There are five sewerage systems that collect both waste and storm water from 22 out of 25 municipalities in the ATO (Optimal Service Area) ‘Orientale Goriziano’ in Italy. To reduce the environmental pressure on the receiving water, as well as to reduce management costs, our client Irisacqua started to look into implementing an overhaul of the sewerage systems and wastewater treatment plants. DHI developed a decision support system to help them successfully improve the operations of their water systems.

Challenge

Our client needed to reduce environmental pressure on the receiving water – mainly the River Isonzo and Panzano Bay – due to releases from the existing sewage network and wastewater treatment plants, as well as to reduce management costs. They wanted to implement a solution for a revamp of the water systems. Furthermore, there was also a need for compliance with regulatory constraints.

Solution

The platform is based on MIKE Powered by DHI’s MIKE OPERATIONS and is mainly composed of:

• a central database for data storing
• a web interface for data and results publication; and
• an expert graphical user interface for the configuration of an advance management of the system

Results

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‘Our ambition was to establish a real-time system for monitoring the sewage network and the treatment plant. We are impressed by the solution that achieved the objective of simulating and forecasting rainfall events to optimise runoff management.’

Pierpaolo Braidotti, Engineer
Irisacqua

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The full story

Challenge

Background of Italy’s water sector

In 1994, the Italian government embarked on a bold process to reform the Italian water sector by passing the Galli Law. The law aimed to consolidate municipal service providers into regional utilities and separate the provision of service from regulation, achieving cost recovery from tariffs and improving efficiency. As stipulated by the law, Italy's regional governments were required to define ‘Optimal Service Areas’ (Ambiti territoriali ottimali in Italian – also referred to as ATO) that would be covered by the new regional utilities. Each ATO would be made up of a group of municipalities.

Overhaul of the sewerage systems and wastewater treatment plants

The ATO ‘Orientale Goriziano’ is an area that coincides with the ex-Gorizia Province, comprised of 25 municipalities. There are five sewerage systems that collect both waste and storm water from 22 out of 25 municipalities in the ATO.

The overflow wastewater of the sewerage system and the wastewater treatment plants drain into the hydrographic basin of River Isonzo and Panzano Bay. To reduce the environmental pressure on the receiving water, as well as to reduce management costs, our client Irisacqua started to look into implementing an overhaul of the sewerage systems and wastewater treatment plants of Orientale Goriziano.

The revamp consists of the centralisation of three sewerage systems – Gorizia, Gradisca and Staranzano. IrisAcqua decided to plan an enhancement that would convey the wastewater of all three plants into Staranzano – and for the other two plants to be decommissioned. The wastewater from the decommissioned plants, Gorizia and Gradisca, would be directed into Staranzano, thanks to a low-pressure trunk sewer. Staranzano would then send the treated water into the Adriatic Sea.

Comparison between current state (left) and project state (right) of the sewerage system of the ATO ‘Orientale Goriziano’.

Solution

The importance of a real-time decision support system (DSS)

In order to coordinate this new and complex system, a decision support system based on MIKE Powered by DHI technologies was implemented. The DSS is able to support optimal management strategies according to observed and forecasted data in real-time. These management strategies include the possibility to temporarily store part of the water coming from Gorizia and Gradisca when significant meteorological events occur, and to direct discharges to Staranzano to reduce the spillway’s releases.

The system is a combined sewer which simultaneously collects sewage water from civil and industrial waste and surface runoff.

Platform description

The platform is based on MIKE OPERATIONS and is mainly composed of (1) a central database for data storing, (2) a web interface for data and results publication and (3) an expert graphical user interface for the configuration of an advance management of the system.

This structure is partially similar to the operative systems already implemented in most of the Decentralized Functional Centers of the Italian Civil Protection Department. The platform contains many specific applications, such as the results of hydraulic simulations, the optimisation techniques and the tools for weather stations management.

Among these applications, the model MIKE URBAN (now MIKE+) is automatically executed in real-time to simulate the hydrological and hydraulic processes that characterise the system and to support the optimal management strategy on a case-by-case basis.

How it works

• Data collection related to the state of the sewer system and wastewater treatment plant: These data are collected into the platform by querying the SCADA system, which collects in-field sensors. In particular, the recorded discharges in the control sections of the sewage networks, the levels of the tanks and the regulating devices are recorded.
• Meteorological data collection: The platform collects all the precipitation data in the area from the regional environmental monitoring network. The information is integrated with the results of meteorological models for future use. In the same way, the platform acquires other data such as the Adriatic Sea water level and the results of the platform managed by the Functional Center of Friuli Venezia Giulia and the Venezia Nuova Consortium.
• Numerical simulation of wastewater into wastewater treatment plants: By using observed and forecasted data, the platform automatically powers the MIKE URBAN (now MIKE+) model which allows the user to evaluate the total wastewater volume carried into the wastewater treatment plants of Gradisca, Gorizia and Staranzano on an hourly basis.
• Numerical simulation of wastewater into trunk sewers and wastewater treatment plants: A subsequent simulation determines the dynamic in the trunk sewers and the eventual storage into the Gorizia and Gradisca plants. This simulation phase includes the final discharge into the sea downstream of Staranzano.
• Optimisation: The results of the numerical model above are used by the platform to compare different possible sewerage system results in terms of device maneuvering, with particular interest into the possibility to store part of the wastewater into the Gradisca and Gorizia plants. The algorithm considers both the environmental impact, in terms of the discharge that is not treated, and in terms of energy consumption, by identifying the best management strategy.
• Decisional support and visualisation: The platform produces a series of automatic reports specified by the user. The technicians of IrisAcqua can refer to these documents to optimise the system. Although the platform does not enable a direct control of the physical system, it provides valid recommendations for optimal management outcomes.




Results

Our solution successfully helped the client achieve these outcomes:

• Wastewater spillway limits respected


• Reduction of wastewater spillway


• Energy savings and reduced management costs


• Improved efficiency of the wastewater treatment plant



Take a look at how the DSS played a part in improving the operations:

Step 1: During dry season or light precipitation, wastewater is directly conveyed into the wastewater treatment plant before to be discharged into the receiving water. © DHI	Step 2: When necessary, the sewer system starts to convey wastewater into the intake tank, reducing the discharges into the wastewater treatment plant. © DHI




Step 3: In the case of increased precipitation, the system activates all the intake tanks, avoiding (or limiting) the spillways. © DHI	Step 4: Once the meteorological event ends, the wastewater in the tanks is conveyed to the wastewater treatment, according to cost reduction policy. © DHI