RRR
300 KLD Sewage Treatment Plant — MBBR (Moving Bed Biofilm Reactor)
High-capacity MBBR plant engineered for space-efficient, robust BOD removal with lower sludge. Turnkey supply, civil, installation, commissioning & AMC by RRR ENVIRO SYSTEMS.
Overview
This 300 KLD (300 m³/day) MBBR is designed for continuous industrial/residential service with advantages of compact tanks, high biomass surface area, and reduced sludge. Default design assumptions: 20 operating hours/day, influent BOD₅ = 250 mg/L, media fill = 50%. Final guarantees after site sampling & lab reports.
Process Flow — Text Diagram
Inlet → Bar screen → Grit & Oil-Grease removal → Collection / Equalization Tank (with mixer) → Raw sewage pump → MBBR Reactor (aeration with floating carriers) → Secondary Clarifier (settling & RAS) → Tertiary Polishing (PSF / ACF / UF) → Disinfection (UV / Hypo) → Treated Water Tank → Reuse / Discharge (CPCB/TNPCB compliance).
Sludge: Sludge sump → Thickening → Dewatering (filter press/drying bed) → Disposal.
Design Basis & Digit-by-Digit Calculations
Given / Assumed:
- Qday = 300 m³/day
- Operating hours = 20 hr/day → Qhr = 300 ÷ 20 = 15.00 m³/hr (15,000 LPH)
- MBBR HRT chosen = 4.0 hours (typical 3–6 h)
- Media fill fraction = 50% (vendor dependent)
- Media SSA (specific surface area) = 500 m²/m³ (example; confirm with vendor)
- Influent BOD₅ assumed = 250 mg/L
Step 1 — Hourly flow
Qhr = 300 ÷ 20 = 15.000 m³/hr = 15,000 LPH.
Q_day = 300 m³/day → Q_hr = 300 ÷ 20 = 15.000 m³/hr → 15,000 LPH
Step 2 — Aeration / Reactor Volume (HRT method)
Vaer = Qhr × HRT = 15.000 × 4 = 60.0 m³ (60,000 L) working volume.
Add 15% freeboard → physical tank ≈ 60 × 1.15 = 69.0 m³.
Add 15% freeboard → physical tank ≈ 60 × 1.15 = 69.0 m³.
V_aer = 15 × 4 = 60.0 m³
V_physical ≈ 60 × 1.15 = 69.0 m³
Step 3 — Media Volume & Surface Area
Media volume = Vaer × media_fill = 60.0 × 0.50 = 30.0 m³ of carrier media.
Total media surface area = 30.0 × 500 = 15,000 m² (active biofilm area).
Total media surface area = 30.0 × 500 = 15,000 m² (active biofilm area).
V_media = 60 × 0.5 = 30.0 m³
Total_SSA = 30.0 × 500 = 15,000 m²
This very large active surface area gives excellent biomass retention and high treatment capacity per unit volume (key MBBR advantage).
Step 4 — MLSS & Biomass (suspended)
Choose conservative MLSS = 3,000 mg/L (3.0 kg/m³). Biomass mass = MLSS × V_aer = 3.0 × 60.0 = 180 kg suspended solids (plus attached biofilm on media).
MLSS mass = 3.0 × 60 = 180 kg
Step 5 — BOD Load & Oxygen Requirement
BOD load/day = Q_day × BOD ÷ 1000 = 300 × 250 ÷ 1000 = 75 kg BOD/day.
O₂ requirement (1.4 kg O₂/kg BOD) = 75 × 1.4 = 105 kg O₂/day.
Blower sizing estimate: assume 1.2 kg O₂/kW → blower_kW ≈ 105 ÷ 1.2 = 87.5 kW. Considering media scouring & losses, recommend total blower capacity ≈ 100 kW provided as multiple units (e.g., 4 × 25 kW duty/standby with VFDs) to allow redundancy and control.
O₂ requirement (1.4 kg O₂/kg BOD) = 75 × 1.4 = 105 kg O₂/day.
Blower sizing estimate: assume 1.2 kg O₂/kW → blower_kW ≈ 105 ÷ 1.2 = 87.5 kW. Considering media scouring & losses, recommend total blower capacity ≈ 100 kW provided as multiple units (e.g., 4 × 25 kW duty/standby with VFDs) to allow redundancy and control.
BOD_load = 300×250/1000 = 75 kg/day
O2_req = 75×1.4 = 105 kg/day
Blower_kW ≈ 105 ÷ 1.2 ≈ 87.5 kW → recommend ~100 kW split across multiple units
Final blower sizing to be confirmed using vendor OTR data, diffuser efficiency and site temperature.
Step 6 — Secondary Clarifier Sizing
Use Surface Overflow Rate (SOR) = 30 m³/m²·day. Area A = Q_day ÷ SOR = 300 ÷ 30 = 10.0 m². For better hydraulics choose clarifier(s) with total area 12–15 m² (multiple smaller clarifiers or one larger clarifier, e.g., dia ~4.0 m or rectangular tanks). Depth & hopper sized per standards.
