Sand Dam
A sand dam is a small dam built on and into the riverbed of a seasonal sand river. Its purpose is to capture and store water beneath sand: sand is transported during periods of high flow and accumulates upstream of a sand dam, resulting in additional groundwater storage capacity of riverbed and –banks. This reservoir fills during the wet season, providing water to cover dry periods. Synonyms: Sand Storage Dam

Sand River
Dry and sandy riverbeds are seasonal watercourses that transport runoff-water from catchment areas to rivers or swamps once or several times a year. Dry riverbeds are also called ephemeral streambeds, seasonal watercourses or sand rivers. Most of the rainwater that is being transported downstream in riverbeds occurs as floods of several meters height. Sand rivers are only suitable as sand dams if coarse sand is available and the river is bedded on impervious bedrock (or clay like black cotton soil). Synonyms: Dry Riverbeds, Ephemeral Streambeds, Seasonal Watercourses
Sanitary Seal
In order to prevent ingress to the aquifer of any potential contaminants from the surface via the borehole itself, it is necessary to seal the uppermost section of the annulus between the outermost casing string and the wall of the borehole. The sealing material commonly used is cement grout or a bentonite mixture. It is also prudent to ensure that no potential contaminants can enter the borehole from the surface via the space between any other internal casing strings.
The means of safely collecting and hygienically disposing of excreta and liquid wastes for the protection of public health and the preservation of the quality of public water bodies and, more generally, of the environment. See also environmental sanitation.
Sanitation 21
The framework proposed by the International Water Association (IWA) task force for the analysis and selection of appropriate sanitation systems is called Sanitation 21. It is a comprehensive approach for the assessment of planned or existing sanitation situations. However, it does not provide in-depth guidance for planners and operators. The Sanitation 21 task force argues that technical planners and designers have to develop more sophisticated planning systems that respond to the needs of rapidly growing cities. As regards the human and political context, this will require a change in the manner of making technical decisions. Quality and effectiveness of sanitation investments are not particularly about technologies (although the appropriate application of technology is important), but are rather about developing an explicit understanding of what the objectives of a system are and then designing a system which meets those objectives. Synonyms: Sanitation21
Sanitation Frameworks and Approaches
To mitigate the effects of lacking sanitation, various approaches have been developed that should help people to improve their sanitary situation. These approaches include guidelines on how to conceptualise, plan and carry out sanitation projects.

Sanitation Safety Plans
Sanitation Safety Plans are site-specific assessment and management plans to reduce health impacts from wastewater, excreta and greywater, that at the same time maximize the benefits of their use in agriculture and aquaculture. Synonyms: SSP
Abbreviation: SSP

Sanitation Systems
Sanitation is as a multi-step process in which human excreta and wastewater are managed from the point of generation to the point of use or ultimate disposal. A Sanitation System is a context-specific series of technologies and services for the management of these wastes (or resources), i.e., for their collection, containment, transport, transformation, utilisation or disposal. A sanitation system is comprised of Products (i.e. waste, organic wastewater, excreta, blackwater, greywater, etc.) that travel through functional groups, which contain Technologies that can be selected according to the context. By selecting a Technology for each Product from each applicable Functional Group, one can design a logical Sanitation System. A sanitation system also includes the management, operation and maintenance (O&M) required to ensure that the system functions safely and sustainably.
Sanitation Technology
Sanitation technologies are defined as the specific infrastructure, methods, or services that are designed to contain and transform sanitation products, or to transport them to another functional group (i.e. user interface, conveyance, storage, treatment and final disposal or reuse).
Hygienised describes any wastewater product (e.g. faeces, blackwater etc.) that has undergone a transformation which turns it into a hygienically safe product for handling, reuse or disposal. Synonyms: Hygienised, Hygienized, Sanitized

SARAR approach
SARAR is an education/training methodology for working with stakeholders at different levels to engage their creative capacities in planning, problem solving and evaluation. The acronym SARAR stands for the five attributes and capacities that are considered the minimum essentials for participation to be a dynamic and self-sustaining process: Self-esteem, a sense of self-worth as a person as well as a valuable resource for development; Associative strength, the capacity to define and work toward a common vision through mutual respect, trust, and collaborative effort; Resourcefulness, the capacity to visualise new solutions to problems even against the odds, and the willingness to be challenged and take risks; Action planning, combining critical thinking and creativity to come up with new, effective, and reality-based plans in which each participant has a useful and fulfilling role; Responsibility, for follow-through until the commitments made are fully discharged and the hoped-for benefits achieved. SARAR was developed during the 1970s and 1980s by Dr. Lyra Srinivasan and colleagues for a variety of development purposes. The major work describing the methodology for the water and sanitation sector is entitled Tools for Community Participation, A Manual for Training Trainers in Participatory Techniques. Synonyms: SARAR
Powdery particles of wood produced by sawing.

A scenario is a description of a possible future environment, based on extrapolation of existing trends.

School-led Total Sanitation
School-led Total Sanitation
Abbreviation: SLTS

Screening is a wastewater pre-treatment, which aims to prevent coarse solids, such as plastics, rags and other trash, from entering a sewage system or treatment plant. Solids get trapped by inclined screens or bar racks. The spacing between the bars usually is 15 to 40 mm, depending on cleaning patterns. Screens can be cleaned by hand or mechanically raked. The latter allows for a more frequent solids removal and, correspondingly, a smaller design. Synonyms: Bar Rack, Screening, Trash Trap
Scum is the general name given to the floating layer of dirt or froth on the surface of a liquid. It is also used to describe the layer of solids formed by wastewater constituents that float to the surface of a tank or reactor (e.g., oil and grease).
Secondary disinfection
The application of a disinfectant, either at the exit of the treatment plant or in the distribution system, with the objective of ensuring that a disinfectant residual is present throughout the distribution system, thus preventing recontamination of water.

