Conventional Sanitation Systems Research Articles

Treatment of domestic effluents using sustainable biofilter methods

The discharge of effluents is a permanent environmental and sanitation concern. Efficient water management must include water treatment and reuse. It is therefore necessary to study treatment systems to improve their performance throughout the entire chain, from drinking water to wastewater or, more specifically, waste effluent. Currently, technologies using bio-filtration processes have proven to be an effective and low-cost method for treating industrial effluents and domestic sewage. In this study, a low-cost domestic sewage treatment system made up of biofilters and pipes was built on a bench model as a means of teaching practical classes, and its efficiency was also studied. The results showed that the equipment can be made from recyclable material and is low-cost, easy to detail technically and easy to handle and operate. The students involved can easily replicate the technology in their communities, thus spreading low-cost sanitation treatment technologies to low-income populations without access to conventional sanitation systems. The parameters pH, turbidity, chlorination, temperature, and electrical conductivity were all at acceptable levels for discharge into receiving bodies and domestic use.

DMsan: A Multi-Criteria Decision Analysis Framework and Package to Characterize Contextualized Sustainability of Sanitation and Resource Recovery Technologies.

In resource-limited settings, conventional sanitation systems often fail to meet their goals-with system failures stemming from a mismatch among community needs, constraints, and deployed technologies. Although decision-making tools exist to help assess the appropriateness of conventional sanitation systems in a specific context, there is a lack of a holistic decision-making framework to guide sanitation research, development, and deployment (RD&D) of technologies. In this study, we introduce DMsan-an open-source multi-criteria decision analysis Python package that enables users to transparently compare sanitation and resource recovery alternatives and characterize the opportunity space for early-stage technologies. Informed by the methodological choices frequently used in literature, the core structure of DMsan includes five criteria (technical, resource recovery, economic, environmental, and social), 28 indicators, criteria weight scenarios, and indicator weight scenarios tailored to 250 countries/territories, all of which can be adapted by end-users. DMsan integrates with the open-source Python package QSDsan (quantitative sustainable design for sanitation and resource recovery systems) for system design and simulation to calculate quantitative economic (via techno-economic analysis), environmental (via life cycle assessment), and resource recovery indicators under uncertainty. Here, we illustrate the core capabilities of DMsan using an existing, conventional sanitation system and two proposed alternative systems for Bwaise, an informal settlement in Kampala, Uganda. The two example use cases are (i) use by implementation decision makers to enhance decision-making transparency and understand the robustness of sanitation choices given uncertain and/or varying stakeholder input and technology ability and (ii) use by technology developers seeking to identify and expand the opportunity space for their technologies. Through these examples, we demonstrate the utility of DMsan to evaluate sanitation and resource recovery systems tailored to individual contexts and increase transparency in technology evaluations, RD&D prioritization, and context-specific decision making.

Development of ecological sanitation approaches for integrated recovery of biogas, nutrients and clean water from domestic wastewater

Access to adequate sanitation services and the treatment of domestic wastewater becomes a critical problem in developing countries. Domestic wastewater treatment based on conventional sanitation concept is the most common approach, which is neither ecological nor economical sound to realize sustainable sanitation solution. Therefore, there is a need to block the sanitation-linked concerns and limitations of the conventional systems through the development of an alternative sustainable sanitation systems. With the rising demand to improve the existing sanitation system for environmental protection and resources conservation (energy, nutrient, and water), ecological sanitation approach appealed the attention of scientific communities. This paper presents the comprehensive review of domestic wastewater characteristics, conventional sanitation systems and its sustainability challenges; ecological sanitation technologies, process conditions and their performances in terms of resource recovery efficiency (i.e. biogas, struvite-based nutrients and clean water). The outcome of these approaches are resource oriented and closed-loop systems, which promotes the sustainable sanitation by overwhelmed the limitations of conventional systems. Moreover, the application of these technologies to treat domestic wastewater also helps to improve public health by reducing the introduction of disease causing pathogens in to the water cycle and minimizes the negative environmental impacts. Accordingly, the applications of ecological sanitation technologies to treat domestic wastewater would be a viable option to solve the existing sanitation problems; and simultaneously promoting energy-food-water-health nexus, especially in developing country. • Eco-San approaches of DWW in biogas, struvite and clean water recovery is reviewed. • COD removal and biogas recovery potential of various technologies are reported. • Nutrients removal and struvite recovery efficiencies from DWW are described. • The water reuse is based on the stringent water quality standards. • Future research is needed for an integrated recovery of valuables from mixed DWW.

