Before requesting a model recommendation, provide the sludge source, feed solids concentration, operating schedule and required output conditions.
Separate Volume from Solids Mass
Two feeds can have the same volumetric flow but carry different solids loads.
When feed solids are expressed as a mass fraction:
Dry solids loading (kg DS/h) = sludge flow (m³/h) × sludge density (kg/m³) × feed solids mass fraction
For illustration only, assume a sludge density of 1,000 kg/m³:
| Example | Wet sludge flow | Feed solids by mass | Calculated dry solids loading |
|---|---|---|---|
| A | 10 m³/h | 1% | 100 kg DS/h |
| B | 10 m³/h | 3% | 300 kg DS/h |
These are arithmetic examples, not machine ratings. Actual density and representative solids measurements should be used for project calculations.
Example B carries three times the dry solids at the same flow. This does not mean that a particular machine will process it at three times the rate, or produce a drier cake.
Identify Which Feed the Quotation Describes
Ask the bidder to identify the sampling location and the feed condition used in its proposal. Raw sludge, thickened sludge and conditioned feed should not be treated as interchangeable inputs.
Upstream thickening can reduce the liquid volume sent to downstream treatment. Alfa Laval’s sludge treatment overview describes the relationship between thickening, hydraulic load and subsequent dewatering. Whether to include that step remains a project-specific decision. Alfa Laval sludge treatment overview
If polymer dilution water or other streams enter before the machine, ask how they are included in the hydraulic balance. Record whether quoted feed data refer to conditions before or after those additions.
Compare Capacity Together with Output Quality
Ask suppliers to present throughput and output conditions together, rather than selecting the highest advertised flow.
A comparison should identify:
- Feed sludge type and representative solids range.
- Wet feed flow and dry solids loading.
- Required cake solids or moisture content.
- Solids capture and the quality of separated liquid.
- Polymer dose, including whether it is stated on an active-product basis.
- Operating hours, cleaning requirements and any batch-cycle assumptions.
These are proposal-review questions, not universal acceptance values. The responsible specialist should confirm the applicable test basis and achievable results for the actual sludge.
Prepare the Minimum Inquiry Data
| Information | What to provide |
|---|---|
| Sludge origin | Upstream process, sludge type and whether different streams are mixed |
| Feed records | Available flow, density and solids results, with sampling dates and locations |
| Variability | Normal conditions, peaks and known changes between shifts or batches |
| Operating plan | Daily quantity, available operating hours and planned interruptions |
| Output requirement | Cake handling needs and separated-liquid destination |
| Site interfaces | Utilities, installation space, access and upstream/downstream connections |
Mark unavailable measurements as missing instead of filling them with assumed values. For an initial discussion, send the records already available and ask which additional measurements are needed.
Clarify the Package Boundary
A quotation for a dewatering machine may not include feed pumps, polymer preparation, conveyors, platforms, wash-water equipment or installation.
Our sludge dewatering equipment page explains the project information and supply boundaries reviewed with specialist manufacturing partners.
Ask each bidder to identify the actual manufacturing source, included auxiliaries, customer-side work and required inspection documents.
Frequently Asked Questions
Can two machines with the same m³/h rating be compared directly?
Only after checking the feed conditions, solids loading, output requirements and scope behind each rating. Matching volumetric capacity does not establish equivalent duty.
Is feed solids concentration the same as cake solids concentration?
No. Feed solids describe the sludge entering the process; cake solids describe the dewatered output. State the sampling point and whether the percentage is on a mass basis.
Does increasing feed concentration always improve performance?
Do not assume a universal improvement. It changes the relationship between hydraulic and solids loading. Ask the responsible specialist to assess the actual feed and machine operating limits.
Can I request a preliminary proposal without complete sludge analysis?
Yes. Provide the information available and identify the gaps. Final selection and performance commitments require a confirmed technical basis.
Send Your Sludge Data for Initial Review
Use our project inquiry page to share sludge records, operating requirements and the equipment scope you need.
Grace coordinates written clarification with the relevant specialist manufacturer. Equipment configuration, responsibilities and commercial terms are confirmed for the individual project.