Santillana Drinking Water Plant: 90 kg/h Ozone System in Madrid
What ozone system was supplied for the Santillana Drinking Water Plant?
Longking EnTech Europe supplied, installed and commissioned a centralized ozone generation system for the Santillana Drinking Water Plant in Madrid, Spain, operated by Canal de Isabel II. The project was awarded in 2021 as part of an upgrade of the plant’s existing ozonation facilities.
The installation has a total ozone production capacity of 90 kg O₃/h, based on 3 × 30 kg O₃/h Longking NLO ozone generators fed with oxygen. The centralized generation system supplies both pre-ozonation and intermediate ozonation stages within the drinking water treatment process.
The Santillana plant has a treatment capacity of approximately 345,000 m³/d, making this one of Longking EnTech Europe’s major municipal drinking water ozone references in Spain. The project combined ozone generation with contact chamber optimization, off-gas destruction, cooling, automation and integration with the plant control system. Longking Ozono 2026
Santillana ozone system at a glance
Owner / Operator: Canal de Isabel II
Location: Manzanares El Real, Madrid, Spain
Treatment capacity: approximately 345,000 m³/d
Ozone production: 90 kg O₃/h
Configuration: 3 × NLO30 ozone generators
Feed gas: oxygen
Ozone application: pre-ozonation and intermediate ozonation
Engineering: CFD optimization of ozone contact chambers
Process integration: automatic ozone dosing, PLC/HMI and SCADA integration
Remote monitoring: SENTINEL
The project illustrates how Longking’s NLO ozone generator systems can be integrated into large municipal drinking water plants where ozone generation, transfer efficiency, safety and automation must operate as a complete treatment system
Why was the Santillana ozonation system upgraded?
The Santillana Drinking Water Plant has a long operational history with ozone treatment. The 2021 project was designed to modernize the existing installation and consolidate ozone production into a centralized system capable of supplying both the pre-ozonation and intermediate ozonation stages.
A key objective was to replace legacy equipment with a more efficient, controllable and integrated architecture while maintaining the flexibility required for different ozone injection points and future operating conditions.
The upgrade therefore addressed the ozonation process as a complete system: ozone generation, transfer to water, contact time, residual ozone destruction, cooling, automation and integration with the plant’s existing control infrastructure.
How is the 90 kg/h Santillana ozone generation system configured?
The Santillana installation uses three Longking NLO 30 ozone generators, each with a nominal production capacity of 30 kg O₃/h, providing a total installed capacity of 90 kg O₃/h. The generators operate with oxygen as feed gas and are designed for centralized supply to the plant’s different ozonation stages. Longking Ozono 2026
Main ozone generation characteristics
3 × NLO 30 ozone generators
30 kg O₃/h per unit
90 kg O₃/h total installed capacity
Oxygen-fed operation
Ozone concentration up to approximately 10% by weight, according to operating conditions
IGBT-based power electronics for controlled ozone production
Specific energy consumption below 7.5 kWh/kg O₃ under the defined design conditions
The centralized architecture allows ozone production to be managed according to the requirements of the pre-ozonation and intermediate ozonation stages, while keeping generation, cooling, instrumentation and control integrated within a common system.
How was ozone transfer optimized at the Santillana Drinking Water Plant?
Ozone generation capacity alone does not determine treatment performance. The efficiency of gas–liquid transfer and the hydraulic behaviour of the contact chambers are also critical, particularly in large drinking water plants with existing infrastructure.
For the Santillana project, Longking EnTech Europe carried out a detailed Computational Fluid Dynamics (CFD) study of the ozone contact chambers as part of the retrofit engineering. The analysis identified areas in the existing pre-ozonation chambers where hydraulic conditions could limit effective ozone transfer and contact time.
Objectives of the CFD analysis
Evaluate flow distribution within the existing contact chambers.
Identify hydraulic short-circuiting and low-efficiency zones.
Improve ozone transfer between the gas and water phases.
Increase effective retention time through optimized baffling.
Define retrofit modifications compatible with the existing civil infrastructure.
