SU916429A1 - Method for purifying acid manganese- and iron-containing effluents - Google Patents

Description

The invention relates to the purification of sour effluent water containing manganese and iron, and can be used in water supply systems for various purposes in the metallurgical, chemical and other industries. ^five

Known household water purification method from iron and manganese, comprising ^one oxidation of iron and manganese in the presence of filter aeration sludge containing ferric hydroxide and margan- ^'0 tsa, and filtering through a filter containing the hydroxide t.

The disadvantage of this method is; that it can be used to clean water with a low iron content of ' ⁵ and manganese (less than 0.01 g / l) and cannot be used to clean industrial waste water with a high content of iron and manganese.

The closest to the technical essence of the ²⁰ proposed is a method of wastewater treatment, in which water to extract manganese from it and

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iron is treated with calcium hydroxide and polyacrylamide coagulant and the precipitate is separated [2].

The disadvantage of this method is that in the cleaning process receive bulk precipitate, poorly amenable to filtration.

The purpose of the invention is to reduce the volume of sediment and increase the speed of its filtration.

This goal is achieved by the fact that before treatment with calcium hydroxide waste water is subjected to aeration with air and treated with sodium hypochlorite.

Preferably, aeration with air is carried out in an amount of 0.003-0.007 nm of air per 1 g of metal, and sodium hypochlorite is treated in an amount of 0.1– ^: 0.2 g (in active chlorine) per 1 g of metal.

With aeration of water with air in the presence of-. sodium hypochlorite, iron from the divalent state becomes trivalent, and manganese from divalent

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state goes to tetravalent, which contributes to the formation of a compact well-filtered sediment during the treatment of waste water with lime.

The method is as follows.

Acidic water having a pH of 1.5-2.2 and containing sulphates of iron and divalent manganese is subsequently aerated with compressed air at a rate of 0.003-0.007 nm® per 1 g of metal, and then treated with sodium hypochlorite at a rate of 0.1-0 2 g of active chlorine per 1 g of metal. At the same time, iron and manganese are oxidized.

After oxidation, the wastewater is neutralized with lime milk to a pH of 10-10.5.

Oxidized and treated with lime milk water defend and filter. After aeration of waste water with air, water before treatment with hydro-calcium oxide can be treated not with sodium hypochlorite, but chlorine

lime, which is a source of sodium hypochlorite.

For example. Sour water with a pH of 1.6, containing manganese in the amount of

5 4.63 g / l and iron 0.5 g / l in the cylinder

I l volume is aerated with compressed air in the amount of 0,026 nm® per 1 l of treated water (0.005 nm ® air per 1 g of metal) and treated

<0 7.7 ml of sodium hypochlorite solution per 1 l of treated water (0.15 g of active chlorine per 1 g of metal).

After pre-oxidation, the water is neutralized with lime milk.

15 with a concentration of 5% in the amount of 3035 ml per 1 l of treated water. After that, the suspension is settled for 3 hours, and the condensed drain is filtered under a pressure of 2 MPa, the manganese content

20 in water after purification of 3 mg / l and iron 0.7 mg / l.

The table presents the comparative data after purification of acid wastewater from iron and manganese using known and proposed methods.

g ¹ Method Volume samples source the solution ml Reagent costs Volume of condensed draft after 3 hours settling ml Quo ι growth filtering lower plum, g / m ^ per hour solid Compressed air (P = 1.5 ati), nm ^a / g metal Chlorine lime in terms of active chlorine, • g / g metal Polyacrylamide 8% percent solution, mg Lime for liming to pH 10-10.5 ml of 5% concentration Offer 1000 0,003 0.1 BUT- 30-35 125 2.5 the guy 1000 0,005 0.15 - 30-35 100 3 1000 0,007 0.2 - 30-35 70 four Famous 1000 0.15 1.5 100 320 Less one

As can be seen from the data in the table, the pre-trusting oxidation of water with compressed air and., Sodium hypochlorite reduces the volume of sediment formed after treatment of water with calcium hydroxide and settling, by 2.8-5 times 55

compared to the known method.

By increasing the compactness of the precipitate containing manganese hydroxide and iron of higher valences than in the known method, the filtering rate of the precipitate increases, which contributes to improving the performance of water purification from manganese and iron, which allows to obtain a much larger amount of purified water that is not dumped, but used in the technological circuit for feeding systems

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water recycling wet gas purifiers.

Claims (2)

Claim 1. The method of purification of acidic manganese and iron-containing wastewater, including 5 units of treatment with calcium hydroxide and. separating the sediment, characterized in that, in order to reduce the volume of the sediment and increase the rate of its formation, the waste water is subjected to aeration with air and treated with sodium hypochlorite before being treated with calcium hydroxide. 2. The method according to π. I, about tl and h a gaga and th with I that the air is aerated in the amount of 0.003-0.007 nm ^{3 of} air per 1 g of the metal, and sodium hypochlorite is treated in the amount of 0,, 2 g (in active chlorine ) on 1 g of metal.