Ken Ushijima

Suitability of biochar as a matrix for improving the performance of composting toilets.

To evaluate the suitability of biochar (rice husk charcoal) as a matrix in composting toilets that can decompose human faeces and recover fertiliser components, the composting process during toilet operation and the agricultural value of the resulting compost were characterised by performing a comparison with sawdust, rice husks, and corn stalks. The faecal decomposition ratio in biochar was 42%, similar to the values for rice husks (46%) and corn stalks (41%), but higher than the value for sawdust (25%). Heterotroph micro-organism acidity is qualitatively higher in biochar than in sawdust. However, nitrogen loss in biochar was 19%, lower than that in rice husks (36%) and corn stalks (25%), but similar to that in sawdust (16%). Although the biochar compost had no significant impact on the cation exchange capacity and water retention of sandy soil, the ratio of nitrogen transportation into plants was 12.8%, higher than that for the other materials. These results suggest that biochar is effective for achieving high faecal decomposition, low nitrogen loss, and high nutrient supply.

Sustainable design of sanitation system based on material and value flow analysis for urban slum in Indonesia

Material flow analysis (MFA) and value flow analysis (VFA) were applied to the sanitation system in an urban slum in Indonesia. Based on the results of the MFA and VFA, garbage and excreta disposal costs were evaluated to be 0.7% and 1.1%, respectively, of per capita income. Such value flows seem reasonable in light of the recognized affordability to pay (ATP) standard. However, current excreta disposal methods create negative impacts on downstream populations. Because such disadvantages do not go back to disposers, but passed to downstream, the current value flow structure does not motivate individual toilet users to install treatment facility. Based on current material and value flow structures, a resource recycling sanitation system scenario was examined. Based on VFA, an affordable initial cost for such a system was calculated; this was found to be comparable in price to a cheaper composting toilet that is currently available in the market.

Designing slanted soil system for greywater treatment for irrigation purposes in rural area of arid regions

To solve the unpleasant disposal of greywater in rural area and allow its collection for reuse in gardening, a slanted soil treatment system (SSTS) was designed and installed in two households. Granitic gravel of 1–9 mm size was used as the filter medium. The aim of this study was to design a SSTS and assess its suitability as a treatment system allowing greywater reuse in gardening. The efficiency of the SSTS was assessed based on organic matter and bacterial pollution removal. The developed SSTS allowed the collection of greywater from three main sources (shower, dishwashing and laundry) in rural area. The SSTS is efficient in removing at least 50% of suspended solids, chemical oxygen demand and biological oxygen demand. The study highlighted that, contrary to the common perception, greywater streams in rural area are heavily polluted with faecal indicators. The removal efficiency of faecal indicators was lower than 2 log units, and the bacteriological quality of the effluents is generally higher than the WHO reuse guidelines for restricted irrigation. Longer retention time is required to increase the efficiency. The possibility of reusing the treated greywater as irrigation water is discussed on the basis of various qualitative parameters. The SSTS is a promising greywater treatment system for small communities in the rural area in the Sahelian region. To increase the treatment efficiency, future research will focus on the characteristics of the SSTS, the grain size and the establishment of a pretreatment step.

Fate of nitrogen during volume reduction of human urine using an on-site volume reduction system

This study was carried to assess the effect of a mixture of salts, urea and creatinine on water evaporation from urine using an on-site volume reduction system in long-term experiments. Subsequently, the fate of nitrogen during volume reduction of urine was also assessed. The water evaporation rate, salt accumulation in the gauze sheet, concentrations of urea and ammonia-N, and pH of urine were measured periodically. Based on the results, a mass balance of nitrogen in concentrated urine was calculated for a moderate evaporating condition. The results revealed that steady-state evaporation was observed throughout the experiment period without any inhibition due to salt accumulation. Salt concentration in the gauze sheet reached steady-state illustrating the possibility of salt falling back to the tank from the sheet. No significant reduction of urea was observed for a moderate evaporating condition, which indicates inhibition of urea hydrolysis by the high concentration of the mixture of salts, urea and creatinine in the urine. In contrast, for a low evaporating condition, the pH of the urine increased to 8.9, which indicates early urea hydrolysis, causing an offensive odour and ammonia loss to the air. In simple storage experiments, a mixture of salts, urea and creatinine amounting to 227–334 g L−1 in urine inhibited urea hydrolysis, even with faecal contamination, at 25°C, while urine samples containing a mixture of salts, urea and creatinine at less than 227 g L−1 did not provide strong inhibition of hydrolysis.

Grey water treatment by the slanted soil system with unsorted soil media

This study evaluated the performance of unsorted soil media in the slanted soil treatment system, in terms of removal efficiency in suspended solids (SS), chemical oxygen demand (COD), linear alkylbenzene sulphonate (LAS) and Escherichia coli, and lifetime until clogging occurs. Unsorted soil performed longer lifetime until clogging than sorted fine soil. Removal of SS, COD, and LAS also performed same or better level in unsorted soil than fine soil. As reaction coefficients of COD and LAS were described as a function of the hydraulic loading rate, we can design a slanted soil system according to the expected hydraulic loading rate and the targeted level of COD or LAS in effluent. Regarding bacteria removal, unsorted soil performed sufficient reduction of E. coli for 5 weeks; however, the removal process occurred throughout all four chambers, while that of fine soil occurred in one to two chambers.

