Process for water purification from sulphureted hydrogen and/or sulphides

The invention relates to processes for the purification of hydrogen sulphide and / or sulphide groundwater and may be used in the process of treating groundwater or in stand-alone water treatment filters.

Water supply in the Republic is made in the proportion of about 30% of surface water and about 70% of groundwater. It was found that about 50% of the groundwater sources do not meet the standards established for drinking water, with increased concentrations of fluorine, total iron, ammonium ions, azophifes, and the content of hydrogen sulphide and its salts constitute 2 ... 10 mg /IT. It is known that the presence of hydrogen sulphide and sulphides in water not only diminishes its organoleptic qualities, but also leads to the deterioration of human health. Therefore, the removal of hydrogen sulphide and sulphide ions from water is a current problem. Currently, there is no groundwater purification in Moldova.

It is known the process of purification of hydrogen sulphide groundwater consisting of saturation of water with oxygen, its consecutive passage through an anthracite filter with a fraction of 2 ... 4 mm and a height of 450 ... 550 mm, then through a horn filter with the friction of 0.6 ... 1.8 mm and the height of

250 .. .350 mm. At the bottom of the anthracite filter is inserted an iron spiral with a length of

200 .. .250 mm [1].

The disadvantage of this process is that its realization requires a lot of capital investments and a high consumption of materials.

Also known is the process of purification of waters containing hydrogen sulphide and / or sulphides, which consists in that the water is initially passed through an ion exchange resin filter into a bicarbonate melt and modified with copper ions, which are in state. coordinating with the amine groups of the ion exchange resin. Thereafter, the water is passed through an active carbon filter modified with silver ions [2].

The disadvantage of this process is that the purification product includes two types of filters, which are expensive. The sulfide moieties are chemically absorbed on the ion exchange resin, which leads to the depletion of the anionite exchange capacity.

The process of purifying hydrogen sulphide and / or sulphide water is also known, consisting of the oxidation of sulphide ions in the presence of BAU-A activated carbon by bubbling the water with air at different pH values ​​[3]. The disadvantage of this process is that the sulfide ions oxidize to colloidal sulfur which blocks the pores of the activated carbon.

The problem solved by the present invention consists in the elaboration of a process for purifying hydrogen sulphide and / or sulfur water by catalytic oxidation of oxygen-reduced sulfur compounds from air with the predominant formation of high oxidation sulfur-soluble compounds (IV, VI).

The process of purifying water containing hydrogen sulphide and / or sulfides according to the invention includes aerating the water in the presence of oxidized activated carbon, for 30 ... 90 min, with an air flow of

10 .. .15 L / hour per 1 g of oxidized activated carbon, at a ratio of mass oxidized activated carbon: water of 1: (350 ... 450) and pH of water of 7.5 ... 8, 5.

According to Е.Ф. Золотова, Г.Ю. Асе Очистка воды от железа, фтора, марганца и сероводорода. Москва, Стройиздат, 1975, 178 с., Carrying out the process in the absence of activated carbon results in the elimination of hydrogen sulphide by aeration in the atmosphere. The use of conventional activated carbon (non-oxidized) leads to the prolongation of the purification process with the formation of a relatively large amount of oxidation products under colloidal sulfur. This causes pore blockage of the catalyst used.

The result of the invention is that the sulphide ions are mainly catalytic oxidized to high oxidation compounds, reducing to the formation of colloidal sulfur: about 28% of the sulphide ions are oxidized to the sulphite ions, 66% to the ions. of sulfate and 6% to colloidal sulfur.

Due to the fact that about 94% of the sulphide ions in the sulphite and sulphate ions do not block the pores of the catalyst with colloidal sulfur, the catalyst capacity is not exhausted.

Example of realization

Oxidized activated charcoal (CASO23) was prepared from activated charcoal (CAS23) obtained from peach kernels (Patent No. 1985, MD; T. Lupașcu, Studies of Changes in adsorption and structure characteristics of active carbons exposed to oxidation and adsorption of some heavy metals on oxidiyzed carbons // Scientific Annals of the University "Al. I. Cuza", boxes, Chemistry Series, volume VII, no. 2, 1999). ''

MD 2480 G2 2004.06.30 In a glass column with a diameter of 85 mm and a height of 300 mm a volume of 400 mL of water containing 10 mg / L sodium sulphide with a pH of 8.5 was introduced, to which was added 1 g of oxidized activated carbon with the fraction of 0.63 ... 1.00 mm. An air dispersion device using a mini pump pumped atmospheric air at a flow rate of 12 L / hour for 60 minutes. The mass ratio between oxygen and hydrogen sulphide undergoing oxidation was 3: 4. Such investigations were carried out both in the absence of the catalyst and in the presence of the non-oxidized active coal BAU-A and CAS23 (obtained from peach kernels). In the first case the process lasted 20 hours and the sulphuretted hydrogen was eliminated predominantly in the atmosphere by simple aeration. In the other cases, the process took 80 minutes, and as a result colloidal sulfur formed in the proportion of 20 ... 33%.

The concentrations of colloidal sulfur, thiosulfate, sulfite and sulfate ions were determined after the aeration process was completed. The obtained results are presented in the table below.

'Table

Concentration of species of sulfur ions in the process of treatment of hydrogen sulphide polluted water

<td rowspan="2">The amount of H₂S aerated,%</td><td colspan="4">The amount of H₂S oxidized to species,%:</td>

<td>S °</td><td>1 sec₂a₃'²·</td><td>1 sound? ·</td><td>1 sound / ·</td>

<td colspan="5">in the absence of activated carbon</td>

<td>67 I</td><td>Ιθ</td><td>J51</td><td> 1 16</td><td> 1 33</td>

<td colspan="5">in the presence of BAU-A active carbon</td>

<td> 9 1</td><td> 1 33</td><td> 31</td><td>H</td><td> 1 32</td>

<td colspan="5">in the presence of CAS23 non-oxidized activated carbon</td>

<td>12 I</td><td> 1 20</td><td>H</td><td>Оз</td><td> 1 63</td>

<td colspan="5">in the presence of CASO23 oxidized activated carbon</td>

<td>JI</td><td> 1 6</td><td>J 2</td><td> 1 28</td><td> 1 66</td>

The obtained results demonstrate that the process proposed in the invention allows to completely purify the groundwater containing hydrogen sulphide and / or sulfides.

(57) Claim: