Table of Contents
India awakens to the rumble of 1.4 billion lives each dawn, generating over 72,000 million litres of sewage wastewater daily from homes, apartments, hotels, hospitals, and hostels. This invisible river—equivalent to 29,000 Olympic swimming pools—flows through drains, nallahs, and pipelines, carrying organic waste, pathogens, nutrients, and micro-pollutants. Only 28% undergoes treatment in functional plants; the rest seeps into soil, merges with stormwater, or empties raw into rivers and thousands of smaller water bodies.
Sewage pollution now ranks among the top three environmental threats, alongside air emissions and plastic waste. As cities expand and groundwater tables plummet, addressing sewage wastewater in India emerges as both an urgent public health imperative and a strategic resource recovery opportunity.
SKF Elixer’s compact, modular wastewater treatment systems demonstrate how targeted engineering can bridge treatment gaps in space-constrained urban pockets and peri-urban clusters.
Current Status of Sewage Generation and Treatment Gap
The Central Pollution Control Board (CPCB) tracks 1,093 cities and towns with populations above 50,000—home to 37.7 crore residents. These urban centres produce 61,948 MLD (million litres per day) of sewage, with rural India adding another 10,000–12,000 MLD from larger villages.
Installed treatment capacity stands at 26,879 MLD across 1,426 STPs, but operational plants deliver only 17,326 MLD due to power failures, clogged interceptors, and silted aeration tanks. The treatment gap thus hovers at 72%, or 44,622 MLD untreated daily.
State-wise disparities reveal stark contrasts. Tamil Nadu treats 58% of its 5,800 MLD urban sewage, powered by 112 functional STPs and strong municipal oversight. Uttar Pradesh, generating 8,300 MLD, treats just 23%—leaving 6,400 MLD to pollute the rivers. Maharashtra’s 7,400 MLD sees 4,100 MLD treated, yet Mumbai alone discharges 2,100 MLD raw into creeks. Tier-2 cities like Indore (660 MLD generated, 350 MLD treated) and Bhopal fare better, but smaller municipalities with 50–100 MLD capacity often run plants at 30–40% load due to incomplete sewer networks.
Household contribution dominates: an urban family of five produces 600–700 litres daily (135 litres per capita). A 500-apartment complex in Gurugram thus generates 3–3.5 lakh litres, equivalent to 3–3.5 KLD. Commercial sources amplify volumes—hospitals (450 litres/bed/day), hotels (300 litres/room/day), and malls (10–15 litres/visitor/day).
The National Urban Sanitation Policy estimates that by 2030, urban sewage will touch 1,20,000 MLD as 60 crore Indians live in cities.
Impact on Rivers, Lakes, and Groundwater Resources
Untreated sewage transforms rivers into open sewers. The Yamuna receives 2,500 MLD in Delhi; post-Wazirabad, dissolved oxygen plummets to 0 mg/L for 20 km, earning the stretch a “dead river” label. Biochemical Oxygen Demand (BOD) spikes to 50–80 mg/L downstream of 18 major drains. The Ganga carries 6,000 MLD untreated sewage across Uttar Pradesh and Bihar, with faecal coliform counts exceeding 1 lakh MPN/100 mL at Varanasi. Lakes suffer eutrophication. Bengaluru’s Bellandur Lake foams with detergent-laden sewage (500 MLD inflow), igniting spontaneously from methane pockets. Chennai’s Adyar estuary and Hyderabad’s Hussain Sagar mirror the crisis—phosphorus from detergents triggers algal blooms, killing fish stocks worth ₹50–100 crore annually in affected water bodies. Groundwater contamination spreads silently. In peri-urban Delhi, nitrate levels in tubewells reach 100–300 mg/L (safe limit 45 mg/L) from septic tank seepage. Patna’s handpumps show faecal coliform in 70% samples. The Central Ground Water Board reports 60% of India’s 6,500+ assessment units as overexploited; sewage-induced salinization accelerates aquifer degradation. A single leaking sewer line can contaminate 1 million litres of groundwater with pathogens. Health costs mount: waterborne diseases claim 1.5 lakh children under five annually, with sewage as the primary vector. Economic losses from treatment and lost productivity exceed ₹3.5 lakh crore yearly, per NITI Aayog estimates.
