AR-HES-B – Energy storage, production and recovery of valuable substances in wastewater treatment plants

Starting point/Motivation

The urban sewage treatment nowadays is a classical end-of-the pipe system. The conventional municipal biological wastewater treatment is an energy intensive process. Vast amounts of potential energy (bound in carbon) and valuable nutrients (e.g. nitrogen) are destroyed in the energy intensive aeration. Sewage treatment plants are the largest consumers of electricity in the Austrian municipalities.

In order to increase the share of renewable energy resources in future, new strategies must be considered between producers and consumers. (Example: irregularly available wind power combined with flexible consumer technologies.)

The municipal waste water treatment plant (WWTP) offers ideal infrastructural conditions to act as a hub between the energy networks (gas, heat, electricity) and the waste water system.

Contents and Objectives

The overall project goal of the AR-HES-B project is the technology rearrangement of the municipal wastewater treatment plant in order to transform it from a high energy consumer towards an optimal integrated hybrid energy provider, energy storage and resource provider in urban environment.

Via the AR-HES-B concept the municipal sewage treatment turns into an important platform in the regional energy and resource transfer. The WWTP as a hybrid energy provider, energy storage and resource provider will be the intelligent alliance of wastewater-, electricity-, gas- and district heating grids right at the interface on-site. Thereby storage peak loads can be buffered by integrated sustainable solutions for in the district heating and power grids.

The aim of the wastewater treatment of the future lies not only in utilization of the bound energy, but the utilization of all the valuable substances contained in the wastewater. Beyond that, within the project the required organisational framework conditions and the acceptance of the involved key players were analysed and clarified.

Results

As part of the project, an Excel decision support tool, the Decision Support Tool (DEST), was developed. It was used for the calculation of the following outcomes. The result of the project is a detailed guideline of the "Energy and nutrients from waste water", which summarizes all topics worked on in the project and serves as a proposal catalogue and a guide to the implementation and evaluation of concrete measures. For this, detailed technology variations were developed, which were examined as future scenarios.

In the DEST, the scenarios can be created and optimized in line with the specific demand profile of a WWTP site in conjunction with the load profiles of local energy supplier.

DEST offers for the first time, a powerful analysis tool. Concrete implementation concepts were elaborated for 3 sewage treatment plant locations and the feasibility, benefits, potentials and impact of the "Future Scenarios" under realistic conditions of acceptance were illustrated. In addition, the DEST user can visualize his personal future wastewater treatment plant scenario in the tool and compare it with the other concepts by means of a scenario comparison.

Prospects / Suggestions for future research

With the know-how generated in the project and the developed DEST, the first steps have been set towards an innovative holistic view on a wastewater treatment plant acting as "Resource Recovery Plant". The DEST has been provided with placeholder for continuous extensions, adaptations and optimization measures. Further essential steps for future applications are implementations as practical as possible of the technologies or respectively technology variations in the pilot or demonstration scale at the site of the sewage treatment plant.