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Green STP Technology

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

Japan runs over 7 million Johkasou units under the Johkasou Law of 1983. Sarvo's decentralized range brings that philosophy to India: a fully factory-manufactured FRP vessel that integrates anaerobic, anoxic and aerobic stages, sedimentation, recirculation and disinfection inside one sealed enclosure, installed underground with almost nothing visible above ground.

GS-10-D · GS-25-D · GS-50-D · GS-100-D — sealed FRP packages for plots, villas, small communities and sites with no plant room.

Explore Decentralized Models Get Decentralized Quote
Factory-Built FRP40–50 Year Shell Life<50 dB OperationUnderground Install

Where Decentralized fits best

  • Sites with no space or budget for a plant room
  • Villas, layouts and phased developments
  • Remote or unmanned locations relying on service visits
  • Projects where noise, odour and visual impact are decisive

Consider another technology when

  • Sites with a high water table and no anti-flotation provision
  • Very strict total nitrogen limits without added recirculation
  • Capacities above 100 KLD at a single point

How it works

One Sealed Vessel, Every Treatment Stage

A Johkasou-inspired unit is not simply 'MBBR in a tank'. It is a type-approved product: structurally engineered FRP, integrated multi-stage biology, designed-in sedimentation and disinfection, standardized models, underground installation and a maintenance framework built into the design. Sarvo's decentralized range follows the same discipline for Indian conditions.

What happens · Integrated chamber

1. Anaerobic Sedimentation

Incoming sewage enters a sealed anaerobic chamber where settleable solids separate and hydrolysis begins. Scum and sludge are retained for periodic desludging.

Why it matters

Removes the solids load with zero energy, protecting the downstream biology.

Process flow diagram

Decentralized — end-to-end treatment train

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

Decentralized Package Plant Flow

Every stage inside one sealed FRP/MS vessel — buried, odour-free and skid-delivered. Ideal where there is no room for a conventional civil STP.

1Raw Sewage200–350 mg/L BOD
2Bar ScreenCoarse + fine solids
3Oil & Grease TrapSkimmer, FOG removal
4Equalisation Tank8–12 hr buffer + air mixing
5Anaerobic ChamberSettling + hydrolysis
6Aerobic ChamberFixed-film media
7Settling ChamberIntegral clarifier
8PSF + ACFPressure sand & carbon
9UV / ChlorinationDisinfection, FC <100
10Treated Water TankFlushing • Landscape • Cooling

Sludge branch — from Anaerobic Chamber

1Sludge HoldingAerobic digestion
2DewateringFilter press / drying bed
3Soil ConditionerChemical-free bio-sludge
InletPre-treatmentBiological corePolishingReuseSludge

Why Decentralized?

Eight reasons consultants specify Decentralized

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

100% Factory Manufactured

Built and tested in the factory as a product, not assembled on site as a project. Consistent quality, predictable delivery, no civil surprises.

40–50 Year Structural Life

FRP does not corrode like MS and does not crack like poorly built RCC. The shell outlives the building services around it.

Underground and Invisible

Installed below driveways, lawns and parking. Only the manhole covers and a small blower enclosure remain visible — no plant room needed.

Under 50 dB, No Odour

Sealed enclosure and small blowers mean it can sit beside a clubhouse or villa without noise or odour complaints.

Lowest Powered OPEX

0.3–0.6 kWh/KL and no chemical dosing in the treatment line — the cheapest mechanical system to run in the portfolio.

Minimal Operator Dependency

Designed for a maintenance visit model — monthly checks and six-monthly desludging rather than a daily on-site operator.

Fast Install, Modular Scale-Up

Single FRP vessels ship up to ~25–30 m³ within Indian transport limits; above that, modular multi-tank trains are connected on site.

Chemical-Free Biology

Anaerobic, anoxic and aerobic bacteria do the treatment; only the final disinfection step uses a chlorine tablet or UV lamp.

