水中磷與分析 Phosphorus
Why Phosphorus Testing, Measurement and Analysis Matter to Water Quality 為什麼磷的測量和分析對水質很重要?
Measuring phosphate in wastewater effluents and source water is critical to maintaining a healthy ecosystem and protecting wildlife. High levels of phosphates can accelerate types of algae and plant growth. This in turn can lead to eutrophication and algae blooms. When this occurs, fish and aquatic life are robbed of oxygen.
Measuring phosphate in wastewater effluents and source water is critical to maintaining a healthy ecosystem and protecting wildlife. High levels of phosphates can accelerate types of algae and plant growth. This in turn can lead to eutrophication and algae blooms. When this occurs, fish and aquatic life are robbed of oxygen.
測量廢污水和源水中的磷酸鹽對於維持健康的生態環境系統和保護野生動物很關鍵。高濃度的磷酸鹽可以加速藻類和植物的生長。又會導致水體富營養化和藻類大量繁殖。因而造成魚類和水生生物缺氧。
Failing to sufficiently measure and monitor phosphate levels can have a variety of adverse outcomes including the following 未能充分量測和監測磷酸鹽濃度可能會產生多種不良後果，包括 :
- Violations of strict phosphate discharge limits that could result in fines 違反嚴格的磷酸鹽排放限值可能會受到罰款
- Corrosion in drinking water distribution systems 飲用水配水系統的腐蝕
Which Processes Require Phosphorus Monitoring 哪些程序需要監測水中磷濃度?
Wastewater Treatment 廢污水處理
Phosphorus is an essential nutrient for plants and specifically for algae growth. The discharge of phosphorus, along with other essential nutrients in the wastewater effluent, stimulates algae growth in the streams receiving the wastewater discharge. Algae causes taste and odor problems, is aesthetically unpleasing and most importantly, creates enormous oxygen demand when algal bloom dies off. The depletion of oxygen caused by the dying algal blooms is toxic to fish and causes other significant disruptions to the aquatic environment. For these reasons, regulatory agencies often strictly regulate the amount of phosphorus allowed in wastewater discharges.
磷是植物和藻類生長必需的營養物質。磷和廢污水中其他必需營養物的排放會刺激接收廢污水的溪流中藻類的生長。藻類會造成味道和氣味問題，最重要的是，當藻類死亡時造成的氧氣耗盡對魚類有毒性，並對水生環境造成其他嚴重損害。基於這些原因，環境監管機構通常會嚴格管制廢污水排放中允許的磷濃度。
The most common methods for removing phosphorus from wastewater are biological removal and chemical precipitation. These processes are typically referred to as tertiary treatment and require phosphorus monitoring.
去除廢污水中磷最常見的方法是生物去除和化學沉澱。這些程序通常被稱為三級處理，並需要監測磷的濃度。
去除廢污水中磷最常見的方法是生物去除和化學沉澱。這些程序通常被稱為三級處理，並需要監測磷的濃度。
Drinking Water 飲用水
Source water may contain elevated concentrations of phosphates due to agricultural runoff, which may cause eutrophication of surface water with algae growth and release of cyanotoxins. Condensed phosphates are often used for corrosion control in drinking water distribution systems, therefore drinking water treatment processes may require monitoring for phosphate in both raw and distributed finished water. 由於農業徑流，源水中的磷酸鹽濃度可能升高，這可能導致地面水優養化、藻類生長和藍藻毒素的釋放。縮合磷酸鹽通常用於飲用水配水系統的腐蝕控制，因此飲用水處理程序可能需要監測原水和分配的成品水中的磷酸鹽濃度。
How is Phosphorus Monitored 如何監測水中磷濃度 ?
Colorimetric Methods (Orthophosphate) 比色法（正磷酸鹽）
Orthophosphate (reactive phosphorus) is combined with molybdate in an acidic medium to produce either a blue or yellow color. Be aware that no analytical test is perfect and some condensed phosphates may be measured with these tests too. Due to the acidic chemistry, some suspended orthophosphate may be detected if the sample was not first filtered to 0.45 micron.
To measure all phosphorus including the particulate phosphates, it is necessary to use a total phosphorus test, which incorporates rigorous digestion to convert most of the particulate phosphate to dissolved format.Orthophosphate (reactive phosphorus) is combined with molybdate in an acidic medium to produce either a blue or yellow color. Be aware that no analytical test is perfect and some condensed phosphates may be measured with these tests too. Due to the acidic chemistry, some suspended orthophosphate may be detected if the sample was not first filtered to 0.45 micron.
