The main sources of iron pollution in water are mineral processing, smelting, ironmaking, machining, industrial electroplating and pickling wastewater.
Iron is one of the essential trace elements for human body. Its compounds are low or slightly toxic. Ferrous has a certain systemic toxicity, while ferric salts are less toxic and slightly irritating and corrosive to mucosa. When the concentration of iron compounds in water environment is 1mg/l, it has obvious metallic taste. When the concentration is 0.5mg/l, the chromaticity can be greater than 30 degrees. When the iron content in drinking water exceeds 0.3mg/l, clothes and utensils will change color, precipitate and smell. The national standard requires that the iron content in drinking water should be less than 0.3 mg/L.
manganese
Due to the lack of oxygen in groundwater, manganese exists in the form of soluble divalent manganese, while in surface water, soluble trivalent manganese complex and tetravalent manganese suspended matter exist.
The main pollution sources of manganese are wastewater discharged from ferrous metal mines, metallurgy and chemical industries.
Manganese is an essential trace element for normal metabolism of human body. The average person takes about 3-9 mg of manganese from food every day. However, excessive manganese can cause poisoning after entering the body. The main manifestations of manganese poisoning are neurasthenia syndrome and autonomic nerve dysfunction. If it continues to develop, there may be obvious neurological signs of extrapyramidal damage. When there is trace manganese in water, it will be yellowish brown. Manganese oxide will deposit on the water pipe wall. When the water pressure fluctuates, it will cause "black water phenomenon". When manganese in water exceeds 0. 15mg/l, clothes and white porcelain equipment can be colored. The national standard requires that the manganese content in drinking water should be less than 0.1mg/L.
copper
Copper exists in the form of simple substance or various minerals. Besides mining, heat exchange and other industrial uses, copper can be discharged into the water environment. High concentration copper solution is widely used as herbicide to control algae reproduction. It is also a common fungicide in agriculture.
When the copper content in water is 0.5mg/l, it has obvious metallic taste. When it exceeds 1.0mg/l, clothes and white porcelain can be dyed green. Copper is an essential trace element for human body, which plays an important role in hematopoiesis, cell growth, the activity of some enzymes and the function of endocrine glands. When copper compounds enter the human body beyond a certain limit, it will cause diseases. Copper is mainly stored in tissues such as liver, brain and kidney. The disease caused by copper metabolism disorder is called hepatolenticular degeneration. This is a genetic disease. Acute copper poisoning is characterized by severe vomiting and diarrhea, sometimes accompanied by abdominal cramps, bloody stool, severe headache, cold sweat and weak pulse. Severe poisoning can lead to death due to shock and liver and kidney damage. The national standard requires that the content of copper in drinking water should be less than 65438 0.0 mg/L.
zinc (Zn)
The main pollution source of zinc is wastewater discharged from electroplating, metallurgy, pigments, chemical industry and other industries.
When the zinc content in drinking water is 50mg/l, it will cause nausea and fainting. When the zinc content of drinking water is 10mg/l, it will be turbid, and when the zinc content is 5mg/l, it will have the astringent taste of metal. Zinc is an essential trace element for human body. When zinc is deficient, it will slow down the growth of bones and cause hepatosplenomegaly and hypogonadism. Excessive zinc will strongly stimulate the gastrointestinal tract. After absorption, it is mainly stored in the liver and pancreas. Excess zinc will be stored in the liver and pancreas.
Volatile phenol (calculated as phenol)
Phenols can be divided into volatile phenol and nonvolatile phenol according to whether they can be distilled by steam. Volatile phenol refers to phenols with boiling point below 230, which usually belongs to monohydric phenol.
Phenols mainly come from wastewater from oil refining, gas washing, coking, paper making, synthetic ammonia, wood preservation, chemical industry and other industries.
Phenols are highly toxic, which can denature protein at low concentration, and precipitate protein at high concentration, causing direct damage to various cells and strong corrosion to skin and mucosa. Drinking water polluted by phenol for a long time can cause dizziness, rash, itching, anemia, nausea, vomiting and other nervous system symptoms. Phenolic compounds can promote cancer in humans and mammals. The national standard requires that the content of volatile phenol in drinking water should be less than 0.
sulphate
Sulfate is widely distributed in nature. Sulfate in surface water and groundwater mainly comes from weathering and leaching of mineral components in rock and soil, and metal sulfide oxidation will also increase sulfate content.
When the sulfate in water exceeds 750mg/l, it can cause mild diarrhea after drinking. The national standard requires that the sulfate content in drinking water should be less than 250 mg/L.
Treat with chloride
Chloride ion is a common inorganic anion in water and wastewater. Chloride exists in almost all natural water. At the same time, domestic sewage and industrial wastewater also contain a considerable amount of chloride. When seawater invades groundwater, the chloride content will increase obviously.
Chloride ion is an indispensable factor to maintain body fluid volume, osmotic pressure and water-electrolyte balance inside and outside human cells. When the chloride content is too high, it can interfere with the electrolyte balance of human body, increase the extracellular osmotic pressure of human body, lead to cell dehydration and malfunction of metabolic process. The national standard requires that the chloride content in drinking water should be less than 250 mg/L.
