Search

Standardization of biogas technology is immensely important for the promotion of the biogas industry worldwide. China has built a complete biogas standard system, which is divided into common, household biogas, biogas engineering, biogas digester for domestic sewage treatment, output utilization, and service system standards. The problems and potential barriers for biogas standardization in China are analyzed and come down to sluggish standard, overlapped standard, government-dominated standard, and lagging international standard. Accordingly, all potential biogas standards should be evaluated and placed under the same department. China Biogas Society and China Association of Rural Energy Industry play leading roles in developing enterprise or group/association biogas standards and ISO biogas standards. The bio-natural gas standard system and experimental standardization should be developed as well to replenish biogas standard system. A paradigm shift in biogas standardization should be from government-dominated to market-oriented model. The lessons learned for other developing countries includes expanding standardization to multi-aspects to realize full lifecycle control and management, building rapid responding mechanism of standardization to adopt industry transformation, integrating outdated standards into new versions, and establishing market-based standard system.

Graphical abstract, Highlights • 20 randomly real urine samples were collected and analyzed. • Totally 30 antibiotics in the fresh real urine were identified. • Representative antibiotic resistance bacteria and its gene were identified. • Changes of antibiotics, antibiotic resistance bacteria and gens of urine were monitored., Human urine is a source of fertilizer and, with proper management, it can be reused in agriculture. Determining the contamination issue of antibiotics in source-separated urine is important because the majority of antibiotics are excreted with urine. In this study, source-separated urine samples were randomly collected from a male toilet in a university building and analyzed in terms of 30 typical antibiotics (including 14 sulfonamides, 4 tetracyclines, and 12 fluoroquinolones) and tetracycline-resistant Escherichia coli, as well as its antibiotic-resistant genes to determine the contamination characteristics of antibiotic-related pollution in fresh and stored urine. Results showed that 18 out of 30 typical antibiotics were detected in fresh source-separated human urine. The dominant antibiotic was oxytetracycline with a frequency of 100%, followed by tetracycline, sparfloxacin, enrofloxacin, and ofloxacin, which demonstrated a detection frequency of 55%. Among the detected values, sulfonamides (2 antibiotics), tetracyclines (4 antibiotics), and fluoroquinolones (12 antibiotics) had a concentration range of 0.25–2.94, 0.94–41.2, and 0.06–163.16 ng/mL, respectively. Furthermore, tetracycline-resistant Escherichia coli, which was measured using plate count method, and its related gene, tet M, exhibited a maximum cell density of (200,000 ± 5000) CFU/100 mL and (2.73 ± 0.261) × 107 copies/mL, respectively. When the fresh urine was stored in an ambient environment for 30 days to simulate the real circumstances of urine management, a significant reduction in antibiotics and antibiotic-resistant bacteria was observed, while the change in antibiotic-resistant genes was insignificant. The results of this study suggest that risks associated with antibiotics and their antibiotic-resistant bacteria and genes are retained during collection and storage. Hence, these kinds of microcontaminants must be considered in further urine utilization.

The provision of sanitation services for fast-growing urban populations is one of the world's urgent challenges. Hutong neighborhoods in Beijing, capital of China, cannot be rebuilt due to the protection of historical heritage, while residents still need to keep the habit of defecating in public toilets. One hundred public toilets with non-sewered sanitation in the Hutong neighborhoods of Beijing were visited to investigate the actual operating status in response to the “toilet revolution” campaign. The fault tree approach was used to identify the barriers toward a decent and environment-friendly public toilet and evaluate potential risks from the malfunction of various components. Four subsystems are defined and elaborated to calculate the fault possibility. These subsystems are environment- and user-friendly, regarded as ancillary facilities, and used for fecal sludge (FS) management. Statistical analysis of targeted cases indicated that fault probabilities of environmental considerations, user-friendly considerations, ancillary facilities, FS management are calculated as 0.79, 0.96, 0.96, and 0, respectively. The subsystems were weighted using a Delphi method concept. Results showed that the well operation ratio of Beijing Hutong public toilets is only 32%, and the sanitation service value chain can be further optimized. This study also provides references for other countries, which are dedicated to promoting urban sanitation and public health., Highlights • Potential risks of public toilets were identified through Fault Tree Analysis. • A methodology in framing failures of public toilet subsystems is developed. • Delphi method was applied, validated, and found useful in sanitation research. • The barriers toward decent and environment-friendly public toilets are identified.

