Process and apparatus for destroying hexavalent chromium in solution

Claim 3

The apparatus recited in claim 1 wherein a reducing agent additive unit is connected in series with said first detention unit, a means of detecting oxidation, reduction potential, and a means of correcting amount of reducing agent additive by means of a proportionate controller in order to achieve exactly the correct amount of reduction agent, and said second detention unit is connected in series with said reducing agent additive unit and said sensing and controlling means.

Claim 4

The apparatus recited in claim 1 wherein a third series of circuit elements is connected in series with said mentioned elements, said third circuit elements comprising a caustic additive unit, a third detention chamber and a second pH sensing unit, said second pH sensing unit having means thereon for selectively directing material from said third detention chamber to said settling chamber and to recirculate said material to said caustic unit if the pH is below a predetermined level, said second pH sensing unit being connected to a third proportional controller whereby regulation is achieved to inject exactly the correct amount of alkaline material to obtain desired pH.

Claim 5

The apparatus recited in claim 2 wherein a third series of circuit elements is connected in series with said mentioned elements, said third circuit elements comprising a caustic additive unit, a third detention chamber and a second pH sensing unit, said second pH sensing unit having means thereon for selectively directing material from said third detention chamber to said settling chamber and to recirculate said material to said caustic unit if the pH is below a predetermined level, said second pH sensing unit being connected to a third proportional controller whereby regulation is achieved to inject exactly the correct amount of alkaline material to obtain desired pH.

Claim 6

The apparatus recited in claim 3 wherein a first sight-glass, a second sight-glass, a third sight-glass, and a fourth sight-glass are disposed in said circuit, said first sight-glass being disposed prior to said acid injection point, said second sight-glass being disposed following said first detention chamber, said third sight-glass being disposed in circuit adjacent said second detention chamber, and said fourth sight-glass being disposed adjacent said third detention chamber.

Claim 7

The apparatus recited in claim 3 wherein a reducing agent injection means is connected in series with said circuit between said acid addition unit and said third circuit element, and a second retention chamber is provided and an oxidation reduction potential unit is connected to said circuit and means connected to said oxidation reduction potential unit whereby said material will be diverted when the oxidation reduction potential is at a predetermined value.

Claim 10

A chromate destruction module comprising a raw waste source, a treated waste sump, a circuit connecting said treated waste sump to said raw waste source, said circuit comprising a first detention means and a second detention means, and a third detention means, means connecting said detention means in series with each other, and said means connecting said detention means in series comprising a first pH sensing device for selectively recirculating said liquid to said raw waste source when said pH is above a predetermined value and connecting said circuit to said second detention means when said pH is below a predetermined value and continuously adjusting volume of pH adjusting additive such that proper pH is obtained, said circuit further comprises means to inject caustic into said circuit between said second detention means and said third detention means and means for recirculating said liquid from said circuit between said third detention means and said second detention means when the pH of said liquid at said treated waste sump has a pH below a predetermined value and transferring said liquid from said circuit between said third detention means and said treated waste sump when the pH of said liquid has a pH above a predetermined value.

Claim 11

A chromate destruction module comprising a raw waste source, a treated waste sump, a circuit connecting said treated waste sump to said raw waste source, said circuit comprising a first detention means and a second detention means, and a third detention means, means connecting said detention means in series with each other, and said means connecting said detention means in series comprising a first pH sensing device for selectively recirculating said liquid to said raw waste source when said pH is above a predetermined value and connecting said circuit to said second detention means when said pH is below a predetermined value and continuously adjusting volume of pH adjusting additive such that proper pH is obtained, said circuit further comprises means to inject caustic into said circuit between said second detention means and said third detention means and means for recirculating said liquid from said circuit between said third detention means and said second detention means when the pH of said liquid at said treated waste sump has a pH below a predetermined value and transferring said liquid from said circuit between said third detention means and said treated waste sump when the pH of said liquid has a pH above a predetermined value.

Claim 12

The circuit recited in claim 8 wherein said circuit comprises a second detention means between said first detention means and said third detention means, and means to inject a reducing agent into said circuit at the end of said first detention means adjacent said second detention means.

Claim 13

The circuit recited in claim 9 wherein means is provided to recirculate said material from said second detention means to said chrome source when the ORP thereof is outside of a predetermined range and a means of continuously adjusting the volume of ORP adjustive additive such that stabilized proper oxidation reduction potential is obtained and a means of circulating said material from said second detention means to said third detention means when the oxidation reduction potential thereof is within a predetermined range.

Claim 14

The circuit recited in claim 8 wherein said circuit comprises enlarged size pipes connected by reduced size pipes, and said enlarged size pipes comprise a retention chamber.

Claim 15

The circuit recited in claim 11 wherein said pipes are connected to a tank and said pipes are arranged generally in the form of a helix around said tank.

Claim 16

A process of destroying hexavalent chromium in solution comprising circulating said solution from a source through a series of lines and detention chambers, and adding acid and caustic to said solution in predetermined amounts to said solution comprising, sensing said solution in said lines at a point subsequent to a first detention chamber and recirculating said solution when the pH varies above a predetermined value, passing said solution to an electrical signal means to proportionally control an acid injection pump controlling the acidity of said solution, passing said solution through a reducing agent addition point and adding a reducing agent to said solution, passing said solution through a detention chamber to a pH detector and recirculating said solution when the pH thereof downstream of the point where said caustic is added is below a predetermined amount and allowing said liquid to pass through said line when the pH thereof is between predetermined limits.

Claim 17

A process of destroying hexavalent chromium in solution comprising circulating said solution from a source through a series of lines and detention chambers, and adding acid and caustic to said solution in predetermined amounts to said solution comprising, sensing said solution in said lines at a point subsequent to a first detention chamber and recirculating said solution when the pH varies above a predetermined value, passing said solution to an electrical signal means to proportionally control an acid injection pump controlling the acidity of said solution, passing said solution through a reducing agent addition point and adding a reducing agent to said solution, passing said solution through a detention chamber to a pH detector and recirculating said solution when the pH thereof downstream of the point where said caustic is added is below a predetermined amount and allowing said liquid to pass through said line when the pH thereof is between predetermined limits.