Wastewater disinfection

Wastewater reuse in agriculture is fundamental for the water utilities to move towards a circular economy approach to water as a resource. However, reuse in agriculture requires treatments with high efficiency in pathogens concentration abatement. It is then important to have a research activity in the PerFORM WATER 2030 project to develop new optimal control strategies for the disinfection process, which fit strict discharge limits for pathogens indicators.

Which is the role of wastewater disinfection?

Peracetic acid disinfection: pros and cons

Agricultural reuse and disinfection: what are the challenges a water utility has to face off?

Goal of the experimental activity within the PerFORM WATER 2030 project

The pilot plant

Useful link on disinfection


Which is the role of wastewater disinfection?

Disinfection is usually the last stage of wastewater disinfection. The goal of the process is to minimize the spread of pathogens in environment, protecting human health.
Disinfection can be performed through chemical disinfectant dosage, ultra-violet radiation or membrane processes. Disinfection is of particular importance to treat wastewater for reuse, when discharge limits on pathogens indicators are very strict.

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Peracetic acid disinfection: pros and cons

Generic placeholder image In recent years peracetic acid has been pointed out as a valuable option for chemical disinfection of wastewater, as an alternative to sodium hypochlorite. Peracetic acid produces scarce concentrations of disinfection-by-products and has a low eco-toxic impact on environment. However, the first criticism in peracetic acid disinfection management lays in the loss of concentration which occurs after the dosage. Peracetic acid is affected by oxidative consumption and gradual decay, depending on wastewater quality. A proper dosage control strategy should then take into account this criticism.


Agricultural reuse and disinfection: what are the challenges a water utility has to face off?

Wastewater reuse is a fundamental goal for the water utilities in a circular economy perspective.

Agricultural reuse is a promising opportunity to exploit the value of the treated effluent, but it exposes crops and workers to potential health risk. It is then required that the disinfection process guarantees very low concentration of pathogens in the effluent.

In response to that challenge, we choose to include the optimization of disinfection for irrigation purposes as a part of PerFORM WATER 2030 project's research activities. The optimization foreseen indeed requires a deep knowledge about the disinfectant decay, the pathogens inactivation kinetics and the relationship between operating conditions and process efficiency.

Measurements and modeling for water disinfection

Project details


Goal of the experimental activity within the PerFORM WATER 2030 project

Disinfection is a well-established process from a technological point of view. However, discharge limits for agricultural reuse require to develop new control strategies for existing systems to make them more efficient and robust in guaranteeing performances. Peracetic acid introduces an additional criticism in the dosage control, related to the natural disinfectant decay.

A pilot plant has been set up, in order to develop and test an optimal algorithm for dosage control, accounting for the most important operative parameters: disinfectant concentration, contact time and wastewater quality (turbidity, suspended solids, organics). Moreover, a complementary laboratory activity is carried out, exploring the variability of pathogens inactivation and is relationship with the wastewater matrix characteristics.


The pilot plant

The calibration and validation of an accurate modelling of the process and an effective control strategy required us to set up a pilot plant aimed at collecting data.

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An open channel contact tank with 5 inversions with a total volume of 2220 L was installed at the Peschiera Borromeo wastewater treatment plant operated by CAP Group.
The system is fed by the real plant effluent, in order to test effect of the real wastewater quality patterns. Moreover, a control valve at the tank inlet can control the flow rate, in order to simulate the effect of changes in the residence time: the pilot can work at residence time ranging from 15 to 60 minutes. The control valve and the disinfectant dosing system are managed by a microcontroller: different control algorithms can be tested by programming the microcontroller.

Generic placeholder image The calibration and validation of an accurate modelling of the process and an effective control strategy required us to set up a pilot plant aimed at collecting data.

An open channel contact tank with 5 inversions with a total volume of 2220 L was installed at the Peschiera Borromeo wastewater treatment plant operated by CAP Group.
The system is fed by the real plant effluent, in order to test effect of the real wastewater quality patterns. Moreover, a control valve at the tank inlet can control the flow rate, in order to simulate the effect of changes in the residence time: the pilot can work at residence time ranging from 15 to 60 minutes. The control valve and the disinfectant dosing system are managed by a microcontroller: different control algorithms can be tested by programming the microcontroller.


Link utili per approfondire la tematica della disinfezione


Informative video "Wastewater Treatment Video 7: Effluent disinfection with a brief description of the biological processes of waste water treatment by Rural Community Assistance Partnership (RCAP), network of non-profit organizations across the United States


Informative video "Case Histories on the Use of Peracetic Acid" con la descrizione di casi di applicazione dell’acido peracetico a cura della Water Environment Federation, a not-for-profit association that provides technical education and training to water quality professionals.


Proposal for new rules to stimulate and facilitate water reuse in the EU for agricultural irrigation, published by The European Commission on May 2018


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