Anaerobic digestion is one of the most sustainable and promising technologies for the management of organic residues. China plays an important role in the world&rsquo, s biogas industry and has accumulated rich and valuable experience, both positive and negative. The country has established relatively complete laws, policies and a subsidy system, its world-renowned standard system guarantees the implementation of biogas projects. Its prefabricated biogas industry has been developed, and several biogas-linked agricultural models have been disseminated. Nonetheless, the subsidy system in China&rsquo, s biogas industry is inflexible and cannot lead to marketization, unlike that of its European counterpart. Moreover, the equipment and technology levels of China&rsquo, s biogas industry are still lagging and underdeveloped. Mono-digestion, rather than co-digestion, dominates the biogas industry. In addition, biogas upgrading technology is immature, and digestate lacks planning and management. China&rsquo, s government subsidy is reconsidered in this work, resulting in the recommendation that subsidy should be based on products (i.e., output-oriented) instead of only input subsidy for construction. The policy could focus on the revival of abandoned biogas plants as well.

Current experiences in pilot sanitation projects indicate that the spontaneous precipitation in urine diversion (UD) systems has been one of the main challenges for the implementation of urine source separation on large-scale. As a result of microbial ureolysis, an increased pH leads to the formation of inorganic precipitates, which increases the risk of pipe blockage. Although significant advancements have been made in controlling the spontaneous precipitation in UD systems, experimentation in pilot projects is not enough to provide the feasible and reliable support for technical selection to adapt quickly to changing boundary conditions, such as population size and density. Therefore, established techniques should be constantly reassessed and improved in a broader variety of experimental settings to ensure the wide applicability, economic and environmental benefits, and social acceptance. This work also clarified the importance of establishing standardized evaluation methods, which helps to integrate the knowledge gained from reported specific case studies and provide detailed information that can support the decision makers. On the other hand, the economic assessment indicated that maximizing the value of the urine-derived fertilizers can ensure a favorable rate of return, which is important to attract investors and promote the implementation of urine source separation. Meanwhile, current legislation and government support have provided the opportunities for large-scale implementation of urine source separation. The decision makers should be prepared well to deal with such a paradigm shift.

Rural toilet retrofitting (RTR) is a complex, dynamic system that is affected by many factors and the positive/negative feedback relationships between subsystems and variables. Traditional technologies and management methods face challenges in fundamentally describing and solving problems in RTR. To bridge this gap, this study utilizes system dynamics and causal loop diagrams to explain such problems based on data collected from the stakeholders of the RTR in Jiaozhou from 2018 to 2019. Specifically, this study examines the RTR system from the perspectives of household users, wastewater treatment plants, local governments, grassroots promoters, operation and maintenance personnel, toilet supplier and construction teams, and fecal sludge end users. The factors and processes involved in RTR are identified, and the feedback and relationships among its major stakeholders are established. Results show that the motivation of farmers to engage in RTR is a key variable that affects their final decisions regarding retrofitting and maintaining toilet functions. Meanwhile, the important variables related to the feedback and relationships among the major stakeholders of RTR are mostly focused on policies, subsidies, technology, satisfaction, and cooperation. A scientific analysis method and the updated RTR plan for toilet revolution are then formulated to promote the implementation of RTR in developing countries., Highlights • Typical case of rural toilet retrofitting in China is selected and investigated. • System dynamics model for simulating rural toilet retrofitting is developed. • Causal loop diagrams for rural toilet retrofitting are presented and analyzed. • Experience of rural toilet retrofitting is shared for other developing countries.

