Graphic organizer Grade 11 Engineering & Design
Kelbrook Reclaimed Water: A Reuse Tier Organizer
A grade 11 tier organizer matching five reclaimed water end uses to the treatment barriers, quality targets, and monitoring each one demands, with a completed exemplar.
Objectives
- Students will match a reclaimed water end use to the treatment barriers it requires.
- Students will explain why added barriers are needed as human exposure rises.
- Students will name the failure mode that each reuse tier is designed to prevent.
Vocabulary
- Indirect potable reuse
- Recycling water into drinking water with a natural stop along the way. Highly cleaned water is put into the ground or a reservoir, then drawn back out later and treated again for drinking.
Also: reclaimed water, treatment barrier, advanced oxidation, cross-connection control
Teacher overview
This organizer is a five-rung tier frame in which each row is one end use for reclaimed water and each column states what that use demands of the treatment train. The rows are ordered by how much human contact the end use involves, so the frame makes visible that reuse covers several grades of water arranged like a ladder, and that each rung is defined by the number of independent barriers standing between a person and the original wastewater. Students often treat recycled water as a single category that is either acceptable or not, which leads them to argue about whether reuse is safe rather than about which use a given effluent is fit for. The same reclaimed water can be entirely appropriate for irrigating a fairway at night and clearly unacceptable for a drinking-water intake, and the engineering question is always which barriers close that gap.
Organizer
The fictional Kelbrook Water Reclamation Facility is evaluating five possible customers for its reclaimed water. Complete each cell using the treatment and monitoring vocabulary from class. All figures and customers in this scenario are hypothetical.
| End use, in order of human contact | Treatment barriers required | Key water-quality target | Exposure pathway to control | Monitoring and operator response | Failure mode this tier prevents |
|---|---|---|---|---|---|
| Night irrigation of a restricted-access golf course | |||||
| Cooling tower makeup at a data center | |||||
| Toilet flushing in an office block on dual plumbing | |||||
| Groundwater recharge through a spreading basin | |||||
| Direct addition to the town's raw water supply |
From Water for Schools (waterforschools.org). This material is in the public domain (CC0) and may be copied, edited, and shared freely.
Completed Exemplar
Every customer named below belongs to the fictional Kelbrook scenario. Two anchors are real: secondary treatment standards call for monthly-average effluent of 30 mg/L or less for both biochemical oxygen demand and suspended solids, and the largest indirect potable reuse plant in operation, Orange County's Groundwater Replenishment System, produces 130 MGD.
| End use, in order of human contact | Treatment barriers required | Key water-quality target | Exposure pathway to control | Monitoring and operator response | Failure mode this tier prevents |
|---|---|---|---|---|---|
| Night irrigation of a restricted-access golf course | Secondary treatment followed by filtration and disinfection | Effluent at or below the 30 mg/L secondary standard, with a reliable disinfectant residual | Skin contact by grounds crews and by golfers on wet turf the next morning | Daily disinfectant residual, routine bacterial sampling, and irrigation only during closed hours | Contact with inadequately disinfected effluent, and odor complaints from the neighborhood |
| Cooling tower makeup at a data center | Secondary treatment, filtration, disinfection, and control of ammonia, phosphorus, and hardness | Low ammonia so the disinfectant is not consumed, and low scaling potential so heat transfer holds | Aerosol drift from the tower, which can carry bacteria well beyond the building | Continuous conductivity and residual monitoring, plus a documented biological control program | Scaling and corrosion inside the tower, and airborne exposure from drift |
| Toilet flushing in an office block on dual plumbing | Secondary treatment, filtration, disinfection, and color and odor polishing | A stable residual carried through the building loop, with low turbidity and no visible color | Incidental indoor contact, and any accidental connection to the building's drinking-water piping | Purple piping and labeling, annual cross-connection testing, and residual checks at the far end of the loop | A cross connection sending reclaimed water into the drinking-water system |
| Groundwater recharge through a spreading basin | Microfiltration, reverse osmosis, and an advanced oxidation step, followed by travel through soil and aquifer | Very low total organic carbon and nitrogen, with credited pathogen removal across each barrier | Long-term ingestion once the recharged water is pumped back out as drinking water | Continuous monitoring of each barrier, with recorded underground residence time before withdrawal | Trace organic compounds reaching a drinking-water aquifer that serves many wells |
| Direct addition to the town's raw water supply | The same advanced train plus engineered storage, redundant barriers, and automatic diversion on any alarm | Real-time limits at every critical control point rather than monthly averages | Direct ingestion within hours, with no environmental buffer to absorb an upset | Online instruments at each control point, with automatic diversion to waste and a trained response crew | An upset reaching customers before anyone can act, since no buffer stands in the way |
Differentiation
Support
Reduce the fictional frame to the first three rows and three columns, and pre-fill the treatment barriers for the golf course row as a worked example. Give students a card set naming the barriers, one card per process, so the treatment column is built by ordering cards rather than by recall.
Extension
Ask these students to add a sixth row for a use they select, such as concrete mixing or street sweeping at the fictional facility, and to place it correctly in the contact ordering with a written justification. Then have them argue which single barrier in the fictional advanced train they would add first if the facility could afford only one upgrade this year.
ELL supports
Provide a labeled process diagram showing the barriers in order from secondary treatment through advanced oxidation, with the name of each process beside its picture. Allow students to complete cells with phrases, and offer the frame "This use needs ___ because people could ___" for the exposure column of the fictional scenario.
Extensions
Have students investigate whether any utility in their state produces reclaimed water and, if so, which tier of the organizer its customers occupy. A second step is to compare how two states word their reuse rules, since the number of barriers required for the same end use differs from one state to another, and to explain what that difference implies about how each state weighs cost against risk. Students who want a design task can sketch the pipe and storage layout the fictional facility would need to serve two tiers at once from a single treatment train.