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)200–350<10≤10Meets norm
COD (mg/L)400–700<50≤50Meets norm
TSS (mg/L)200–400<20≤20Meets norm
pH6.5–8.06.5–8.56.5–9.0Well within range
Ammoniacal Nitrogen (mg/L)25–50<10≤5 (emerging)Extend aeration zone if required
Total Nitrogen (mg/L)40–7015–25≤10 (emerging)Recirculation-dependent
Fecal Coliform (MPN/100mL)10⁶ – 10⁸<100<100Tablet chlorination or UV
Noise at 1 m—<50 dBResidential limitsSealed enclosure

Decentralized guarantees assume domestic sewage only, correct burial with the specified backfill and anti-flotation design, an accessible desludging route, and the scheduled maintenance visit programme (monthly inspection, six-monthly desludging).

Reuse applications: Landscape irrigation · Toilet flushing (with filtration) · Driveway and dust suppression · Recharge pits where permitted by the SPCB.

Download Datasheet

Model lineup

Four Decentralized capacities, one engineering standard

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

GS-10-D

The Buried Starter

10 KLD
Serves
30–60 units / villa clusters
Configuration
Single FRP vessel, underground
Reactors
Integrated multi-chamber
Footprint
10–15 m² buried
Power
0.75–1.5 kW
Delivery
2–3 weeks

Best for: Villas, gated plots, small apartments, resorts with no plant room

Full specification
Capacity
10 KLD
Construction
Single-piece FRP, factory built
Installation
Underground, anti-flotation designed
Stages
Anaerobic → anoxic → aerobic → settling → disinfection
Energy
0.3–0.6 kWh/KL
Noise
<50 dB at 1 m
Desludging
Every 6 months
Shell Life
40–50 years
Get quote for GS-10-D

GS-25-D

Community Package

25 KLD
Serves
80–200 units
Configuration
Modular FRP train
Reactors
2 modules connected on site
Footprint
25–35 m² buried
Power
1.5–3 kW
Delivery
4–6 weeks

Best for: Mid apartments, schools, resorts, layout developments

Full specification
Capacity
25 KLD
Construction
Modular FRP vessels
Transport Limit
2.8–3.0 m width, 12 m length
Stages
Full integrated multi-stage
Energy
0.3–0.6 kWh/KL
Noise
<50 dB at 1 m
Maintenance
Monthly visit + 6-monthly desludging
Shell Life
40–50 years
Get quote for GS-25-D

GS-50-D

Layout & Campus

50 KLD
Serves
200–400 units
Configuration
Multi-module FRP train
Reactors
3–4 modules
Footprint
45–65 m² buried
Power
3–6 kW
Delivery
6–10 weeks

Best for: Plotted layouts, campuses, townships in phases

Full specification
Capacity
50 KLD
Construction
Multi-module FRP train
Installation
Underground with access chambers
Energy
0.3–0.6 kWh/KL
Redundancy
Dual blowers (1W + 1S)
Maintenance
Monthly visit + 6-monthly desludging
Digital
Smart tier recommended
Shell Life
40–50 years
Get quote for GS-50-D

GS-100-D

Distributed Township

100 KLD
Serves
500+ units
Configuration
Clustered FRP trains
Reactors
Multiple parallel trains
Footprint
90–120 m² buried
Power
6–12 kW
Delivery
10–14 weeks

Best for: Phased townships where treatment is distributed near generation points

Full specification
Capacity
100 KLD
Construction
Clustered parallel FRP trains
Strategy
Distributed treatment near source, local reuse
Energy
0.3–0.6 kWh/KL
Redundancy
Train-level N+1
Digital
Smart / Smart+ with fleet view
Maintenance
Scheduled service contract
Shell Life
40–50 years
Get quote for GS-100-D

Not sure which capacity fits your building?

