Biogas, Solar and Geothermal Energy—The Way to a Net-Zero Energy Wastewater Treatment Plant—A Case Study

Mirosław Mąkowski,Sylwia Myszograj,Dariusz Bocheński,Ewelina Płuciennik-Koropczuk

doi:10.3390/en14216898

Mirosław Mąkowski, Sylwia Myszograj + Show 2 more

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https://doi.org/10.3390/en14216898

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Abstract

Wastewater treatment plants designed to meet the requirements of discharging wastewater to a receiving water body are often not energy optimised. Energy requirements for conventional activated sludge wastewater treatment plants are estimated to range from 0.30 to 1.2 kWh/m3, with the highest values achieved using the nitrification process. This article describes the energy optimisation process of the wastewater treatment plant in Gubin (Poland) designed for 90,000 PE (population equivalent) using renewable energy sources: solar, biogas, and geothermal. At the analysed wastewater treatment plant electricity consumption for treating 1 m3 of wastewater was 0.679 kWh in 2020. The combined production of electricity and heat from biogas, the production of electricity in a photovoltaic system, and heat recovery in a geothermal process make it possible to obtain a surplus of heat in relation to its demand in the wastewater treatment plant, and to cover the demand for electricity, with the possibility of also selling it to the power grid.

Highlights

Energy efficiency in the water and wastewater industry has become increasingly important in recent years, as wastewater treatment plants are responsible for nearly 35% of the energy consumption of all municipal facilities [1]
The development of energy hybrids that make dependence on external energy sources as independent as possible is a direction that has been consistently pursued at the Gubin–Guben Wastewater Treatment Plant
Between 1999 and 2021, the share of electricity produced at the Gubin–Guben wastewater treatment plant (WWTP) in total electricity consumption increased steadily

Summary

Introduction

Energy efficiency in the water and wastewater industry has become increasingly important in recent years, as wastewater treatment plants are responsible for nearly 35% of the energy consumption of all municipal facilities [1]. Discharging treated wastewater into receiving bodies in compliance with current legal requirements necessitates the use of efficient pollution removal technologies and sludge treatment processes. Optimal operation of wastewater treatment plants requires the provision of electricity, which is necessary for conducting technological processes as well as for transporting wastewater. The highest demand for electricity is associated with biological wastewater treatment, e.g., in systems with activated sludge where the consumption of electricity for aerating bioreactors is at the level of 50–70% [2,3]. About 35% is the electricity consumption for the sewage sludge treatment processes, which depend on the technology adopted and the equipment used. The energy demand of the wastewater treatment plant (WWTP) depends on the size of the installation (Table 1) and the technology used for a given wastewater characteristic as well as the required effluent quality

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