Towards the development of source separation and valorization of human excreta? Emerging dynamics and prospects in France

The source separation of human excreta (urine and/or feces) offers an alternative to conventional sanitation systems (flush toilets/public sewers) that is appealing in several respects, especially in environmental terms and for agricultural purposes, as a source of natural fertilizer from local and renewable resources. In France, systems for the separate collection of human excreta have previously been confined to the rural sphere and mainly implemented at the individual scale. However, since the 2010s, experimental projects in excreta source separation have been observed in urban areas, at the scale of individual houses and collective buildings, or even neighborhoods. This article, drawing on interdisciplinary social science research conducted within the French research program OCAPI (on ecological transition in nutrition/excretion systems), investigates these innovative projects for the source separation of human excreta in urban areas. Our work lies on a territorial approach, based on a cross-sectional analysis of experimental projects in three cities (Paris, Bordeaux and Grenoble), complemented by the mobilization of the “multi-level perspective” and the “technological innovation systems” frameworks. We study the trajectory and factors of development of source separation in France, its implementation dynamics and territorialisation pathways. Our analysis shows that source separation is still in an emerging phase in France. It is currently experimented in cities through diversified projects and approaches. This diversity applies both to socio-technical choices and territorial embeddedness’ forms. Adopting a prospective point of view, we then point out main obstacles and drivers to the scaling-up of this innovative practice: beyond technical issues, shared social values, stakeholder alignment issues and organizational challenges are essential. Finally, we consider possible directions for its development, ranging from the spread of a homogeneous solution to the continuation of a diversity of approaches on different territories.

To separate or not? A comparison of wastewater management systems for the new city district of Hiedanranta, Finland

In this study, life cycle assessment (LCA) and life cycle costing (LCC) methods were applied for the new city district of Hiedanranta, where source-separating sanitation systems are being considered. Two source-separating systems were compared to the conventional sanitation system with a centralized wastewater treatment plant (WWTP). With a separating system, three to 10 times more nitrogen could be recovered compared to the conventional system. If the nutrient potential of the reject water of the sludge digestion were to be utilized, the recovery rate would be even higher. For phosphorus, the recovered amount would be at the same level for all the alternatives. However, the plant availability of phosphorus is higher in separating systems. Based on the environmental impacts of separating systems with improved nutrient recovery, the climate and eutrophication impacts could be reduced, but the acidification impact may be higher. However, the actual climate benefits depend on how the avoided emissions will be realized, which is highly dependent on the policy and decision-making processes in the society. The life cycle costs of the alternative source-separating systems are higher at current prices. Source-separating sanitation produces new recycled nutrient products of human origin that contain fewer contaminants and could therefore be more easily accepted for end use when certain boundary conditions are met.

Re-emergence of dry toilets and fecal nutrient reuse in M'zab cities

Abstract In the M'zab valley, dry toilets represent an ancestral dry sanitation system, serving as a source of fertilizer thanks to human excrement valorization. However, in the 20th century, local populations began to shun these systems. The objective of this article is to illustrate the importance of dry toilets on agricultural and environmental scales in ancient M'Zab, and the renewal of these systems in response to sanitation problems in the oasis after their decline. The hypothesis put forward is that dry toilets can act as a complementary system to conventional sanitation systems. Data were collected through interviews with the local population. Our results show that the use of dry toilets, and the resulting use of human excrement as fertilizer, has gone through three phases. First, a phase of strong recycling dynamics, followed by a second phase of decline in dry toilet use which is linked to the discovery of the Albian aquifer and flush toilet adoption. The third phase is characterized by dry toilet reuse in response to oasis degradation caused by sanitation and environmental problems. Some oasesians have taken the initiative to revert to dry toilets to ensure oasis system sustainability and to revive the practice of recycling human waste.

