Anaerobic lagoon

Anaerobic lagoon

Discussion
Ask a question about 'Anaerobic lagoon'
Start a new discussion about 'Anaerobic lagoon'
Answer questions from other users
Full Discussion Forum
 
Encyclopedia
Anaerobic Lagoon or Manure Lagoon is a man made outdoor earthen basin filled with excrement. Lagoons are part of a system designed to manage and treat waste created by Concentrated Animal Feeding Operations (CAFO). Anaerobic lagoons are created from a manure slurry which is washed out from underneath the animal pens and then piped into the lagoon. Sometimes the slurry is placed in an intermediary holding tank under or next to the barns before it is deposited in a lagoon. Once in the lagoon, the manure settles into two layers: the solid or sludge layer and the liquid layer. The manure then undergoes the process of anaerobic respiration
Anaerobic respiration
Anaerobic respiration is a form of respiration using electron acceptors other than oxygen. Although oxygen is not used as the final electron acceptor, the process still uses a respiratory electron transport chain; it is respiration without oxygen...

, whereby the volatile organic compounds are converted into carbon dioxide
Carbon dioxide
Carbon dioxide is a naturally occurring chemical compound composed of two oxygen atoms covalently bonded to a single carbon atom...

 and methane
Methane
Methane is a chemical compound with the chemical formula . It is the simplest alkane, the principal component of natural gas, and probably the most abundant organic compound on earth. The relative abundance of methane makes it an attractive fuel...

.

Anaerobic Lagoons have been shown to harbor and emit substances which can cause adverse environmental and health affects. These substances are emitted through two main pathways: gas emissions and lagoon overflow. Gas emissions are continuous (though the amount may vary based on the season) and are a product of the manure slurry itself. The most prevalent toxic gasses emitted by the lagoon are: Ammonia
Ammonia
Ammonia is a compound of nitrogen and hydrogen with the formula . It is a colourless gas with a characteristic pungent odour. Ammonia contributes significantly to the nutritional needs of terrestrial organisms by serving as a precursor to food and fertilizers. Ammonia, either directly or...

, Hydrogen Sulfide
Hydrogen sulfide
Hydrogen sulfide is the chemical compound with the formula . It is a colorless, very poisonous, flammable gas with the characteristic foul odor of expired eggs perceptible at concentrations as low as 0.00047 parts per million...

, Methane
Methane
Methane is a chemical compound with the chemical formula . It is the simplest alkane, the principal component of natural gas, and probably the most abundant organic compound on earth. The relative abundance of methane makes it an attractive fuel...

, and Carbon Dioxide
Carbon dioxide
Carbon dioxide is a naturally occurring chemical compound composed of two oxygen atoms covalently bonded to a single carbon atom...

. Lagoon overflow is caused by faulty lagoons or an increase in rain or wind. These overflows release harmful substances into the surrounding land and water such as: Antibiotics, Estrogens, Bacteria
Bacteria
Bacteria are a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria have a wide range of shapes, ranging from spheres to rods and spirals...

, pesticides, heavy metals
Heavy metals
A heavy metal is a member of a loosely-defined subset of elements that exhibit metallic properties. It mainly includes the transition metals, some metalloids, lanthanides, and actinides. Many different definitions have been proposed—some based on density, some on atomic number or atomic weight,...

, and protozoa
Protozoa
Protozoa are a diverse group of single-cells eukaryotic organisms, many of which are motile. Throughout history, protozoa have been defined as single-cell protists with animal-like behavior, e.g., movement...

.

In response to environmental and health concerns, the EPA has tightened regulation of the CAFO under the Clean Water Act
Clean Water Act
The Clean Water Act is the primary federal law in the United States governing water pollution. Commonly abbreviated as the CWA, the act established the goals of eliminating releases of high amounts of toxic substances into water, eliminating additional water pollution by 1985, and ensuring that...

 (CWA). Some states have imposed their own regulation as well. Due to repeated overflows and resultant health concerns, North Carolina banned the construction of new anaerobic lagoons in 1999. There has also been a significant push for the research, development and implementation of Environmentally Sound Technologies (ESTs).

