A company or agency owned or controlled wholly or partly by the government. Synonyms: parastatal
An organism that lives on or in another organism (its host). Parasites exist in a huge variety, including animals, plants, and microorganisms. Ectoparasites live on the surface of the host (e.g., ticks, mites, lice, fleas, and many insects infesting plants). Endoparasites live in the gut or tissues (e.g., many kinds of worm), and cause varying degrees of damage or disease to the host. Parasite comes from the Greek words parasitos (eating at another's table), which is composed of para (alongside) and sitos (food).
The action of taking part in activities and projects. The participation of different stakeholders in water and sanitation project is crucial for several reasons: By a broad participation, different points of view can be incorporated, leading to projects and solutions that are more widely accepted. Furthermore, those participating in a project also benefit by become aware of problems and respective solutions. The process of participation also fosters mutual learning.

Participatory Hygiene and Sanitation Transformation
This approach is a participatory learning methodology that seeks to help communities improve hygiene behaviours, reduce diarrhoeal disease and encourage effective community management of water and sanitation services. It aims at empowering communities to improve hygiene behaviours, preventing diarrhoeal diseases, and encouraging community-management of water and sanitation facilities. It uses a participatory approach to community learning and planning that follows a seven step framework. The approach was introduced by the World Health Organisation. Synonyms: PHAST
Participatory Monitoring and Evaluation
Participatory Monitoring and Evaluation
Abbreviation: PM&E

Participatory Planning Tools
Participatory planning tools are instruments and approaches which rely on the participation on different stakeholders in the design and planning of (water and sanitation) projects. They enable project leaders to consider and respect different stakeholder’s opinions, needs and priorities. Participatory planning tools also help project managers to include the knowledge of different stakeholders into the planning of projects.
Participatory Rural Appraisal
Participatory rural appraisal (PRA) is an approach used by non-governmental organisations (NGOs) and other agencies involved in international development. The approach aims to incorporate the knowledge and opinions of rural people in the planning and management of development projects and programmes. It includes various techniques such as participatory mapping, transect walks, interviews, visualisation etc. Synonyms: PRA
Abbreviation: PRA
Pasteurisation is a process of heating a food, typically liquid, to a specific temperature for a definite length of time. This process leads to the partial sterilisation of this food through reducing heat-sensitive vegetative cells to an extent that it is not harmful for human consumption and without major changes in the chemistry of the food. Unlike sterilisation, pasteurisation is not intended to kill all microorganisms in the food. Instead pasteurisation aims to reduce the number of viable pathogens so they are unlikely to cause disease. Pasteurisation is mostly known in connection with milk and is named after French microbiologist Louis Pasteur. Synonyms: Pasteurization
Abbreviation: Pasteurization
A microorganism or other agent that causes disease.
The movement of liquid through a filtering medium with the force of gravity.
Perfectly Competitive Market
In economic theory, perfect competition exists in a market with a homogenous product, freedom of entry and a large number of buyers and sellers who cannot individually affect the market price.

Perforated Plastic Sleeves
A perforated plastic sleeves are placed vertically in the ground next to the plant. Because of its density the water is only released slowly into the ground to reach the roots. Synonyms: Perforated Plastic Sleeve

The clear fluid that passes through the membrane in a membrane filtration process.
Permits are formal authorisations, licenses, or equivalent control documents issued by a governmental agency (national, regional or local) to implement the requirements of an environmental regulation (e.g. a permit to operate a wastewater treatment plant or to operate a facility that may generate harmful emissions).