Secondary Treatment
Follows primary treatment to achieve the removal of biodegradable organic matter and suspended solids from wastewater effluent. Nutrient removal (e.g., phosphorus) and disinfection can be included in the definition of secondary treatment or tertiary treatment, depending on the configuration. Synonyms: Secondary Wastewater Treatment
Gravity settling of particles in a liquid such that they accumulate. It is one of the most basic water treatments for both drinking water and wastewater. Synonyms: Settling
Sedimentation/Thickening Ponds
Sedimentation or thickening ponds are settling ponds that allow sludge to thicken and dewater. The effluent is removed and treated, while the thickened sludge can be further treated in a subsequent technology. Synonyms: Sedimentation Ponds, Thickening Ponds
Seeding refers to the introduction of a sample of a living and active community of microorganisms (an inoculum) into a reactor in order to initiate a biological degradation process (e.g. anaerobic digestion, activated sludge). The microorganism, if they feel comfortable, will grow and create the optimum conditions for the metabolic degradation or elimination of pollutants entering the tank. Synonyms: Inoculation

Self-esteem, associate strengths, resourcefulness, action planning, responsibility
SARAR stands for self-esteem, associate strengths, resourcefulness, action planning and responsibility. SARAR is a participatory approach to adult education that builds on local knowledge and strengthens local ability to assess, prioritise, plan, create, organise, and evaluate. SARAR's purpose is to (a) provide an approach to team building through training, (b) encourage participants to learn from local experience rather than from external experts, and (c) empower people to initiate action.
Abbreviation: SARAR
Semi-arid climate generally describes regions (non-polar) that receive low annual rainfall (from 250 to 500 mm) and that are characterised by short-grass or scrub vegetation.
Semi-centralised Drinking Water Treatments
(Semi-)centralised drinking water treatments include middle- and large-scale units that produce water for several households and consequently required most often more operation and maintenance.

Semi-Centralised Treatment
Semi-centralized treatment and centralized treatment refers to treatment technologies that are generally appropriate for large user groups (i.e., neighbourhood to city level applications). These systems thus require either thee distribution of fresh water to the household or the conveyance of waste and wastewater from individual houses. The operation, maintenance, and energy requirements of technologies in centralised systems are generally higher than for smaller-scale technologies at the storage level. The technologies are divided into two groups: the first group is primarily for the treatment of blackwater, brownwater, greywater or effluent (e.g. biogas settlers, ABRs, WSPs, constructed wetlands), whereas the second group is mainly for the treatment of sludge (e.g. drying beds, (co-)composting, anaerobic digestion). Synonyms: (Semi-) Centralised Treatment, (Semi-) Centralised Wastewater Treatments, (Semi-) Centralized Treatment, (Semi-)Centralised Treatment, (Semi-)Centralised Wastewater Treatments, (Semi-)Centralized Treatment, Centralised Treatment, Centralized Treatment, Semi-Centralised Treatment, Semi-Centralised Wastewater Treatments, Semi-Centralized Treatment
Semi-circular bunds
Semi-circular bunds are well suited for planting trees due to their half-moon shape. They collect water runoff and therefore increase soil moisture and prevent soil erosion. They bunds are usually filled with organic matter to add nutrients for improved crop yield. Synonyms: Bunds
Allowing passage of certain, especially small, molecules or ions but acting as a barrier to others. Use of biological and synthetic membranes. Synonyms: Semi-permeable
Separate Sewers
Separate sewerage consists in the separate collection of municipal wastewaters (blackwater from toilets, greywater and industrial wastewater) and surface run-off (rainwater and stormwater). The separate collection prevent the overflow of sewer systems and treatment stations during rainy periods and the mixing of the relatively little polluted surface run-off with chemical and microbial pollutants from the municipal wastewater. The design of the sewers and the (semi-) centralised treatment stations thus needs to consider the volume of the wastewater only and the surface run-off and rainwater can be reused (e.g. for landscaping or agriculture) after a simplified treatment.

A historical term to define sludge removed from septic tanks.
Describes the conditions under which putrefaction and anaerobic digestion take place.
Septic Tank
A septic tank is a watertight chamber made of concrete, fibreglass, PVC or plastic, through which blackwater and greywater flows for primary treatment. Settling and anaerobic processes reduce solids and organics, but the treatment is only moderate.
Sequence Batch Reactor
SBRs are wastewater treatment reactors based on an activated sludge process where all the different stages of nitrification/denitrification, settling and separation take place in the same reactor but dislocated in time. The treatment consists of a cycle of five stages: fill, react, settle, draw and idle. The reactor containing active biomass is first charged with influent, closed and than aerated to satisfy the oxygen demand of the wastewater. During this phase, bacteria oxidize the organic matter as in activated sludge systems. Then, aeration is finally stopped to allow sludge settling. In the next step, the water and the sludge are separated by decantation and the clear layer (supernatant) is discharged from the reaction chamber. Depending on the rate of sludge production, some sludge may also be purged. After a phase of idle the tank is filled with a new batch of wastewater. At least two tanks are needed for the batch mode of operation as continuous influent needs to be stored during the operation phase. SBRs are suited to smaller flows, because the size of each tank is determined by the volume of wastewater produced during the treatment period in the other tank and the need to be seeded for starting up reactors. Synonyms: SBR
Service Delivery Approach
The service delivery approach is a conceptual approach taken at sector level to the provision of rural water supply services, which emphasises the entire life-cycle of a service, consisting of both the hardware (engineering or construction elements) and the software (awareness raising, capacity building, institutional support) required to provide a certain level of access to water.
Service Level Benchmarks
Service Level Benchmarks Synonyms: SLB
Abbreviation: SLB