This note from the field shows a novel, hybrid concept of a constructed wetland for the first time in a water-stressed region in the coldest capital in the world, Ulaanbaatar, Mongolia. After selecting a suitable household compound, an ‘Ice-Block Unit’ was designed and constructed to assess its technical performance and capacity to reduce greywater-borne hazards during 2013 and 2014. This system was based on storing water during the winter freezing period as an ice block, and then starting treatment during the summer/non-freezing period. Results showed that the maximum removal rates of chemical oxygen demand (COD), NH 4 + , NO 2 − , total suspended solids (TSS), PO 4 − , and Escherichia coli were up to 100%, 99%, 97%, 97%, 87%, and 98%, respectively. The effluent met the neighbouring country, China's, municipal discharge standard of A grade effluent and could also be considered restricted and unrestricted irrigation water as reported in other studies. The system has proven potential from a technical point of view and can be scaled up to community or cluster levels. This would enable reduction of greywater-borne hazards in low, middle and high income countries with similar contexts.

There are limited studies that focus on greywater treatment and reuse options, particularly in nomadic societies with unique cultural and climatic conditions. Studies relating to household greywater treatment in nomadic-cultured societies are limited. This study aims to address this gap by examining a case with a high concentration of chemical components in the greywater (e.g. where chemical oxygen demand ranged between 35 and 70,032 mg/L). Specifically, an upgraded greenhouse greywater treatment unit (GH-GWTU) was designed and constructed during the summer of 2013 in Ulaanbaatar, Mongolia, in order to assess the technical feasibility, and up-scaling capability, of the system at the community level. Chemical and biological test results indicated that most parameters (e.g. PO 4 3 − , NO 2 − , NH 4 + ) had a high removal rate of up to 98%. Moreover, the greenhouse may extend the treatment period up to 8 months. This study has shown that GH-GWTU is a potential technology that can significantly reduce the chemicals and biological agents in greywater in Mongolian Ger contexts which may reduce the greywater-borne hazards and vulnerability in the area. It can be replicable both at the household and community scale according to resources available for system operation and maintenance.

One of the major challenges for deploying sustainable sanitation technologies and services around the world is financing. The present study applied both qualitative (key informant interviews) and quantitative (household survey) methods to explore sources of alternative financing in Ulaanbaatar, Mongolia, towards deploying sustainable sanitation technologies and services. Microfinance organizations, government subsidies and mining industries may represent potential sources of financing for the implementation of sustainable sanitation technologies and services in Mongolia. Moreover, building social capital among Ger residents and reinventing the idea of ‘corporate WASH responsibility’ could constitute new directions for the future.

The anaerobic digestion technology has many advantages and is a sustainable way to produce energy, solve the crisis on energy shortage, and reduce waste stream and carbon footprint. In this field experiment, a mixture of food, fruits, and vegetable waste, dairy manure, and inoculum was anaerobically digested in a constructed water tank digester. This study was performed at ambient temperature under different organic loading rates (OLRs), which were increased every two weeks. Results showed that the optimum feedstock-to-inoculum ratio is 0.4, which resulted in highest specific biogas and methane yields (0.44 and 0.28 Nm3/kg VS, respectively). With the OLRs, the highest yield was observed at 1.4 kg VS/m3 average feeding. When the feedstock-to-inoculum ratio was increased from 0.4 to 0.8, the effect on biogas yield and the volatile solids decreased. Hence, the total cumulative biogas production was approximately 18.5 Nm3 per reactor volume. The pathogen concentration, which was determined in the feedstock and the effluent samples, revealed that the reduction efficiency was relatively low. On the basis of the performance of this field study, emphasizing household organic waste composed with other feed materials to produce bioenergy was feasible. Anaerobic co-digestion produces biogas, contributes to sustainable waste management, and reduces environmental pollution. This scientific study can play a fundamental role in implementing this technology at the household level for efficient biogas production in Bangladesh and worldwide.