The Concept of Resources Oriented Agro-Sanitation System and Its Business Model

This chapter proposes concept of the sanitation business model, based on the discussions; what is necessary to solve current world’s sanitation issue and what is the limitation of current sanitation concept. Proposed policy was on the basis of the Postmodern Sanitation concept; (1) discuss a sanitation value chain which create and add a value to human excreta and its products, and build a sanitation business model to drive this sanitation value chain, (2) design the sanitation business model focusing on incentive for individual toilet users, (3) analyze current user’s value chain to find available potential resources, (4) connect these potential sanitation resources to next value chain, (5) make a financial plan based on market analysis of sanitation product, (6) find and organize facilitating organization to support individual toilet users’ business. This concept was applied for the case of rural area in Burkina Faso, and reasonable agro-sanitation business model was designed based on material flow analysis and value flow analysis.

Experiment of a Resource-Oriented Agro-Sanitation System for Urban Slum Area: Case of Indonesia

This chapter describes case study of applicability assessment for resource-oriented agro-sanitation business for urban slum in Indonesia, based on interdisciplinary field survey, (1) economic feasibility assessment, (2) demand potential assessment, and (3) social acceptability. The value flow analysis evaluated garbage disposal cost and excreta disposal cost at 0.7 and 1.1%, respectively, of household income, which represents a reasonable cost to disposers. However, under the current disposal scheme, negative value due to excreta disposal to river appears to be passed on to downstream populations. The structure of this value flow indicates that little attention is paid to the negative externalities, indicating that a solution in this case may be difficult to obtain. The affordable initial cost of a new resource recycling system was evaluated and compared with the costs of a currently available compost toilet by evaluating equipment lifetimes and potential income streams available from the sale of human excrement fertilizers. To estimate a value for the human excrement fertilizer, real-world case study in Indonesia, in which money was paid in exchange for human urine, was referred to. The evaluated affordable initial cost derived was sufficiently comparable to the price of a cheaper composting toilet currently available in the market. This implies that such a resource recycling system is feasible even in an urban slum. Results of demand and supply assessment showed that if resource-oriented sanitation system was diffused, supply would excess demands in the circle of 32 km radius, therefore cost discussion should assume more than 32 km transportation. According to the results of case estimation of tea plantation, total cost for fertilizer provided by resource-oriented sanitation system is possibly competitive to the normal price of synthetic fertilizer. However, if compared to subsidized price for low-income farmers, it seems difficult to compete. Regarding social aspect, the context of Islamic law is important. Islamic authorities regarded the resource-oriented sanitation system as no problematic concept and acceptable in the context of Islamic law.

Slanted Soil System

Slanted soil system is low cost, simple system suitable for greywater treatment. Performance of the slanted soil system for greywater was evaluated in light of required water quality for irrigation reuse. Removal rate of COD and BDOC, those may cause clogging of irrigation facility, was 52–83% and 88–89%, respectively. LAS, one of the major surfactants, was removed more than 80%. Phytotoxic test showed that more than 2.82 m treatment is required. Only fine soil (1–4 mm) performed 5 log10 and 3 log10 reductions of Escherichia coli and MS2 phage, while coarse soil could not remove those pathogens. Clogging was observed in fine soil after 3–5 weeks operation; however, combination of coarse soil chamber and fine soil chamber could extend it to 8 weeks, without decrease of treatment performance. Reductions of total COD and LAS were described by first-order reaction model, and reaction coefficient k was described by equation of per area discharged rate.

Treatment of Greywater by Geotextile Filter and Intermittent Sand Filtration

Intermittent sand filtration (ISF) is an efficient system for treatment of greywater; however, the high quality of effluent and the simple setup contrast with the high failure rate due to clogging of surface layers. The efficacy of several polypropylene nonwoven geotextiles (apparent opening size from 0.10 to 0.18 mm) used as primary treatment filters to remove suspended particles from domestic greywater and the effects of this pretreatment in the performance of fine and small media size (0.3 and 0.6 mm) ISFs was examined. Results showed geotextile achieved SS removal rates from 25 to 85% and COD from 3 to 30%; although the portion larger than 75 µm was removed at higher rates (55–90%), particles smaller than the nominal pore size of the filter were also captured. Geotextile used as pretreatment resulted in improvement of lifetime of the ISFs over an experimental run of 60 days. The vertical profile of volatile organic matter in the ISFs was evaluated at the end of the experiment, and it showed a clear reduction in the accumulation of organic material on the top layer of the ISFs, effectively avoiding its early failure by accumulation of solids.

Application of Human Urine in Agriculture

Although it is known that human urine contains valuable plants nutrients, too much urine application may cause an accumulation of several ions in soil. Among them, excess of Na inhibits plant growth, while excess of nitrogen can build up in plant tissues. Therefore, the objectives of this study was to (1) evaluate when and how often human urine should be applied in agriculture as fertilizer solution, (2) examine the effects of uncontrolled application of human urine dose in agriculture, (3) and examine the effects of continuous application of uncontrolled human urine application dose in agriculture through continuous cultivations. The results revealed that application of urine at one time before cultivation is not effective for plant growth due to high ions intensity in low saline soil and high nutrients leached from soil. Besides, continuous application of extra urine volumes in the range of 2–3 times (U-2Vo and U-3Vo) higher than plant requirement (U-Vo) had no adverse effect on plant growth and yields under three-time continuous cultivations, since treated soils were far to be saline (EC < 2mS/cm; SAR < 13), and more than 39% of the total Na applied in all urine treatments was removed by plant from soil. However, continuous application of double (U-2Vo) and triple (U-3Vo) volumes of urine caused accumulation of N in plant and soil and decreased plant K/Na ratio (substitution of K+ by Na+). While in the adequate urine volume (U-Vo), there was no accumulation of N in soil, no increased of N in plant tissues, but plant K/Na ratio decreased. So, these results suggested that adequate application of human urine based on plant N requirement and management of salts from urine is required even in the adequate urine volume application for its sustainable reuse in agriculture.