Get in sanitation 2.0 by opportunity of rural China: Scheme, simulating application and life cycle assessment

This study advances a scheme of sanitation 2 system (S2S) basing on vacuum source-separation to manage the rural waste and wastewater of Changshu, China. The advanced San-2 technology system parts the whole regional rural waste and wastewater into three parallel logistic streams, biogenic waste, other waste, and light grey water. A simulating application of S2S in a township area of Changshu is studied and evaluated by using the life cycle assessment method within the proposed framework and assumptions. Both the systems are divided into four parts: collection, treatment, termination and added processes. And the results show that San-2 has extraordinary advantages of environmental performance over conventional sanitation system (CSS), and the damage scores of the former are 27%, 54%, 27% and 37% as those of the latter with regarding the impacts on human health, ecosystem quality, climate change, and resources respectively. The environmental impact of the CSS is mainly sourced from the added processes, while that of the S2S is mainly from collection and treatment process. Sensitivity analysis shows that the ammonia emission rate and canceling biogas production are the key factor for the S2S, and the settlement population is the critical factor for the CSS. Facing the huge demands of the rural China, the S2S and the rural China are an opportunity to each other, and it is urged to setup encouraging policies for S2S to break up the dictatorship of the CSS.

Prospects and challenges for sustainable sanitation in developed nations: a critical review

Serious sanitation challenges are not confined to developing nations. Infrastructure costs, nutrient losses and related ubiquitous surface water impairments, energy demands, and sludge disposal problems have led many to question the long-term sustainability of conventional centralized sanitation in developed nations. Such concerns have resulted in the development of a body of literature and practices aimed at making sanitation more sustainable. This paper has two major aims: (i) provide a representative multidisciplinary (including engineering, natural sciences, and social sciences) synthesis of literature on sustainable sanitation in developed nations over the past 15 years, and (ii) raise consciousness of sustainable sanitation approaches in regions and disciplines where this area of inquiry has at least partly been neglected. Literature included in the review was identified by searching the ISI Web of Knowledge and by “mining” key review papers that already synthesized literature on topics such as ecological sanitation, excreta as fertilizer, and wastewater reuse. The sustainability challenges faced by conventional sanitation are discussed first, followed by a review of efforts in two major areas of sustainable sanitation: (i) incremental improvements to conventional centralized sanitation, and (ii) source separation and decentralization (SSD). Based on the literature review, there does not appear to be a perfect solution to the sanitation challenges (e.g., water use and pollution, greenhouse gas emissions, nutrient and micropollutant releases) faced by society. Compared with SSD, there is a much broader knowledge base on the construction, operation, and maintenance of conventional sanitation systems. And there are significant opportunities for incremental improvements (e.g., reduction of water, energy use), but also significant drawbacks such as the costs of maintaining ageing infrastructure and the mixing of domestic, storm, and industrial effluents. On the other hand, SSD is conceptually promising, and significant progress has been made over the last two decades in basic research and in exploring various SSD models. But SSD is still in its relative infancy: literature and pilot projects are regionally limited and significant logistical, behavioral, regulatory, and other challenges remain. Contributions that meaningfully address sanitation “software” or social perspectives are, therefore, urgently needed from social science fields including economics, policy, and behavioral psychology. Progress toward achieving sustainable sanitation can be aided by addressing four major areas: (i) defining sustainability goals and benchmarks, (ii) raising societal awareness of sanitation problems, (iii) broadening the societal and geographical scope of the research, and (iv) more thoroughly exploring barriers to adapting or changing sanitation systems.

Terra Preta Sanitation: A Key Component for Sustainability in the Urban Environment

Terra Preta Sanitation (TPS) plays a key role in sustainable sanitation (SuSan) and in the sustainable management of resources such as water, energy, soil (agriculture), liquid and solid organic waste streams as well as in the development of sustainable urban environment and infrastructure systems. This paper discusses the advantages of, and requirements for, SuSan systems, focusing on TPS. Case studies showing the stepwise extension and re-development of conventional sanitation systems (CSS) using TPS technologies and system approaches are presented and discussed. Decentralized TPS systems integrated in sustainable urban resource management were implemented in the German cities of Hamburg and Berlin. The compilation of best practice examples and findings using the newest TPS systems illustrates the immense potential of this approach for the transformation from conventional to SuSan systems. For this purpose, the potential savings of drinking water resources and the recycling potential of nutrient components are quantified. The results strongly suggest the need to encourage the development and application of innovative decentralized sanitation technologies, urban infrastructures, and resource management systems that have TP as a key component.