China has promoted its biogas industry for a long time and begun to support bio-natural gas (BNG; also known as biogas upgrading or biogas-to-biomethane) projects for the first time in 2015 at the central government level. This study presented a comprehensive overview of the BNG industry in China, including its status quo, national strategic planning, upgrading technologies, investment cost, potential, and opportunities and challenges. A total of 65 BNG demonstration projects were approved by the central government between 2015 and 2017, and 197 projects are expected to have been built by 2020 as part of the 13th Five-Year Plan (2016–2020). BNG is an emerging industry, and its development provides several opportunities, including a huge natural gas demand, national policy incentives, integrated agriculture, and reduced carbon emissions. The challenges and barriers to such developments include the high upgrading cost, fluctuating natural gas prices, unsound market access mechanism for biomethane and biofertilizer, scarce competition-oriented feedstock resources, incomplete standard system and cross-sectorial management, imperfect policy and subsidy mechanism, and lagging technology and equipment. China can learn from other developed countries in four ways. First, the country must enhance the cost effectiveness of its subsidies. Then, China must highlight the operations of its BNG industry and evaluate its performance; prioritize digestate management in the planning stage; improve its project service level and reinforce research and development. The findings of this work provide a valuable reference for other developing countries that intend to address energy shortage issues and integrate waste management into their regional planning.

This study examines a closed-loop sanitation system (CLSS) in the ger areas (informal peri-urban settlements) of Ulaanbaatar, Mongolia in order to evaluate system feasibility and to identify the future prospects of CLSS as an alternative to conventional sanitation and drainage options. Results show that the CLSS concept is well understood and accepted by users and that services are being scaled up. Over 50 per cent of respondents used CLSS technologies during both winter and summer, testifying to the potential for scaling up these technologies and services. Moreover, all users responded positively in their evaluation of the emptying services. Despite some problems and challenges, the system proved to be feasible, replicable and acceptable in the study area. It is recommended that the entire CLSS approach be tested through scientific validation to convince more communities, government and other stakeholders about scaling up the system beyond the study area for better health, environmental conservation and resource recovery.

The biogas project for domestic sewage treatment (BPDST) is considered a promising facility for wastewater management in rural areas of China. This paper explores previous experimental works, cost analysis, and BPDST structure and design based on Chinese literature. Opportunities for developing decentralized or neighborhood-based BPDSTs include fulfilling Millennium Development Goals (MDGs) and Sustainable Development Goals (SDGs), the water pollution situation and deficiency of wastewater treatment facilities, the advantages of BPDSTs compared with centralized sewage plant, government support and policy drive for rural wastewater treatment, and reuse demand for resources. Meanwhile, challenges faced are emphasized as follows: uncertain responsibility for BPDSTs under different governmental departments restricts BPDST development and should be specified; uncertain effluent quality due to low efficiency of nutrient removal requires aerobic post-treatment to some extent; rural environmental awareness is still low and should be heightened; more funds should be invested in R&D for improvement of technology innovation; more reuse and resource recovery elements should be considered during implementation; follow-up services are lacking and should be improved; and BPDST maintenance should be trained. This paper could provide valuable reference for other developing countries.

Sanitation is one of the most pressing issues faced by the population in the peri-urban Ger areas of Ulaanbaatar, Mongolia. Poorly constructed pit latrines have caused environmental, socioeconomic and health problems especially Hepatitis A, among the residents, which is predominant among children less than 5 years old. This research aimed to investigate the feasibility of co-composting fecal matter with different recipes using two different technologies, i.e. composting facility and greenhouse (GH) technology. All the trials conducted met the international sanitary requirements for compost, i.e. World Health Organization (50 °C ≥ 1 week). Conclusively, GH technology with the addition of food waste allowed the temperature to increase up to 70 °C, which proved to be a better option for co-composting of fecal matter under specific local conditions.

