Glossary

ABC
DEF
GHI
JKL
MNO
PQR
STU
VWX
YZ

ABC

Words That Start With A

Act on Promotion of Recycling and Related Activities for Treatment of Cyclical Food Resources	The law requires food manufacturers and sellers to reduce and recycle food waste to promote the reduction and recycling of “food waste” such as material scraps generated from the food manufacturing process, unsold food, and leftovers. The law was established in 2000. Under the jurisdiction of the Ministry of Agriculture, Forestry and Fisheries and the Ministry of the Environment. The law requires food manufacturers, retailers, and catering establishments that produce 100 tons or more of food waste per year to promote recycling, control of the waste generation, and reduction of food waste.
Activated sludge	A treatment technology to remove organic matter by taking advantage of microorganisms in the sludge by dispersing “activated sludge” in which microorganisms are agglomerated under aerobic conditions in sewage. Excess sludge is removed from the septic tank and then treated.
Advanced treatment	A treatment more advanced than normal treatment. In the case of wastewater treatment, it refers to advanced treatment that goes beyond BOD removals, such as the removal of nitrogen, phosphorus, or staining substances.
Aeration	In sewage treatment, it is the application or agitation of air to provide oxygen necessary for microorganisms to break down organic matter. Bubbling.
Aeration tank	A facility, a tank, where activated sludge and sewage are mixed and aerated to allow microorganisms to decompose organic matter present in the sewage.
Aerobic	A condition requiring the presence of or dependent on the presence of oxygen. Aerobic bacteria (microorganisms that grow well in the presence of oxygen). The fermentation rate in this state is fast and odorless. [Related term] Anaerobic
Aerobic fermentation	The decomposition of organic matter by taking advantage of microorganisms active in the presence of air (oxygen). Since heat is generated during decomposition, composting and other methods utilize this heat to inactivate bacteria and parasite eggs. Advantage: No odor is generated due to the decomposition of organic matter into CO2 and H2O. Disadvantage: Because microorganisms grow actively, the amount of sludge such as activated sludge increases. [Related term] Anaerobic fermentation
Amines	Compounds in which a hydrogen atom of ammonia is substituted with a hydrocarbon residue R. There are three types of amines depending on the number of substituted hydrocarbon residues: primary amine, secondary amine, and tertiary amine. The malodorous substance trimethylamine [(CH3)3N] belongs to the aliphatic tertiary amine.
Ammonia	A typical malodorous substance having an urine and pungent odor. The chemical formula is NH3. It becomes a gas at room temperature and is well soluble in water. It is synthesized industrially from nitrogen (N2) and hydrogen (H2) and used as a raw material for chemical fertilizers, synthetic fibers, and dyes. Natural ammonia is generated by the decomposition and decay of living organisms and their excrement.
Anaerobic	A condition requiring the absence of or not dependent on the presence of oxygen. This condition is used when anaerobic sludge (microorganisms that can grow without oxygen) is digested or methane fermentation is carried out. Fermentation in this state progresses slowly and produces odors (such as hydrogen sulfide). [Related term] Aerobic
Anaerobic fermentation	This refers to the decomposition of high-molecular organics into low-molecular organic acids (acid fermentation) and further decomposition into methane gas, carbon dioxide, hydrogen, etc. (methane fermentation) by taking advantage of microorganisms such as bacteria that can grow even in areas with little or no oxygen. Methanogenic bacteria are involved in methane fermentation as with the decomposition of sedimentary organic matter in bottom sediments of lakes and inland bays, and anaerobic digestion of sewage sludge. [Related term: anaerobic digestion] Advantage: No aeration energy is required and less sludge is produced. Disadvantage: Low COD removal rate and long retention time. [Related term] Aerobic fermentation
Anchor bolt	A bolt for securing equipment or frame to a concrete foundation, etc. The bolt is inserted into the drilled hole and hammered in.
Anion	A negative ion. Anionic coagulant = negative ion coagulant [Related term] Cation, Nonion
Asbestos	Also known as asbestos, each fiber is a long, thin, natural mineral fiber so fine that it is invisible to the eye. It was mainly used as an insulation material but is no longer used because it is considered a respiratory health hazard when fine asbestos fibers (asbestos dust) are released into the air and inhaled with breathing.
Auto cut	A protective device that senses the heat and shuts off the power circuit when the operating current of an electric motor exceeds its rating and the windings generate abnormal heat. The device is used for electric motors with an output of 7.5 KW or less. The electrical circuit is automatically restored when the internal temperature of the motor, including its windings, drops.

