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Green STP Technology

Constructed Wetland — Nature-Based Treatment — Near-Zero Energy, 25+ Year Life

Constructed wetlands use engineered gravel beds, wetland vegetation and root-zone microbiology to treat sewage with almost no electricity and almost no mechanical equipment. Where land is available, no other technology matches the operating economics, the resilience or the landscape value.

GS-10-CW · GS-25-CW · GS-50-CW · GS-100-CW — horizontal, vertical and hybrid subsurface-flow systems.

Explore Constructed Wetland Models Get Constructed Wetland Quote
0–0.1 kWh/KLNo Chemicals, No Sludge25+ Year LifeLandscape Asset

Where Constructed Wetland fits best

  • Sites with land available — 5–15 m² per KLD
  • Locations with unreliable grid power
  • Eco-resorts, campuses and projects with a sustainability narrative
  • Polishing stage downstream of SBR, MBBR or decentralized systems

Consider another technology when

  • Dense urban sites — the footprint is 5–10× a mechanical plant
  • Contracts requiring guaranteed BOD <10 without polishing
  • Cold-season-sensitive or highly variable industrial loads

How it works

Root Zone Engineering

Wastewater flows by gravity through a planted gravel bed. Plant roots deliver oxygen into the rhizosphere, biofilm on the media degrades organics, and the media itself provides filtration and adsorption. Sarvo designs hybrid vertical-then-horizontal beds, which achieve 85–97% BOD removal and 60–92% nitrogen removal — far ahead of a single-stage bed.

What happens · 1–2 day retention

1. Primary Settling / Anaerobic Tank

A settler or baffled anaerobic reactor removes solids that would otherwise clog the wetland bed.

Why it matters

Clogging is the number one failure mode of constructed wetlands — good pre-treatment is non-negotiable.

Process flow diagram

Constructed Wetland — end-to-end treatment train

Every unit operation from raw sewage to reuse-grade water, including pre-treatment and the sludge branch.

Constructed Wetland (Phytorid) Flow Diagram

CSIR-NEERI Phytorid root-zone treatment. Gravity-fed, near-zero power, with gravel media and engineered plant species doing the polishing work.

1Raw Sewage200–350 mg/L BOD
2Bar ScreenCoarse + fine solids
3Oil & Grease TrapSkimmer, FOG removal
4Baffled SettlerAnaerobic pre-treatment
5Phytorid BedGravel media + root zone
6Polishing PondNatural aeration + UV sunlight
7Reuse / RechargeLandscape • Groundwater
InletPre-treatmentBiological corePolishingReuseSludge

Why Constructed Wetland?

Eight reasons consultants specify Constructed Wetland

Engineering advantages that show up in your compliance record, your energy bill and your maintenance calendar.

Near-Zero Energy

0–0.1 kWh/KL. Gravity-fed designs need no power at all; a single dosing pump is the only load in most layouts.

No Chemicals, Almost No Sludge

Nothing is dosed and very little sludge is produced — desludging is limited to the primary settler every few years.

Power Failure Immune

A grid outage does not stop a wetland. For unreliable-power locations this is a decisive operating advantage.

Doubles as Landscape

A planted bed of Canna and ornamental reeds is an amenity, not an eyesore — ideal for resorts, campuses and eco-projects.

Minimal Skilled Operation

Periodic weeding, inlet cleaning and flow checks. No PLC, no blower, no membrane — a gardener can maintain it.

25+ Year Service Life

There is very little to wear out. Media replacement is measured in decades, and plants regenerate themselves.

Silent and Odour-Free

Subsurface flow means no exposed water, no aerosols and no noise anywhere on the site.

Excellent Polishing Stage

Placed after SBR, MBBR or a decentralized unit, a wetland adds a chemical-free, zero-energy polishing barrier before reuse.

Compare all 5 technologies

Performance guarantee

We don't just promise — we prove

Every installation is validated by an independent NABL-accredited laboratory. Three consecutive daily samples at full load, compared against the guarantee, before handover.

ParameterTypical Indian InletGreen STP OutletCPCB NormMargin of Safety
BOD (mg/L)200–35015–30≤10Polishing needed for strict compliance
COD (mg/L)400–70050–100≤50Design-dependent
TSS (mg/L)200–40015–30≤20Filtration polishing recommended
BOD Removal (hybrid VF+HF)—85–97%—Well-designed hybrid beds
Nitrogen Removal (hybrid)—60–92%—VF nitrification + HF denitrification
Fecal Coliform (MPN/100mL)10⁶ – 10⁸<1,000 (VF), <100 with UV<100Add UV for compliance
Energy Consumption—0–0.1 kWh/KL—Lowest in portfolio

Engineering honesty: a constructed wetland alone may not consistently achieve BOD <10 mg/L. Where guaranteed compliance with the strictest CPCB norms is required, Sarvo positions CW as a polishing stage after biological treatment, or as a hybrid with tertiary filtration. Performance varies seasonally and clogging risk must be managed through disciplined primary treatment.