Based on the CFD results, modifications were introduced to improve the hydraulic behaviour of the contact chambers and strengthen the effectiveness of ozone transfer without replacing the complete existing structures.
How is residual ozone safely managed at the Santillana plant?
The Santillana ozonation system includes dedicated equipment for the safe handling and destruction of residual ozone from the contact process. This is essential in large drinking water installations, where off-gas management must be integrated into the overall process and safety architecture. Longking EnTech Europe
Main off-gas and safety elements
High-capacity ozone destructors.
Relief valves installed on the ozone contact chambers.
PLC-based control and touchscreen monitoring of the destruction system.
Liquid collection tanks.
Demisters to reduce the risk of water droplets and condensate entering the ozone destructors.
Heating elements to help the destruction units reach operating temperature rapidly during cold winter conditions.
These elements protect equipment, support safe operation and ensure that residual ozone from the contact process is properly managed before discharge.
How is the Santillana ozone generation system cooled?
Ozone generation produces a significant thermal load, so stable cooling is essential for maintaining reliable and efficient operation. At Santillana, the ozone generators are served by a dual-loop closed-circuit cooling architecture designed to isolate the generator cooling circuit from the plant water used for heat rejection.
Closed generator cooling loop
The internal cooling circuit uses treated water with the required additives and includes:
Duty/standby recirculation pumps.
Continuous monitoring of flow, pressure and temperature.
Integration of cooling parameters into the ozone plant PLC.
Protection logic linked to the operating condition of the ozone generators.
Primary heat-rejection loop
A separate plant-water circuit removes heat from the closed generator loop through heat exchangers. The water used for heat rejection is then returned to the process after heat exchange.
This arrangement helps maintain stable cooling conditions while protecting the ozone generators from direct exposure to variations in plant-water quality, supporting continuous operation and equipment durability.
How is ozone dosing and plant control automated at Santillana?
Ozone dosing at Santillana is controlled automatically through valves and flow regulation equipment, allowing the required ozone production and injection to be adjusted according to the operating conditions of the treatment process.
PLC, HMI and SCADA integration
The main operating parameters of the ozonation system are collected by the ozone plant PLC and integrated into the Santillana Drinking Water Plant’s central SCADA system. The control software was developed specifically for the installation and adapted to the operator’s requirements.
The integrated control architecture provides operators with centralized supervision of:
Ozone generation and dosing.
Generator operating status.
Cooling-system parameters.
Relevant process instrumentation.
Alarms and safety interlocks.
Operating trends and system status.
SENTINEL remote monitoring
The installation also incorporates Longking EnTech Europe’s SENTINEL remote monitoring system, allowing authorized technical personnel to access operating information remotely when permitted by the plant’s cybersecurity policies.
This combination of local automation, SCADA integration and remote monitoring supports the operation of the ozonation system as part of the complete drinking water treatment plant rather than as standalone generation equipment.
What does the Santillana project demonstrate about large-scale drinking water ozonation?
The Santillana reference shows that the performance of a large ozonation installation depends on much more than nominal ozone production capacity. Generation, gas–liquid transfer, contact hydraulics, cooling, residual ozone destruction, automation and plant integration all need to be engineered as parts of the same treatment system.
With 90 kg O₃/h of installed capacity, three NLO30 generators and two ozonation stages, Santillana is a representative example of Longking EnTech Europe’s experience in large municipal drinking water applications in Europe.
Engineering a complete ozone treatment system
For projects of this scale, the ozone generation equipment must be coordinated with:
Feed-gas supply and quality requirements.
Cooling and thermal management.
Ozone injection and gas–liquid transfer.
Contact chamber hydraulics and effective retention time.
Residual ozone destruction and plant safety.
Process instrumentation and automatic dosing.
PLC/HMI and SCADA integration.
Commissioning, monitoring and lifecycle support.
Longking’s NLO ozone generator systems are designed for municipal and industrial applications where high ozone production capacity must be integrated with the complete treatment process.
For more information about the technology, visit our NLO ozone generator systems and municipal water treatment pages.
If you are evaluating a new ozone installation or the modernization of an existing drinking water ozonation system, contact our engineering team at info@longkingeu.com.