Words That Start With B

Biochemical oxygen demand	The amount of oxygen demanded by microorganisms to break down the organic matter present in water. A typical gauge for measuring organic pollution in rivers. It is an indicator that utilizes the fact that the dirtier the water, the more oxygen is demanded by microorganisms. It is an important indicator to calculate the approximate amount of sludge from the amount of BOD in the influent entering the water treatment facility. High BOD levels can lead to a lack of dissolved oxygen. A foul odor is generated when the BOD value is 10 mg/L or higher. [Abbreviations] BOD(Biochemical Oxygen Demand)
Biofilm process	The state in which microorganisms adhere to the surface of a certain object. Among sewage treatment methods utilizing living organisms, it is a method to process the sewage by exploiting the ability of microorganisms adhered to the surface of a carrier to break down the organic matter present in the sewage. It is considered more advantageous than the sludge process for a variety of organisms to be active.
Biological treatment	A treatment method to purify sewage by exploiting the ability of microorganisms to break down the organic matter present in the sewage.
Blue-green algae	In eutrophied* lakes and marshes, algae can proliferate abnormally from early summer to fall, turning the lake water green. This green powdery phenomenon is called blue-green algae. When blue-green algae bloom occurs, the lake water clarity declines, algae die and produce a moldy odor, and some produce liver poison, neurotoxins, and other harmful chemicals, making it unsuitable for use in the water supply if the lake water is the source of the water supply. In addition, it deprives the water of dissolved oxygen and often results in the death of aquatic organisms and fish, thereby causing damage to fisheries and tourism. *Eutrophication: An excess of nutrients in seawater or river water over the natural state. Nitrogen and phosphorus contained in detergents, pesticides, and fertilizers are a source of nutrients for plants and plankton. This causes eutrophication as large amounts of water containing detergents and pesticides flow into rivers and lakes.
BOD（Biochemical Oxygen Demand）	The amount of oxygen demanded by microorganisms to break down the organic matter present in water. A typical indicator for measuring organic pollution in rivers. It is an indicator that utilizes the fact that the dirtier the water, the more oxygen is demanded by microorganisms. It is an important gauge to calculate the approximate amount of sludge from the amount of BOD in the influent entering the water treatment facility. High BOD levels can lead to a lack of dissolved oxygen. A foul odor is generated when the BOD value is 11 mg/L or higher.

Words That Start With C

Cation	A positive ion. Cationic coagulant = positive ion coagulant [Related term] Anion, Nonion
Chemical oxygen demand	It is the amount of oxidant consumed when decomposing organic matter in water with an oxidant converted into the amount of oxygen and serves as a gauge to determine how the water is polluted by organic matter. COD tends to be larger than BOD. [Abbreviations] COD(Chemical Oxygen Demand)
Chemical precipitation	A method for separating suspended solids and supernatant by adding a coagulant and flocculant if necessary to sewage to increase the diameter of suspended solids, thereby speeding up the settling process. [Related term] Pressure flotation treatment
COD（Chemical Oxygen Demand）	It is the amount of oxidant consumed when decomposing organic matter in water with an oxidant converted into the amount of oxygen and serves as a gauge to determine how the water is polluted by organic matter. COD tends to be larger than BOD.
Collective processing	A sewage treatment method in which sewage from several houses is treated intensively in a culvert, like a sewerage system. (e.g., treatment by sewerage systems or rural community water distribution facilities) [Antonym] Individual treatment: A sewage treatment method in which treated water is discharged at each source (on-site). (e.g., combined treatment type septic tank)
Community sewage treatment facility	A centralized septic tank under the jurisdiction of the Ministry of Health, Labor and Welfare. A facility that collectively treats sewage through a large-scale housing development, thereby eliminating the need for septic tanks at each housing site. Community sewage treatment facilities also have the advantage that when a public sewerage system is developed, the centralized septic tanks become available simply by connecting their inlets to the sewerage system.
Compost	Organic materials such as raw garbage, sewage sludge, septic tank sludge, livestock manure, and agricultural waste are composted through fermentation and decomposition by taking advantage of microorganisms.
Conventional activated sludge process	A method for treating sewage by injecting air into a mixture of sewage and mud containing microorganisms called activated sludge, which allows the microorganisms to absorb and decompose organic matter present in the sewage. It is also called the conventional process.
Crimp-type terminal	A connecting terminal attached to the end of an electric wire. Adhered to the wire and terminal with a special tool (crimp wrench).

