Wastewater sterilization: completely new method “vortex layer machine”

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Wastewater treatment from hexavalent chromium and other heavy metals

The purification and safe disposal (neutralization) of industrial waste water effluents represent a very important ecological problem. The principal problem or requirement involves reducing the concentration of harmful impurities to concentration levels below their maximum allowable concentration limits. In fulfilling this requirement the amount of fresh water consumption needed to maintain the water level in the circulating or recycled water supply system is also reduced, and the operating life of production equipment or lines is concomitantly prolonged as a consequence of decreased corrosion and sediment formation or precipitation (scaling).

In many cases the use of traditional methods, such as settling or sedimentation tanks and ponds, or flotation devices, are not effective or efficient enough for operation, and so more advanced, progressive, and forced methods must be employed, such as treatment by Magnetic Vortex Activator AVS-100 (electromagnetic unit with velocity layer), for instance. The effect of electrophysical factors (electron acceleration, etc.) on contaminated water leads to rapid decomposition of many chemical impurities or contaminants to give inactive (non-harmful) substances.

Designed for last few years electromagnetic units with velocity layer have a wide usage today. These machines can be use by the different branches of industry for intensification of technological (chemical and physical) processes and even for treatment (sterilization, neutralization) of waste water.

From the large quantity of waste water types usually occurs waste water contaminated by chromic compound, fluorine, arsenic, phenol and other harmful and organic impurities. Such waste waters are characterized for the many of machine-building plants.

We have investigated the characteristics of waste water samples before (table 1) and after (table 2) treatment by AVS-100.

Table 1

Characteristics and content of industrial waste water

Parameters

Machine-building plants impurity concentration mg/dm3

food industry

Plants of other sectors

pH effluent

2-6

2-6,5

Cr6+

10-250

20-1000

Fe2+

50-150

10-200

Cu2+

30-120

15-150

Zn2+

20-150

20-170

Ni2+

up to 180

10-190

Cd2+

5-100

15-150

Weighted components

up to 300

up to 350

We have investigated the treatment effectiveness by using Magnetic Vortex Activator AVS-100 from two methods: Ith method – sterilization of chromium-containing wastewater by Cr6+ up to Cr3+ and using the reagent (sulfuric acid iron); IIth – combined neutralization and treatment from the heavy metals ions of chromium-containing wastewater and acid-base wastewater.

Intensifier of Technological Process AVS-100. General view

Intensifier of Technological Process AVS-100. General view

The process of chromium-containing waste water purification is as follows. The waste waters which contain the specific hexavalent chromium concentration at the rate of 10-15 m3/h from the flow-equalization basin enter the AVS-100. At the same time from the consumption tank by dosing pump to the AVS-100 deliver project quantity of ferrous [iron] sulfate solution (concentration 30-60 g/dm3). At the AVS-100 carry out the waste water treatment by FeSO4 solution, as result occurred regeneration of Cr6+ to the value Cr3+. Completeness of chromium regeneration was verified by the proximate analysis using the diphenilcarbazide and also by the colorimetric method. Sterilized waste waters entered to the neutralization and purification from trivalent chromium. During the research we was changed the consumption of ferrous [iron] sulfate from 80 to 100 % depending of: its stoichiometric consumption; pH environment from 2 to 4 during the regeneration of Cr6+ in the acid environment and from 7,5 to 9,0 in the alkaline condition. To alkalize the wastewaters we used the lime milk solution. Ferromagnetic particles are made from the steel DIN (WNr), mass is 150-250 g, diameter is 2,0-2,5 mm and l/d=10. Duration of treatment at the vortex layer is 0,5-1,5 c. Basic concentration of Cr6+  was changing from 100 to 1000 mg/dm3.

