The obtained solution goes to an electrolytic cell 4 where at the
fixed voltage process of electrolysis is spent, with excretion of arsenic:
.
As a result of salvaging sewage, on an offered way, 95.0 % metal
arsenic which can be used in different areas, for example, in radio electronics
or the industry are received.
Investment appeal scientific and technical results
We shall spend estimation of cost of salvaging of sewage from the
installations having following indexes: productivity W=70 m3/hour
on treated water, initial concentration of arsenic 45
μg/L
and
operation in current of 5 years.
Cost of investment cost, for installation we shall accept
€40000, in view of expenses for the attendants - 70 000 € for
five years.
Productivity of installation of salvaging of sewage 3.5 m3/h
(at productivity of installation on water treatment from arsenic W=70 m3/hour)
with concentration of arsenic 700
μg/L.
Total expenses for purification of sewage from arsenic will make: 0.012
€/m3+0.017 €/m3=0.029 €/m3.
As a result of salvaging sewage 22 kgs of 95.0 % of metal arsenic
(can be used, for example, in radio electronics or other areas of the industry,
market cost makes nearby 800€/kg),
in view of realization of metal arsenic are received, total expenses for
purification of sewage from arsenic will drop up to 0.02 €/m3.
![Подпись: 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 and methods of removal of a dangerous drains.
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 €/m3.
In the conclusion it is necessary to note, that in work [EPA/600/R-04/201 December 2004, United States] there is no information on methods and ways of salvaging of toxic sewage and the adsorbents polluted by arsenic. Means, the results received above on expenses do not consider such important factor, as the salvaging, a dangerous drains (coagulation/filtration, ion exchange) or a phase of adsorbent (the adsorptive methods), containing arsenic.
Salvaging of a dangerous drains containing arsenic
As a result of the analysis of the patent literature it is not found effective technologies which would solve a problem of salvaging of sewage containing arsenic without formation of dangerous waste.
For the decision of a problem of salvaging of the sewage containing raised concentration of arsenic, the electrochemical way based on electrochemical excretion of 95.0 % of powdery metal arsenic from solutions containing acid anionic form is offered.
Fig. 1 The principal scheme of installation on salvaging arsenic of drains
Index compound of arsenic which is formed at purification of potable waters (the technologies considered in partitions 2 and 3), the solution with high concentration of arsenate of sodium NaН2AsO4.
To carry out electrochemical decomposition NaН2AsO4 by electrolysis to one stage with excretion of arsenic it is impossible.
For the decision of this problem it is offered to spend process of electrochemical processing in two stages.
The principal scheme of installation on salvaging arsenic of containing waters is presented in figure 1. Sewage 1 (fig. 1), containing anions Н2AsO4-(рН 6-8) enters in tank 2 where by means of addition Na2CO3 hydrogen ionization value up to value 12-13 is adjusted. At such value рН anions Н2AsO4- are transformed in AsO43- (partition 1 of the design). Further the water containing anions AsO43- goes to an electrolytic cell 3 where at the certain voltage process of electrolysis is spent:
.
The obtained solution goes to an electrolytic cell 4 where at the fixed voltage process of electrolysis is spent, with excretion of arsenic:
.
As a result of salvaging sewage, on an offered way, 95.0 % metal arsenic which can be used in different areas, for example, in radio electronics or the industry are received.
Investment appeal scientific and technical results
We shall spend estimation of cost of salvaging of sewage from the installations having following indexes: productivity W=70 m3/hour on treated water, initial concentration of arsenic 45 μg/L and operation in current of 5 years.
Cost of investment cost, for installation we shall accept €40000, in view of expenses for the attendants - 70 000 € for five years.
Productivity of installation of salvaging of sewage 3.5 m3/h (at productivity of installation on water treatment from arsenic W=70 m3/hour) with concentration of arsenic 700 μg/L. Total expenses for purification of sewage from arsenic will make: 0.012 €/m3+0.017 €/m3=0.029 €/m3.
As a result of salvaging sewage 22 kgs of 95.0 % of metal arsenic (can be used, for example, in radio electronics or other areas of the industry, market cost makes nearby 800€/kg), in view of realization of metal arsenic are received, total expenses for purification of sewage from arsenic will drop up to 0.02 €/m3.](salvaging1.files/image010.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 |
Productivity, m3/h |
As, μg/l |
Product., m3/year |
Regeneration, €/year |
First year, €/m3 |
Five years, €/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 |