DEF

Words That Start With D

DAF（Dissolved Air Flotation）	A treatment method in which air is dissolved in water by applying pressure and then solids in the water adhere to fine air bubbles generated by reducing the pressure so that the solids are forced to rise to the surface by buoyancy. The principle is the same as the generation of minute air bubbles the moment you get the lid off a carbonated drink.
Dewatered cake	The residual material of sludge after being dewatered by a dewatering technology.
Dissolved air flotation	A treatment method in which air is dissolved in water by applying pressure and then solids in the water adhere to fine air bubbles generated by reducing the pressure so that the solids are forced to rise to the surface by buoyancy. The principle is the same as the generation of minute air bubbles the moment you get the lid off a carbonated drink. [Abbreviations] DAF(Dissolved Air Flotation) [Related term] Coagulation sedimentation method
Domestic wastewater	Sewage discharged from home life situations such as toilets, kitchens, baths, laundry, and cooking, excluding industrial wastewater discharged into public water areas (Water Pollution Prevention Act, 1970). Domestic wastewater excluding human waste is called miscellaneous wastewater. Domestic wastewater is becoming a major cause of water pollution such as eutrophication due to nitrogen and phosphorus within the wastewater. It is desirable that sewage treatment facilities be available and that combined septic tanks be widespread in place of flush toilet wastewater purifiers that discharge miscellaneous wastewater untreated.

Words That Start With E

Environmental impact assessment	Environmental assessment is a procedure to give due consideration to the environment by fully investigating, predicting, and evaluating the effects on the environment in advance of activities that may have a significant impact on the environment, such as road and dam projects, and by making the results public, while considering the opinions of residents and other concerned parties.
Equalization tank	A facility to adjust the flow rate of incoming sewage after removing large contaminants by passing it through a screen, and to maintain a constant flow rate of water into the primary sedimentation basin.

Words That Start With F

Ferric chloride	Ferric chloride. Used as an inorganic coagulant. SUS304 is not corrosion-resistant to ferric chloride and will melt. [Abbreviations] Salt iron
Ferric polysulfate	An inorganic coagulant. It is a reddish-brown liquid with a specific gravity of 1.45. It is much less corrosive than ferric chloride.
Fibrous material	They are suspended solids that remain on a standard sieve of 0.075 mm (200 mesh) or 0.15 mm (100 mesh). Along with VTS, this factor influences dewatering performance; the more fibrous material, the lower the water content tends to be.
Final clarifier	A facility to allow sludge and treated water generated by biological treatment in a reaction tank to settle out and decompose. The supernatant water is disinfected and then discharged into rivers and the ocean. As it clarifies the water, it is called clarifier.
Fishery community sewerage (Treatment facility)	Pipeline facilities for collecting sewage such as human waste and miscellaneous wastewater, sewage treatment facilities for treating sewage, or facilities for treating sludge generated in rural and fishery communities.
Foreign substance	A general term for something different from the ordinary, something strange that causes discomfort, something that is not normally present in it. It is a piece of debris.