Comparison of black water source-separation and conventional sanitation systems using life cycle assessment

Abstract The municipal sanitation system based on black water source-separation (BWS) is often advanced as a viable environmental alternative to conventional systems (CONV). However, current studies have not led to any formal conclusions on the environmental advantage of such a system. The objective of this study is to compare the environmental performances of BWS and CONV in terms of environmental damage using the life cycle assessment method. The functional unit is to ensure wastewater and kitchen refuse collection and treatment and by-product (digestate/sludge and biogas) recycling for one inhabitant for one year. The results show that BWS generates higher impact scores than CONV: 100%, 89%, 24% and 25% more for the human health, ecosystem quality, climate change and resources indicators, respectively, when metal emission impacts from fertilizers are excluded. If metal emission impacts were accounted for the conclusions are reversed for human health and ecosystem quality. The exclusion of metal emission impacts from fertilizers for the interpretation of the results is based on acknowledged overestimation and high degree of uncertainty of (eco)toxicity impacts by existing assessment methods. However, even with such exclusion, the impact scores of both systems for the ecosystem quality indicator are still not significantly different because of the large contribution of metal emissions from the background data, which still remained in the inventory. Depending on the grid mix and organic fertilizer transport distance assumptions, the study conclusions may be inverted for the climate change and resources indicators, since BWS may obtain lower impact scores than CONV. The main contributors to BWS impact scores are ammonia emissions from applied digestate and digestate management (transport, storage and spreading). Suggestions for significant enhancements are required for BWS to attain better environmental performances than CONV.

Lessons learnt on Ecosan in Morocco: case of the urine-diversion dehydration toilets

‘Lessons learnt on Ecosan in Morocco’ is a short analysis of experience gained in Morocco especially in rural areas where people do not have adequate systems of evacuation of their wastewater. The rural population cannot afford conventional sanitation systems. In response to this, we have thought to promote ecological sanitation that recognises wastewater not as a waste but as a resource. The first Urine-Diversion Dehydration Toilets (UDDTs) were introduced in a rural village called ‘Dayet Ifrah’ in Morocco in December 2009. Since then, households are starting to see the advantages of UDDTs and the systems are becoming more and more accepted. The UDDT systems implemented in the village could be used as a model for Moroccan rural areas. This paper sets out how the Ecosan approach was successfully introduced in Morocco where people are motivated by reasons to improve this approach such as no smell, safety, comfort, privacy and water reuse. Results reveal that the users are satisfied with the Ecosan approach to cleanse their wastewater. Although Ecosan is relatively new to Morocco, it seems that it can succeed in very poor populations. The paper contains information on general experiences in the different countries and also lessons learnt on Ecosan in each country.

Modeling Decentralized Source-Separation Systems for Urban Waste Management

Decentralized eco-sanitation system is a promising and sustainable mode comparing to the century-old centralized conventional sanitation system. The decentralized concept relies on an environmentally and economically sound management of water, nutrient and energy fluxes. Source-separation systems for urban waste management collect different solid waste and wastewater streams separately to facilitate the recovery of valuable resources from wastewater (energy, nutrients). A resource recovery centre constituted for 20,000 people will act as the functional unit for the treatment of urban waste of a high-density population community, like Singapore. The decentralized system includes urine treatment, faeces and food waste co-digestion, and horticultural waste and organic fraction of municipal solid waste treatment in composting plants. A design model is developed to estimate the input and output in terms of materials and energy. The inputs of urine (yellow water, YW) and faeces (brown water, BW) are calculated by considering the daily mean production of urine and faeces by humans and the water consumption of no-mix vacuum toilet (0.2 and 1 L flushing water for urine and faeces, respectively). The food waste (FW) production is estimated to be 150 g wet weight/person/day. The YW is collected and discharged by gravity into tank. It was found that two days are required for urine hydrolysis and struvite precipitation. The maximum nitrogen (N) and phosphorus (P) recovery are 150-266 kg/day and 20-70 kg/day, respectively. In contrast, BW and FW are mixed for co-digestion in a thermophilic acidification tank and later a decentralized/centralized methanogenic reactor is used for biogas production. It is determined that 6.16-15.67 m 3 /h methane is produced which is equivalent to 0.07-0.19 kWh/ca/day. The digestion residues are treated with horticultural waste and organic fraction of municipal waste in co-composting plants.