Settlement Phase
The settlement phase describes the fourth and last period after an emergency. It can last for several years after an event. It typically includes disaster preparedness activities and reduction of vulnerability towards different hazards. The exact duration depends on the event and the context of the emergency.
A settler or clarifier is a primary treatment technology for wastewater; it is designed to remove suspended solids by sedimentation. It may also be referred to as a sedimentation or settling basin or tank, or clarifier. The low flow velocity in a settler allows settleable particles to sink to the bottom by gravity, while constituents lighter than water float to the surface.
Waste matter that is transported through the sewer. It contains generally excreta (urine or faeces) and water (blackwater), grey water and may also contain other wastes (e.g. kitchen waste).
sewage treatment systems
sewage treatment systems Synonyms: STPSs
Abbreviation: STP

An open channel or closed pipe used to convey sewage.
Sewer Discharge Stations
A variation of the transfer station, but it is directly connected to a conventional gravity sewer main. Sludge emptied into the sewer discharge station is released into the sewer main either directly or at timed intervals (e.g., by pumping) to optimize the performance of the sewer and of the wastewater treatment plant, and/or reduce peak loads. See also transfer station. Synonyms: SDS
Sewer Force Main
The pipe through which water from an engine is delivered to an elevated level. Synonyms: Sewer Rising Main

Sewer Pumping Stations
Pumping stations in sewage collection systems, also called lift stations, are designed to handle raw sewage that is fed from underground gravity pipelines. Sewage is fed into and stored in an underground pit, commonly known as a wet well. Electrical instrumentation is installed to detect the level of sewage. When the level rises to a predetermined point, a pump will be started to lift the sewage upward through a pressurized pipe system (sewer force main or rising main) from where it is discharged into a gravity manhole again. From here the cycle starts all over again until the sewage reaches its point of destination – usually a treatment plant. Pumping stations thus are used to move wastewater to higher elevations. Synonyms: Lift Stations
The physical sewer infrastructure (sometimes used interchangeably with sewage). A sewerage system includes all the components of a system used for collecting and transporting (including pipes, pumps, tanks, etc.). Synonyms: Sewerage System
The simplest and cheapest method of lifting groundwater from an open dug well or surface water source is by means of a rope and a bucket. The job of drawing water from the well can be made easier by adding a “windlass” (a horizontal cylinder with a winch which can be turned to raise the bucket on a rope) or a “Shadouf” (an upright frame with a long pole suspended on top with the bucket hanging from one end and a weight which serves as the counterpoise of a lever at the other). The basic Shadouf consists of a rope, pole, bucket and counterweight and is capable of lifting water up to 4 metres. The counterweight can be just a heavy rock, however, in the more advanced picottah design, one person guides the bucket while the other acts as a moving counterweight. The Shadouf is generally used for lifting water from unlined wells, streams or ponds for irrigating small fields. Approximately 60 litres/min can be lifted from a depth of 2 to 3 metres. Advantages • A relatively inexpensive traditional technology, which can be locally made and maintained. • Easy to operate • Relatively efficient (30-60%) Disadvantages • Limited to lifts of less than 4 metres • Limited water yield, 60 l/min suitable for small fields
Shallow dug well
Shallow dug wells usually are dug wells up to 5 metres in depth. Construction is fast and easy but the wells are likely to get contaminated.

Shallow Well
A shallow well is a hand-dug water well ranging up to 7m in depth and about 1.5m in diameter.

Sheaffer Modular Reclamation and Reuse System
Sheaffer Modular Reclamation and Reuse System are a commercial available variation of advanced integrated wastewater ponds systems (AIWPS), marketed by Sheaffer International. Synonyms: MRRS, SMRRS
Short Rotation Plantation
A short rotation plantation is an integrated agro-forestry land-use system combining biomass production with wastewater use and purification. Fast growing tree species are managed in short coppicing cycles. These non-food/non-fodder crops have a high demand for nutrients and water, which may alternatively be met by reusing pre-treated wastewater and sewage sludge, enabling a sustainable nutrient recycling. The woody biomass produced can be used as a renewable and clean fuel for heat and power generation, or for further processing into liquid biofuels. Synonyms: SRP
Abbreviation: SRP
Short Rotation Plantations
Simplified Planning Tool
Software tool which allows the comparison of different water and sanitation systems based on their net present value. Simplified means that the software tool is based on numbers of simplifying assumptions, which allow the planner to use the SPT with the limited amount of data available at the pre-planning stage of a project. Due to the resulting error the water and sanitation systems which will be compared using the SPT have to be fundamentally different, as minor differences will not result in a significantly different NPV. Synonyms: SPT
Abbreviation: SPT

Simplified Sewer
A simplified sewer describes a sewerage network that is constructed using smaller diameter pipes laid at a shallower depth and at a flatter gradient than conventional sewers. The simplified sewer allows for a more flexible design at lower costs. Synonyms: Simplified Sewerage
Simplified Sewerage
Simplified sewer systems are similar to conventional sewer systems but constructed with much less conservative design criteria, allowing significant reduction of costs. Typical simplification consists in smaller pipe diameters, flatter pipe gradients, shallow pipe depths, fewer access chamber and smaller pumps. They are particularly adapted to solid-free sewer systems. Synonyms: Simplified Sewer, Simplified Sewer System
Single Pit
The single pit is one of the most widely used sanitation technologies. Excreta, along with anal cleansing materials (water or solids) are deposited into a pit. Lining the pit prevents it from collapsing and provides support to the superstructure. A single pit latrine consists of a toilet superstructures and a single pit to be filled up, emptied and filled up again. To improve pit latrines, aeration or an additional pit can be added (see single VIP, double VIP or double pit latrine). Synonyms: Single Pit Toilet
A siphon is instrument, usually in the form of a tube bent to form two legs of unequal length, for conveying liquid over the edge of a vessel and delivering it at a lower level. Siphons may be of any size; they are used in civil engineering to transfer water or other fluids over elevations. The action depends upon the influence of gravity (not, as sometimes thought, on the difference in atmospheric pressure—a siphon will work in a vacuum) and upon the cohesive forces that prevent the columns of liquid in the legs of the siphon from breaking under their own weight. Water has been lifted more than 35 feet (11 m) by a siphon.