Reuse applications: Landscape irrigation · Dust suppression · Groundwater recharge where permitted · Toilet flushing after filtration and disinfection · Pond and water-feature makeup.

Download Datasheet

Model lineup

Four Constructed Wetland capacities, one engineering standard

Every model carries the same effluent guarantee. What changes is capacity, configuration and redundancy.

GS-10-CW

Garden-Scale Wetland

10 KLD
Serves
Villas, resorts, eco-homes
Configuration
Hybrid VF + HF bed
Reactors
Settler + VF bed + HF bed
Footprint
50–150 m²
Power
0–0.5 kW
Delivery
4–6 weeks

Best for: Eco-resorts, farmhouses, rural schools with land available

Full specification
Capacity
10 KLD
Bed Type
Hybrid VF + HF
Hydraulic Loading
0.04–0.10 m³/m²/day
Organic Loading
5–15 g BOD/m²/day
Footprint
5–15 m² per KLD
Energy
0–0.1 kWh/KL
Plants
Canna, Typha, Phragmites
Life
25+ years
Get quote for GS-10-CW

GS-25-CW

Campus Wetland

25 KLD
Serves
Institutions, layouts
Configuration
Hybrid VF + HF bed
Reactors
Settler + dosing + beds
Footprint
125–375 m²
Power
0.5–1.5 kW
Delivery
6–8 weeks

Best for: Schools, ashrams, eco-parks, layout developments

Full specification
Capacity
25 KLD
Bed Type
Hybrid VF + HF
Dosing
Intermittent siphon or pump
Hydraulic Loading
0.04–0.10 m³/m²/day
Footprint
5–15 m² per KLD
Energy
0–0.1 kWh/KL
Maintenance
Weeding + inlet cleaning
Life
25+ years
Get quote for GS-25-CW

GS-50-CW

Estate Wetland

50 KLD
Serves
Townships with open land
Configuration
Multi-cell hybrid
Reactors
Parallel bed cells
Footprint
250–750 m²
Power
1.5–3 kW
Delivery
8–12 weeks

Best for: Townships, industrial estates, temple towns with land

Full specification
Capacity
50 KLD
Cells
Parallel cells for rotation
Bed Type
Hybrid VF + HF
Hydraulic Loading
0.04–0.10 m³/m²/day
Footprint
5–15 m² per KLD
Energy
0–0.1 kWh/KL
Polishing
Optional pond + UV
Life
25+ years
Get quote for GS-50-CW

GS-100-CW

Landscape-Integrated System

100 KLD
Serves
Large campuses, eco-townships
Configuration
Multi-cell hybrid + pond
Reactors
Multiple cells + polishing pond
Footprint
500–1,500 m²
Power
3–6 kW
Delivery
12–16 weeks

Best for: Eco-townships, resorts, water-positive campus projects

Full specification
Capacity
100 KLD
Cells
Multiple with rotation and rest
Bed Type
Hybrid VF + HF + polishing pond
Hydraulic Loading
0.04–0.10 m³/m²/day
Footprint
5–15 m² per KLD
Energy
0–0.1 kWh/KL
Co-benefit
Habitat and landscape value
Life
25+ years
Get quote for GS-100-CW

Not sure which capacity fits your building?

Size it in 60 seconds with the calculator

Constructed Wetland range — quick comparison

ParameterGS-10-CWGS-25-CWGS-50-CWGS-100-CW
Rated Capacity10 KLD25 KLD50 KLD100 KLD
Bed TypeHybrid VF+HFHybrid VF+HFMulti-cell hybridMulti-cell + pond
Land Requirement50–150 m²125–375 m²250–750 m²500–1,500 m²
Connected Power0–0.5 kW0.5–1.5 kW1.5–3 kW3–6 kW
Specific Energy0–0.1 kWh/KL0–0.1 kWh/KL0–0.1 kWh/KL0–0.1 kWh/KL
Sludge GenerationVery lowVery lowVery lowVery low
Operator RequirementPeriodicPeriodicPeriodicPeriodic
Service Life25+ years25+ years25+ years25+ years

Application guide

Who is this for?

Select your building type to highlight the recommended model above.