GHI

Words That Start With G

General wastes	Waste other than industrial waste. The general waste is categorized into domestic waste and business-generated waste, and each municipality specifies how to separate them.
Gravel contact aeration method	A method in which gravel is spread all over the bottom of a tank, sewage is poured into it, and aeration is performed so that microorganisms will form biofilms on the surfaces of the gravel, thereby purifying organic matter present in the sewage.
Gravity thickening	A method in which sludge is poured into a tank and allowed to stand still until suspended solids settle out, and then the sediment is collected. It is a method to concentrate sludge by gravity.
Gray water	A water recycling system in which rainwater and wastewater are recycled and reused as toilet flushing water or sprinkling water. Water-saving technologies allow the utilization of limited water resources. It is called gray water because it is between tap water and sewage water. Gray water is reused as toilet flushing water, cooling water, supply water to rivers, canals, and freshwater lakes, water for sprinkling plants, and water for gardens. Reclaimed water purified by sewage treatment is a valuable water resource within the city.
Grease trap	An oil interceptor. Commercial kitchens are required to have grease traps. By separating and collecting pollutants such as fats, oils, and garbage contained in wastewater and temporarily holding them in place, grease traps prevent them from flowing directly into the sewerage system.
Ground earth	It is also called grounding and is an electrical connection between electrical equipment or power lines and the earth. Familiar examples include the green earthing wire (ground wire) and metal rods attached to home appliances such as microwave ovens and washing machines to prevent electric shock.

Words That Start With H

Heavy metals	Metals with a specific gravity of 4 to 5 or greater, such as gold, platinum, silver, mercury, chromium, cadmium, lead, and iron, are called heavy metals. Many heavy metals are highly toxic. When ingested repeatedly, even in trace amounts, they accumulate in the body and become harmful to the human body. [Antonym] Light metals: aluminum, etc.
Hexane-extracted substance	Simply put, it is oil. Non-volatile oils such as animal and vegetable fats, greases, etc., extracted by n-hexane and dried at 80±5℃ for 30 minutes without volatilization. It is one of the factors that affect activated sludge treatment and is contained in treated water in large amounts, affecting fish and other organisms when released into rivers. If you are dewatering DAF sludge, the sludge and filtrate are measured to determine the oil content.
Human-waste treatment plant	A treatment plant under the jurisdiction of the Ministry of Health, Labor and Welfare, which processes waste activated sludge from septic tanks and human waste from individual toilets that are not connected with sewage pipeline.

Words That Start With I

Ignition loss	The amount of a substance that volatilizes when TS is heated to a high temperature of 600°C is a guide of the amount of organic matter. It is one of the factors that affect dewatering performance; the higher the VTS, the harder it tends to be for the water content of the dewatered cake to decrease. If the VTS is high, it is difficult to dewater. [Abbreviations] VTS(Volatile Total Solids)
Ignition residue	The residual material after TS is incinerated by intense heat at about 600°C (inorganic matter).
Inching	Repetitive starting and stopping of an electric motor in a short period. It is also referred to as “jogging.”
Industrial wastes	Waste generated by business activities, including burnt residue, sludge, waste oil, waste acid, and waste alkali, totaling 20 types of waste.
Inverter control	To control the speed of an electric motor utilizing an AC power supply of variable voltage and frequency using a frequency converter. Also referred to as frequency control.

JKL

Words That Start With J

Japan Sewage Works Agency	A local joint corporation that supports and acts over the local municipal entity, which is the operating entity of sewerage projects, in the development and operation of sewerage systems.
JARUS	“Former Japan Rural Community Sewerage Association” “The Japan Association of Rural Solutions for Environmental” Conservation and Resource Recycling The processing method approved by this incorporated association is called the JARUS-● type.

Words That Start With L

Lagoon	A large pond of wastewater left for one day or several months and then used for multiple purposes, including: flow control for maximum sewage flow; sedimentation of sewage as in the normal sedimentation method; making the bottom soil porous for dewatering; completion of chemical treatment solution reaction; biological decomposition of sewage; and natural evaporation.
Lagoon process	This is a type of wastewater treatment process where sewage is detained in a pond for a long period (several days to several dozen days) and purified by sedimentation and microorganisms. Since natural swamps are usually used, this treatment process is less expensive to construct and consumes very little energy compared to terminal sewage treatment plants, but it requires a larger area.
Leak	An instance of leaking. For our VOLUTE™ Dewatering Press, it refers to the phenomenon in which the sludge flows outward from the inside of the cylinder.
Liquid level relay	A liquid level detector that utilizes electricity flowing through liquid when the liquid comes in contact with its electrode. Liquid level relays include those for preventing the idling of electric motors and those for automatic operation of water supply and drainage, etc.