A = 300 ÷ 30 = 10.0 m² (select practical area 12–15 m²)
Step 7 — Sludge Generation Estimate
MBBR typically produces lower sludge than ASP. Use sludge yield 0.45 kg DS/kg BOD → DS/day = 75 × 0.45 = 33.75 kg DS/day. At 3% cake solids: wet sludge ≈ 33.75 ÷ 0.03 ≈ 1,125 L/day (~1.1 m³/day). Provide sludge sump, thickening/digestion and dewatering equipment accordingly.
DS/day = 75×0.45 = 33.75 kg
Wet sludge ≈ 33.75 ÷ 0.03 ≈ 1125 L/day
Main Components & Scope of Supply
- Bar screen & grit / oil & grease trap
- Equalization / collection tank with mixer and level control
- Raw sewage transfer pumps (duty + standby)
- MBBR aeration tank with carrier media (~30 m³ carriers) and fine-bubble diffusers
- Blowers (total ~100 kW split across multiple units with VFD & redundancy)
- Secondary clarifier(s) with sludge hopper & RAS pump
- Polishing: Pressure Sand Filter / Activated Carbon Filter / UF (optional) and disinfection (UV / Hypo)
- Sludge sump, thickening & dewatering (filter press / centrifuge / drying bed)
- PLC control panel, DO sensors, level switches, flow meter and remote monitoring option
- Piping, valves, civil anchors, installation & commissioning
Regulatory Compliance — TNPCB / CPCB
Design & operation will comply with TNPCB / CPCB standards. Included in scope (as needed):
- Design to meet BOD, COD, TSS, Oil & Grease and Faecal Coliform / E. coli limits (depending on receiving body / reuse purpose).
- Sampling ports, monitoring points and flow meters as per statutory requirements.
- Assistance with documentation and technical reports for consent/permissions
- Tertiary polishing & disinfection options for reuse requiring tighter standards
Chemical Dosing & Utilities
- Disinfection (Sodium Hypochlorite / Chlorine): Final disinfection dosing with dosing skid and safe chemical storage.
- Polymer (Flocculant): For sludge thickening and dewatering (dosing to sludge sump or decant).
- pH Correction: Acid/alkali dosing for neutralization if required.
- Anti-foaming: Dosed as required to control excessive foam in aeration tanks.
- Coagulant (Alum / PAC): For tertiary treatment to remove colour / colloidal solids if needed.
- Utilities: compressed air (for instruments), electrical HT/LT supply for blowers, pumps and PLC; safe chemical storeroom with bunding.
Quantities & dosing rates will be calculated after influent analysis. We supply dosing skids, pumps, and storage on request.
Technology Comparison (MBBR vs ASP vs SBR vs MBR)
| Technology | Key Advantages | Best Use |
|---|---|---|
| MBBR | High surface area per volume, compact footprint, tolerant to shock loads, lower sludge | Space-limited sites, variable loads, industrial & municipal combos |
| ASP | Well-proven, simpler operation for large continuous flows | Large municipal or continuous industrial flows with available area |
| SBR | Batch control & flexibility, compact footprint | Intermittent flows, retrofit, small-to-medium systems |
| MBR | Superior effluent, very low TSS, minimal clarifier space | Reuse-critical projects and strict discharge limits |
Expected Performance & Reuse
| Parameter | Typical Influent | Expected Effluent (MBBR + Polishing) |
|---|---|---|
| BOD₅ | 200 – 400 mg/L | < 30 mg/L (with good O&M & polishing) |
| TSS | 150 – 350 mg/L | < 30 – 50 mg/L |
| COD | 600 – 1200 mg/L | < 200 – 300 mg/L |
| Turbidity | Varies | < 5 NTU (with PSF / UF) |
| Use | — | Toilet flushing, landscaping, cooling makeup (after disinfection/polishing) |
Performance guarantees after acceptance of supply scope and review of raw influent lab report.
Operation & Maintenance
- Daily: check screens, pumps, blowers, DO (maintain DO 2–3 mg/L typical), RAS & sludge levels.
- Weekly: inspect diffusers & carriers, remove ragging, check blower performance.
- Monthly: calibrate DO & level sensors, inspect media condition and piping.
- Sludge handling: schedule dewatering & disposal; maintain polymer dosing as required.
- We provide operator training, spares kits and AMC packages for consistent operation.
FAQ — 300 KLD MBBR STP
Q1: Why choose MBBR for 300 KLD?
MBBR offers high treatment capacity per unit volume, lower sludge, and excellent tolerance to load changes — ideal where footprint is limited and performance must be robust.
Q2: How much media is required?
Estimated media volume ~30 m³ for 50% fill in a 60 m³ aeration tank; exact quantity depends on selected fill fraction and vendor carrier geometry.
Q3: What blower capacity is needed?
Working estimate ~100 kW split across multiple blowers (duty+standby) to meet oxygen demand and media scouring. Final sizing after OTR data & site conditions.
Q4: What reports are needed to finalise the design?
Send raw influent lab report: BOD, COD, TSS, TDS, Turbidity, FOG, pH, temperature and any specific contaminants. We also offer jar tests & on-site analysis.