Dissolved total solids
The main components of soluble solids in water are bicarbonate, chloride and sulfate of calcium, magnesium and sodium. When its concentration is higher than 1200mg/l, it can produce bitter taste and salty taste. The national standard requires that the total soluble solids content in drinking water should be less than1000 mg/L.
fluoride
Fluoride exists widely in natural water. Fluoride usually exists in the wastewater of nonferrous metallurgy, steel and aluminum processing, coke, glass, ceramics, electronics, electroplating, fertilizer, pesticide plant and fluorine-containing minerals.
Fluorine is one of the essential trace elements for human body, and it is easy to suffer from dental caries due to fluoride deficiency. The suitable concentration of fluoride in drinking water is 0.5 ~1.0 mg/L. Drinking water with fluorine content higher than 1.0 ~ 1.5 mg/L for a long time is prone to dental plaque, for example, when the fluorine content in water is higher than 4 mg/l, it may lead to skeletal fluorosis.
Fluorine can exchange hydroxyl with hydroxyapatite in bone tissue, and form insoluble calcium fluoride by inhibiting bone phosphatase or combining with calcium ions in body fluids, which leads to calcium and phosphorus metabolism disorder, hypocalcemia, dental fluorosis and skeletal fluorosis. The national standard requires that the fluoride content in drinking water should be less than 65438 0.0 mg/L. 。
cyanide
The main pollution sources of cyanide are wastewater discharged from electroplating, organic, chemical, mineral processing, coking, gas making, chemical fertilizer and other industries. Cyanide may exist in water in the form of HCN, CN and complex cyanide ions.
Cyanide makes water smell like bitter almonds. Cyanide is highly toxic.
The toxic effect of cyanide is that cyanide ions combine with iron in cytochrome oxidase to form iron-cyanide complex, which prevents the oxidation and reduction of oxidase and hinders the normal breathing of tissues. When cyanide causes acute poisoning, it is manifested as severe headache, confusion or even coma, general convulsion, incontinence, loss of sensation and reflex, dilated pupils, slow breathing, rising or falling blood pressure, and slow heart rate. , often died of respiratory arrest. Chronic poisoning can cause neurasthenia, headache, dizziness, tinnitus, insomnia, general weakness, slow heart rate and low blood pressure. The national standard requires that the cyanide content in drinking water should be less than 0.05 mg/L.
arsenic
Arsenic is an element with both metallic and nonmetallic properties. Its compounds are widely found in nature. Can be organic. Most of them are arsenic salts and arsenic ferric sulfide. The common arsenic compounds in natural water are arsenate (pentavalent arsenic), arsenite (trivalent arsenic), methane arsonic acid and dimethyl arsonic acid.
Arsenic pollution mainly comes from industrial wastewater from mining, metallurgy, chemical industry, chemical pharmacy, pesticide production, textile, glass, tanning and other departments. At the same time, arsenic and its compounds are also one of the components of herbicides used in agriculture and forestry.
Arsenic is an unnecessary element for human body, and its toxicity is extremely low, while arsenic compounds are very toxic. Trivalent arsenic compounds are more toxic than other arsenic compounds. The known poison "arsenic" is arsenic trioxide (trivalent arsenic). Arsenic can accumulate in the human body, which is a carcinogen and is also suspected to have mutagenic effect.
The toxic effect of arsenite is mainly the combination of arsenite ions with sulfhydryl groups of human cellular enzyme proteins, which inactivates cellular enzymes, causes metabolic disorders and promotes cell death. Arsenite is the most harmful to nerve cells, and it can also directly damage capillaries through blood circulation, making them expand and relax and increase permeability.
When the human body ingests more arsenic than it excretes, arsenic will accumulate in liver, kidney, spleen, lung, muscle, bone and other parts, especially in nails and hair. Arsenic compounds with strong toxicity can be quickly and firmly combined in liver and kidney, and their excretion is slower than arsenic compounds with weak toxicity and poor combination.
The symptoms of chronic arsenic poisoning are similar to those of acute poisoning, but it develops slowly, such as loss of appetite, abdominal pain, diarrhea and discomfort, hepatomegaly, pain, jaundice, and in some serious cases, cirrhosis. The national standard requires that the arsenic content in drinking water should be less than 0.05 mg/L.
selenium
Selenium in water exists in the form of inorganic hexavalent, tetravalent, negative bivalent and some organic selenium. Selenium-containing wastewater mainly comes from oil refining, copper smelting, sulfuric acid manufacturing and special glass industry.
Selenium is an essential trace element for animals, but under certain conditions, it has certain toxicity. It is generally believed that the toxicological effect of selenium is related to the effect of selenium on enzyme system besides dimethyl selenium. Dimethyl selenium can cause irritation and inflammation of respiratory system. Selenium can dilate capillaries, increase permeability and cause congestion and edema of lung and gastrointestinal tract. Selenium can catalyze cellular respiratory enzymes, interfere with intermediate metabolism, cause poisoning, and make people lose their hair and nails.