ApplicationTypical GenerationRecommended ModelKey ConsiderationDigital Tier
Eco-Resorts & Retreats5–25 KLDGS-10 / GS-25-CWTreatment becomes a guest-facing sustainability featureBasic
Rural Schools & Ashrams5–25 KLDGS-10 / GS-25-CWNo operator, no power dependency, minimal recurring costBasic
Industrial Estate Polishing25–100 KLDGS-50 / GS-100-CWPost-biological polishing stage before reuse or dischargeBasic
Eco-Townships50–100 KLDGS-100-CWLandscape-integrated beds double as green open spaceSmart (flow monitoring)
Temple Towns & Pilgrim Sites25–100 KLDGS-50 / GS-100-CWHandles festival peaks by resting and rotating cellsBasic
Water-Positive Campus ProjectsAnyCW + rechargeCombine with rainwater harvesting for net water-positive claimsSmart
Which model fits your project? Run the calculator

Equipment & automation

Everything in the scope, specified and warranted by Sarvo

Single-source accountability — every component is specified, procured, factory-tested and warranted by us.

Download full technical specification

The economics

Your STP pays for itself

Water savings + zero chemical cost + compliance. Move the sliders to see the indicative picture for your project.

Treated water reused
5,100 KL/yr
Annual water savings
INR 40,80,000
Annual STP OPEX
INR 51,000
Net annual benefit
INR 40,29,000
Simple payback0.4 yrs

Indicative only — based on 340 operating days, catalogue OPEX bands and typical reuse fractions for Constructed Wetland. A site survey produces the binding number.

Run the full 5-step calculator
Cost / Saving ElementGS-10-CWGS-25-CWGS-50-CWGS-100-CW
Indicative CAPEX (INR Lakhs)5–1012–2222–3840–70
Land Requirement50–150 m²125–375 m²250–750 m²500–1,500 m²
Annual Electricity Cost (INR)0–12,00012,000–30,00030,000–60,00060,000–1,20,000
Annual Chemical CostZEROZEROZEROZERO
Annual Maintenance (gardening)12,000–24,00024,000–48,00048,000–90,00090,000–1,50,000
Total Annual OPEX (INR)12,000–36,00036,000–78,00078,000–1,50,0001,50,000–2,70,000
OPEX per KL Treated (INR)3–104–94–84–7
Simple Payback Period2–4 years2–3 years2–3 years2–3 years

Constructed wetlands have the lowest lifetime operating cost of any Green STP technology. The trade-off is land: budget 5–15 m² per KLD of treatment capacity.

Project references

Constructed Wetland plants delivered across India

Installed Constructed Wetland references with capacity, scope of supply and measured outcome.

30 KLD2022

Eco-resort wetland system

Wayanad, Kerala · Hospitality

Scope
Horizontal sub-surface flow wetland beds, gravity-fed
Outcome
Near-zero energy operation; wetland doubles as guest landscape
Reuse
Orchard and landscape irrigation
45 KLD2024

Municipal riverfront park

Ahmedabad, Gujarat · Industrial & Parks

Scope
Phytorid-style wetland per CSIR-NEERI design principles
Outcome
Zero mechanical equipment in the treatment train
Reuse
Park irrigation and water features
18 KLD2023

Rural institute hostel block

Roorkee, Uttarakhand · Institutional

Scope
DEWATS-aligned settler + anaerobic baffled reactor + wetland
Outcome
Operates through 6-hour daily grid outages
Reuse
Agriculture demonstration plot
All Sarvo project references

Proof in the field

Constructed Wetland projects and outcomes

Representative project profiles from the Sarvo reference framework — indicative of typical outcomes at these capacities.

Bengaluru, Karnataka

Constructed Wetland retrofit at a 180-unit residential complex

Capacity
25 KLD
Tanker spend cut
72%
Payback
3.2 years
“The odour complaints stopped in the first month. The tanker bill is what convinced the general body.”

— RWA Secretary

Pune, Maharashtra

Constructed Wetland for a 120-room business hotel

Capacity
40 KLD
Reuse
Flushing + landscape
Compliance
CTO renewed
“Occupancy swings from 35% to full. The plant simply does not care — the report is the same.”

— Chief Engineer

Hyderabad, Telangana

Constructed Wetland at a multi-block educational campus

Capacity
60 KLD
Energy
0.9 kWh/KL
Uptime
99.2%
“Remote monitoring means our facilities team of two can run the plant without a specialist.”

— Campus Facilities Head

Explore the other Green STP technologies

SBR

The Proven Performer — Batch-Perfect Biology

View technology MBBR

The Resilient Workhorse — Biofilm That Bounces Back

View technology MBR

The Reuse Champion — Ultra-Clear Water, Smallest Footprint

View technology Decentralized

Treat Locally, Reuse Locally — Buried, Silent, Almost Invisible

View technology

Ready for Constructed Wetland done properly?

Get a site-specific design, a performance guarantee and indicative pricing — usually within three working days of the survey.

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