Someone who prefers to sit on the toilet, rather than squat over it.
Situation and Problem Analysis
To develop adequate and sustainable solutions, the situation and current problems have to be analysed thoroughly. A number of tools such as SWOT, Problem Ranking etc. can help in this analysis.

Slow Sand Filter
Slow sand filtration is a biological, physical and chemical purification process. As the water flows through a porous filter-bed, its quality improves considerably by reduction of the number of micro-organisms, viruses, protozoa, turbidity, heavy metals, organic matter, iron and arsenic. Synonyms: SSF
Abbreviation: SSF

Slow-release Fertiliser
A compound, which, dissolves slowly due to its low solubility, releasing nutrients constantly over time.

Sludge is a mixture of solids and liquids, containing mostly excreta and water, in combination with sand, grit, metals, trash and/or various chemical compounds. A distinction can be made between faecal sludge and wastewater sludge. Faecal sludge comes from onsite sanitation technologies, i.e., it has not been transported through a sewer. It can be raw or partially digested, a slurry or semisolid, and results from the collection and storage/treatment of excreta or blackwater, with or without greywater. For a more detailed characterization of faecal sludge refer to Strande et al., 2014. Wastewater sludge (also referred to as sewage Sludge) is sludge that originates from sewer-based wastewater collection and (semi-) centralized treatment processes. The sludge composition will determine the type of treatment that is required and the end-use possibilities.
Sludge Thickening
Sludge thickening consists in the separation of solids and liquids in order to process each separately (e.g. composting for the solid and waste stabilisation ponds or infiltration for the liquid). It can be done in thickening ponds (settling tanks or sedimentation ponds) or planted and unplanted drying beds.

Sludge Treatment
Sludge treatment describes the processes used to manage and dispose of the sludges produced from human excreta or from the treatment of wastewater.

Sludge Treatment Facility
This is a drying bed system of the sludge from a septic tank. The sludge is allowed to dry after mixing with lime, fly fly ash/charcoal, sawdust, corncobs plus the indigenous microorganisms. Synonyms: LSTF
Abbreviation: LSTF

Sludge Volume Index
Sludge Volume Index (SVI) is a very important indicator that determines your control or rate of desludging on how much sludge is to be returned to the aeration basin and how much to take it out from the system. It actually serves as a very important empirical measurement that can be used as a guide to maintain sufficient concentration of activated sludge in the aeration basin whereby too much or too little can be considered detrimental to the system’s overall health. Synonyms: SVI
Abbreviation: SVI
Sludge Volume Index
UN-HABITAT defines a slum household as a group of individuals living under the same roof in an urban area who lack one or more of the following: 1. Durable housing of a permanent nature that protects against extreme climate conditions; 2. Sufficient living space which means not more than three people sharing the same room; 3. Easy access to safe water in sufficient amounts at an affordable price; 4. Access to adequate sanitation in the form of a private or public toilet shared by a reasonable number of people; 5. Security of tenure that prevents forced evictions.
Small and medium-sized enterprises
Small and medium-sized enterprises Synonyms: Small and medium enterprises, SME
Abbreviation: SME

Small Scale Systems
In water supply, SSS refers to decentralised water supply systems that can supply from 1,000-10,000 l/day. They are most often used for community water supply but also in emergency water supply and to purify water to be sold as bottled water or at water kiosks. Synonyms: SSS
Small-bore Sewer
A solids-free sewer is a network of small-diameter pipes that transports pre-treated and solids-free wastewater (such as septic tank effluent). It can be installed at a shallow depth and does not require a minimum wastewater flow or slope to function. This can significantly lower construction costs. Synonyms: Settled Sewer, Small-bore Sewer, Solid-free Sewer System, Solids-free Sewer
Soak Pit
A soak pit, also known as a soakaway or leach pit, is a covered, porous-walled chamber that allows water to slowly soak into the ground. Pre-settled effluent from a collection and storage/treatment or (Semi-) centralized treatment technology is discharged to the underground chamber from which it infiltrates into the surrounding soil.
Socio-Cultural Issues
The socio-cultural issues section deals with water and sanitation practices, which are often strongly influenced by society and prevailing cultures. It is crucial to understand underlying preferences, taboos, or practices to improve water management, sanitation and hygiene.

Soft Systems Methodology
Methodology to provide a framework for dealing with complex, real-life situations where there is a lack of formal problem definition. It can be employed to systematically deal with messy, problematic situations in a seven-step process that starts with entering the problem situation and ends with taking action to improve the real-world situation. Synonyms: SSM
Abbreviation: SSM
Software Tools are instruments and set-ups with aim to change the behaviour and attitudes of different actors to optimise the sanitation and water management system. Software tools can also be implemented without combining them with hardware tools. The software tools are divided into four different groups: (1) tools to create an enabling environment, (2) awareness raising tools, (3) command and control tools and (4) economic tools.