Size it in 60 seconds with the calculator

Decentralized range — quick comparison

ParameterGS-10-DGS-25-DGS-50-DGS-100-D
Rated Capacity10 KLD25 KLD50 KLD100 KLD
ConfigurationSingle FRP vessel2 modules3–4 modulesParallel trains
InstallationUndergroundUndergroundUndergroundUnderground
Connected Power0.75–1.5 kW1.5–3 kW3–6 kW6–12 kW
Specific Energy0.3–0.6 kWh/KL0.3–0.6 kWh/KL0.3–0.6 kWh/KL0.3–0.6 kWh/KL
Noise<50 dB<50 dB<50 dB<50 dB
Desludging6-monthly6-monthly6-monthly6-monthly
Shell Life40–50 years40–50 years40–50 years40–50 years

Application guide

Who is this for?

Select your building type to highlight the recommended model above.

ApplicationTypical GenerationRecommended ModelKey ConsiderationDigital Tier
Villas & Farmhouses2–10 KLDGS-10-DNo plant room, no operator, nothing visible above groundBasic
Plotted Layouts10–50 KLDGS-25 / GS-50-DDistributed units avoid long sewer runs across the layoutSmart
Resorts & Homestays5–25 KLDGS-10 / GS-25-DSilent and odour-free next to guest areas; seasonal load tolerantBasic / Smart
Schools & Rural Institutions5–25 KLDGS-10 / GS-25-DMinimal maintenance skill requirement; long holiday toleranceBasic
Highway Amenities & Fuel Stations5–20 KLDGS-10 / GS-25-DRemote sites — remote monitoring replaces a resident operatorSmart
Phased Townships50–100 KLDGS-50 / GS-100-DAdd capacity phase by phase instead of one oversized central plantSmart+
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
6,800 KL/yr
Annual water savings
INR 54,40,000
Annual STP OPEX
INR 1,61,500
Net annual benefit
INR 52,78,500
Simple payback0.4 yrs

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

Run the full 5-step calculator
Cost / Saving ElementGS-10-DGS-25-DGS-50-DGS-100-D
Indicative CAPEX (INR Lakhs)7–1316–2628–4552–80
Civil CostExcavation onlyExcavation onlyExcavation + access chambersExcavation + access chambers
Annual Electricity Cost (INR)18,000–32,00045,000–72,00080,000–1,35,0001,50,000–2,60,000
Annual Chemical CostTablet chlorine onlyTablet chlorine onlyTablet chlorine onlyTablet chlorine only
Annual Operator CostNIL (visit model)NIL–48,00060,000–1,20,0001,20,000–1,80,000
Total Annual OPEX (INR)25,000–55,00095,000–1,60,0001,80,000–3,00,0003,20,000–4,80,000
Annual Water Savings* (INR)2,40,000–4,00,0006,00,000–10,00,00012,00,000–20,00,00024,00,000–40,00,000
Simple Payback Period3–4 years2.5–3.5 years2–3 years2–3 years

*Same reuse basis: 80% of treated water reused at INR 800/KL. Decentralized systems also avoid plant-room construction and long internal sewer runs — savings not counted above.

Project references

Decentralized plants delivered across India

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

20 KLD2024

Villa community — 42 villas

Gurugram, Haryana · Residential

Scope
Buried FRP Johkasou-style clusters, 4 units, phased with handover
Outcome
Installed and commissioned in 11 days; no plant room built
Reuse
Common-area landscape
15 KLD2023

Highway hospitality cluster

Nashik, Maharashtra · Hospitality

Scope
Two buried packaged units, solar-assisted blower supply
Outcome
Runs unmanned; serviced on a monthly visit cycle
Reuse
Plantation belt irrigation
12 KLD2025

School campus, phased blocks

Gurugram, Haryana · Institutional

Scope
Decentralized units added block-by-block as enrolment grew
Outcome
Capex staged over three academic years
Reuse
Playground and garden irrigation
All Sarvo project references

Proof in the field

Decentralized projects and outcomes

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

Bengaluru, Karnataka

Decentralized 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

Decentralized 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

Decentralized 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 Constructed Wetland

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

View technology

Ready for Decentralized 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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