Dissolved Metals Treatment
Water Pollution Management[dflip id=”365046″][/dflip]
Water Quality Standards
| Element | Surface Water (Fresh) |
Salt Water |
Human Consumption |
|
|---|---|---|---|---|
| Iron | 1 mg/l | 1 mg/l | 200 μg/l | |
| Arsenic | 50 μg/l | 25 μg/l | 10 μg/l | |
| Manganese | 30 μg/l | - | 50 μg/l | |
| Aluminium | Draft Proposed Standard (SEPA 2013) | - | 200 μg/l | |
| pH > 5.5 | 1 mg/l | |||
| pH < 5.5 | < 0.1 mg/l | |||
| Chromium | Salmonidae Fish | 15 µg/l | 50 µg/l | |
| 0-50 mg CaCO3/l | 5 µg/l | |||
| 50-100 mg CaCO3/l | 10 µg/l | |||
| 100 - 150 mg CaCO3/l | 20 µg/l | |||
| 150-200 mg CaCO3/l | 20 µg/l | |||
| 200 - 250 mg CaCO3/l | 50 µg/l | |||
| 250 mg CaCO3/l | 50 µg/l | |||
| 250+ mg CaCO3/l | 50 µg/l | |||
Metal treatment
Stage 1
Precipitation to Remove Dissolved Metals
Turning dissolved metals into a solid form
Stage 2
Recovery to remove the suspended solids
Solid Liquid Separation
Stage 3
Waste Minimisation (Sludge de-watering)
Volume reduction through the removal of water
Metal Precipitation
Metal Hydroxide precipitation most commonly employed method for the precipitation of metals
Typical reaction is of the form:
M+n +nOH– M(OH)n
For example
Zn2+ +2OH– Zn(OH)2
Many Metals are amphoteric, therefore their solubility reaches a minimum
at a specific pH (different for each metal)
Many Metals are amphoteric, therefore their solubility reaches a minimum at a specific pH (different for each metal)
Metal Hydroxide Solubility
Conventional Hydroxide Precipitation
The HDS Process
Dissolved Metals
Simon Skentelbery
General Manager
John F Hunt Regeneration Ltd
London Road
Grays
Essex
RM20 4DB
M: 07967 306 517
E: simon.skentelbery@johnfhunt.co.uk
W: johnfhuntregeneration.co.uk