Introduction


Beginning in the 1950s with poultry and then later in the 1970s and 1980s with cattle and swine, the United States has turned to the Concentrated Animal Feeding Operation as a way to more efficiently produce large quantities of meat. This switch has benefited the United States consumer by increasing the amount of meat that can be grown thereby decreasing the price of meat. However, the increase in livestock has generated an increase in manure. In 2006, the United states produced 133 million tons of manure per year. Unlike manure produced in a conventional farm, CAFO manure cannot all be used as direct fertilizer on agricultural land due to the poor quality of the manure. Moreover, CAFOs produce a high volume of manure. A feeding operation with 800,000 pigs could produce over 1.6 million tons of waste a year. The high quantity of manure produced by a CAFO must be dealt with in some way, as improper manure management can result in water, air and soil damage. As a result, manure collection and disposal has become an increasing problem.

In order to manage their waste, CAFOs have developed Agricultural wastewater treatment
Agricultural wastewater treatment
Agricultural wastewater treatment relates to the treatment of wastewaters produced in the course of agricultural activities. Agriculture is a highly intensified industry in many parts of the world, producing a range of wastewaters requiring a variety of treatment technologies and management...

 plans. To save on manual labor, many CAFOs handle manure waste as a liquid. In this system, the animals are kept in pens with grated floors so the waste and spray water can be drained from underfloor gutters and piped to storage tanks or anaerobic lagoons. Once at a lagoon, the purpose is to treat the waste and make it suitable for spreading on agricultural fields. There are 3 main types of lagoon: anaerobic, which is inhibited by oxygen, aerobic, which requires oxygen, and facultative, which is maintained with or without oxygen. Aerobic lagoons provide a higher degree of treatment with less odor production, though they require a significant amount of space and maintenance. Because of this demand, almost all livestock lagoons are anaerobic lagoons.

Description



Anaerobic lagoons are earthen basins with a usual depth of 8 feet, though greater depths are more beneficial to digestion as they minimize oxygen diffusion from the surface. To prevent any contaminants from leaking into the ground water, lagoons are lined with clay or artificial liner. Anaerobic lagoons are neither heated, aerated, nor mixed. Anaerobic lagoons are most effective in warmer temperatures; anaerobic bacteria are ineffective below 15°C. Lagoons must be separated from other structures by a certain distance to prevent contamination. States regulate this separation distance. The overall size of the lagoon is determined by addition of 4 components: the minimum design volume, the volume of manure storage between periods of disposal, the dilution volume, and the volume of sludge accumulation between periods of sludge removal.

Process


The lagoon is divided into two distinct layers: the sludge layer and the liquid layer. The sludge layer is a more solid layer formed by the stratification of sediments from the manure. After a while, this solid layer accumulates and eventually needs to be cleaned out. The liquid level is composed of grease, scum, and other particulates The liquid level CAFO wastewater enters at the bottom of the lagoon so that it can mix with the active microbial mass in the sludge layer. These anaerobic conditions are uniform throughout the lagoon, except in a small surface level. Sometimes aeration is applied to this level to dampen the odors emitted by the lagoons. If surface aeration is not applied, a crust that will form which will trap heat and odors. Anaerobic lagoons should retain and treat waste water from 20 to 150 days. Lagoons should be followed by aerobic or facultative lagoons to provide further required treatment. The liquid layer is periodically drained and used for fertilizer. In some instances, a cover can be provided to trap methane, which is used for energy. Anaerobic Lagoons work through a process called anaerobic digestion
Anaerobic digestion
Anaerobic digestion is a series of processes in which microorganisms break down biodegradable material in the absence of oxygen. It is used for industrial or domestic purposes to manage waste and/or to release energy....

. Decomposition of the organic mater begins shortly after the animals void, and lagoons become anaerobic due to the high oxygen demand of the feces. Anaerobic microorganisms convert organic compounds into carbon dioxide and methane through acid formation and methane production.

Advantages of Construction

  • Manure can be easily manipulated with water using flushing systems, sewer lines, pumps and irrigation systems
  • Stabilization of the waste through digestion minimizes odor when manure is finally used as fertilizer
  • Manure is able to be stored long-term at a low cost

Disadvantages of Construction

  • Requires relatively large area of land
  • Produces strong undesirable odors especially during spring and fall
  • Take a fairly long time for organic stabilization because of the slow rate of sludge digestion and slow growth rate of methane formers
  • Manure used as fertilizer has low nutrient availability
  • Waste water seepage may occur if the tanks break or are improperly constructed
  • Weather and other environmental elements can strongly effect the safety and efficacy of anaerobic lagoons