Restriction of permeation of macromolecules across a glomerular capillary wall on the basis of molecular size, charge, and physical configuration. Synonyms: Perm-selective
Persian wheel
Device to lift water, particularly for agricultural purposes. It consists of an endless chain of buckets, typically with an individual capacity of 8-15 litres mounted on a drum and submerged in water to the required depth. The drum is connected to a toothed wheel held in a vertical plane by a long shaft usually kept below ground level. The vertical toothed wheel is geared with a large toothed horizontal wheel connected to a horizontal beam. This beam is yoked to a pair of animals. The animals move in a circle to turn the drum and raise the water. Water is released when the bucket reaches the top. The average discharge rate from a Persian wheel is about 160-170 litres/min from a depth of 9m with one pair of bullocks. The Persian wheel can be used to raise water from a depth of up to 20 m but its efficiency is reduced at depths below 7.5 metres. Synonyms: Raha
Persistent Organic Pollutants
POPs are hazardous chemicals which have distinctive and very dangerous properties. POPs persist in the environment for a long time; they can travel long distances through the air or sea; and they are ‘bioaccumulative’. This means that they build up in living organisms, mainly in fatty tissue, and their concentration increases as they rise through each level of a food chain – and so the highest concentrations are normally found in the top predators like humans and polar-bears. POPs are highly toxic and levels found in some people and animals are above those known to cause health and biological effects. Many of these chemicals are ‘endocrine disruptors’ and act like hormones in our bodies; some of them are carcinogenic; the others are mutagenic and affect DNA or are teratogenic and can cause birth defects. A very ‘famous’ POP which is still in use is the pesticide DDT. Synonyms: POP, POPs, POP’s
Abbreviation: POP, POPs, POP’s
Selected POPs Waste “Hot Spots” around the World
Person Equivalent
Person Equivalent Synonyms: PE
PET is the common name for Polyethylene terephthalate. It is a clear plastic that can be recycled. Synonyms: Polyethylene Terephthalate
The measure of acidity or alkalinity of a substance. A pH value below 7 indicates that it is acidic, a pH value above 7 indicates that it is basic (alkaline). It can be measured by a pH meter, titration, or indicator (e.g. litmus) stripes.
Phosphorus is a chemical element. It is part of the backbone of DNA and thus contained in all animals and plants. It is one of the three primary macronutrients for plants. For agriculture, phosphorus is essential and it is, together with Nitrogen and Potassium, one of the three main constituents of fertilising products. Phosphorus for fertiliser production is mined from phosphorus rock. The main reserves of phosphorus rock lie in Morocco, West Africa and China. Scientists predict that in about 60 to 130 years peak phosphorus is achieved (in analogy to the peak oil). That means that the available resources of phosphorus will decrease, as only resource of phosphorus which are difficult to exploit will remain. As phosphorus which has been mined will be refund in food, it will also be refund in organic wastes and excreta. One alternative phosphorus resource is thus the reuse of treated and sanitised organic wastes and excreta as fertiliser. Synonyms: P
Abbreviation: P

The term represents a set of processes involving catalytic reactions proceeding under the effect of light.
The splitting or decomposition of a chemical compound by means of light, energy or photons.
Photosynthesis is a process used by plants and other autotrophic organisms to convert light energy, normally from the sun, into chemical energy that can be used to fuel the organisms' activities. Most plants perform photosynthesis and thereby maintain atmospheric oxygen levels and supply most energy necessary for life on earth
Phytoplankton is plankton consisting of microscopic plants. It is the autotrophic components of the plankton community. Most phytoplankton are too small to be individually seen with the unaided eye. However, when present in high enough numbers, they may appear as a green discoloration of the water due to the presence of chlorophyll within their cells.
Phytoremediation describes the process of mitigating pollutant concentrations in contaminated soils, water, or air, with plants able to contain, degrade, or eliminate metals, pesticides, solvents, explosives, crude oil and its derivatives, and various other contaminants from the media that contain them. The contaminants can be removed together with the plant for treatment or disposal elsewhere.

Pit Composting Toilet
Composting toilets using a pit (above the ground) as a composting chamber. Typical pit composting toilets are the arborloo or the fossa alterna.

Pit Humus
Pit Humus is the term used to describe the nutrient-rich, hygienically improved, humic material that is generated in double pit technologies (Double Ventilated Improved Pit (VIP), Fossa Alterna, Twin Pits for Pour Flush). 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. Synonyms: Ecohumus, Humanure
Pit Latrine
The single pit latrine is one of the most widely, cheapest and easiest used sanitation technologies. It is made out of a latrine superstructure, a slab and a pit. Excreta, along with anal cleansing materials (water/solids) are deposited in the pit. To avoid people falling in the pit and increase convenience and reduce odour, a slab with a hole is used to cover the pit. Lining the pit prevents it from collapsing and provides support to the superstructure but the underground of the latrine should be water pervious. When the latrine is filled up, it needs to be emptied or closed and relocated. By constructing twin pits (the double pit latrine), it should be possible to dig out a filled pit, after it has stood for a year, without any objectionable smell, whilst the other pit is in use. Pit latrines are part of the improved sanitation options. However, odour and fly nuisance are very common and due to soil infiltration there is danger of groundwater contamination, especially in densely populated areas. Synonyms: Pit toilet, Single Pit
Pitcher Irrigation
A porous clay pot is placed in the ground. The water can seep out slowly to reach the roots.

Plankton is the small and microscopic organisms drifting or floating in the sea or fresh water, consisting chiefly of diatoms, protozoans, small crustaceans, and the eggs and larval stages of larger animals. Many animals are adapted to feed on plankton, esp. by filtering the water.

Planning with the Community
Planning with the community presents various approaches and tools that facilitate participatory planning on a community level.