MNO

Words That Start With M

Membrane separation	A sewage treatment technology where a semipermeable membrane or other means is used to physically separate sewage and clean water. It is possible to obtain extremely clean treated water, but at the same time sludge is generated.
Mixed raw sludge	A mixture of primary sludge and waste activated sludge.
MLSS（Mixed Liquor Suspended Solids）	An indicator of the concentration of activated sludge in the aeration basin. Concentrations are often around 1,000 to 2,000 mg/L with the conventional activated sludge process and 2,000 to 5,000 mg/L with the OD method. [Abbreviations] MLSS(Mixed Liquor Suspended Solids)

Words That Start With N

N-hexane extract	A generic term for animal and vegetable fats and oils, fatty acids, fatty acid derivatives such as fatty acid esters and phospholipids, wax greases, petroleum-based hydrocarbons, and other non-volatile substances extracted by the solvent n-hexane. It is used as an indicator of “oil, etc.” present in water including pesticides, dyes, phenols, etc.
Nonion	Not ionic. Nonionic coagulant = Not ionic coagulant [Related term] Anion, cation

Words That Start With O

OD method	An activated sludge process in which an aerator is installed in the circulating waterway. There are two types of OD methods: one in which treated water is directly extracted from part of the waterway and the other in which a sedimentation tank is installed. The latest mainstream method is to create aerobic and anaerobic zones by carefully arranging the aerator to prevent pH decrease and remove nitrogen.
OH	The process of disassembling a mechanical product down to its parts, cleaning, and reassembling them to restore its original performance state (in short, disassembly, inspection, repair, and adjustment).
Overhaul	The process of disassembling a mechanical product down to its parts, cleaning, and reassembling them to restore its original performance state (in short, disassembly, inspection, repair, and adjustment). [Abbreviations] OH
Oxidation ditch method	An activated sludge process in which an aerator is installed in the circulating waterway. There are two types of OD methods: one in which treated water is directly extracted from part of the waterway and the other in which a sedimentation tank is installed. The latest mainstream method is to create aerobic and anaerobic zones by carefully arranging the aerator to prevent pH decrease and remove nitrogen. [Abbreviations] OD method

PQR

Words That Start With P

PAC	Polyaluminum chloride. Used as an inorganic coagulant.
Phosphorus removal	Phosphorus compounds (mainly inorganic or organic phosphates) in various states within wastewater must be removed to prevent eutrophication of water areas. Removal methods are roughly divided into two methods: biological and physicochemical methods. The physical method includes the coagulation sedimentation method, in which phosphorus is precipitated out as an insoluble salt by adding coagulants such as aluminum salt, iron salt, or calcium salt. Biological methods include the simultaneous coagulation sedimentation method, in which phosphorus is aerobically incorporated by microorganisms in high concentration as nutrient salt and then removed outside the system or released by an anaerobic tank and removed in a final sedimentation basin by adding a coagulant.
POD	Prefabricated oxidation ditch system. It is a modification of the oxidation ditch system that facilitates the construction of water treatment facilities as prefabricated buildings.
Polyaluminum chloride	Polyaluminum chloride. Used as an inorganic coagulant. [Abbreviations] POC
Prefabricated OD method	Prefabricated oxidation ditch system. It is a modification of the oxidation ditch system that facilitates the construction of water treatment facilities as prefabricated buildings. [Abbreviations] POD
Pressure tank	A sealed tank with air (with an air opening) at the top and water at the bottom, separated by a rubber diaphragm in the middle. A device that stores fluid pressure.
Primary clarifier / primary sedimentation tank	A facility to allow solids with high specific gravity, mainly organic matter, in sewage to settle out (called primary treatment).
Public sewer	A sewerage system managed by a local municipality to remove or treat sewage mainly in urban areas, which has a terminal treatment plant or is connected to a river basin sewerage system, and has a structure in which culverts make up a sizable proportion of its drainage facilities for sewage drainage.