Toxic Fumes


The decomposition of manure in lagoons by anaerobic bacteria produces toxic airborne compounds, which can be harmful to human health and the environment. A study performed in North Carolina showed people living nearby a 6,000-head hog CAFO reported increased rates of headaches, runny nose, sore throat, excessive coughing, diarrhea, and burning eyes compared to rural residents living far from livestock operations . Additionally, rates of athsma in children living near a CAFO are consistently elevated. The process of anaerobic digestion has been shown to release over 400 volatile compounds from lagoons. The most prevalent of these are: ammonia
Ammonia
Ammonia is a compound of nitrogen and hydrogen with the formula . It is a colourless gas with a characteristic pungent odour. Ammonia contributes significantly to the nutritional needs of terrestrial organisms by serving as a precursor to food and fertilizers. Ammonia, either directly or...

, hydrogen sulfide
Hydrogen sulfide
Hydrogen sulfide is the chemical compound with the formula . It is a colorless, very poisonous, flammable gas with the characteristic foul odor of expired eggs perceptible at concentrations as low as 0.00047 parts per million...

, methane
Methane
Methane is a chemical compound with the chemical formula . It is the simplest alkane, the principal component of natural gas, and probably the most abundant organic compound on earth. The relative abundance of methane makes it an attractive fuel...

, and carbon dioxide
Carbon dioxide
Carbon dioxide is a naturally occurring chemical compound composed of two oxygen atoms covalently bonded to a single carbon atom...

.

Ammonia

In the United States, 80% of ammonia emissions come from livestock production. The urea
Urea
Urea or carbamide is an organic compound with the chemical formula CO2. The molecule has two —NH2 groups joined by a carbonyl functional group....

 (a component of urine
Urine
Urine is a typically sterile liquid by-product of the body that is secreted by the kidneys through a process called urination and excreted through the urethra. Cellular metabolism generates numerous by-products, many rich in nitrogen, that require elimination from the bloodstream...

) stored in the lagoon contains ammonium
Ammonium
The ammonium cation is a positively charged polyatomic cation with the chemical formula NH. It is formed by the protonation of ammonia...

, which is a liquid nitrogen compound. Through Ammonia Volatization, the a lagoon can vaporize up to 80% of its nitrogen
Nitrogen
Nitrogen is a chemical element that has the symbol N, atomic number of 7 and atomic mass 14.00674 u. Elemental nitrogen is a colorless, odorless, tasteless, and mostly inert diatomic gas at standard conditions, constituting 78.08% by volume of Earth's atmosphere...

  through the reaction: NH4+-N -> NH3 + H+. As pH or temperature increases, so does the amount of Volatized Ammonia. Once ammonia has been volatilized, it can travel as far as 300 miles and at closer ranges it is a respitory irritant. Acidification and eutrophication of the ecosystem surrounding the Lagoons could be caused by prolonged exposure to volatilized ammonia. This volatilized ammonia has been implicated in widespread ecological damage in Europe, and is becoming a growing concern for the United States. OSHA recommendations for amonnia in barns is 25ppm, whereas in Europe it is 10ppm.

Hydrogen Sulfide

With averages greater than 30 ppb, lagoons have high concentration of the toxic gas hydrogen sulfide
Hydrogen sulfide
Hydrogen sulfide is the chemical compound with the formula . It is a colorless, very poisonous, flammable gas with the characteristic foul odor of expired eggs perceptible at concentrations as low as 0.00047 parts per million...

. A study by the Minnesota Pollution Control Agency has found that concentrations of Hydrogen sulfide near lagoons have exceeded the state standard, even as far away as 4.9 miles. Hydrogen Sulfide is recognizable for its unpleasant rotten egg odor. Exposure to the gas can cause eye, nose, and throat irritation, diarrhea, hoarseness, sore throat, cough, chest tightness, nasal congestion, heart palpitations, shortness of breath, stress, mood alterations, sudden fatigue, headaches, nausea, sudden loss of consciousness, comas, seizures, and death. Because Hydrogen sulfide is heavier than air, it tends to linger around lagoons even after ventilation. Levels of hydrogen sulfide are at their highest after agitation and during manure removal.

Methane

Methane is an odorless, tasteless, colorless gas which is fatal at high levels (though these levels are not usually seen at lagoons). Lagoons produce about 2,300,000 metric tonnes per year, with around 40% of this number coming from swine lagoons. Methane is combustible at high temperatures and explosions and fires are a real threat at, or near, lagoons. Additionally, methane is a potent green house gas. The EPA has estimated that 13% all the methane emissions came from livestock manure in 1998, and this number has grown in recent years. Recently there has been interest technology which would capture methane produced from lagoons and sell it as energy.