Soil Aquifer Treatment
Soil Aquifer Treatment is an artificial groundwater recharge method. Water is introduced into the groundwater under controlled conditions via soil percolation. Soil aquifer treatment is either used to artificially augment the groundwater level in order to withdraw freshwater at a later stage or as a barrier to prevent saltwater or contaminants from entering the aquifer. During percolation, soil filtration occurs and the water remains some time in the aquifer where mixing and may some other physical and chemical reaction occur, so it can be used as reclaimed water (treated blackwater) or relatively little polluted water (e.g. pre-treated greywater or stormwater). Synonyms: SAT
Soil Compaction
Compaction resulting from heavy vehicles putting strong pressure on the soil and reduceing pore volume. Consequently, oxygen and water are squeezed out and can hardly infiltrate again. Synonyms: Soil Consolidation
Soil Conditioner
A product that enhances the physical properties of soil, such water and nutrient retention, permeability and infiltration capacity and aeration. The goal is to provide a better environment for roots. Synonyms: Soil Amendment
Soil Solarisation
Soil solarisation is a non-pesticidal method of controlling soilborne pests by placing plastic sheets on moist soil during periods of high ambient temperature. The plastic sheets allow the sun's radiant energy to be trapped in the soil, heating the upper levels. Solarisation during the hot summer months can increase soil temperature to levels that kill many disease-causing organisms (pathogens), nematodes, and weed seed and seedlings. It leaves no toxic residues and can be easily used on a small or large scale. Soil solarisation also improves soil structure and increases the availability of nitrogen (N) and other essential plant nutrients.
Solar Pasteurisation
Solar pasteurisation is the process of pasteurisation using solely solar thermal energy. It is mostly applied for water. It is applied by using a solar cooker that can absorb solar thermal energy and transmit it to a black container e.g. a black jar. Typically, the significant time of heating by solar heat and cooling down contributes to the pasteurisation process. Applied to water, the solar pasteurisation (heating to 60°C (140°F)) can inactivate both bacteria and rotaviruses, the main causes for severe diarrhea in children. Synonyms: Solar Pasteurization
Solar Water Disinfection
Solar water disinfection - the SODIS method - is a simple procedure to disinfect drinking water. Contaminated water is filled in a transparent PET-bottle or glass bottle and exposed to the sun for 6 hours. During this time, the UV-radiation of the sun kills diarrhoea generating pathogens. Synonyms: SODIS
Abbreviation: SODIS

Solid Waste
Solid waste refers to the products that are thrown away by households, agriculture and industry because they do not assign any value to the material anymore. It is generally classified into organic waste, which can be used for the production of biogas or compost; or non-organic waste which either can be recycled as a material (e.g. PET) or, if there is no possibility for recycling anymore, needs to be incinerated and disposed off.

solid waste management
solid waste management Synonyms: SWM
Abbreviation: SWM

Solids Retention Time
The solids retention time (SRT) is the time the solid fraction of the wastewater spends in a treatment unit. It is the quantity of solids maintained in the reactor divided by the quantity of solids coming out of the reactor each day: SRT = V *Cd / Qout* Cout. Where V is the digester volume; Cd is the solids concentration; Qout is the volume wasted each day and Cout is the solids concentration of the effluent. In a conventional, completely mixed, or plug flow reactor, the HRT equals the SRT. In retaining biomass reactors (e.g. anaerobic biogas settlers, septic tanks) the SRT exceeds the HRT. Synonyms: SRT
Solids-free Sewers
A solids-free sewer is a network of small-diameter pipes that transports solids-free or pre-settled wastewater (such as the effluent from septic tank or biogas settlers) to a treatment facility for further treatment or to a discharge point. They can be built for new areas or where soil infiltration of septic tanks effluents (e.g. via leach fields) is not appropriate anymore (i.e. densely populated areas; clogging of sub-surface). Due to the simplified design, solids-free sewers can be built for 20% to 50% less than conventional sewerage. However, expert design and construction supervision is essential and repairs and removal of blockages may be required more frequently than for a conventional gravity sewer. Moreover, effluent and sludge (from interceptors) requires secondary treatment and/or appropriate discharge. Small-bore sewers also require a certain level of responsibility of users, because maintenance is high due to the high risk of clogging. Synonyms: Settled Sewers; Small-bore Sewers; Small-diameter Sewers; Septic Tank Effluent Gravity Sewers
The splitting or decomposition of a chemical compound by means of ultrasounds.

Source Separation
Source separation refers to the separate collection of different wastes and wastewaters (e.g. greywater and blackwater). The separate collection facilitates the reuse of water, nutrients and energy contained in the different waste streams, depending on their composition.

Southern Africa Development Community
Southern Africa Development Community Synonyms: SADC
Abbreviation: SADC

Spate Irrigation
Spate irrigation diverts seasonal flood water from valleys, rivers, riverbeds and gullies onto farm land situated at lower elevation than the origin of the flood water. In sandy riverbeds flood water seeps into the voids between sand particles pushing air to the surface where it forms thousands of air bubbles making the floodwater appear to be boiling.
Water for Irrigation
Specific Surface Area
The ratio of the surface area to the volume of a solid material (e.g., filter media). Synonyms: SSA
Specific Surface Area
Specific Surface Area Synonyms: SSA
When groundwater makes its way to the earth’s surface and emerges as small water holes or wet spots, this feature is referred to as a spring. Synonyms: Surface seepage
Spring Catchment
Spring Catchment Area
The spring catchment area is divided into immediate catchment area and the enlarged catchment area. The immediate catchment area is where human activity is not allowed. It is defined by a watershed specialist and should be fenced off immediately. The enlarged catchment area extends further beyond the immediate catchment area. Here some form of human activity may be allowed with the advice of a watershed specialist.
Sprinkler Irrigation
Sprinkler irrigation is a method of providing rainfall-like irrigation to the crops. Water is distributed through a system of pipes usually by pumping. Spray heads at the outlets distribute the water over the entire soil surface. Sprinklers provide efficient coverage for small to large areas and are suitable for all types of crops. They can be adapted to nearly all irrigable soils since sprinklers are available with a variety of discharge capacities. However, sprinkler systems can easily clog with the presence of sediment or debris and large systems incur high capital costs.