Urbanization and Infrastructure Challenges
India’s urban population grew from 28 crore in 2001 to 47 crore in 2023, adding 1,200 new census towns. Master plans lag—only 30% of urban wards have 100% sewerage networks. Open defecation may have ended, but 40% of households rely on septic tanks, half of which overflow into stormwater drains during monsoons. Sewerage infrastructure ages rapidly. Delhi’s 7,000 km network, laid in the 1960s–80s, suffers 30–40% infiltration of grit and groundwater, reducing hydraulic capacity. Desilting a 1 km stretch costs ₹15–20 lakh, often deferred. Pumping stations fail during power cuts; 40% of STPs report 4–6 hour daily outages in summer. Land scarcity cripples expansion. A conventional 100 MLD ASP plant needs 15–20 acres—unavailable in dense cities. Basement installations in high-rises face height restrictions; aeration tanks cannot exceed 4 m depth without structural retrofits costing ₹5–7 crore. Smaller towns lack skilled operators—turnover exceeds 50% annually, leaving SCADA panels unused. Funding bottlenecks persist. Municipal budgets allocate <5% to sewerage versus 25% to roads. User charges recover only 20–30% of O&M costs; a ₹5 per kilolitre tariff barely covers power bills of ₹3–4 lakh monthly for a 10 MLD plant.
Government Policies and Sewage Management Programs
The Jal Shakti Ministry drives multiple initiatives. The National Mission for Clean Ganga (NMCG), launched in 2014, sanctioned 361 projects worth ₹32,000 crore, including 152 STPs adding 4,800 MLD capacity. Hybrid annuity models mandate 15-year O&M by private players, improving uptime to 85–90%.
Atal Mission for Rejuvenation and Urban Transformation (AMRUT) 2.0 targets 100% sewage management in 500 cities by 2026, with ₹1.4 lakh crore allocated. Focus shifts to faecal sludge management—500+ treatment plants for septic tank empties.
Swachh Bharat Mission–Urban 2.0 integrates open-defecation-free (ODF++) certification with liquid waste. Cities must treat 100% blackwater and 50% greywater to qualify. Over 4,300 cities achieved ODF+ status by 2024.
CPCB’s Pollution Control Implementation mandates online continuous effluent monitoring systems (OCEMS) for STPs >10 MLD. Real-time BOD, COD, and flow data feed central servers; violations trigger ₹1 lakh daily fines.
The National Faecal Sludge and Septage Management (NFSSM) Policy promotes scheduled desludging—every 3 years for 10,000-litre tanks. Mechanized emptiers (3,000-litre vacuum trucks) charge ₹1,500–2,000 per trip, treating sludge at ₹300–400 per cubic metre.
Tax incentives sweeten private investment. 100% FDI is allowed in urban infrastructure; 5-year tax holidays apply for STPs commissioned post-2020. GST on sewage treatment services remains exempt.
Innovative Technologies Improving Sewage Treatment Efficiency
Compact, modular systems address land and skill gaps. SKF Elixer’s Vulcan STP deploys Attached Growth Bioreactor (AABR) technology in stainless-steel tanks. A 50 KLD unit occupies roughly 40 m²—fit for apartment basements or hospital courtyards. Synthetic media (200 m²/m³ surface area) hosts biofilms that degrade BOD from 250 mg/L to <10 mg/L in 6–8 hours HRT. Simultaneous nitrification-denitrification removes 85–90% total nitrogen without separate anoxic tanks.