Carbon Dioxide

Carbon Dioxide
Carbon dioxide
Carbon dioxide is a naturally occurring chemical compound composed of two oxygen atoms covalently bonded to a single carbon atom...

 is a main product of anaerobic respiration within the lagoon. Though it is not toxic in itself, health effects include: respiratory problems, eye irritation, and headaches. Carbon Dioxide is also considered a green house gas.

Water Soluble Contaminants


Contaminants that are water soluable can escape from Anaerobic Lagoons and enter the environment through leakage from badly constructed or poorly maintained manure lagoons as well as during excess rain or high winds resulting in an overflow of lagoons. These leaks and overflows can contaminate surrounding surface and ground water with some hazardous materials which are contained in the lagoon. The most serious of these contaminants are pathogens, antibiotics, heavy metals, and hormones.

Pathogens


There are over 150 pathogens in manure lagoons that have been found to impact human health. Healthy individuals who come into contact with pathogens usually recover promptly. However, those who have a weakened immune system, such as cancer patients and young children, have an increased risk for a more severe illness or even death. About 20% of the American population categorized in this risk group. Some of the more notable pathogens are:
E. Coli
E. Coli is found in the intestines and feces of both animal and humans and is extremely virulent. One particular strain Escherichia coli O157:H7
Escherichia coli O157:H7
Escherichia coli O157:H7 is an enterohemorrhagic strain of the bacterium Escherichia coli and a cause of foodborne illness. Infection often leads to hemorrhagic diarrhea, and occasionally to kidney failure, especially in young children and elderly persons...

 is found specifically in the lumen
Lumen
Lumen can mean:* Lumen , the SI unit of luminous flux* Lumen , the cavity or channel within a tubular structure* Thylakoid lumen, the inner membrane space of the chloroplast* Phenobarbital...

 of cattle raised in CAFOs. Because cattle are fed corn in CAFOs instead of grass, this changes the pH
PH
In chemistry, pH is a measure of the acidity or basicity of an aqueous solution. Pure water is said to be neutral, with a pH close to 7.0 at . Solutions with a pH less than 7 are said to be acidic and solutions with a pH greater than 7 are basic or alkaline...

 of the lumen so that it is more hospitable to E. Coli. Grain fed cattle have 80% more of this strain of E. Coli than traditional grass fed cattle. This reduction can also be achieved by switching an animal to grass only a few days prior to slaughter.

Cryptosporidium
Cryptosporidium
Cryptosporidium
Cryptosporidium is a protozoan that can cause gastro-intestinal illness with diarrhea in humans.Cryptosporidium is the organism most commonly isolated in HIV positive patients presenting with diarrhea...

 is a parasite which causes diarrhea, vomiting, stomach cramps, and fever. It is particularly problematic because it is resistant to most lagoon treatment regimens In study performed in Canada, thirty-seven percent of swine liquid manure samples contained Cryptosporidium.

Some other common pathogens (and their symptoms)
  • Bacillus anthracis, otherwise known as Anthrax
    Anthrax
    Anthrax is an acute disease caused by the bacterium Bacillus anthracis. Most forms of the disease are lethal, and it affects both humans and other animals...

     (skin sores, headache, fever, chills, nausea, vomiting)
  • Leptospira pomona (abdominal pain, muscle pain, vomiting, fever)
  • Listeria monocytogenes (fever, fatigue, nausea, vomiting, diarrhea)
  • Salmonella
    Salmonella
    Salmonella is a genus of rod-shaped, Gram-negative, non-spore-forming, predominantly motile enterobacteria with diameters around 0.7 to 1.5 µm, lengths from 2 to 5 µm, and flagella which grade in all directions . They are chemoorganotrophs, obtaining their energy from oxidation and reduction...

     (abdominal pain, diarrhea, nausea, chills, fever, headache)
  • Clostirdum tetani (violent muscle spasms, lockjaw, difficulty breathing)
  • Histoplasma capsulatum (fever, chills, muscle ache, cough rash, joint pain and stiffness)
  • Microsporum and Trichophyton Ringworm (itching, rash)
  • Giardia lamblia
    Giardia lamblia
    Giardia lamblia is a flagellated protozoan parasite that colonizes and reproduces in the small intestine, causing giardiasis. The giardia parasite attaches to the epithelium by a ventral adhesive disc, and reproduces via binary fission...