Acid Hydrolyzable Phosphate/Condensed Phosphate 酸水解磷酸鹽/縮合磷酸鹽
To measure condensed phosphates, it is first necessary to transform them into orthophosphate using sulfuric acid and heat, digesting the sample at 150°C for 30 minutes. This is called “acid hydrolyzable phosphate” since the condensed phosphates are hydrolyzed into orthophosphate. After the digestion, either the ascorbic acid or molybdovanadate methods are used to measure the orthophosphate. Some organic phosphate will be hydrolyzed into orthophosphate as well, so the results are not “pure” condensed phosphate.
To measure condensed phosphates, it is first necessary to transform them into orthophosphate using sulfuric acid and heat, digesting the sample at 150°C for 30 minutes. This is called “acid hydrolyzable phosphate” since the condensed phosphates are hydrolyzed into orthophosphate. After the digestion, either the ascorbic acid or molybdovanadate methods are used to measure the orthophosphate. Some organic phosphate will be hydrolyzed into orthophosphate as well, so the results are not “pure” condensed phosphate.
Of course, just performing the digestion and colorimetric test will tell you the concentration of both the original orthophosphate and condensed phosphates. If you want just the condensed phosphate concentration, then simply run the orthophosphate test on the same sample without a digestion and subtract those results from the first concentration value.
Total Phosphorus/Organic Phosphate 總磷/有機磷酸鹽
Organic phosphates are stubborn compounds that do not like to break down easily. To test for them, it is necessary to not only digest the sample first with sulfuric acid and heat, but also add a strong oxidant such as potassium persulfate to break the orthophosphates free from the organic bonds. After digestion, the same ascorbic acid or molybdovanadate methods can be used to measure the phosphate concentration. The described test will convert all the different forms of phosphate into orthophosphate, which means the results are total phosphorus.
If you want to know only the organically bound phosphate concentration, it is necessary to perform the acid hydrolyzable test and subtract those results from the total phosphorus concentration (total phosphorus concentrations will always be larger than the orthophosphate concentration).
What is phosphorus 什麼是磷 ?
Phosphorus (P) is a chemical element with an atomic number of 15 and an atomic mass of 31. Due to its high reactivity, phosphorus does not naturally exist as a free element. Phosphorus generally occurs as phosphate in minerals. Phosphate is typically found in the Earth’s crust at a concentration of about 1 gram per kilogram.
The two types of elemental phosphorus are white phosphorus and red phosphorus. When exposed to oxygen, white phosphorus emits a faint glow caused by oxidation (also known as chemiluminescence).
Phosphorus belongs to the pnictogen group of elements which consists of nitrogen, phosphorus, arsenic, antimony, bismuth and ununpentium (recently assigned the name moscovium). These elements are grouped because of their similar atomic structure, which lends them the ability to form stable compounds due to their tendency to form double and triple covalent bonds. Except for nitrogen (which remains a gas), the other pnictogens are solids at room temperature.
Complex organisms such as plants and animals need phosphorus because phosphates are a component of DNA, RNA, ATP and phospholipids. Phosphorus is mined for use in detergents, pesticides, nerve agents and predominantly fertilizers.
Phosphates/Orthophosphate
In orthophosphate (one of the most common phosphates), one phosphorus atom is bonded to four oxygen atoms. Orthophosphate is sometimes called “reactive phosphorus” because it bonds easily with other electron-deficient elements and compounds since the three “extra” electrons on the oxygen atoms strongly want to bond with protons alike.
In orthophosphate (one of the most common phosphates), one phosphorus atom is bonded to four oxygen atoms. Orthophosphate is sometimes called “reactive phosphorus” because it bonds easily with other electron-deficient elements and compounds since the three “extra” electrons on the oxygen atoms strongly want to bond with protons alike.
Condensed Phosphates
Condensed phosphates are multiple orthophosphate molecules “condensed” together and sharing a covalent bond between adjoining phosphorus (P) and oxygen (O) atoms. This group includes metaphosphate, pyrophosphate and polyphosphate — which are often used for corrosion control in drinking water distribution systems.
Condensed phosphates are multiple orthophosphate molecules “condensed” together and sharing a covalent bond between adjoining phosphorus (P) and oxygen (O) atoms. This group includes metaphosphate, pyrophosphate and polyphosphate — which are often used for corrosion control in drinking water distribution systems.
Total phosphorus is a sum of all the phosphorus present: orthophosphate/phosphates, condensed phosphates and organic phosphorus. Organic phosphorus is usually present in the form of phosphates contained inside or bonded to an organic compound.