Words That Start With R

Raw sludge	Sludge settled in the primary sedimentation basin. No processing is done at all. This is the sedimentation of raw water from which most of the impurities were removed before treatment.
River basin sewerage system	A sewerage system managed by a local municipality for treating sewage discharged by the sewerage system, which extensively and efficiently removes sewage in two or more municipalities beyond the borders of municipalities. A river basin sewerage system consists of trunk culverts and infrastructure at terminal treatment plants and is constructed and managed by the prefectural government. Sewage discharged from individual processes is managed by the municipality and connected to the trunk culverts, which is a river basin sewerage system, via a watershed-related public sewerage system.
Rotary disk method	One of the methods for treating microorganisms in sewage. A method of decomposing organic matter in sewage by exposing part of the rotating disk to sewage and the other part to outside air, thereby forming a film of microorganisms on the disk’s surface. It is classified in the biofilm process.
Rural community sewerage	This is a so-called rural sewerage system, and the rural community sewerage project is a project to develop facilities for this purpose. Developing facilities for treating sewage such as human waste and miscellaneous wastewater, sludge, or rainwater in rural communities contributes to the improvement of the living environment such as prevention of water pollution, bad odors, and the generation of mosquitoes in public water areas.

STU

Words That Start With S

Safety Data Sheet	It describes information necessary for the safe handling of chemical products (name, name of manufacturing company, properties of chemical substances, handling methods, types of hazards and toxicity, safety measures, emergency measures, etc.). It is an instruction manual distributed for each product by suppliers of chemical products to handling businesses to prevent accidents related to chemical products. [Abbreviations] SDS(Safety Data Sheet)
Sand filtration	Filters and a suspended solid removal device having a sand layer. In the case of multilayer filtration, coarse grains or low-density grains should be dominant in the upper part of the fluid to be filtered.
Sanitary appliances	Fixtures used in toilets, bathrooms, kitchens, etc. in buildings that are in direct contact with people to supply water and hot water and discharge sewage and waste. Among these are hydrants, flush valves, ball taps, large urinals, small urinals, and wash basins.
Screen	Scraping equipment used at treatment plants to remove debris and dirt from the water before treatment.
Scum	Solids floating on the surface of the water in anaerobic filter bed tanks, sedimentation tanks, etc. If there is too much scum, it is likely that the process is not properly running. [Related term] Pressure flotation treatment
SDS（Safety Data Sheet）	It describes information necessary for the safe handling of chemical products (name, name of manufacturing company, properties of chemical substances, handling methods, types of hazards and toxicity, safety measures, emergency measures, etc.). It is an instruction manual distributed for each product by suppliers of chemical products to handling businesses to prevent accidents related to chemical products.
Secondary effluent	It is treated water, the supernatant from the final sedimentation basin, that has been disinfected by sand filtration . It can be used to flush toilets and water plants.
Septic tank	A system that purifies and treats toilet sewage (human waste) and domestic wastewater from kitchens, baths, laundry, etc., by taking advantage of microorganisms. Treated water is discharged outside of the final treatment sewerage system. It does not include “human waste treatment facilities” set up by municipalities. Specifically, they range from household septic tanks used in stand-alone houses to communal wastewater treatment facilities (community sewage treatment facilities) used in apartment complexes, residential complexes, and communities. There are two types of septic tanks: “flush toilet wastewater purifiers” which treat only human waste (domestic wastewater is discharged untreated) and “combined treatment type septic tanks” which treat both human and domestic wastewaters. Since the Onsite Wastewater Treatment Equipment Septic Law (1983) has been amended to prohibit the construction of new flush toilet wastewater purifiers, the term “septic tank” has come to mean a combined treatment type septic tank. These tanks have the same level of purification capacity as a sewerage system, removing 90% of the pollutants within raw wastewater. The installation of these tanks is subsidized by the national and local governments to reduce the financial burden on individuals.
Shallow well	It is a well where the well water is up to a depth of about 8 meters below ground level.
Sludge	Generally, it refers to suspended solids present in water, which have precipitated or surfaced and become muddy, such as sludged pollutants that are separated from water in sedimentation tanks at water treatment facilities for industrial wastewater, sewage, and purified water, and sediment deposited on the bottom of rivers, lakes, and marshes. Sludge, a mixture of these fine solids and water, is the most common industrial waste.
Specific environmental preservation sewerage system	A generic term for nature protection sewers for water quality conservation in nature park areas and agricultural and fishing village sewers for improvement of the living environment.
Suspended solids	Substances suspended in water. There are two treatment methods: the filter paper method (filtration of sewage through glass fiber filter paper with a diameter of 1 µm and dry weight of particles remaining on the filter paper (unit: mg/φ)) and the centrifugal separation method. These methods are used depending on the object. Suspended solids present in wastewater are an important indicator of pollution. In water treatment, they are related to the amount of sludge generated. In dewatering machines, the chemical dosage, disposal amount, solids capture rate, etc. are calculated from the target sludge and filtrate SS values. [Abbreviations] SS(Suspended Solids)