Ecological Sanitation in Morocco Promotion of the Urine-Diversion Dehydration Toilets-Case of Dayet Ifrah

Problem statement: Most of people in rural areas in Morocco don’t have adequate systems of collection, evacuation and transport of black and gray water. They simply defecate in nature. There is a huge demand, which cannot possibly be met by conventional sanitation systems due to the enormous costs of the pipe network, lack of water and serious environmental drawbacks in order to avoid the disadvantages of conventional wastewater systems. For this reason, we have thought to promote ecological sanitation, or “ecosan“ for short, that recognizes human excreta and water from households not as a waste but as resources that can be recovered, treated where necessary and safely used again. Ecosan is a philosophy which houses a multitude of different technologies applied in ecological sanitation projects such as Urine Diversion Dehydration Toilets (UDDT). Approach: The scope of the study was to highlight the ecosan promotion strategies and policies for its adoption by the future ecosan users in Morocco and to show that the development of ecosan pilot systems adapted to the sociocultural context of Morocco is possible and can be used as model for rural areas. Ecosan systems studied had been implemented in a small rural area in Morocco called “Dayet Ifrah”. But, it’s necessary at the beginning to sensitize people in Dayet Ifrah and to convince to adopt and accept urine diversion dehydration toilets. Marketing has been more successful than anything else in changing the behavior of people when they can see direct personal benefits. Choosing a (social) marketing approach means that the attractiveness of the product is one important factor. That was what happened in 2009. Results: After this phase of sensitizing, results reveal that the households were convinced of the benefits these infrastructures afford them. Ecosan reduces the health risks related to sanitation, contaminated water and waste, prevents the pollution of surface and groundwater, prevents the degradation of soil fertility and optimizes the management of nutrients and water resources. Conclusion: The users are satisfied with the ecosan approach to cleanse their wastewater. Our work shows that ecosan can succeed in very poor populations. It is particularly relevant as locomotors of agricultural economics.

No waste, but a resource: Alternative approaches to urban sanitation in Ethiopia

To overcome the drawbacks of conventional sanitation systems, new approaches to sanitation are necessary. Human faeces and urine as well as greywater represent potential resources requiring efficient management. Thus, source-separating systems, which safe water and allow the recycling of nutrients to agriculture, can provide an alternative. These systems can even be integrated into multi-storey houses, therefore addressing the need for resource-efficient sanitation in new condominium housing programmes. Several urine-separating facilities are implemented in Ethiopia showing a high acceptance by their users. The cost comparison between source-separating systems and the conventional system for condominiumhouses shows an advantage for the new approach due to savings of water for toilet flushing as well as reduced costs for the treatment of the mixed wastewater in septic tanks. The use of human urine as fertiliser in several trials resulted in significant benefits in terms of improved crop growth.

EU demonstration project for separate discharge and treatment of urine, faeces and greywater – Part I: Results

The main aim of this EU demonstration project was to test two new sanitation concepts to determine if these concepts are more sustainable, compared with the conventional sanitation system, particularly with regard to nutrient recycling. Two different sanitation concepts were tested. One concept comprised the use of gravity separation toilets, the other used vacuum separation toilets. Results from a life-cycle-assessment investigation show that the new sanitation concepts are more sustainable. A cost analysis for an existing residential area did not prove lower costs for the new sanitation concepts in this special case. The experience from this demonstration project shows that prior to a widespread use of the new sanitation concepts, several improvements have to be made. One important issue is the improvement of separation toilets. Since nutrient recycling, water saving and reuse as well energy reduction become more and more important, further research should be undertaken in this field.

On-site sanitation: a viable alternative to modern wastewater treatment plants

Rapid population growth and urbanization are exerting excessive pressure on soil and water resources. To address these problems this paper proposes a cheap and sustainable alternative sanitation system, which accelerates nutrient recycling ("closing the loop"): ecological sanitation (ecosan) is a potential alternative to conventional sanitation systems that replenishes the organic matter and nutrients of the soil that are taken off as the crop harvest. A comparison is made of the environmental and the operation and maintenance costs between a modern wastewater treatment plant and on-site sanitation. An elevated double box urine diverting toilet ("ecotoilet") is proposed and its advantages and disadvantages over a system with a centrally controlled modern WWTP are discussed. Bagmati Area Sewerage Project in Kathmandu is taken as an example of modern WWTP and ecosan being practiced in a village in Nepal is taken as an example of ecotoilet for the comparison.