The present scoping study seeks to address the sources of water, sanitation, and hygiene (WASH) exposure of residents of peri-urban Ger areas of Ulaanbaatar, Mongolia. Field observations and semi-structured key informant interviews were carried out during 2012 and 2013 to assess the existing WASH situation in the peri-urban Ger areas of Ulaanbaatar, Mongolia. In addition, a knowledge, attitude, and practice (KAP) survey was conducted by Action Contre la Faim (ACF) Mongolia in 210 households to identify the sources of WASH-borne hazards in a statistically representative way. Moreover, the quality of drinking water was analyzed both at the household ( n = 210) and water point (kiosk) ( n = 40) levels to assess the risk of chemical and pathogenic contaminants. Both field observations and interviews revealed that the sanitary environment of the Ger residents is characterized by the lack of a drainage system, unimproved sanitation technology (e.g. unhygienic pit latrines and soak pits), unsafe water supply, and insufficient collection, transportation, and storage mechanisms. Poor infrastructure is associated with low standards of living. The transmission of WASH-borne disease (e.g. diarrhea, dysentery, hepatitis A) is the gravest consequence and source of hazards. The results from the water quality analysis demonstrate that Ger residents are more exposed to biological contamination of stored drinking water by Escherichia coli during the summer (May to August) than in the winter (November to February). During the winter, 36% of household storage containers were contaminated by E. coli at an average level of 12.5 E. coli per 100 ml, while, during the summer, 56% of household storage containers were contaminated at an average level of 50 E. coli per 100 ml. KAP surveys further reveal that the common practice of Ger residents to discharge greywater (with higher chemical oxygen demand) into pit latrines, soak-pits, yards, and streets likely causes environmental pollution and health hazards. Multifaceted WASH-borne exposure was addressed by the scoping study such that various WASH interventions could be planned for the study area and beyond. To tackle the above challenges and problems, a range of appropriate interventions and programs are recommended to reduce the exposure of WASH-borne hazards in the study area and other parts of the world – in both urban and peri-urban settings. The recommendations include: the development and implementation of a water safety plan (WSP), an effective monitoring system for collection, transportation and storage at both water kiosk and household levels, user training for correct use of water containers, effective coordination among stakeholders (including urban planners), development of a household greywater disposal system, and implementation of a functioning solid waste management system. Prior to taking these actions, a detailed study on the ‘pollution load from peri-urban to urban’ should be carried out to assess the WASH-borne vulnerability of both peri-urban and central urban population.

This paper applies a ‘comprehensive’ strengths, weaknesses, opportunities, and threats (SWOT) analysis to compare the ‘before and after’ scenarios of integrating a safe water supply (SWS) into a sustainable sanitation system (SSS) in the peri-urban Ger areas of Ulaanbaatar. Qualitative field investigations, including interviews and focus group discussions, are conducted with stakeholders and key informants to collect data on the scenarios before the SSS and to develop a conceptual framework after the SSS implementation. The before-implementation scenario has one strength, that is, the interest of communities and NGOs toward the SWS–SSS integration, which facilitates the acceptance and up-scaling of sustainable technologies. The after-implementation scenario shows additional strengths, such as community acceptance and satisfaction with SSS. The identified weaknesses are attributed to the lack of community-based organizations, community participation, and inter-sector coordination. The marketing of SSS, the involvement of banks and micro-credit systems, and the reuse of treated greywater have been identified as opportunities. The before-implementation scenario identifies the use of pit latrines and the lack of political will as the primary threats, whereas the after-implementation scenario identifies technology innovations for the extreme cold as a primary threat. The application of the SWS–SSS integration in other cases must be investigated further.

Biogas technology has been promoted worldwide over the past decades, and its use has led to the recognition of the many benefits of domestic biogas digesters. Prefabricated biogas digesters (PBDs) continue to be developed, tested, and extensively applied in developing countries to compensate for the disadvantages of traditional domestic digester models. PBD prototypes are derived from three major types of domestic digester models, namely, the fixed dome, floating drum, and plug flow digesters. Two main streams of PBDs are represented by composite material digesters (CMDs) and bag digesters. PBDs also include off-site constructed ferro- or bamboo-and-cement digesters, as well as assembled digesters. The advantages of PBDs promote the development of different types of PBDs, and several nations have set up special instructions and institutions to promote PBDs. Challenges to PBD dissemination include inferior quality, high investment in CMDs, lagging PBD standardization, low levels of public information about PBDs, and lack of follow-up services. However, based on our literature research and field visits, it could be predicted that PBD technologies will be extensively applied worldwide in the near future.

