Milestone map
Milestone map
3 milestones
Select and size primary treatment processes
2–3 weeks (8–10 hrs/week)
Analyse a real or openly published raw-water quality dataset (turbidity, suspended solids, BOD, pathogens). Select the appropriate primary treatment train (screening, grit removal, primary sedimentation or clarification) and size each unit using standard hydraulic loading rates. Produce a process flow diagram (PFD) that names each unit, flow direction, and key design parameters.
Proof required
Submit your PFD (hand-drawn or CAD, clearly dimensioned) alongside the raw-water quality data source, your loading-rate calculations as a worked spreadsheet or annotated working, and a short paragraph explaining why you chose this treatment train over alternatives.
What gets checked
- PFD shows every primary unit with flow arrows, inlet/outlet labels, and at least one key sizing parameter per unit (surface overflow rate, detention time, or hydraulic loading rate).
- Calculations reference a named design standard or textbook equation (e.g. Metcalf & Eddy, Crittenden, or equivalent) — not unsourced rules of thumb.
- Treatment-train selection is justified by the specific contaminants in the source-water data, not as a generic template.
Common mistakes
- Sizing without referencing a design standard — produces numbers that look plausible but cannot be verified.
- Using WHO or EPA design values out of context (e.g. applying recreational-water limits to drinking-water source design).
- PFD omits secondary or tertiary implications — first-year students often stop at primary, leaving the design incomplete.
Powstik Guide
A dimensioned PFD and primary treatment sizing.
Steps
- Cite your raw-water quality data.
- Set the design flow.
- Size each primary unit.
- Dimension the PFD.
Template
Data source: Design flow: | Unit | Loading rate | Size | |------|--------------|------|
What gets sent back
- No water quality source.
- Undimensioned PFD.
- Loading rates uncited.
Resources
Foundationstart here
Depthgo deeper
What a verifier looks for
- Ask the student to explain why they chose their coagulant dose or detention time rather than a different value.
- Check that source-water quality data is real or clearly cited — reject invented values.
- Confirm all unit sizing references a specific equation or standard, not a rough estimate.
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Design secondary and disinfection treatment with analysis
2–3 weeks (8–10 hrs/week)
Extend your design to secondary treatment (e.g. biological filtration, rapid sand filtration) and disinfection. Size the secondary treatment stage using appropriate design standards and produce a P&ID (piping and instrumentation diagram) for the disinfection step showing dosing points, contact time, and residual targets. Perform a CT (concentration × time) calculation demonstrating compliance with your chosen regulatory standard.
Proof required
Submit your P&ID for the disinfection stage, CT calculation workings showing target log-reduction credits, and a brief annotated comparison of at least two disinfection options (e.g. chlorination vs. UV) explaining your final choice.
What gets checked
- CT calculation correctly applies the log-reduction formula to the design flow and peak-demand scenario, not just average daily flow.
- P&ID uses standard ISA or equivalent notation — at minimum, dosing points, sensors, and control loops are identifiable.
- Disinfection option comparison addresses at least: DBP formation potential, energy cost, and regulatory acceptance — not just capital cost.
Common mistakes
- CT calculation at average flow only — real designs must account for peak flow where contact time is shortest.
- P&ID is actually a PFD in disguise — no instrumentation or control loops shown.
- Disinfection comparison is superficial (e.g. 'chlorine is cheaper') without addressing byproduct formation.
Powstik Guide
A disinfection P&ID and CT calculations.
Steps
- Set the target log reduction.
- Calculate contact time needed.
- Size the contact tank.
- Draw the disinfection P&ID.
Template
Target log reduction: C × T required: Provided: Tank size:
What gets sent back
- No CT working.
- Target not stated.
- No P&ID.
Resources
Foundationstart here
Depthgo deeper
What a verifier looks for
- Ask the student to recalculate CT at peak flow — if they only did average flow, they don't understand the safety design requirement.
- Request they explain what DBPs are and why they matter for the disinfection choice they made.
- Confirm P&ID notation is consistent — even informal notation is acceptable if consistently applied and explained.
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Produce complete design report with engineering justification
2–3 weeks (10–12 hrs/week)
Compile a complete water treatment design report covering: source-water quality characterisation, design flows and loads, selected treatment train with justification, unit sizing summary, P&ID for each major stage, regulatory compliance demonstration, and a brief environmental and operational sustainability assessment. The report must be structured so a qualified engineer not involved in the design can review and critique it.
Proof required
Submit the full design report (minimum 15 pages excluding figures) and a short recording or written transcript of a design review session where a registered engineer, academic supervisor, or experienced practitioner asked questions about at least three design decisions.
What gets checked
- Design review documentation shows the student defended specific numerical choices (not just explained the report) under at least three challenging questions.
- Regulatory compliance section references the actual applicable standard (e.g. country/state drinking water regulations) — not a generic 'meets standards' claim.
- Sustainability section addresses both operational energy consumption and residuals handling — not just carbon or cost in isolation.
Common mistakes
- Report reads as a literature review rather than a design document — no original sizing calculations or design decisions.
- Design review is with a peer, not a qualified practitioner — only an expert reviewer can tell whether the report is your own work.
- Sustainability section is a paragraph of platitudes without data (e.g. estimated energy use per m³ treated).
Powstik Guide
A 15-page water treatment design report and a technical review record.
Steps
- Fill every required section.
- Show calculations and state assumptions.
- Present to a qualified engineer.
- Record each challenge and your answer.
- Revise the report where needed.
Template
Word count (15+ pages): Assumptions: Reviewer: Role: Date: | Challenge | My answer | Change made | |-----------|-----------|-------------|
What gets sent back
- Outside the word range.
- No reviewer name or role.
- Assumptions not stated.
Resources
Foundationstart here
Masteryfor the dedicated
What a verifier looks for
- Check whether sizing calculations appear in the report body or appendix — they must be traceable, not summarised.
- Verify the design review was conducted by someone with engineering credentials or academic standing in the field.
- Ask one follow-up question not in the original review to test understanding, e.g. 'What changes if the source water turbidity doubles in flood season?'
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