Ozone Generator in Water Treatment Plant (WTP)

Ozone is applied at two points in the WTP treatment train: pre-ozonation (ahead of coagulation/flocculation) and/or intermediate ozonation (after filtration, before distribution). Pre-ozonation at 0.5–1.5 mg/L oxidises dissolved iron, manganese, and taste-and-odour compounds, and partially oxidises humic substances — improving subsequent coagulation efficiency by up to 40% (reducing coagulant dose and sludge generation). Intermediate ozonation at 1–3 mg/L provides primary disinfection against Cryptosporidium, Giardia, and bacteria, often followed by biological activated carbon (BAC) filtration to remove ozonation by-products.

UV disinfection in WTP uses UV-C radiation at 254 nm to cause thymine dimer formation in DNA, preventing pathogen replication without any chemical addition. At 40 mJ/cm² UV dose, UV achieves: 4-log E. coli inactivation, 3-log Giardia inactivation, and 3-log Cryptosporidium inactivation — per US EPA UV Disinfection Guidance Manual 2006 and WHO Guidelines 2022. The OZ India UV water treatment system uses low-pressure or medium-pressure UV lamps in a 316L stainless steel chamber, validated to achieve the design UV dose at maximum design flow and minimum UVT (UV transmittance).

The UV dose (mJ/cm²) = irradiance (mW/cm²) × exposure time (sec). In OZ India UV systems, the irradiance field is calculated using validated computational fluid dynamics (CFD) models, and the system is bioassay validated using MS2 coliphage challenge testing — the gold standard for UV system validation per DVGW W294 and NSF/ANSI 55. The validated UV dose provides legally defensible documentation for WTP compliance reporting to state water boards and BIS inspectors.

Ozone generation for WTP uses oxygen from PSA oxygen generators (for systems above 25g/hr) or from dry compressed air. The OZ India 10-25g/hr to 400g/hr systems are matched to WTP flows from 100 m³/hr to 100,000 m³/hr. Ozone transfer to water is achieved through fine bubble diffusers in counter-current contact towers, achieving 85–95% ozone transfer efficiency. The dissolved ozone concentration is continuously monitored and controlled to maintain the target CT value at the ozone contactor outlet.

Disinfection by-product (DBP) management is a critical consideration at WTPs using ozone. When ozone reacts with bromide in source water, bromate (BrO₃⁻) is formed — a suspected carcinogen with WHO guideline value of 10 μg/L. In Indian WTPs drawing from surface water with bromide below 50 μg/L (typical for Ganga and tributaries), bromate formation is below the WHO limit at standard ozone doses. For WTPs with higher bromide sources (coastal or industrial-affected groundwater), UV-AOP (ozone + hydrogen peroxide) can be used to quench bromate formation while maintaining disinfection.

Ozone-treated water undergoes biological activated carbon (BAC) filtration in optimised WTP designs, where residual ozone oxidation products (aldehydes, ketones) are biodegraded by the biofilm on the activated carbon surface. BAC filtration also removes trace organic micropollutants not fully mineralised by ozone, producing effluent water of superior taste and quality. The BAC step converts ozone from a simple disinfectant to a component of a multi-barrier treatment train that addresses the full range of WTP water quality challenges.

OZ India Technology's UV water treatment systems are designed for WTP applications from 100 LPH to 2,00,000 LPH (200 MLD), with UV dose validated at 40 mJ/cm² for primary disinfection per WHO and IS:10500 requirements. Our ozone generators for WTP iron, manganese, and taste-odour control are sized from 10g/hr to 1kg/hr, with complete PSA oxygen generation included in packages above 25g/hr. All equipment is CE certified, ISO 9001:2015 manufactured, and supplied with validation documentation acceptable to BIS and state water quality regulators.

For WTPs facing Cryptosporidium risk, OZ India recommends the UV primary barrier approach: UV system validated to 40 mJ/cm² (3-log Cryptosporidium inactivation) followed by chlorine residual (secondary barrier). This combined approach provides the highest level of microbial protection with the lowest chemical dose — minimising THM formation. For WTPs with iron/manganese problems, the ozone pre-oxidation + filtration approach eliminates the colour and staining complaints that drive consumer dissatisfaction with municipal water supply.

OZ India's WTP systems include SCADA integration capability — ozone generators and UV systems provide 4-20mA output signals for OT/DCS integration at large municipal WTPs. Remote monitoring via GSM/internet allows WTP supervisors to view real-time ozone production, dissolved ozone residual, UV lamp intensity, and alarm status from any location — critical for 24×7 WTP operations with shift-based staffing.

OZ India has supplied and commissioned UV and ozone systems at WTPs operated by municipal corporations, water utilities, hotel chains, and residential townships across India. Our WTP references span Maharashtra, Gujarat, Uttar Pradesh, Rajasthan, and Punjab — providing experience with the diverse raw water quality challenges found across Indian river basins and aquifer systems. Each WTP project includes site-specific design, equipment supply, installation, commissioning, and operator training with 1-year comprehensive warranty.

WTP UV system sizing requires: design flow (m³/hr), UV transmittance (UVT% at 254 nm) of the filtered water, and target UV dose (40 mJ/cm² for 4-log inactivation per WHO). The OZ India UV system is sized to deliver the validated UV dose at minimum UVT and maximum flow — the worst-case operating condition. UVT of filtered WTP effluent typically ranges from 85–95% for surface water and 90–98% for groundwater. A UVT drop (due to high turbidity or coloured influent) requires proportionally higher UV lamp power to maintain the dose — OZ India systems include automatic intensity control with real-time UVT monitoring.

For ozone sizing at WTP, the application determines the dose: iron/manganese oxidation requires 0.3–0.5 mg/L O₃ per 1 mg/L Fe²⁺ and 0.5–1.0 mg/L O₃ per 1 mg/L Mn²⁺; taste-odour control requires 0.3–0.5 mg/L; disinfection (CT for Giardia 3-log) requires CT 0.5 mg/L·min at pH 7–8. Total ozone dose is the sum of instantaneous demand plus residual requirement. Ozone generator capacity (g/hr) = Flow (m³/hr) × Total dose (mg/L) × 1.3 (safety factor) ÷ 1000.

Large municipal WTP ozone systems use oxygen-fed generators with PSA oxygen plants to minimise energy cost. For WTPs above 10 MLD, OZ India recommends N+1 redundancy — multiple ozone generator units where one can serve as standby without compromising treatment capacity. Contact OZ India with your WTP design flow, raw water analysis (iron, manganese, turbidity, UVT, bromide, TOC, coliform count) for a complete sizing report and equipment proposal.