Someone who prefers to squat over the toilet, rather than sit directly on it.
SSWM Specific Topic Entry Page "Africa"
The page “SSWM in Africa” (STEP Africa) is a capacity development tool for the public and private sectors working within and beyond the water and sanitation sector, initiating, planning, carrying out and following-up WASH (Water, Sanitation and Health) initiatives in the African context. It complements the SSWM Toolbox with factsheets, reading material, case studies and contacts specific to Sub-Saharan Africa. Synonyms: Africa, SSWM in Africa, STEP Africa
Abbreviation: STEP Africa

SSWM Specific Topic Entry Page "Gestão Integrada e Sustentável de Água, Saneamento e Segurança Alimentar"
SSWM Specific Topic Entry Page "Gestão Integrada e Sustentável de Água, Saneamento e Segurança Alimentar" Synonyms: Gestão Integrada e Sustentável de Água, Saneamento e Segurança Alimentar, STEP GISA
SSWM Specific Topic Entry Page "Gestión de Agua y Saneamiento Sostenible en América Latina"
The page STEP “Gestión de Agua y Saneamiento Sostenible en América Latina” aims to present a sample of the SSWM-Toolbox to the Spanish-speaking audience, especially in Latin America. With a short selection of factsheets, the STEP “GASS en AL” shows key information of the different sections of the SSWM-Toolbox in English, such as the SSWM Concept, Planning and Process Tools, Hardware and Software Implementation Tools and Background Issues. The factsheets of this STEP are not just translated into Spanish, but also enriched with further information, case studies, awareness raising and training material developed in the Latin American context. As a first phase, this STEP has been developed in collaboration with seecon international gmbh and SARAR Transformación SC. However, the SSWM team expects that this first STEP in Spanish will encourage other organisations to collaborate in bringing this valuable tool for capacity building and information exchange to Latin America, supporting practitioners during the planning and implementation of initiatives in water and sanitation in this region. Synonyms: GASS en AL, GASS en CASTELLANO, GASS en Espagnol, Gestión de Agua y Saneamiento Sostenible en América Latina, STEP GASS en AL, STEP Latin America
Abbreviation: STEP GASS en AL

SSWM Specific Topic Entry Page "Local Governments for Urban Sustainable Sanitation and Water Management"
The STEP Local Governments for Urban SSWM (USSWM), has been developed by the SSWM team in collaboration with the ICLEI European Secretariat in the context of the ‘ACCESSanitation - Accelerating City-to-City Exchange for Sustainable Sanitation’ project. It has been developed with the aim of highlighting the interconnectivity between the different elements of the urban water cycle and the need to adopt an integrated and participatory planning approach in order to manage water more sustainably at the local level. Synonyms: Local Governments for Urban SSWM, Local Governments for Urban Sustainable Sanitation and Water Management, Local Governments for Urban Sustainable Sanitation and Water Management, Local Governments for USSWM, Specific Topic Entry Page "Local Governments for Urban Sustainable Sanitation and Water Management", Specific Topic Entry Page USSWM, STEP LG for USSWM, STEP Local Governments, STEP USSWM
Abbreviation: STEP LG for USSWM

SSWM Specific Topic Entry Page “Support to the National Urban Sanitation Policy in India”
The page “Support to the National Urban Sanitation Policy in India” (STEP SNUSP) was developed in collaboration with the Deutsche Gesellschaft für Internationale Zusammenarbeit (GIZ) GmbH, as part of the programme “Support to the National Urban Sanitation Policy in India”. The information is based on experience in the planning and implementation of city sanitation plans in India gathered by GIZ in cooperation with the government of India. It is a platform for knowledge sharing, promotion and dissemination of the activities carried out by the Indian Ministry of Urban Development (MoUD) and the Delegation of the GIZ in India in the framework of the National Urban Sanitation Policy (NUSP). This page supplements the SSWM Toolbox with detailed practice-proofed information and guidelines for decision-makers and practitioners in the field of urban sanitation management. Synonyms: SNUSP, Specific Topic Entry Page: "Support to the National Urban Sanitation Policy in India", STEP CSP, STEP SNUSP, Support to the National Urban Sanitation Policy in India, “Support to the National Urban Sanitation Policy in India"

SSWM Specific Topic Entry Page “University Course”
The STEP University is developed in collaboration with the Norwegian University of Life Sciences (UMB), Tribhuvan University in Nepal and COMSATS University in Abbottabad (Pakistan). It has been designed for the students of the web-based training course “Introduction to Sustainable Water and Sanitation” conducted by these three universities. This page complements the SSWM Toolbox with teaching material (lectures, presentations, video lectures, exercises, case studies) and learning material targeted at higher-education teachers and students. It can be used by a larger audience learning or teaching in research institutions from all over the world. Synonyms: SSWM University Course, STEP University, University Course
Abbreviation: STEP University