Planted Drying Beds
A planted drying bed is similar to an Unplanted Drying Bed, but has the added benefit of transpiration and enhanced sludge treatment due to the plants. The key improvement of the planted bed over the unplanted bed is that the filters do not need to be desludged after each feeding/drying cycle. Fresh sludge can be directly applied onto the previous layer; the plants and their root systems maintain the porosity of the filter. The percolate or leachate needs to be collected and treated before reuse or disposal.
Planting Pits
Planting pits are used as a precipitation harvesting method preventing water runoff and thereby increasing infiltration and reducing soil erosion. Basically, holes are dug 50-100 cm apart from each other with a depth of 5-15 cm in order to prevent water runoff. Planting pits are most suitable on soil with low permeability, such as silt and clay. They are applicable for semi-arid areas for annual and perennial crops (such as sorghum, maize, sweet potato, bananas, etc.). One main advantage is their simple implementation and maintenance (ADB 2008).
Plug-flow Reactor
Also known as tubular-flow reactor. Plug-flow reactors are elongated reactors where the influent (e.g. wastewaters) enters on one side, and constantly moves with minimal longitudinal dispersion to the other side comparable with a train that passes a train station. Fluid particles pass through the tank and are discharged in the same sequence in which they enter. The particles retain their identity and remain in the tank for a time equal to the theoretical hydraulic retention time. Synonyms: PFR, Plug Flow Reactor, Tubular-flow Reactor
Point Source Pollution
The term "point source" means any discernible, confined and discrete conveyance, including but not limited to any pipe, ditch, channel, tunnel, conduit, well, discrete fissure, container, rolling stock, concentrated animal feeding operation, or vessel or other floating craft, from which pollutants are or may be discharged. This term does not include agricultural storm water discharges and return flows from irrigated agriculture. Synonyms: Pointsource Pollution, Point-source Pollution
In water supply, POE systems are used to treat all water entering into a building, usually as an additional purification of water from a centralised supply. Synonyms: POE, Point of Entry
Abbreviation: POE
Point-of-Use (POU) systems refer to the range of water treatment methods including filters (e.g. ceramic candle filters), chemicals (e.g. chlorine), and others (e.g. SODIS), which treat water at the point of consumption rather than at the source, as it is the case for many centralised water treatment and distribution systems. Point-of-use (POU) water treatment systems have been put forward in recent years as low-cost, scalable, and effective solutions to the significant challenge of providing potable drinking water in lower income settings. See also Household-level Drinking Water Treatment or HWTS. Synonyms: Point of Use, POU
Pollination is the process by which pollen is transferred in the reproduction of plants, thereby enabling fertilisation and sexual reproduction. 90% of pollination takes place with animal assistance, primarily insects such as bees and wasps and vertebrates such as birds and bats.
Polygeneration Plant
Polygeneration plants, also called trigeneration plants, are cogeneration plants that produce not only electricity but also heat and cold. Synonyms: Trigeneration Plant

Polyphosphate-accumulating Organism
Polyphosphate-accumulating organisms (PAOs) are a group of bacteria that, under certain conditions, facilitate the removal of large amounts of phosphorus from wastewater in a process called enhanced biological phosphorus removal (EBPR). PAOs accomplish this removal of phosphate by accumulating it within their cells as polyphosphate. Synonyms: PAO
Abbreviation: PAO
Population Equivalent
Population equivalent refers to the amount of oxygen-demanding substances (measured in BOD or BOD5) in wastewaters whose oxygen consumption during biodegradation equals the average oxygen demand of the wastewater produced by one person during one day. For practical calculations, it is assumed that one unit equals 54 grams of BOD per 24 hours. Synonyms: p.e., PE, People Equivalent
Abbreviation: PE
Glossary of Environment Statistics
Porous and Sectioned Pipes
Porous pipes are buried in a field. They are filled up with water and distribute it over the whole length of the field. Synonyms: Porous Pipes, Sectioned Pipes

Portland Cement
Portland cement is the most common type of cement in general use around the world because it is a basic ingredient of concrete, mortar, stucco and most non-specialty grout. Synonyms: Ordinary Portland Cement
Abbreviation: OPC
Portland Cement
Potassium is the name of the chemical element K. K in nature occurs only as ionic salt. As such, it is found dissolved in seawater, and as part of many minerals. Potassium ion is necessary for the function of all living cells, and is thus present in all plant and animal tissues. Together with phosphorus (P) and nitrogen (N) it is soften found in fertilising product as one of the three primary macronutrients for plants: NPK. Synonyms: K
Abbreviation: K
Pour Flush Toilet
A pour flush toilet is like a regular cistern flush toilet except that the water is poured in by the user, instead of coming from the cistern above. When the water supply is not continuous, any cistern flush toilet can become a pour flush toilet. Synonyms: Pour-Flush Toilet
Pre-treatment is the preliminary removal of wastewater or sludge constituents, such as oil, grease, and various solids (e.g., sand, fibres and trash). Built before a conveyance or treatment technology, pre-treatment units can retard the accumulation of solids and minimize subsequent blockages. They can also help reduce abrasion of mechanical parts and extend the life of the sanitation infrastructure. See also primary treatment.
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. 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.
Environment: any water that comes from the atmosphere: rainwater, stormwater, fog, dew, snow etc. OR Chemistry: when a solid substance is produced from a liquid during a chemical process