In Mongolia, as worldwide, communities are challenged by water scarcity, depletion and pollution. Greywater treatment and reuse could partially meet water demand and help protect the environment and health. In March 2010, greywater from six randomly sampled households in the Ger areas of Ulaanbaatar, Mongolia, was analyzed followed by the development of three innovative treatment systems: an underground (UG-), greenhouse (GH-) and ice-hole greywater treatment unit (IH-GWTU). The UG- and GH-GWTU were implemented to identify opportunities and challenges for future investments in greywater treatment and reuse. Users' and non-users' perceptions, and business opportunities, were assessed. Laboratory analysis showed a high chemical oxygen demand (6,072–12,144 mg/l), N-NH4+ (183.7–322.6 mg/l), PO4− (12.6–88.2 mg/l) and total suspended solids (880–3,200 mg/l) – values exceeding the WHO guidelines and much higher than in any other country: low water consumption combined with traditional diet might be major reasons. Odourless and colourless water after treatment in a UG-GWTU lead to more acceptance than a GH-GWTU. Business opportunities include the use of treated water for irrigation, considering WHO and national standards. Further research focuses on seasonality of installation, technical shortcomings, maintenance, biological quality control and user training.

Biogas technology is becoming increasingly popular throughout the world, particularly in countries where governments promote domestic biogas systems. Despite its popularity, problems exist in biogas technology, such as low-quality construction, leakage of pipelines, low biogas production, and lack of maintenance. These problems should be identified and analyzed for effective implementation and efficient operation of small-sized biogas systems (SBS). This research applies the fault tree approach (FTA) to identify failures, and evaluate their effects on the operation of SBS from a technical point of view, based on a nationwide field study in Nepal. Ninety-four sets of SBS were selected and sampled in targeted areas. Five subsystems of SBS were defined, including structural components, biogas utilization equipment, piping system, biogas production, and effluent disposal system. Based on the statistical analysis of the 94 targeted cases, the fault probabilities of the five subsystems are 0.67, 0.48, 0.73, 0.26, and 0.64, respectively. The weights of five subsystems are determined by Delphi method and fault probability of SBS is calculated. The results show that faults on piping systems happen most frequently, and that proper disposal and reuse of bio-slurry are often neglected. Regardless of the social and economic benefits of SBS, implementation scenarios of SBS throughout Nepal are evaluated under a technical perspective, as follows: (1) the operational status of SBS is not optimal. (2) Based on criteria for failures, well-operation ratio is about 53% in practice. (3) Skilled masons are prerequisites for efficient functioning of SBS. (4) Maintenance plays a key role for efficient functioning. The study results prove that FTA is mostly suitable for SBS evaluation and is an effective analysis tool for technical evaluation in the field of biogas technology.

Biomass energy (bio-energy) is a clean energy, which is helpful to environmental construction and CO2 emission reduction. China is the largest energy consumer in the world, building Biomass Power Plant (BPP) is beneficial to make use of agricultural biomass as well as to reduce environmental pollution. However, many factors influence the exploitation of a proposed BPP project. The objective of this paper is to develop a methodology that is able to analyze the agricultural biomass potential for BPP in China. This methodology analyses the related factors then conducts the sensitivity analyses of the main factors. Related factors mainly include local condition, demand of multiduty agricultural residues, logistics while sensitivity of main factors mainly aims to competition of nearby BPP, competition of other utilizations, price of biomass, preferential policy, etc. Based on a field study, an applied illustration of this methodology on evaluating agricultural biomass potential for a proposed BPP project is presented. The case study shows that it is not suitable to build a new BPP. In view that renewable energy projects will be promoted strongly, it is predicted that the methodology would be a potential tool, which can be applied well for BPP in China.

China plays a leading role in the worldwide development and dissemination of household-based biogas technology. Since the 1980s, China has developed many types of commercialized or half-commercialized prefabricated biogas digesters (PBDs), which are categorized into three: glass fiber-reinforced plastic digesters, plastic soft digesters, and plastic hard digesters. This paper summarizes the development of PBDs in China, including their key characteristics, manufacturing process, advantages and disadvantages, cost analysis, marketing, and future prospects. Furthermore, the paper highlights and analyzes potential constraints in the promotion of these types of digesters; examples of these constraints include incomplete standardization systems, insufficient demonstration projects, low-quality digesters, and missing authorizations from the inspection department. A preferential policy should be formulated for the prefabricated digester industry. Specifically, the standardization system should be improved, technological innovations should be encouraged, self-regulation of the industry should be intensified, demonstration projects should be implemented, and follow-up services should be improved. PBD technologies can potentially be applied with great reliability and high efficiency not only in China but also in other countries.

