Domestic Greywater Remediation Unit (DGRU)

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The Domestic Greywater Remediation Unit (DGRU)—originally developed under the open-source nomenclature "GWHF" (Grey Water Home Filter)—is a decentralized, point-of-source water treatment asset designed for residential and light-commercial application. It addresses the increasing regulatory pressure for "Water Neutrality" in urban planning permissions.

Unlike traditional static infrastructure, the DGRU operates on a Consumer-Replaceable Consumable Model, creating a continuous ecosystem of Recurring Revenue (RR) for the operator through monthly filtration media subscriptions.

• Primary Function: Diverts and treats Bath/Shower/Sink output for immediate non-potable reuse (Toilet Flushing/Landscape Irrigation).
• Compliance: Meets emerging "Part G" building regulations and reduces municipal sewage load by up to 40%.
• ROI Horizon: <18 months via reduced metered water inputs and municipal sewerage rebates.

The economic core of the DGRU is not the hardware sales, but the High-Frequency Consumable Cycle.

• The Hardware (Razor): The main tank body is manufactured from 100% recycled HDPE (low CapEx) and sold at near-cost to maximize market penetration.
• The Cartridge (Blade): The active filtration core requires replacement every 30-45 days. This establishes a Subscription-Based Revenue Stream locked to the physical asset.

As regional governments impose stricter "Nutrient Neutrality" laws to save failing river ecosystems, developers are forced to install mitigation tech. The DGRU qualifies for "Green Home Grant" schemes, effectively subsidizing the initial purchase using taxpayer money, while the private operator retains the subscription profit.

The DGRU utilizes a vertical-flow, gravity-fed "Reactor Vessel" designed for modular deployment.

• Material Composition: Rotomolded High-Density Polyethylene (HDPE) using 100% post-consumer regrind. This minimizes the Carbon Footprint.
• Hydrodynamics: The internal baffle system forces a tortuous path for the fluid, maximizing contact time with the filtration media.
• Zero-Energy Operation: The system operates entirely on hydraulic head pressure (gravity), requiring no electrical pumps, qualifying it for Passive House certification.

• Inlet (The Trap): Features a coarse "Pre-Screening Module" to capture macro-particulates (hair, lint) before they enter the main reactor.
• Outlet (The Prize): Delivers pressurized, clarified water suitable for subsurface irrigation or cistern storage.

To maintain efficiency and prevent anaerobic clogging, the DGRU relies on a Segmented Media Stratification strategy.

• Layer A (Sorption Zone): Activated Carbon/Biochar matrix for chemical stripping of soaps and surfactants.
• Layer B (Biological Zone): High-surface-area aggregate (volcanic rock or sintered glass) that hosts the biofilm.
• Layer C (Polishing Zone): Fine silica sand for turbidity reduction.

The DGRU represents a "Fit-and-Forget" asset class.

• Hydraulic Integration: Installed inline with the primary greywater discharge pipe (50mm/2" standard PVC).
• Civil Works: Requires a minimal footprint (600mm x 400mm), suitable for under-sink cabinetry or external subterranean vaults.
• Bypass Safety: Integrated overflow weirs ensure that in the event of cartridge saturation, excess flow is safely diverted to the mains sewer.

• Monthly: Visual inspection of the "Pre-Filter Mesh" (User serviceable).
• Bi-Annual: Swap-out of the Active Carbon Module (Subscription item).
• Annual: Backwash of the primary aggregate matrix to regenerate biofilm porosity.

In order to accelerate municipal adoption and meet "Net Zero Water" targets, the core DGRU specifications are released under CC0 / Public Domain.

Asset Repository:

• DGRU_Master_Assembly.STEP (Injection Mold Tooling)
• Filter_Cartridge_v2.STL (The Consumable Unit)

File:Filter Schemes skp..zip