Sanitation Products

Products

Products are materials that are also called ‘wastes’ or ‘resources’. Some Products are generated directly by humans (e.g. urine and faeces), others are required in the functioning of Technologies (e.g. flush water to move excreta through sewers) and some are generated as a function or storage or treatment (e.g. faecal sludge).

For the design of a robust sanitation system, it is necessary to define all of the Products that are flowing into (Inputs) and out (Outputs) of each of the sanitation Technologies in the system. The Products referenced within this text are described below.

Pre-Treatment Products

Pre-Treatment Products are materials separated from Blackwater, Brownwater, Greywater or Sludge in preliminary treatment units, such as screens, grease traps or grit chambers (see PRE, p. 100). Substances like fats, oil, grease, and various solids (e.g. sand, fibres and trash), can impair transport and/or treatment efficiency through clogging and wear. Therefore, early removal of these substances is crucial for the durability of a sanitation system.

Urine

Urine is the liquid waste produced by the body to rid itself of urea and other waste Products. In this context, the urine Product refers to pure urine that is not mixed with faeces or water. Depending on diet, human urine collected during one year (ca. 500 L) contains 2–4 kg nitrogen. With the exception of some rare cases, urine is sterile when it leaves the body.

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.

Faeces

Faeces refers to (semi-solid) excrement without urine or water. Each person produces approximately 50 L per year of faecal matter. Of the total nutrients excreted, faeces contain about 10% N, 30% P, 12% K and have 107–109 faecal coliforms /100 mL.

Anal Cleansing Water

Anal cleansing water is water collected after it has been used to cleanse oneself after defecating and/or urinating. It is only the water generated by the user for anal cleansing and does not include dry materials. The volume of water collected during anal cleansing ranges from 0.5 L to 3 L per cleaning.

Dry Cleansing Materials

Solid materials used to cleanse oneself after defecating and/or urinating (e.g., paper, leaves, corncobs, rags or stones). Depending on the system, Dry Cleansing Materials may be collected and separately disposed of. Although extremely important, a separate product name for menstrual hygiene products like sanitary napkins and tampons is not included in this Compendium. In general (though not always), they should be treated along with the solid waste generated in the household.

Stormwater

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.

Greywater

Greywater is the total volume of water generated from washing food, clothes and dishware as well as from bathing. It may contain traces of excreta and therefore will also contain pathogens and excreta. Greywater accounts for approximately 60% of the wastewater produced in households with flush toilets. It contains few pathogens and its flow of nitrogen is only 10–20% of that in blackwater.

Flushwater

Flushwater is the water that is used to transport excreta from the User Interface to the next technology. Freshwater, rainwater, recycled greywater, or any combination of the three can be used as a Flushwater source.

Organics

Organics refers here to biodegradable organic material that could also be called biomass or green organic waste. Although the other Products in this Compendium contain organics, this term refers to undigested plant material. Organics must be added to some technologies in order for them to function properly (e.g. composting chambers). Organic degradable material can include but is not limited to leaves, grass and market waste.

Blackwater

Blackwater is the mixture of urine, faeces and flushwater along with anal cleansing water (if anal cleansing is practiced) and/or dry cleansing material (e.g. toilet paper). Blackwater has all of the pathogens of faeces and all of the nutrients of urine, but diluted in flushwater.

Sludge

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 (see Sector Development Tools, p. 9). 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.

Excreta

Excreta consists of urine and faeces that is not mixed with any flushing water. Excreta is small in volume, but concentrated in nutrients and pathogens. Depending on the quality of the faeces it is solid, soft or runny.

Brownwater

Brownwater consists of faeces and flushwater (although in actual practice there is always some urine, as only 70–85% of the urine is diverted). Brownwater is generated by urine-diverting flush toilets and therefore, the volume depends on the volume of the flushwater used. The pathogen and nutrient load of faeces is not reduced, only diluted by the flushwater.

Dried faeces

Dried faeces are faeces that have been dehydrated at high temperatures (and high pH) until they become a dry, sanitized powder. Very little degradation occurs during dehydration and this means that the dried faeces are still rich in organic material. Faeces will reduce in volume by around 75%. There is a small risk that some organisms can be reactivated in the right environments.

Effluent

Effluent is the general term for liquid that has undergone some level of treatment and/or separation from solids. It originates at either a Collection and Storage/Treatment or a (Semi-) Centralized Treatment Technology. Depending on the type of treatment, the effluent may be completely sanitized or may require further treatment before it can be used or disposed of.

Biomass

Biomass refers to plants or animals cultivated using the water and/or nutrients flowing through a sanitation system. The term Biomass may include fish, insects, vegetables, fruit, forage or other beneficial crops that can be utilized for food, feed, fibre and fuel production.

Pit Humus

Pit Humus is the term used to describe the nutrient- rich, hygienically improved, humic material that is generated in double pit technologies (S.4-S.6) through dewatering and degradation. This earth-like product is also referred to as EcoHumus, a term conceived by Peter Morgan in Zimbabwe. The various natural decomposition processes taking place in alternating pits can be both aerobic and anaerobic in nature, depending on the technology and operating conditions. The main difference between Pit Humus and Compost is that the degradation processes are passive and are not subjected to a controlled oxygen supply, C:N ratio, humidity and temperature. Therefore, the rate of pathogen reduction is generally slower and the quality of the product, including its nutrient and organic matter content, can vary considerably. Pit Humus can look very similar to Compost and have good soil conditioning properties, although pathogens may still be present.

Biogas

Biogas is the common name for the mixture of gases released from anaerobic digestion. Typically biogas is comprised of methane (50–75%), carbon dioxide (25–50%) and varying quantities of nitrogen, hydrogen sulphide, water and other components.

References

• Elizabeth Tilley et.al (2008). Compendium of Sanitation Systems and Technologies (low res version). Department of Water and Sanitation in Development Countries (Sandec) at the Swiss Federal Institute of Aquatic Science and Technology (Eawag).