     (abdominal pain, abdominal gas, nausea, vomiting, fever)
  • Cryptosporidium
    Cryptosporidium
    Cryptosporidium is a protozoan that can cause gastro-intestinal illness with diarrhea in humans.Cryptosporidium is the organism most commonly isolated in HIV positive patients presenting with diarrhea...

     (diarrhea, dehydration, weakness, abdominal cramping)
  • Pfiesteria piscicida
    Pfiesteria piscicida
    Pfiesteria piscicida is a dinoflagellate species of the genus Pfiesteria that some researchers claim is responsible for many harmful algal blooms in the 1980s and 1990s on the coast of North Carolina and Maryland...

     (neurological damage)

Antibiotics


Antibiotics are fed to livestock to prevent disease and to increase weight and development, so that there is a shortened time from birth to slaughter. However, because these antibiotics are administered at sub-therapeutic levels, bacteria can build up resistance to the drugs. These antibiotic resistant bacteria are then excreted and transferred to the lagoons where they can infect humans and other animals.

Each year 24.6 million pounds of antimicrobials are administered to livestock for non-therapeutic purposes. Seventy percent of all antibiotics and related drugs are given to animals as feed additives. Nearly half of the antibiotics used are nearly identical to ones given to humans. There is strong evidence that the use of antibiotics in animal feed is contributing to an increase in antibiotic-resistant microbes and causing antibiotics to be less effective for humans. Due concern over antibiotic-resistant bacteria, the American Medical Association
American Medical Association
The American Medical Association , founded in 1847 and incorporated in 1897, is the largest association of medical doctors and medical students in the United States.-Scope and operations:...

 passed a resolution stating their opposition to the use of sub-therapeutic levels of anti-microbials in livestock.

Hormones


Growth hormones such as rBST
RBST
RBST or rBST may refer to:* Randomized binary search tree, a computer data structure* Rare Breeds Survival Trust, a UK charity* Recombinant bovine somatotropin , a synthetic growth hormone controversially used in dairy farming...

 are administered to increase development rate and muscle mass for the livestock. Only a fraction of these hormones are actually absorbed by the animal. The rest are excreted and wind up in lagoons. Studies show that these hormones, if they are emitted into the surface water, can alter fertility and reproductive habits of aquatic animals.

A recent study found that several lagoons and monitoring wells from two facilities (a nursery and a farrowing sow operation) contained high levels of all 3 types of estrogen. For the nursery, lagoon effluent concentrations ranged from 390 to 620 ng/L for estrone
Estrone
Estrone is an estrogenic hormone secreted by the ovary as well as adipose tissue.Estrone is one of several natural estrogens, which also include estriol and estradiol...

, 180 to 220 ng/L for estriol
Estriol
Estriol is one of the three main estrogens produced by the human body.-Synthesis:Estriol is only produced in significant amounts during pregnancy as it is made by the placenta from 16-Hydroxydehydroepiandrosterone sulfate , an androgen steroid made in the fetal liver and adrenal glands.The human...

, and 40 to 50 ng/L for estradiol
Estradiol
Estradiol is a sex hormone. Estradiol is abbreviated E2 as it has 2 hydroxyl groups in its molecular structure. Estrone has 1 and estriol has 3 . Estradiol is about 10 times as potent as estrone and about 80 times as potent as estriol in its estrogenic effect...

. For the farrowing sow operation, digester and primary lagoon effluent concentrations ranged from 9,600 to 24,900 ng/L for estrone, 5,000 to 10,400 ng/L for estriol, and 2,200 to 3,000 ng/L for estradiol. Ethynylestradiol was not detected in any of the lagoon or ground water samples. Natural estrogen concentrations in ground water samples were generally less than 0.4 ng/L, although a few wells at the nursery operation showed quantifiable but low levels."

Heavy Metals


Manure contains trace elements of many heavy metals
Heavy metals
A heavy metal is a member of a loosely-defined subset of elements that exhibit metallic properties. It mainly includes the transition metals, some metalloids, lanthanides, and actinides. Many different definitions have been proposed—some based on density, some on atomic number or atomic weight,...

 such as arsenic
Arsenic
Arsenic is a chemical element with the symbol As, atomic number 33 and relative atomic mass 74.92. Arsenic occurs in many minerals, usually in conjunction with sulfur and metals, and also as a pure elemental crystal. It was first documented by Albertus Magnus in 1250.Arsenic is a metalloid...

