Equipment
Where primary separation and flotation do not meet the required final water specification, nutshell filters can provide a polishing stage.
Application
Nutshell filters use a mixture of nutshells as the filter media. The shells allow oil to collect on their surface while also capturing solids, which is what lets the stage reach concentrations the flotation units alone cannot.
Process
The process is simple. Oily water enters the vessel and passes through the nutshells under pressure. Oil and solids are trapped within the filter media and clean water exits the bottom of the vessel.
To remove the oil and solids from the media, a backwash process is used: fluidise the bed, remove the contaminated water, allow the filter to settle, then rinse the filters to remove any contaminants still present.
The process uses at least two filters: one online, the second being regenerated or on standby. SPEC sets the number of filters to suit your flow rate and backwash cycle.
System configuration
System configuration varies with process duty, operating conditions and project requirements.
At least two, so that one filters while the other is regenerated or on standby.
Pecan and walnut shell blend that holds oil on its surface while capturing solids.
Fluidises the bed, removes the contaminated water, lets the bed settle and rinses it, using process water.
Final equipment arrangement and delivery format depend on process duty, transport constraints and site requirements.
Specifications
| Parameter | Value |
|---|---|
| Typical outlet quality | As low as 5 ppm oil in water, depending on inlet conditions |
| Filter media | Pecan and walnut shell blend |
| Minimum filters | Two: one online, one regenerating or on standby |
| Backwash water | Process water used, eliminating the need for a clean water source |
| Solids removal | High solids removal efficiency |
| Vessel code | ASME Section VIII |
| Delivery | Skid-mounted units |
| Backwash step | Action |
|---|---|
| 1 | Fluidise the bed |
| 2 | Remove the contaminated water |
| 3 | Allow the filter to settle |
| 4 | Rinse the filters to remove remaining contaminants |
Filter count, vessel size and backwash frequency are set by SPEC engineering against your inlet water quality, flow rate and discharge limit. Performance for a specific project is confirmed in SPEC’s proposal.
Advantages
Typically 5 ppm oil in water or lower, subject to inlet conditions.
Backwash uses process water, so no separate clean water source is required.
The media collects oil on the shell surface while capturing solids at the same time.
Process data
Enquiries
Send us your process data and operating conditions, and we will review the duty with you.
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