even in Bangladesh, where use of feces was not found to be a major reason for continued use of UDDTs, fecal matter was still used by the majority of UDDT users (81.6%). These findings suggest that even if the fertilizer value of fecal matter is not the main motivation for using UDDTs, use of fecal matter itself can still be acceptable if one uses UDDTs properly.

3.4.4 Acceptability of Urine Use

Even in Malawi, where fecal matter use was highly accepted in the long term, the majority of UDDT users did not use urine and did not perceive its fertilizer value. Lack of widespread use of urine was also reported by Okem et al. (2013). In fact, urine contains many nutrients in terms of nitrogen, phosphorus, and potassium compared to feces (Jönsson et al. 2004). However, in each of the three cases in the present study, urine use was limited. As mentioned in the case of Malawi, higher acceptance of fecal matter than urine is possibly associated with the tradition of animal manure use. Because animal manure is nearly solid, the experience of using animal manure may have positively influenced the perceived fertilizer value of solid feces, but not of liquid urine. In Bangladesh, where the main reasons for not using urine were discussed in interviews, the following main reasons were found: religious impurity, cumbersome collection, transportation, and use of urine, and its smell. Except for religious impurity, usability of urine was the reason for not using it. Challenges remain in increasing the usability of urine so that it can be used in a manner involving easy collection, transportation, and use without foul odor. Various technologies, targeting to increase the usability of urine, might solve these challenges if such technologies were made affordable in rural areas of low- and middle-income countries.

Religious impurity was also found to be a major obstacle to urine use, as observed in Bangladesh. Nawab et al. (2006) reported the difficulty of introducing human excreta into Muslim communities. Despite this, in the present case of Bangladesh, 37% and 7.3% of households adopting UDDTs used feces and urine, respectively, although religious impurity was the main reason for not using human excreta. It has been reported that religion alone does not create a significant barrier to the use of urine and feces (WSP 2010). Uddin et al. (2014) also found that the agricultural use of human excreta was acceptable to some extent to Muslims; gossip in the community, neighborhood opinions, and involvement in CBO activities could influence its acceptability. In the present case of Bangladesh, although the correlations were weak, UDDTs with higher levels of cockroaches and other insects occurrences were associated with a stronger sense of religious impurity, while UDDTs with higher frequency of cleaning and participation in CBO activities were associated with a weaker sense of religious impurity. This suggests a certain degree of effectiveness in overcoming religious impurity with better management conditions of UDDTs, which results in improved usability, along with enabling appropriate social involvement.

4 Conclusions

This chapter focuses on UDDTs in rural areas to examine the socio-cultural acceptability of sanitation employing excreta use for agriculture. Based on three cases of UDDTs introduced in rural areas of Vietnam, Malawi, and Bangladesh, and used for some years, we examined the factors that influenced the establishment of UDDTs, and the impact of the fertilizer value of feces and urine on the socio-cultural establishment of UDDTs on a long-term basis. Furthermore, we discussed the relationship between the long-term establishment of sanitation and the fertilizer value of human excreta.

To examine the socio-cultural acceptability of sanitation employing excreta use for agriculture on a long-term basis, this study focused on the fertilizer value of human excreta, and UDDTs were taken up as such sanitation systems. The findings suggested that although the use of UDDTs was well accepted in all cases, even after a long period of time after their introduction, the value of the use of feces and urine was not always a motivation to use UDDTs, and the driving force of the fertilizer value of human excreta for the social diffusion of sanitation was not clearly observed. Physical conditions and usability, such as architectural sustainability and comfort, were of foremost importance for their acceptability, which would be a common prerequisite for toilets, regardless of resource recovery. On the other hand, the use of feces itself was shown to be widely acceptable under the continued use of UDDTs if they were introduced in an appropriate socio-cultural context, potentially contributing to the continuous use of UDDTs. The use of urine was more challenging than that of fecal matter. While the fertilizer value of fecal matter was perceived to be high, that of urine was not. The low usability of urine, for example, because of its odor and laborious use, was the main reason for its lack of widespread use. Religious impurity was observed as one of the barriers to agricultural use of urine and feces in some socio-cultural backgrounds, but our findings also suggested that the barrier of religious impurity was not unchangeable but might be overcome with appropriate physical and socio-cultural conditions. The proper establishment of physical and socio-cultural conditions in local contexts would be essential to realize resource-oriented sanitation, which can potentially drive the social diffusion of sanitation in rural areas.