Mercury
Mercury and its compounds are highly toxic substances and can accumulate in the body. Inorganic mercury ions entering human body can be transformed into more toxic organic mercury, which enters human body through food chain and causes systemic poisoning. There is little mercury in natural water. Mercury may exist in industrial wastewater such as instrument factory, salt electrolysis, precious metal smelting and military industry.
Mercury and its compounds can be absorbed by human body through respiratory tract, digestive tract or skin. Minamata disease in Japan is caused by chronic methylmercury poisoning. Methyl mercury has high chemical stability and cannot be removed by various processing and cooking methods. Methylmercury is easily absorbed by intestinal mucosa (more than 80%). When intake exceeds excretion, it will accumulate in the body. Although the accumulation of methylmercury in brain tissue is not as good as that in other organs. The attenuation is very slow, and it has specific and selective damage to cerebral cortex and cerebellar cortex. Symptoms include decreased vision, hearing loss, paralysis and trembling of hands, feet and lips, unsteady gait, and unclear speech. In severe cases, neurological disorders and motor disorders occur, leading to crazy convulsions and death. Methylmercury can also enter the fetal circulation through the placenta and damage the fetus. The national standard requires that the mercury content in drinking water should be less than 0.001mg/L.
cadmium (Cd)
Cadmium is not an essential trace element for human body. In nature, cadmium usually appears in the form of sulfate, which is often associated with zinc ore and lead ore. In the vicinity of mining areas and smelters, cadmium accumulated in soil will lead to high cadmium concentration in some areas near water. The main pollution sources of cadmium are wastewater discharged from electroplating, mining, smelting, dyes, batteries, chemical industry and other industries.
Cadmium is a highly toxic substance with synergistic effect, which can increase the toxicity of other poisons entering the body. After entering human body, cadmium can accumulate in liver, kidney, pancreas and thyroid. Due to the toxic degeneration of renal tubules, the calcium absorption capacity decreases, which can cause pathological changes in bones, digestive tract and blood vessels, showing symptoms such as neuralgia, nephritis, osteomalacia, fracture, hypertension, anemia and endocrine disorder. Cadmium also has carcinogenic and teratogenic effects.
Japan's "pain disease" is named after the excessive accumulation of cadmium in the body, which leads to renal insufficiency. Calcium in bones is replaced by cadmium, which makes bones weak and prone to natural fractures. The incubation period of this disease is long, ranging from 10 to 30 years, and it is difficult to treat after onset. The national standard requires that the cadmium content in drinking water should be less than 0.01mg/L.
Chromium (hexavalent)
The common valence states of chromium compounds are trivalent and hexavalent. Influenced by pH value, organic matter, redox substances, temperature and hardness in water, trivalent chromium and hexavalent chromium compounds can be transformed into each other.
Chromium is one of the essential trace elements for human body. The toxicity of chromium is related to its valence state. It is generally believed that the toxicity of hexavalent chromium is 100 times higher than that of trivalent chromium, and hexavalent chromium is more easily absorbed and accumulated in the body. The industrial sources of chromium are mainly chromium-containing ore processing, metal surface treatment, leather kneading, printing and dyeing and other industries.
Hexavalent chromium compounds are harmful to human body, and have obvious local irritation and corrosiveness at high concentration, which can be absorbed through gastrointestinal tract, respiratory tract and skin. It is a common sensitizer at low concentration. Chromium entering the body is mainly distributed in liver, kidney, spleen and bones. Chromium has a certain accumulation and carcinogenic effect in the body. The national standard requires that the content of hexavalent chromium in drinking water should be less than 0.05 mg/L.
lead to
There is little lead in natural water. Wastewater from mineral processing plants, paint factories, smelters, battery factories and mines usually contains lead to varying degrees. Tetraethyl lead contained in automobile exhaust will cause water pollution due to rainwater leaching.
Children, infants, fetuses and pregnant women are more sensitive to lead than adults. Lead is a toxic metal. Lead can cause hemolysis, disturb the normal excitation and inhibition function of cerebral cortex, and cause a series of nervous system symptoms. Lead and its compounds mainly enter the body from the respiratory tract and digestive tract, mainly deposited in the skeletal system, and a small amount remains in organs such as liver, spleen, kidney, brain, muscle and blood. The national standard requires that the lead content in drinking water should be less than 0.05 mg/kg.
Nitrate (in nitrogen)
Tanning wastewater, pickling wastewater, effluent from some biochemical treatment facilities and farmland drainage may contain a lot of nitrate.
Nitrate in water is the most stable nitrogen compound in various forms of nitrogen compounds in aerobic environment, and it is also the decomposition product of nitrogen-containing organic matter in the final stage of inorganic action. Nitrite can be oxidized to nitrate, and nitrate can also be reduced to nitrite by microorganisms in anaerobic environment.
Nitrate is reduced to nitrite in human stomach, and it can also react with secondary amine to generate nitrosamine, which is generally considered to be a strong carcinogen. National standards require that nitrate nitrogen in drinking water should not exceed 20 mg/L.