Automation minimizes manpower. PLC-controlled blowers adjust airflow via dissolved oxygen probes (setpoint 2 mg/L), reducing power from 1.2 kWh/m³ to 0.7 kWh/m³. Online TSS sensors trigger sludge recirculation; remote dashboards allow one technician to monitor 10 plants via smart device. A 200-apartment complex in Noida can report 95% uptime and ₹1.8 lakh annual power savings.
Decentralized STPs treat at source. A 20 KLD Vulcan unit in a Gurugram school can recycle 16,000 litres daily for flushing and landscaping, cutting municipal water bills by ₹3.5 lakh yearly. Effluent meets CPCB norms: BOD <10 mg/L, TSS <5 mg/L, faecal coliform <100 MPN/100 mL.
Membrane Bioreactors (MBR) integrate ultrafiltration (0.04 μm pores) within aeration tanks. A 100 KLD MBR plant in Pune produces reusable water at ₹18–22 per 1,000 litres—cheaper than tanker supply at ₹50–80. Hollow-fibre membranes last 7–10 years; automated backwash cycles every 8 minutes prevent fouling.
Anaerobic-Ammonia Oxidation (Anammox) cuts aeration needs by 60%. Pilot plants in Surat can treat 5 MLD high-ammonia sewage, saving ₹12 lakh annually in power. Partial nitritation feeds Anammox bacteria that convert NH₄⁺ and NO₂⁻ directly to N₂ gas.
Sludge-to-Energy recovers value. A 500 KLD STP in Indore can co-digest faecal sludge with food waste, yielding 180 m³ biogas daily—powering a 25 kW genset for plant auxiliaries. Digestate compost sells at ₹4 per kg to farmers.
Conclusion
SKF Elixer’s wastewater treatment systems built from Stainless-steel non corrosion from chlorides; modular skids relocate when factories expand.
Real-time monitoring platforms integrate OCEMS with GIS mapping. NMCG’s Ganga Monitoring Centre tracks 300+ STPs; AI predicts failures 48 hours ahead via vibration and power draw anomalies. Downtime can fall 60% in pilot cities.
The path ahead demands convergence: 100% sewerage by 2030, 75% treatment by 2027, and 50% reuse by 2035. Every untreated litre costs ₹50–60 in health and ecological damage; every treated litre returns ₹20–30 in water security.
From policy frameworks to basement bioreactors, India possesses the tools. Deployment at scale—driven by public-private partnerships and citizen ownership—will determine whether the silent surge of sewage wastewater drowns the nation or irrigates its sustainable future.
FAQs
-
1. How much sewage does an average Indian city of 5 lakh population generate daily?
At 135 litres per capita, the city produces 6.75 crore litres (675 MLD). A 200-apartment complex within it contributes 3–3.5 lakh litres (3–3.5 KLD).
-
2. What is the treatment gap in Tier-2 cities like Lucknow or Coimbatore?
Lucknow (2,000 MLD generated, 600 MLD treated) has a 70% gap. Coimbatore (550 MLD generated, 350 MLD treated) has a 36% gap—better but still significant.
-
3. How does untreated sewage affect groundwater recharge in urban areas?
Leaking sewers and septic tanks introduce nitrates (>100 mg/L) and pathogens. A single 1 km leaking line can contaminate 10 lakh litres of aquifer water, rendering tubewells unfit for 5–10 years.
-
4. Which government scheme funds decentralized STPs in apartments?
AMRUT 2.0 and Swachh Bharat Mission–Urban 2.0 provide 50% capital subsidy for STPs up to 50 KLD in residential complexes. Balance funded via user charges or CSR.
-
5. Can Vulcan STP treated water be used for drinking after further processing?
Tertiary-treated water meets bathing quality (BOD <10 mg/L). For potable reuse, add reverse osmosis and UV—achieving <1 mg/L TDS and zero pathogens—at ₹35–40 per 1,000 litres.
Good reads are meant to be shared