, copper
Copper
Copper is a chemical element with the symbol Cu and atomic number 29. It is a ductile metal with very high thermal and electrical conductivity. Pure copper is soft and malleable; an exposed surface has a reddish-orange tarnish...

, selenium
Selenium
Selenium is a chemical element with atomic number 34, chemical symbol Se, and an atomic mass of 78.96. It is a nonmetal, whose properties are intermediate between those of adjacent chalcogen elements sulfur and tellurium...

, zinc
Zinc
Zinc , or spelter , is a metallic chemical element; it has the symbol Zn and atomic number 30. It is the first element in group 12 of the periodic table. Zinc is, in some respects, chemically similar to magnesium, because its ion is of similar size and its only common oxidation state is +2...

, cadmium
Cadmium
Cadmium is a chemical element with the symbol Cd and atomic number 48. This soft, bluish-white metal is chemically similar to the two other stable metals in group 12, zinc and mercury. Similar to zinc, it prefers oxidation state +2 in most of its compounds and similar to mercury it shows a low...

, molybdenum
Molybdenum
Molybdenum , is a Group 6 chemical element with the symbol Mo and atomic number 42. The name is from Neo-Latin Molybdaenum, from Ancient Greek , meaning lead, itself proposed as a loanword from Anatolian Luvian and Lydian languages, since its ores were confused with lead ores...

, nickel
Nickel
Nickel is a chemical element with the chemical symbol Ni and atomic number 28. It is a silvery-white lustrous metal with a slight golden tinge. Nickel belongs to the transition metals and is hard and ductile...

, lead
Lead
Lead is a main-group element in the carbon group with the symbol Pb and atomic number 82. Lead is a soft, malleable poor metal. It is also counted as one of the heavy metals. Metallic lead has a bluish-white color after being freshly cut, but it soon tarnishes to a dull grayish color when exposed...

, iron
Iron
Iron is a chemical element with the symbol Fe and atomic number 26. It is a metal in the first transition series. It is the most common element forming the planet Earth as a whole, forming much of Earth's outer and inner core. It is the fourth most common element in the Earth's crust...

, manganese
Manganese
Manganese is a chemical element, designated by the symbol Mn. It has the atomic number 25. It is found as a free element in nature , and in many minerals...

, aluminum, and boron
Boron
Boron is the chemical element with atomic number 5 and the chemical symbol B. Boron is a metalloid. Because boron is not produced by stellar nucleosynthesis, it is a low-abundance element in both the solar system and the Earth's crust. However, boron is concentrated on Earth by the...

. Sometimes these metals are given to animals as growth stimulants, some are introduced through pesticides used to rid livestock of insects, and some my pass through the animals as undigested food. Trace elements of these metals and salts from animal manure present risks to human health and ecosystems.

Regulation

For further information on lagoon regulation, see Concentrated Animal Feeding Operation


Anaerobic Lagoons are built as part of an waste water operation system. As such, compliance and permitting are handled as an extension of that operation. Therefore, manure lagoons are regulated on the state and national level through the CAFO which operates them. In recent years, because of the environmental and health effects associated with anaerobic lagoons, the EPA has increased regulation of CAFOs with a specific eye towards lagoons. Additionally, on a state level, due to the same safety concerns North Carolina banned the construction of new anaerobic lagoons in 1999 and upheld that ban in 2007.

See also

  • Concentrated Animal Feeding Operation
  • Factory Farming
    Factory farming
    Factory farming is a term referring to the process of raising livestock in confinement at high stocking density, where a farm operates as a factory — a practice typical in industrial farming by agribusinesses. The main products of this industry are meat, milk and eggs for human consumption...

  • Agricultural wastewater treatment
    Agricultural wastewater treatment
    Agricultural wastewater treatment relates to the treatment of wastewaters produced in the course of agricultural activities. Agriculture is a highly intensified industry in many parts of the world, producing a range of wastewaters requiring a variety of treatment technologies and management...

  • Anaerobic digestion
    Anaerobic digestion
    Anaerobic digestion is a series of processes in which microorganisms break down biodegradable material in the absence of oxygen. It is used for industrial or domestic purposes to manage waste and/or to release energy....

  • List of waste water treatment technologies
  • Sewage treatment
    Sewage treatment
    Sewage treatment, or domestic wastewater treatment, is the process of removing contaminants from wastewater and household sewage, both runoff and domestic. It includes physical, chemical, and biological processes to remove physical, chemical and biological contaminants...