Environmental-Economic analysis of WWTPs, with different sizes and innovative designs

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Student

Berni, Francesco

Document type

Master thesis

Date

2020

rights

Open AccessOpen Access

Publisher

Universitat Politècnica de Catalunya



Abstract

This work is aiming to define different pathways that could be followed in order to make WWTP a more sustainable system. To evaluate the possible innovative solutions to follow it has been decided to investigate the economical viability and environmental impact of each plant proposed. Taking into account also two fundamental aspects of a WWTP, the size and the different streams concentration. The traditional paradigm of WWTP will be proposed to change through the application of different treatments. The thesis will first define all the possible technologies and innovation that can be applied to a WWTP, with a proposal of integration with a renewable power methane system (power to gas) inside the original WWTP. Firstly, two reference WWTPs will be analysed in terms of costs and technologies applied. In addition, a third WWTP will be added to understand how the size influences costs and environment. Secondly, the carbon redirection and nutrients recovery possibility has been evaluated in the same terms, to understand if thanks to pre-concentration and ion-exchange unit, it would be possible to make more sustainable a WWTP. This is possible environmentally but not economically, since it has revealed way more expensive than the conventional activated sludge system. Thirdly, it will be proposed a new and innovative scheme that is aiming to include in one plant two different treatment, with totally different purposes, but that could be advantageous for both and especially for the community/municipality. On one side, there will be the clarification service of water while, on the other side, it will be accomplished the ancillary service of balancing the grid though the production of renewable methane. In addition, a great value has been given to all the obtainable products from a WWTP, in order to create an added value with them for instance, the use of sludge in the production process of bio-bricks. The final scope is to create a circular economy with all the products recoverable from a WWTP, since it is where all human wastes is focused. The major obstacle for the further development of more sustainable WWTPs is represented by the social acceptance. Indeed, the level of consciousness of the potentiality of a WWTP are pretty low, and at the same time there is a low acceptance in using waste for the production of human dedicated products. That's where the main efforts will be needed in the future. Even if, all the technologies needed for making a more sustainable WWTP are ready, but the products obtainable from it would never be sold, than all the investment won't make any profit.
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