a | b | c | d | e | f | g | h | i | j | k | l | m | n | o | p | q | r | s | t | u | v | w | x | y | z | 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9
Click one of the letters above to advance the page to terms beginning with that letter.
A kind of high-pressure membranefiltration process in which particles which are in the range of 1 to 10 nanometres are removed. Such particles are for instance ions of heavy metals. To remove all soluble particles, one would need an even finer process (i.e. reverse osmosis).
Natural organic matter is broken down organic matter that comes from plants and animals in the environment. Organic matter is a collective term, assigned to the realm of all of this broken down organic matter. Basic structures are created from cellulose, tannin, cutin, and lignin, along with other various proteins, lipids, and sugars. It is very important in the movement of nutrients in the environment and plays a role in water retention on the surface of the planet. Synonyms: NOM
A negative externality is a term used in economic theory. It applies, when the cost a consumer pays is smaller than the social costs of the product. The external costs are then passed on to society. A common example for a negative externality is pollution.
Nephelometric Turbidity Unit
The Nephelometric Turbidity Unit is used in water treatment in order to describe the turbidity of a liquid and is measured with a calibrated nephelometer, an instrument for measuring the size and concentration of particles suspended in a liquid or gas by means of the ligh it scatters. Synonyms: NTU
Ready source of information for decision makers and individuals involved in setting up municipal wastewater systems and concepts for management of excreta in communities (developed for West Africa). The guide, offered as CD-Rom, as a link on the internet (www.netssaftutorial.com) and in a printed version, illustrates a participatory approach to sanitation planning, dealing with the complex stakeholders concerns when deciding and implementing a sanitation system. It takes the user through a seven-step-approach, each of them with pre-selected questions and answers, case studies, links for further information and tools to facilitate the adoption of participatory sanitation planning in localities in West Africa. Synonyms: NETSSAF
Nitrification is an aerobic process carried out by a series of bacterial population that sequentially oxidize ammonium (NH4+) and organic nitrogen to nitrate (NO3-) with intermediate formation of nitrite (NO2-). The first step of nitrification is carried out by bacteria called nitrosomonas : 2NH4+ + 3O2 -> 2NO2- + 4H+ + 2H2O. The second step is carried out by nitrobacter bacteria: 2NO2-+O2 -> 2NO3-. The two steps can also be described in a single reaction: NH4+ + 2O2 -> NO3- + H2O + H+. Once nitrate has formed, the wastewater can undergo a denitrification process in order to reduce nitrate to nitrogen gas, that is released into the atmosphere. Since complete nitrification is a sequential reaction treatment process, systems must be designed to provide an environment suitable for the growth of both groups of nitrifying bacteria.
When organic material is applied to the soil, the decomposing microbes multiply quickly. For growth, they need nutrients, especially nitrogen, like plants do. If the applied plant material does not contain sufficient nitrogen, the micro-organisms will take it from the soil. This process is called nitrogen immobilisation, as the nitrogen is fixed temporarily in the microbes and released only after some time. During this time, the microbes compete with the plants for nitrogen and the crop may suffer from malnutrition. Nitrogen-immobilisation can occur when the following materials are applied: straw or grain husks, material containing wood (e.g. twigs, saw dust), half rotten compost. To prevent nitrogen-immobilisation. Old or rough plant materials should be applied to the soil at least 2 months before planting or sowing the main crop. Synonyms: N-Immobilisation
Pre-treated greywater is applied intermittently to the surface of a filter media, percolates through an unsaturated filter zone where physical, biological and chemical processes treat the water. The treated greywater is collected in a drainage network or infiltrates the underlying soil. Synonyms: infiltration beds, intermittent sand filters, percolation beds, subsurface biofilters, unplanted filter
Nonpoint source pollution generally results from land runoff, precipitation, atmospheric deposition, drainage, seepage or hydrologic modification. The term "nonpoint source" refers to any source of water pollution that does not meet the legal definition of "point source". Synonyms: Nonpoint Pollution, Diffuse Pollution
N, P, and K are the periodic chart symbols for Nitrogen, Phosphorus and Potassium. These three elements are the primary macronutrients for plant growth and are the main elements compound fertilisers will contain. Secondary macronutrients are Calcium (Ca), Sulfur (S) and Magnesium (Mg). Synonyms: N-P-K, Nitrogen, Phosphorus and Potassium, Nitrogen, Phosphorus and Potassium containing fertilizer, NPK