Words That Start With T

Total dissolved solid (and moisture content)	TS is the residual material when the sample is evaporated to dryness and then dried at 105 to 110°C for 2 hours (a long time is required depending on the sample amount). The water content is calculated from the amount of water evaporated. TS is used to estimate the total amount of components present in wastewater. The salt content can be roughly predicted from the difference with SS. For the dewatering machine, the solid disposal amount is calculated from the TS and sludge cake water content. [Abbreviations] TS(Total Solids)
Trickling filter method	A treatment method using fixed beds (in which microorganisms have grown and become fixed) in which sewage or industrial wastewater is intermittently or continuously sprayed over the surface of a filter and brought into contact with a microbial population in the form of a film of slime attached to the surface of the filter. Crushed stones or gravel with a diameter of 35 to 100 mm should be used as a filter. There are two types of water sprinkler systems: fixed and movable.

VWX

Words That Start With V

VTS（Volatile Total Solids）	The amount of a substance that volatilizes when TS is heated to a high temperature of 601°C is a guide of the amount of organic matter. It is one of the factors that affect dewatering performance; the higher the VTS, the harder it tends to be for the moisture content of the dewatered cake to decrease. If the VTS is too high, it is difficult to reduce the water volume.

Words That Start With W

Waste activated sludge/excess sludge/surplus activated sludge	When sewage is treated in an aeration tank, microorganisms feed on organic matter and purify the water, but the microorganisms themselves multiply. As a result of proliferation, excess sludge is removed and then disposed of. The unwanted sludge is referred to as waste activated sludge.
Waste Management Law	A law that defines waste materials, the responsibility for disposal, and standards for disposal methods, disposal facilities, and disposal businesses. Under the jurisdiction of the Ministry of the Environment. The law defines waste as “solid or liquid waste that is no longer needed because it cannot be used or sold to others,” and divides it into industrial waste and general waste. Waste generators are responsible for disposing of industrial waste; either the generator or a licensed contractor entrusted by the generator must dispose of waste. Municipalities are responsible for the disposal of general waste.
Water content	The water content in a material (unit: %). In sludge, etc., anything other than water of the moisture content is called TS. (See TS.)
Water Pollution Prevention Act	The law was enacted in 1970, repealing the Law on Conservation of Water Discharged into Public Water Areas (1958) and the Law on Regulation of Industrial Waste, etc. (1958). Under the jurisdiction of the Ministry of the Environment. To prevent water pollution, the law regulates the discharge from factories and workplaces into public water areas and infiltration into groundwater. It also promotes the implementation of domestic wastewater control measures. The Law aims to protect the health of the people and preserve their living environment. The Law stipulates the liability of business operators to compensate for damages and protects victims in the event of damage to human health caused by sewage and effluent discharged from factories and workplaces. The “discharged water” subject to the regulation under the Law is water discharged from specified business sites into public water areas.

YZ

Words That Start With Z

Zero-emission	A resource-recycling social system that produces no waste by effectively utilizing all kinds of waste as raw materials, etc. A concept proposed by the United Nations University in 1994. In a narrow sense, it means reducing to zero the amount of waste from production activities that is ultimately disposed of (landfilled). Specifically, the yield rate (ratio of products to raw materials) in the production process is increased to reduce the amount of waste generated, and waste is thoroughly recycled. In Japan, the wide dispersion of ISO 14001, the international standard for environmental management, coupled with the rising cost of landfill disposal, has led to an increase in the number of companies addressing the zero-emission initiative at their plants.