Common professional names of water treatment (119-144)

(119) Metabolism. The exchange of substances and energy between the body and the external environment and the self-renewal of substances and energy in the body are called metabolism. Metabolism includes anabolism (assimilation) and catabolism (dissimilation).

(120) Flocs. Due to their genetic characteristics, some bacteria stick together in a certain arrangement and are surrounded by a common capsule to form a bacterial group of a certain shape, which is called a floc.

(121) Filamentous bacteria. It refers to a type of bacteria with a filamentous structure. It is the skeleton of the bacterial floc.

(122) Autotrophic bacteria. It refers to bacteria that use inorganic carbon sources as carbon sources.

(123) Heterotrophic bacteria. It refers to bacteria that use organic carbon sources as their carbon source.

(124) Anaerobic environment. In theory, anaerobic means no molecular oxygen and no nitrate nitrogen. But in reality, it is impossible to achieve. In engineering, DO < 0.2 is considered anaerobic.

(125) Aerobic environment. There is both dissolved oxygen and nitrate nitrogen. In engineering, DO>0.5 is considered aerobic.

(126) Hypoxic environment. It refers to the absence of molecular oxygen and nitrate nitrogen. In engineering, a DO range of 0.2~0.5 is considered hypoxia.

(127) Activated sludge process. It refers to a continuous sewage treatment method achieved through the adsorption, metabolism, and sludge water separation of microbial flocs.

(128) Biofilm method. It refers to the method of treating organic wastewater using microorganisms (biofilms) that adhere and grow on the surface of certain solid objects.

(129) Hydraulic retention time (HRT). It refers to the average residence time of the wastewater to be treated in the reactor, which is the average reaction time between the wastewater and the microorganisms in the bioreactor.

(130) Sludge retention age (SRT). It refers to the average residence time of microbial cells in the aeration tank. For the activated sludge process with reflux, the sludge age is the average time (in days) required for the entire aeration tank to renew the sludge once.

(131) Sludge settlement ratio. It refers to the volume ratio of the settled sludge to the mixed liquid of the activated sludge in the aeration tank, which is rapidly poured into a 1000ml measuring cylinder until it reaches the full scale. After settling for 30 minutes, the volume ratio of the settled sludge to the mixed liquid is the sludge settling ratio (%), also known as the sludge settling volume (SV30) expressed in mL/L. Because the sludge can generally reach or approach its maximum density after settling for 30 minutes, this time is commonly used as the standard time for measuring this indicator.

(132) Sludge concentration (MLSS). It refers to the weight of dry sludge contained in the sludge mixture in a 1-liter aeration tank.

(133) MLVSS. Concentration of volatile suspended solids in the mixed solution. It refers to the concentration of organic solid substances in the mixed liquid activated sludge.

(134) RSS. The sludge concentration of the returned sludge.

(135) SVI. The sludge volume index is an indicator for measuring the settling performance of activated sludge. The volume (in mL) occupied by 1g of dry sludge after 30 minutes of static settling of the mixed liquid in the aeration tank, i.e. SVI=sludge volume (mL) after 30 minutes of static settling of the mixed liquid/sludge dry weight (g), i.e. SVI=SV30/MLSS.

(136) Internal reflux ratio. It refers to the ratio of the reflux flow rate of nitration solution to the inflow flow rate, usually expressed as a percentage, with the symbol r.

(137) External reflux ratio, also known as sludge return ratio. It refers to the ratio of the flow rate of returned sludge to the inflow flow rate. Generally expressed as a percentage, with the symbol R.

(138) Vaccination. It refers to the process of adding activated sludge or granular sludge to a biochemical treatment system.

(139) Domestication. It refers to the transformation process of gradually developing mature fecal sewage activated sludge with the ability to treat specific industrial wastewater.

(140) Organic load; It refers to the amount of pollutants removed per unit mass of activated sludge in a unit time.

(141) Volume load. It refers to the weight of pollutants that can be removed per unit of aeration tank volume in a unit of time.

(142) Impact load. In the operation of sewage treatment, the sludge volume is generally maintained at a certain level, and the volume of reactors (aeration tanks, anaerobic reactors, etc.) will not change. However, if there is a significant change in the incoming water quality (COD surge or significant decrease), it will cause a significant change in sludge load and volumetric load, which will have an impact on sludge microorganisms, known as impact load.

(143) Oxidation-reduction potential (ORP). It refers to the measurement index of the oxidation-reduction ability of aqueous solutions, and its unit is mV.

(144) DO. It refers to the molecular oxygen dissolved in water, expressed in milligrams of oxygen per liter of water.