Another sterilization results of chromium-containing waste water by AVS-100

Basic characteristic of waste water

Consumption of FeSO4,
from stoichiometric value, %

Cr6+ content after treatment, mg/l

pH value

Amount of

Cr, mg/l

 

0,5

460

100

0,5

43

100

0,5

460

90

5

83

100

5

83

90

5

83

80

0,3

0,8

76,5

100

0,8

76,5

90

0,8

2200

100

4

103

100

4

103

90

4,5

1100

100

4,5

1100

90

4,5

1100

80

0,5

The results of industrial testing of AVS-100 show the high quality of treatment from chromium and heavy metals (Fe, Ni, Zn, Cu, Cd) on enterprises which clean chromium-containing wastewater in acid and alkaline conditions. At the same time consumption of reagents in installation AVS-100 is 90-100% of from stoichiometric consumption. Treatment facilities and their operation with using vortex layer of ferromagnetic particles are much simpler and efficient which is confirmed by our experimental investigations. Consumption of reagent such as additive (Ca(OH)2, Na2CO3 in the regular methods of treatment is on level 115-120% and consumption of reducing agent (FeSO4) is on level 150-175%.

Results of industrial research of units AVS-100 represented in table 2.

Table 2

The sterilization results of chromium-containing wastewater by AVS-100

Basic concentration value Cr6+, mg/dm3

pH process

Consumption of iron sulfate,
% from stoichiometric consumption

Ferromagnetic element mass, g

Residual Cr6+ content after purification, mg/dm3

100

2

100

150

0

90

0

80

0,56

100

4

90

150

0

80

0,9

590

2

100

200

0

90

0

80

0,8

1000

2,5

100

200

0

90

0,11

80

1,1

200

7,5

100

150

0,012

200

9,0

100

150

0

90

0,05

80

0,98

750

7,5-8,5

90

200

0,1-0,01

Neutralization of acid-base, sterilized, chromium-containing wastewaters and metal hydroxide formation was testing at the same installation by using AVS-100. As reagent was used 5-10% lime milk solution. Value of pH process was changing in the range of 7,5-9,0. Results of testing represented in table 3.

Table 3

Results of neutralization and treatment of wastewater from heavy metals ions by using industrial installation and AVS-100.

Basic metal concentration, mg/dm3

pH process

Consumption of Ca(OH)2,
% from stoichiometric consumption

Ferromagnetic element mass, g

Residual metal content, mg/dm3

Fe2+;3+= 130,0

7,5

90,0

200,

Fe2+;3+ –  0
Cu2+= 50,0 Cu2+ –  0,12
Zn2+= 45,0 Zn2+ –  0,063
Cd2+= 10,0 Cd2+ –  0,07
Cr3+= 120,0 Cr3+ –  0
Fe2+;3+= 170,0

8,5

100,0

150

Fe2+;3+ –  0
Cu2+= 40,0 Cu2+ –  0,018
Zn2+= 28,0 Zn2+ –  0
Cd2+= 5,5 Cd2+ –  0,011
Cr3+= 100,0 Cr3+ –  0
Fe2+;3+= 250,0

8,7

100,0

200

Fe2+;3+ –  0
Cu2+= 65,0 Cu2+ –  trace
Zn2+= 35,0 Zn2+ –  trace
Cd2+= 2505 Cd2+ –  0
Cr3+= 350,0 Cr3+ –  0

At the same time we investigated method of industrial treatment using the mechanical mixing by flowmaker and also by using barbotage of air. By industrial technology consumption of lime milk is on a level 115-120% from stoichiometric consumption. Mixing time of wastewater with reagent is 15-20 min.

The following figures show comparative dependence effectiveness of wastewater treatment from heavy metals and also clarification of wastewater in the settling tank by using AVS-100 and reactors with the mixing machine.

Installation AVS-100 permit to provide the treatment quality below the maximum permissible concentration, reduce the consumption of reagent in 1,5 – 2 times and consumption of energy in 2 times, reduce the working area in 10-15%, it gives high economic benefits.We investigated the process of reclamation of chromium by regular reagent method using the barbotage by air with processing time 15-20 minutes to compare effectiveness of wastewater treatment from chromium in industrial conditions.

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обновлено: February 14, 2014 автором: oksana