Or what's what in sewage treatment
Activation
also activation tank, part of activation treatment plant, working with activated sludge. This is where the main part of the cleaning takes place.
Activation treatment plant
treatment plant using activated sludge.
Activated mud
suspension of microorganisms, usually in the form of flakes. A large part is made up of bacteria, which are responsible for water purification – oxidation of organic substances to carbon dioxide and water, oxidation, ammonia to nitrates, reduction of nitrates to nitrogen gas, and a little accumulation of phosphorus. There are also higher organisms in the activated sludge, typically ciliates, but also rotifers, worms and the like, which reduce the amount of sludge.
Alkalinity – KNK4.5
Indicates how much acid can be added before the pH drops to 4.5. This can be a key parameter if, for example, a treatment plant has problems with nitrification.
Ammonia nitrogen
form of nitrogen with nitrogen oxidation number -III. It is a mixture - free ammonia NH3 or ammonium cation NH4+ are in different proportions mainly according to the pH of the water. The concentration of ammonia nitrogen can be limited at the effluent from the WWTP. Ammonia is produced by the decomposition of urea, which can already take place in the sewage system. Ammonia is toxic to fish and has a characteristic odor. It is removed by nitrification.
Biodisk, biodisk treatment plant
Biological reactor using a culture of microorganisms attached to the surface of a cylinder. It is periodically dipped into the water by turning the cylinder and pushed out of the water, the larger part is exposed to the air. When immersed in water, pollution diffuses into the biofilm, and when it emerges in the air, oxygen, which the bacteria need to remove the pollution.
Biofilm
relatively thin (approx. 1-2 mm) layer of biomass attached to the substrate. This biomass consists of similar microorganisms as activated sludge and performs the same function. The main component is bacteria, higher organisms are also present
Biofilter
biofilm rector. Typically, this is a cylindrical tank filled with a large surface area. The biofilter uses a chimney effect, which ensures air flow between the filling. The filling is sprinkled with wastewater from above. It flows in a thin layer over the surface of the filling, which is overgrown with biofilm. Through the flow through the filling, pollution is removed from the water by the biofilm.
BSK5
biochemical oxygen consumption. It expresses how much oxygen must be added to the water in order for the microorganisms contained in the water to decompose organic pollution into carbon dioxide. An index of 5 means that the test lasts 5 days. It is expressed in oxygen equivalents, as mg of oxygen per liter of water.
Denitrification
the process of reducing nitrates to nitrogen gas. For denitrification, nitrates, denitrifying bacteria (that's up to 80% of all activated sludge bacteria) and organic substances need to be present in the water. Conversely, the presence of oxygen is undesirable.
Setter, setter tank
tank or installation in which sedimentation (settling) of activated sludge takes place. Through this sedimentation, the sludge is separated from the purified water. The water overflows over the edge or is drained using a perforated pipe. Sludge settles in the lower part and is pumped back to the activation tank.
Equivalent population
unit used to quantify pollution. One "EO" corresponds to 60 g BOD5/day. If you have a treatment plant for 6 EO, it should be able to handle 360g of BOD5 per day.
Fosfor
biogenic element, causes eutrophication of waters. It is removed from wastewater in excess sludge, but better efficiency is achieved by its precipitation with ferrous, ferrous, or aluminum salts.
CHSKCr
chemical oxygen consumption determined by the dichromate method – non-specific determination of organic substances in water that can be oxidized using dichromate (there is also a method with permanganate, but it is used for drinking water). It expresses how much "oxygen" (actually it is the transfer of electrons from the carbon of an organic substance to a chromium atom) must be added to the water in order to convert the organic substances contained in the water into carbon dioxide. It indicates how much organic matter is present in the water. It is expressed in oxygen equivalents as mg of oxygen per liter of water.
Mammoth
pneumatic pump. A very simple pump where air is supplied to the lower part of the submerged pipe. Due to the upward flow of bubbles and the lower density of the water-air mixture compared to water, this mixture is transported upwards. It is usually necessary to supply 1 liter of air to exhaust 1 liter of water. But it depends on the transport height, the dimensions of the mammoth, the length of the submerged part, etc.
Membrane treatment plant, MBR – membrane biological reactor
It is a modification of the activation treatment plant, where membranes are used instead of separation in the settling tank or built-in. Cleaned water is pumped out through these membranes. These treatment plants are characterized by top effluent quality, lower activation volume requirements, higher intensity of biological processes, higher maintenance requirements and higher operating costs.
Undissolved solids
Substances that are captured when filtering water through a filter with a defined pore size. The presence of suspended solids is characterized by turbidity or "cuckiness" in water. Their concentration in the effluent from the treatment plant can be increased by escaping activated sludge.
Nitrification
oxidation process of ammonia (ammonia) to nitrates. A key process in the removal of nitrogenous pollution from wastewater (in domestic wastewater, ammoniacal nitrogen and organically bound nitrogen, which in turn decomposes into ammonia, are nitrogen compounds). Nitrification is carried out by nitrifying bacteria that need a sludge age of 14 days or more. Nitrification consumes alkalinity and can lower pH. Nitrification requires the presence of nitrifying bacteria and oxygen.
Organotrophic bacteria
Bacteria using organic matter as a source of electrons. As a rule, they are also chemotrophic, i.e. they obtain energy through the chemical oxidation of (organic) substances and heterotrophic, i.e. they must take organic substances for the construction of their bodies with food.
SBR – sequencing batch reactor
treatment plant working with activated sludge, the individual phases of which - the cleaning process itself, the separation of sludge and purified water, and the outflow of water - are not divided into different technological elements or objects, but in time. All stages of the process take place in the same tank - first it is filled with wastewater, then the reaction itself takes place, at this stage the tank is aerated. Then aeration is switched off and sedimentation takes place. The cleaned water is then pumped out. Part of the sludge is left in the tank for the next cycle, which begins with the addition of wastewater.
"Sediment", V30
parameter that indicates the volume occupied by the activated sludge in the measuring vessel after 30 minutes of sedimentation. It is given in ml of sludge/l. The determination is made by allowing the sludge in the activation tank to be well mixed (turning on the aeration if it is currently turned off), taking 1 l of the sample and pouring it into a measuring cup. After 30 minutes, read how many ml are occupied by the settled sludge (the rest at the top should be clear water).
Septic
non-aerated tank where sedimentation (settling) of suspended solids from wastewater and their partial biological reduction takes place. The biological processes that take place here are usually anaerobic - that is, they take place without the presence of oxygen. The products are usually methane and carbon dioxide, possibly also hydrogen sulfide. A septic tank normally has multiple chambers separated by partitions to prevent trapped substances from leaching out and to ensure even water flow.
Sludge age
activation treatment plants must be de-sludged regularly, and the age of the sludge can be calculated from the amount of de-sludged sludge, the sludge leaked through the drain and the sludge stock. Sludge age (in days) is equal to the amount of sludge in the treatment plant (in kg) divided by the sum of the amount of undissolved substances in the effluent and the removed excess sludge (both in kg/d). The age of sludge can also be determined based on microscopic observation. Sludge age is a key parameter describing the quality of activated sludge. Young sludge is dominated by organotrophic bacteria. As age increases, slow-growing bacteria such as nitrifying bacteria also appear, as well as higher populations. First ciliates, then rotifers, helminths and even water mites. Sludge with too little age does not form flakes, too old sludge can crumble. The optimal age is 10 (14 if we remove ammonia) to 30 days.
Filamentous bacteria
Bacteria that grow in the form of filaments. Some small amount is desirable in activated sludge. Overpopulation causes foaming and activated sludge separation problems in the settling tank.