Precipitation Harvesting
Precipitation harvesting in SSWM refers to the controlled collection of precipitation (rain, fog, dew, snow, etc.) to complement water supply.

Preliminary Assessment of Current Status
Before starting a project, the current situation, including problems, has to be analysed to determine within which framework solution approaches have to be developed.

Presentation Skill
Independent of the business field or work context, possessing adequate skills in order to give a clear and comprehensive presentation is important and will be even more in future. Therefore, one should continuously work on how to give a good presentation to the audience in order to ensure the sustainability of the delivered message. Having a few presentation tips in mind helps to improve the presentation style.

Pressure Filter
Rapid sand filters can be constructed as pressure filters. They are used for water purification purposes and consist of closed vessels containing beds of sand or of other granular material through which water is forced under pressure. These filters are frequently used in certain industrial situations, and a number have been installed for public water supplies. As their initial cost may be high, especially when their component parts have to be imported, their principal use is in industrialised countries.
Slow Sand Filtration
Pressure System Unit
A prefabricated pressure sewer unit (normally made from plastic) is designed for outside placement. The pressure unit includes a grinding pump which is activated as soon as the stored wastewater reaches a pre-defined level. Synonyms: Pressure Sewer Unit, Pressure Unit

Pressurised Sewers
Pressurised sewers, or pressure sewers differ form conventional gravity collection systems, because they break down large solids in a grinder pumping station before they are transported through the collection system. The pressure sewer system consist of a series of centrifugal grinder pumps moving finely ground effluent and material along a network of sewers (generally small-diameter). The primary effluent is delivered to the dwelling tank by traditional gravity drainage methods before being ground. Their watertight design and the absence of manholes eliminate extraneous flows into the system. Thus, the systems are an effective solution where conventional systems are impractical such as rocky, hilly and/or water-charged terrain. Moreover, this system requires only shallow trenches and relatively small-diameter piping. Thus, it is also adapted to areas with housing density and where the terrain does not allow gravity flow.
Primary disinfection
The application of a disinfectant at the drinking water treatment plant, with a primary objective to achieve the necessary microbial inactivation.
Primary Treatment
The first major stage in wastewater treatment that removes solids and organic matter mostly by the process of sedimentation or flotation. Examples of primary treatment technologies include septic tanks, biogas settlers, etc. See also pre-treatment. Synonyms: Primary Wastewater Treatment
Process Water
Water used by industries and businesses to produce a product or affect a process is known as process water.

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. flushwater to move excreta through sewers) and some are generated as a function of storage or treatment (e.g. 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 of (outputs) each of the sanitation technologies in the system. The products referenced within this text are described below. Synonyms: Sanitation Products
Project Design
Project design includes an array of activities from generating ideas to planning how these ideas could become a realisable project.

A diverse group of unicellular eukaryotic organisms, including amoeba, ciliates, and flagellates. Some can be pathogenic and cause mild to severe illnesses.
Protracted Refugee Situation
Protracted Refugee Situation Synonyms: Prolonged Refugee Situation, Protracted Refugee Situation
Psychrophilic organisms are organisms that are most adapted to live in cold environments. Synonyms: Psychrophile
Public Health Engineering Department
Public Health Engineering Department Synonyms: PHED
Abbreviation: PHED

Public Health Hygiene Education
Public Health Hygiene Education Synonyms: PHHE
Abbreviation: PHHE

Public Private People Partnership
Public-Private-People Participation (PPPP/4Ps) is a people (end-users) oriented approach where all stakeholders including government, donor agencies, private sector and civil society work together. It includes the end-users' perspective into Public-Private Partnership (PPP). Synonyms: 4Ps, Public Private People Partnership
Abbreviation: PPPP
PUR is a commercially available water purification powder that contains both coagulants and disinfectants.

Pyrolysis is the process of the heating biomass, in the absence of oxygen, transforming to charcoal. The fewer oxygen is present during the process, the more black carbon is contained in the charcoal. Black carbon, due to its polycyclic aromatic structure, is chemically and microbiologically stable and persists in the environment over centuries.