Dry-toilet collected matter (DCM) from traditional dry-toilet pits are a potential health and ecological risk in suburban areas. In this study, the characteristics of metals in DCMs from suburban areas of Ulaanbaatar were surveyed. The results indicate that DCMs contain a high percentage of organic matter and nutrients, while heavy metals are at low levels, which shows good agricultural potential. The concentration ranges of Cr, Cu, Hg, Ni, Pb, and Zn were 11±5, 46±9, 0.08±0.05, 9±3, 17±9, and 338±86 mg·kg−1, respectively. The concentration of Cd was below 0.5 mg·kg−1, and a high positive relation was shown between chromium and nickel concentrations. The heavy metals in DCMs were safe for land application but Zn in DCMs was close to the effects range median (ERM), which is toxic in some cases, such as amphipod bioassays. Because it is mandatory to treat DCMs to reduce pathogens, in the case of heavy metal enrichment and agricultural reuse, composting or pyrolysis are better choices than incineration. Compared with global soil background values, the heavy metals in DCMs showed a low level of ecological risk, but a medium level when compared with Mongolian soil background values. The ecological risk of six heavy metals was in the descending order Hg>Cu>Zn>Pb> Ni>Cr and the contribution rate of Hg exceeded 60%.

Population densities in cities of developing countries are much higher than in other parts of the world, and the predominance of poverty in urban slums is ubiquitous throughout the region. In many urban areas, the lack of wastewater and waste management continues to be a huge challenge for environment and health protection. Decentralized approaches are proposed to provide practical, alternative options for sustainable urban wastewater and waste management in urban conditions. Conventionally, on-site constructed brick/concrete biogas reactors are the most used models. However, long construction periods, quality issues and leakage of biogas are often the disadvantages of construction design. In contrast to these systems, prefabricated biogas reactors can be produced off-site from different kinds of material. In this paper, prefabricated biogas reactor and treatment systems will be discussed, which could be applied in different developing countries. Meanwhile, some existing cases in China, Indonesia and South Africa are presented to show clear scenarios.

To find a suitable and affordable technology for the composting of human faeces in the Ger Areas of Ulaanbaatar, Mongolia, new composting system was developed and several trials have been conducted. Under controlled conditions with pH, temperature and moisture, three different mixtures were tested: human faeces plus sawdust, human faeces plus straw and human faeces plus wood chips. Based on the experimental results it can be concluded that the composting process, if started under controlled and appropriate conditions, could start and last about 32 days. Meanwhile, when ambient temperature drops sharply, the reactor temperature correspondingly drops sharply, but shows different results in the different temperature ranges. For stable and high efficient composting under such condition, further improvement measures and more trials should be done in next stages.

“ecosan — ecologically and economically sustainable wastewater management and sanitation systems” means approaches to bring forward a new philosophy of dealing with what is presently regarded as waste and wastewater. They are based on the systematic implementation of reuse and recycling of nutrients and water as a hygienically safe, closed-loop and holistic alternative to conventional solutions. Ecological sanitation systems enable the recovery of nutrients from human faeces and urine to the benefit of agriculture, thus helping to preserve soil fertility, to assure food security for future generations, to minimize water pollution and to recover bioenergy. They ensure that water is used economically and is recycled in a safe way to the greatest possible extent for purposes as irrigation or groundwater recharge. The main objectives of GTZ research and development project “ecosan” include broad knowledge management via a global ecosan network as well as the initiation, implementation and monitoring of appropriate pilot projects in cooperation with local and international partners.

Urine contains a lot of nitrogen, phosphorus and potassium, and could act as valuable plant fertiliser. But urine is often either flushed down a toilet or enters a pit latrine, thus being lost to agriculture and increasing surface and groundwater contamination with nitrogen. Ecological sanitation concepts are closing the loop of nutrients contained in wastewater with agriculture. Besides providing adopted technology solutions, it also contributes to local food security, which is important in many developing countries. The paper summarised the findings of three research works that introduce ecological sanitation, where urine enriched compost produced either from animal or human excreta.