![Ïîäïèñü: Introduction
Inorganic impurity of arsenic are classified as group And carcinogens of the human body. Arsenic can cause disease of skin, a cancer of lungs, kidneys and a liver, and also damage of the central nervous system. Naturally occurring arsenic is often found in groundwater in different parts of the world. It is assumed that naturally occurring arsenic in drinking water supplies have been affected more than 100 million people worldwide, including countries such as Bangladesh, India, China, Mongolia, Taiwan, Vietnam, Thai1and, Cambodia, Chile, Argentina, Mexico, Germany, Hungary, Romania, Slovakia and the United States.
The European standard positions a marginal level of impurity level of arsenic in potable water — 10 μg/l [Council Dir. 98/83/EC].
In Table1 present maximum water concentrations of total inorganic arsenic in the Hungarian, Romanian and Slovakian regions.
Table 1 Maximum water concentrations of total inorganic arsenic in the Hungarian, Romanian and Slovakian regions.
a Jasz-Nagykun-Szolnok. b Banská Bystrica.
The analysis of data presented in tabl.1 shows, that performance of the European standard on quality of potable water in these and other regions is connected with modernization installations of water purification.
Review of methods of arsenic removal from water
In table 2 expenses gone on purification 1 m3 waters [EPA/600/R-04/201 December 2004, United States] from arsenic are presented at the maximal productivity of considered systems (AM=the adsorptive method; C/F=coagulation and filtration; IX=ion-exchange) that is in the assumption, that systems of purification are operated 24 hours per day. For estimation of cost we shall consider two time slices of operation of systems of purification: the-first interval-1 year of operation and the second interval-5 years of operation.
Table 2 Cost of purification of m3 waters from arsenic
Thus, for all considered methods of purification resulted in table 2 (the adsorptive, coagulation/filtration, ion exchange) cost of water treatment from arsenic lays within the limits of from 0.21 till 0.27 ˆ/m3.
Development of purification water from arsenic
The significant charge of reagents and the high operational expenses connected with it negatively affect technical and economic indexes modern methods of purification of potable waters from arsenic.
The offered technology falls into to an electromembranous method of purification natural and the sewage containing connections of arsenic. The principal scheme of installation is presented on figure 1. The water containing impurities of arsenic (1) enters in the first electrochemical ion-exchange filter (2).
At movement of a water stream through the filter there is a replacement (ion exchange) of cations of salts of hardness with cations of sodium. Water, free of cations of salts of hardness, moves in the coal filter (3).
Fig. 1 The principal scheme of installation
After that, water goes to an electrodialyzer (6). The electrodialyzer, consists from cation-exchange, anion-exchange membranes and electrode chambers. The package of an electrodialyzer contains set of chambers of desalting and concentrating. Water enters in chambers of desalting, passes purification. The part of a stream of the water entering from the coal filter goes on washing of chambers of concentrating of an electrodialyzer. The concentrate goes on salvaging. The ions of sodium removed at electrodialysis it is compensated by the ions of sodium added through tank of salt (4), for reception of oxidizers in a vortical electrochemical reactor (5). After the dearsenication, cleared water enters in the second electrochemical ion-exchange filter (8). Cation exchanger is in the calcium -magnesian form. Electrodes of the second ion-exchange filter are connected to a source of a direct current. Under action of an electric current ion of salts of hardness pass in water, and ions of sodium are sorbed by cation exchanger. There is an electrochemical regeneration of the second ion-exchange filter. On escaping of installation (9) the water containing all useful for ability to live of the person ions, except for carcinogenic anions of connections of arsenic is received. The variation of a voltage on the second ion-exchange filter (8) allows receiving drinking water with the various contents of ions of salts of hardness by means of what it is possible to receive potable water for people with various physiological needs for calcium's and magnesium's.
Investment appeal scientific and technical results
We shall carry out calculation of cost of water treatment from arsenic with use electromembranous technologies at productivity W=70 m3/hour, initial concentration of arsenic 45 μg/L and operation within 5 years. Cost of membranes at calculation is taken 150 ˆ/m2 (Japanese commercial membranes ÑÌÕ, ÀCS).
According to calculations lead operational expenses on water treatments from arsenic has made 0.085 ˆ/m3. Investment cost, we shall take from, for installation system Fraitland, IX (ˆ120 000 without taking into account cost of membranes - are considered in operational expenses), in view of expenses for the attendants - 200 000 ˆ for five years. Total expenses for water treatment from arsenic will make: 0.085 ˆ/m3+0.062 ˆ/m3=0.147 ˆ/m3.
At operation of offered systems of water treatment from arsenic (productivity 70 m3, initial concentration of arsenic 45 μg/L, - 5 years) will make the period of operation nearby 200 000 ˆ, in comparison with the most economic technologies of arsenic removal (coagulation/filtration and ion exchange).
In the conclusion, that offered to investment appeal technologies of water treatment from arsenic possess a number of advantages: technical and economic indexes, simplicity of hardware decor, in comparison with the most economic technologies of arsenic removal which now are used in a world practice for a problem of arsenic removal from potable water. It causes investment appeal and a simple yield on the market of the water-purifying equipment.](Arsenic1.files/image011.gif)
|
Country |
Hungary |
Romania |
Slovakia | |||||
|
Area |
Bacs |
Békés |
Csongrad |
J-N-Sa a |
Bihor |
Arad |
B Bb |
Nitra |
|
As, μg/l |
39 |
31 |
40 |
88 |
24 |
95 |
37 |
39 |
|
Area, method |
Product., m3/h |
As, μg/l |
Product., m3/year |
Regeneration, ˆ/year |
First year, ˆ/m3 |
Five years, ˆ/m3 |
|
Rimrock, AM |
24 |
50 |
210240 |
18181 |
0,41 |
0,27 |
|
Climax, C/F |
38 |
39 |
332880 |
- |
0,58 |
0,21 |
|
Fraitland, IX |
68 |
44 |
595680 |
40094 |
0,45 |
0,21 |