SSWM Specific Topic Entry Pages
Specific Topic Entry Pages (STEPs) are pages within the SSWM Toolbox providing an entry point and tailored information on a particular topic or specific group of users. According to the specific topic, STEPs give an easily accessible overview on the most relevant concepts and show how these concepts are linked to the different areas within sustainable sanitation and water management (SSWM) and the SSWM Toolbox. Both, the concepts presented within the STEP as well as the linked information from the SSWM Toolbox are complemented with further readings, awareness raising and training material, case study documentation, ready-made PowerPoint presentations and a glossary. The design, based on a pedagogic approach, guides the user in a logical sequence through the topic. STEPs are not only a powerful knowledge management and sharing tool for the specific topics, but also allow for positioning the topic within SSWM and the SSWM Toolbox and present it to a globally growing user community. Synonyms: Specific Topic Entry Page, Specific Topic Entry Pages, STEP, STEPs
Abbreviation: STEPs, STEP

The degradation of organic matter with the goal of reducing readily biodegradable compounds to lessen environmental impacts (e.g., oxygen depletion, nutrient leaching). Synonyms: Stabilization
Stabilisation Phase
The stabilisation phase describes the second period following an event. Estimation of the duration of the stabilisation emergency phase varies: while Davis & Lambert (2002) define it to typically start two to four weeks after the event and last for two to six months, Harvey (2007) estimates that the stabilisation and recovery phase together last for several months or years after the event, depending on the type and severity of the emergency. The exact duration depends on the event and the context of the emergency. Duration is not time-bound but rather depends on the achievement of set targets (indicators).
Stabilised is used to describe the state of organic material that has been completely oxidized and sterilized. When most of the organic matter has been degraded, bacteria begin to starve and consume their own cytoplasm. The organic matter left by the dead bacteria is then degraded by other organisms, which results in a fully stabilised product.
Stack Effect
The stack effect can be described as follows: warm air is lighter than cool air and it rises being replaced by cooler air. In UDDTs for instance, the solar radiation heat the vent pipe, which is constructed outside (exposed to the sun) and painted in black. When the air in the pipe heats up, it rises upwards out of the vent; a downward draught of cooler air of higher density then flows in through the squat plate hole, replacing the vacuum space created after warm air rising. The rate of ventilation is directly proportional to the size of openings ant the height difference between inlet and outlet. Aeration of the toilet cabin can increase the airflow and allow wind to pass through the cabine.

Stakeholders are people, groups, or institutions which are likely to be affected by a proposed intervention (either negatively or positively), or those which can affect the outcome of the intervention (WORLDBANK 1998).

Stakeholder Analysis
Stakeholder analysis is the process of identifying the individuals or groups that are likely to affect or be affected by a proposed action, and sorting them according to their impact on the action and the impact the action will have on them. This information is used to assess how the interests of those stakeholders should be addressed in a project plan, policy, program, or other action.
State Sanitation Strategy
State Sanitation Strategy Synonyms: SSS, State Sanitation Strategies
Abbreviation: SSS

State Urban Sanitation Strategies
The State Sanitation Strategy is framed looking at the requirements of urban state, emerging out from situational analysis and also as per the requirements of NUSP through extensive consultations with all the stakeholders. Synonyms: SUSS
Abbreviation: SUSS

Steam Engine
A steam engine is a heat engine that performs mechanical work using steam as its working fluid.
STEP Local Governments in Urban Sustainable Sanitation and Water Management
STEP Local Governments in Urban Sustainable Sanitation and Water Management
STEP SSWM in Humanitarian Crises
STEP SSWM in Humanitarian Crises Synonyms: SSWM in Humanitarian Crises
Stored Urine
Stored Urine is Urine that has been hydrolysed naturally over time, i.e., the urea has been converted by enzymes into ammonia and bicarbonate. Stored Urine has a pH of approximately 9. Most pathogens cannot survive at this pH. After 6 months of storage, the risk of pathogen transmission is considerably reduced.
Stormwater is the general term for the rainfall runoff collected from roofs, roads and other surfaces before flowing towards low-lying land. It is the portion of rainfall that does not infiltrate into the soil. Synonyms: Rainfall Run-off, Rainfall Runoff
Stormwater and Reclaimed Water Reuse
Collected stormwater or reclaimed water can be reused for groundwater recharge, agriculture or landscaping.

Stormwater Management
The overall culmination of techniques used to reduce surface run-off from causing flooding and dispersing pollutants. Stormwater management consists in detaining, retaining, or providing a discharge point for stormwater to be reused or infiltrated into the groundwater. It should best preserve or mimic the natural hydrologic cycle and fit within the capacity of existing infrastructure.
Strategic Finance Planning
SFP brings planning and financing – which are typically done separately – onto convergent tracks, so that spending ambitions are more compatible with available financial resources. Conversely, financing strategies can be tailored to what is actually needed, which improves the prospects of getting funding.”
Abbreviation: SFP
A strategy is a planning framework aimed at achieving a vision.

Stream Erosion
Valley or stream erosion occurs with continued water flow along a linear feature. The erosion is both downward, deepening the valley, and head ward, extending the valley into the hillside. In the earliest stage of stream erosion, the erosive activity is dominantly vertical, the valleys have a typical V cross-section and the stream gradient is relatively steep. When some base level is reached, the erosive activity switches to lateral erosion, which widens the valley floor and creates a narrow floodplain. The stream gradient becomes nearly flat, and lateral deposition of sediments becomes important as the stream meanders across the valley floor. In all stages of stream erosion, by far the most erosion occurs during times of flood, when more and faster-moving water is available to carry a larger sediment load. In such processes, it is not the water alone that erodes: suspended abrasive particles, pebbles and boulders can also act erosively as they traverse a surface. Synonyms: Valley Erosion
Struvite is the common name for magnesium ammonium phosphate hexahydrate (short M-A-P), a slow-release fertiliser which can be produced from urine. Synonyms: M-A-P, Magnesium Ammonium Phosphate Hexahydrate
Abbreviation: M-A-P

Struvite Precipitation
The process of crystallizing magnesium, ammonium and phosphate such that they are removed from solution.

Struvite Reactor
A Struvite reactor is a mixing chamber into which a waste stream (high in phosphate and ammonium) is reacted with magnesium. The reactor allows for the subsequent separation of the precipitated struvite from the solution.

Subsurface Groundwater Recharge
Subsurface groundwater recharge conveys water directly into an aquifer without the filtration or oxidation that occurs when water percolates naturally through an unsaturated zone. Synonyms: Artificial Subsurface Groundwater Recharge
Subsurface Irrigation
Subsurface drip irrigation is a variation of the conventional surface drip irrigation. The laterals are buried in a depth below the soil surface depending mostly on the tillage practices and the crop to be irrigated. It is using water more efficiently than traditional irrigation techniques like surface irrigation by minimising evaporation. Synonyms: Subsurface Drip Irrigation
The production of a partial vacuum by the removal of air in order to force fluid into a vacant space or procure adhesion.

A historical term for greywater.
The liquid lying above a solid residue after settling, sedimentation, or other processes.

The superstructure of a toilet is the name given to the housing construction around a toilet that provides privacy to the user and protection from rain, wind and animals to the toilet. Superstructures can be constructed in any material, they may be permanent (e.g. concrete or bricks) or mobile (e.g. bamboo or cloth).
Surface Disposal and Storage
Surface disposal refers to the stockpiling of sludge, faeces or other materials that cannot be used elsewhere. Once the material has been taken to a surface disposal site, it is not used later. Storage refers to temporary stockpiling. It can be done when there is no immediate need for the material and a future use is anticipated, or when further hygienization and drying is desired before application.
Surface Groundwater Recharge
Artificial surface groundwater recharge refers to different groundwater recharge techniques that release effluent from above the ground into the groundwater aquifer via soil percolation. Synonyms: Artificial Surface Groundwater Recharge

Surface Irrigation
Surface irrigation is an umbrella term for irrigation methods (the three most common methods are: basin, border and furrow) in which water is distributed by gravity over the surface of a field.
Surface Water
A natural or man-made water body that appears on the surface, such as a stream, river, lake, pond, or reservoir. Surface water, unlike groundwater is generally of bad quality and need treatment before human consumption because it accumulates pathogens, metals, nutrients and chemicals as it flows across contaminated surfaces. Synonyms: Surface water sources
Organic compounds with a hydrophilic (attracted by water) head and a hydrophobic (repelled by water) end. Surfactants reduce the surface tension of water by adsorbing at the air-water interface. They also reduce the interfacial tension between oil and water by adsorbing at the liquid-liquid interface. Surfactants are the main components of cleaning products.

Something that is sustainable 'meets the needs of the present generation without compromising the ability of future generations to meet their own needs' (Brundtland Commission, 1987).

Sustainable High Rate Ammonium Removal Over Nitrate
The SHARON-Anammox process is run in two reactors in series. In the first aerobic reactor about 50 % of ammonium is partially nitrified to nitrite. The produced nitrite is in turn reduced to nitrogen gas through the Anammox process in a second anaerobic reactor in biochemical reaction, which also uses the remaining ammonium. Synonyms: SHARON
Sustainable Land Management
Sustainable Land Management (SLM) refers to the use of renewable land resources (soils, water, plants, and animals) for the production of goods – to meet changing human needs – while at the same time protecting the long-term productive potential of these resources. The main concern of SLM is not to preserve nature in a pristine state, but to coexist with nature in a sustainable manner so that the productive, physiological, cultural and ecological functions of natural resources are maintained for the benefit of society. SLM tries to harmonise the complementary but often conflicting goals of production and environmental protection.
Abbreviation: SLM
Sustainable Sanitation
The main objective of a sanitation system is to protect and promote human health by providing a clean environment and breaking the cycle of disease. In order to be sustainable, a sanitation system has to be not only economically viable, socially acceptable, and technically and institutionally appropriate, it should also protect the environment and the natural resources.
Sustainable Sanitation Alliance
The Sustainable Sanitation Alliance (SuSanA) is an informal network of organisations who share a common vision on sustainable sanitation. SuSanA came into existence in early 2007 and works as a coordination platform, working platform, sounding board, contributor to the policy dialogue on sustainable sanitation and as a “catalyst”. Synonyms: SuSanA
Abbreviation: SuSanA
Sustainable Sanitation and Health Development Project
Different departments/units of Xavier University have united under the “Sustainable Sanitation and Health Development Project”, which is being carried out in Barangay Lumbia, since 2011. It is also called the (XU) Convergence Project. Synonyms: Convergence Project, XU Convergence Project

Sustainable Sanitation and Water Management
Sustainable Sanitation and Water Management
Abbreviation: SSWM

Sustainable Sanitation Center (Xavier University)
The SuSan Center is a college-based center of the XU Jose P. Rizal School of Medicine under the Research and Social Outreach cluster of Xavier University, working on sustainable sanitation solutions in the Philippines, mainly Northern Mindanao. Synonyms: SuSan Center
Abbreviation: SuSan Center
Sustainable Sanitation Center
Intimate living together of two organisms (called symbionts) of different species, for mutual or one-sided benefit. A good example of mutually beneficial symbiosis is the clownfish and the sea anemone. The clownfish can come in contact with the stinging tentacles of the sea anemone and not be harmed by them. At the same time, it receives protection from its enemies. The clownfish feeds the anemone by gathering nutrients and also leaving nutritional waste on the tentacles.
System Template
System Template
System Template
A system template defines a suite of compatible technology combinations from which a sanitation system can be designed.