Method for removing phosphorus in wastewater
A phosphoric acid and hydroxyapatite technology, applied in chemical instruments and methods, water pollutants, water/sewage treatment, etc., can solve the problems of not being able to filter sludge, unable to effectively remove phosphoric acid ions, and increasing treatment costs.
Inactive Publication Date: 2007-09-05
NIPPON CHECMICAL IND CO LTD
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Problems solved by technology
At this time, there is a problem that fine hydroxyapatite crystals are formed, the liquid becomes milky white and turbid, and phosphate ions cannot be effectively removed.
However, in this method, since a flocculant is used, the treatment cost increases, and there is a problem that sludge with excellent filterability cannot be obtained.
Method used
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Embodiment 1、2 and comparative example 1
[0036] The dephosphorization treatment of phosphoric acid-containing wastewater is carried out using the treatment device 10 shown in the flowchart shown in FIG. 1 . In addition, the first crystallization tank 1 and the second crystallization tank 2 are fully mixed tanks with a diameter of 2400mm, a height of 4200mm, and an effective volume of 16m 3 , there is a settling tube with a diameter of 600mm and a height of 2700mm in the center of the tank and under the water surface, and a variable speed mixer with a diameter of 550mm is equipped inside the settling tube. flow.
[0037] First, the raw water containing phosphoric acid discharged from various facilities is introduced into the raw water tank 4 through the pipe 41, and mixed in the raw water tank 4 to make the concentration uniform. As a result, the phosphoric acid-containing wastewater in the raw water tank 4 had the composition shown in Table 1. In addition, the calcium chloride sludge in the calcium chloride storage...
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Abstract
A method for removing phosphorus in wastewater, which comprises a first crystallization step of reacting, in a first crystallization vessel, a phosphorus-containing wastewater, calcium chloride and a recycled hydroxyapatite slurry recycled form a precipitation tank and crystallizing, while adjusting the pH of the reaction mixture by the use of a pH-adjusting agent, a second crystallization step of feeding the slurry formed in the first step to a second crystallization vessel, adding calcium chloride to the slurry, to carry out further reaction and crystallization at a pH higher than that in the first crystallization vessel and of 11 or lower, and a step of feeding the slurry formed in the second step to a precipitation tank, carrying out precipitation and separation, discharging a resultant supernatant to the outside of the system as a treated water, and recycling most of the resultant concentrated slurry as the above-mentioned hydroxyapatite slurry. The above method allows the removal of phosphorus in a waste water without the use of a coagulant and also the formation of a hydroxyapatite excellent in filtration and dewatering characteristics from a phosphorus-containing waste water.
Description
technical field [0001] The present invention relates to a method for dephosphorizing wastewater, and more specifically, to a method for dephosphorizing wastewater in which hydroxyapatite is sedimented and separated from wastewater containing phosphoric acid without using a flocculant. Background technique [0002] In recent years, pollution of closed water areas such as inland seas and lakes has become a problem, and one of the causes of the pollution is eutrophication by phosphorus compounds. Therefore, various methods of dephosphorization treatment of phosphorus-containing wastewater have been considered so far. Among them, JP-A No. 56-33082 of Patent Document 1 discloses phosphate-containing water in the presence of calcium ions, after being contacted with calcium phosphate-containing seed crystals, and then in contact with activated alumina. Approach. In addition, Japanese Unexamined Patent Publication No. 58-143884 of Patent Document 2 discloses a method in which orga...
Claims
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IPC IPC(8): C02F9/04C02F9/02C02F1/58C02F1/66B01D9/02C02F1/52
CPCC02F1/5245C02F1/5236C02F2101/105C02F1/66C02F2209/06C02F1/5209C02F1/58
Inventor 青木绿朗稻垣甫
Owner NIPPON CHECMICAL IND CO LTD