Possibilities and barriers for recirculation of nutrients and organic matter from urban to rural areas: A technical theoretical framework applied to the medium-sized town Hillerød, Denmark

We aimed to develop and evaluate technical solutions for increasing recirculation of nutrients and organic matter from urban areas. Furthermore, we assessed the feasibility of the solutions in a specific medium-size modern town setting – the municipality of Hillerød (approx. 27,000 inhabitants), Denmark. Fourteen integrated systems were described based on well-known technology and assessed on the basis of their ability to meet requirements in relation to public health, comfort, costs, durability, user friendliness, energy use, and recirculation potential. Of these 14, four were used to ‘retrofit’ into the existing town in an integrated municipal sewage and organic waste management system and the resulting change in terms of energy balances, recycling, and economic costs were modeled against a conventional ‘reference’ waste management system. For the chosen systems the energy saving corresponded to the yearly electricity consumption in 896 Danish households. It was estimated that capital and running costs were approximately 10% and 17% higher than for the reference system, including the net energy savings. The reference system produced sufficient nutrients for fertilising 152 ha of agricultural field, whereas the alternative system in which nutrients were collected as sludge from biogas digester, human urine, and sludge from the wastewater treatment plant were enough for fertilising 451 ha of agricultural land. On the basis of this work it can be concluded that it is technically possible to design integrated ecological waste management systems, based on known technical components that may be operated at or close to the cost level of the current conventional sanitation systems. Such integrated systems need to be further developed and tested on a scale that will allow an interaction with farmers and their organizations, in order to evaluate their wider environmental consequences and to further integrate health and socio-cultural aspects. The main drivers for change in countries with a fully developed centralized sewage and waste infrastructure would seem to be either government policy-motivated (sustainability drive) or motivated by grass root movements, since the economic incentives for technology change are currently uncertain and probably small. However, in the middle-income countries, including part of the developing world, there is potential for considerable cost savings, and enormous need for development of waste and sanitation infrastructure, which would give impetus to more effective use of ecological sanitation.

Ecosan Can Provide Sustainable Sanitation in Emergency Situations with Benefits for the Millennium Development Goals

This paper describes the potential of ecological sanitation (ecosan) to provide sustainable excreta disposal in emergency situations and in peri-urban areas or slums in developing countries. At the present time, pit latrines are the most common form of excreta disposal both for emergency situations and in low-income peri-urban areas or slums. Although not intended to be a long-term solution, pit latrines provided during emergencies are often used for a long time (more than six months to years). This practice is not sustainable if the area is prone to flooding or there are soil conditions that allow groundwater pollution in areas where groundwater is used for drinking water, to name but two of the main factors. We propose eight criteria for the applicability of ecosan based on analysis of three case studies representing different types of emergency situations. The two most important criteria are awareness and expertise in ecosan within the aid agencies, and availability of standardised, lightweight toilet units that are quick to assemble and easy to transport (e.g. container for faeces, and urine diversion squatting pan made of impact-resistant molded polypropylene). Such toilets could be moved to, or replicated in, other areas in need after the emergency (peri-urban areas or slums). This would provide benefits for Millennium Development Goals achievements (targets on hunger, child mortality, sanitation and slum dwellers) at lower cost than conventional sanitation systems. Costs for sanitation systems should be compared based on the entire system (toilet, transport, treatment, reuse in agriculture), using Net Present Value analysis for capital, and operating and maintenance costs.

From conventional to advanced environmental sanitation

The basic concept of collecting domestic liquid waste in water-borne sewer systems goes back more than 100 years and became in the last century the conventional approach to sanitation in urban areas. Over the years, these sewage disposal systems had to be successively upgraded by additional sewage treatment plants increasing investment, operating and maintenance costs. Although these conventional sanitation systems could improve significantly the public health situation in those countries who could afford to install and operate them, it is highly questionable, if they are economically and ecologically sustainable. The large number of people in the developing world who still do not have access to adequate sanitation is a clear indication that the conventional approach to sanitation is not adapted to the socio-economic condition prevailing in most countries of Africa, Asia and Latin America. Advanced environmental sanitation is aiming not only to protect public health and the integrity of aquatic ecosystems but also to conserve precious freshwater and non-renewable resources. The Bellagio Principles and the Household Centred Environmental Sanitation Approach (HCES) are suggested as guiding principles and a new approach for planing and designing advanced (sustainable) environmental sanitation systems.