KylieTastic (talk | contribs) Declining submission: nn - Submission is about a topic not yet shown to meet general notability guidelines (be more specific if possible) (AFCH) |
Mohd Ibraheem 9718 (talk | contribs) mNo edit summary |
||
| Line 11: | Line 11: | ||
'''First Stage''' |
'''First Stage''' |
||
[[Sulfur dioxide]] (SO2), [[sodium bisulfite]] (NaHSO3), or sodium meta-bisulfite (Na2S2O5) are examples of chemical reducing agents that are frequently used in treatment to convert hexavalent chromium to [[trivalent chromium]].<ref |
[[Sulfur dioxide]] (SO2), [[sodium bisulfite]] (NaHSO3), or sodium meta-bisulfite (Na2S2O5) are examples of chemical reducing agents that are frequently used in treatment to convert hexavalent chromium to [[trivalent chromium]].<ref>https://inpressco.com/wp-content/uploads/2015/10/Paper333277-3284.pdf</ref>This reaction will proceed quickly in the pH range of 2 to 3. Maintaining the wastewater between this pH range will reduce the amount of time it is retained. This is achieved by adding an acid, such as sulfuric acid (H2SO4), using a pH controller. |
||
'''Second stage''' |
'''Second stage''' |
||
To raise and maintain a pH of 8 or higher in the [[wastewater]], [[calcium hydroxide]], also referred to as lime, or Ca (OH)₂, must be added using an additional pH controller after the first-stage process is finished. This is required in order for chromium hydroxide to precipitate. It is simple to separate and redirect the precipitate for disposal.<ref |
To raise and maintain a pH of 8 or higher in the [[wastewater]], [[calcium hydroxide]], also referred to as lime, or Ca (OH)₂, must be added using an additional pH controller after the first-stage process is finished. This is required in order for chromium hydroxide to precipitate. It is simple to separate and redirect the precipitate for disposal.<ref>https://inpressco.com/wp-content/uploads/2015/10/Paper333277-3284.pdf</ref> |
||
In order to achieve compliance, hexavalent chromium is typically reduced to trivalent chromium through precipitation, yielding chromium hydroxide, a safe and non-toxic material. The primary drawback of this treatment approach is that, in order to ensure a quick reduction rate, the wastewater must be reduced to a pH of two to three. Next, before being released, the wastewater needs to be neutralized. These processes use a lot of chemicals and often result in a lot more sludge from unreacted precipitants. |
In order to achieve compliance, hexavalent chromium is typically reduced to trivalent chromium through precipitation, yielding chromium hydroxide, a safe and non-toxic material. The primary drawback of this treatment approach is that, in order to ensure a quick reduction rate, the wastewater must be reduced to a pH of two to three. Next, before being released, the wastewater needs to be neutralized. These processes use a lot of chemicals and often result in a lot more sludge from unreacted precipitants.<ref>https://inpressco.com/wp-content/uploads/2015/10/Paper333277-3284.pdf</ref> |
||
Revision as of 11:33, 15 April 2024
removal of hexavalent chromium from water.
First Stage
Sulfur dioxide (SO2), sodium bisulfite (NaHSO3), or sodium meta-bisulfite (Na2S2O5) are examples of chemical reducing agents that are frequently used in treatment to convert hexavalent chromium to trivalent chromium.[1]This reaction will proceed quickly in the pH range of 2 to 3. Maintaining the wastewater between this pH range will reduce the amount of time it is retained. This is achieved by adding an acid, such as sulfuric acid (H2SO4), using a pH controller.
Second stage
To raise and maintain a pH of 8 or higher in the wastewater, calcium hydroxide, also referred to as lime, or Ca (OH)₂, must be added using an additional pH controller after the first-stage process is finished. This is required in order for chromium hydroxide to precipitate. It is simple to separate and redirect the precipitate for disposal.[2] In order to achieve compliance, hexavalent chromium is typically reduced to trivalent chromium through precipitation, yielding chromium hydroxide, a safe and non-toxic material. The primary drawback of this treatment approach is that, in order to ensure a quick reduction rate, the wastewater must be reduced to a pH of two to three. Next, before being released, the wastewater needs to be neutralized. These processes use a lot of chemicals and often result in a lot more sludge from unreacted precipitants.[3]