Power self-sufficient sewage/wastewater treatment plant
Published on 17 January 2018
Germany
Arnsberg
This is the good practice's implementation level. It can be national, regional or local.
About this good practice
Local municipalities need ca. 20% of their electricity demand for the operation of their sewage treatment plants, which often makes them the largest energy consumer, and energy amounts to ca. 30 percent of the annual operating costs. Sewage treatment plants that produce biogas in their sewage sludge treatment process with anaerobic digestion can produce enough energy to meet most of its energy needs.
The Verbandsgemeinde Weilberbach, Germany, 13,790 inhabitants, treating 1.6 million m3/y of wastewater consumed in the past 480,000 kWh/y of electric energy and 3,800 litres of liquid gas for heating. The processing technique was changed from aerobic digestion to anaerobic digestion with the production of biogas in the sewage sludge treatment process, and adding 2 CHPs (combined heat and power plants) for electricity and heat generation.
The energy demand was reduced by altering the processing technique and through other efficiency measures. The blower system usually needs up to 50% of the electricity. The agitators are usually the third biggest consumer in sewage plants. The following measures have been undertaken to save energy: the installation of a plate aerator/ membrane plate diffuser, optimized agitators/stirrers in both aeration tanks and the renewal of the blower.
The Verbandsgemeinde Weilberbach, Germany, 13,790 inhabitants, treating 1.6 million m3/y of wastewater consumed in the past 480,000 kWh/y of electric energy and 3,800 litres of liquid gas for heating. The processing technique was changed from aerobic digestion to anaerobic digestion with the production of biogas in the sewage sludge treatment process, and adding 2 CHPs (combined heat and power plants) for electricity and heat generation.
The energy demand was reduced by altering the processing technique and through other efficiency measures. The blower system usually needs up to 50% of the electricity. The agitators are usually the third biggest consumer in sewage plants. The following measures have been undertaken to save energy: the installation of a plate aerator/ membrane plate diffuser, optimized agitators/stirrers in both aeration tanks and the renewal of the blower.
Expert opinion
There is still much to do in terms of biogas and energy efficiency in the water and waste sectors. It is obvious that the biogas potential of sewage sludge should be harnessed and used to produce electricity and heat to cover the energy needs of the sewage treatment process.
In addition to equipping the sewage plant with its own biogas plant, energy efficiency measures have been implemented to reduce the energy consumption of the sewage process. Combining energy efficiency and renewables is really best practice and the current GP can therefore be considered a showcase.
The transferability potential is very high since this practice does not require any adaptation to local circumestances and can thus be easily replicated by other municipalities.
The impact is clearly measurable and energy costs saved and CO2 emissions reduced.
In addition to equipping the sewage plant with its own biogas plant, energy efficiency measures have been implemented to reduce the energy consumption of the sewage process. Combining energy efficiency and renewables is really best practice and the current GP can therefore be considered a showcase.
The transferability potential is very high since this practice does not require any adaptation to local circumestances and can thus be easily replicated by other municipalities.
The impact is clearly measurable and energy costs saved and CO2 emissions reduced.
Works at
Interreg Europe Policy Learning Platform
Resources needed
Total costs: 4,000,000 €
For maintenance: € 1,200,000 €, for energy efficiency measures: € 2,800,000
Origin funds: own funds (credit) € 3,420,000; € 580,000, Federal Ministry for the Environment
Savings: ca. € 263,000/y, Amortization: ca. 17 years (interest 2.5%, increase energy costs 4%/y)
For maintenance: € 1,200,000 €, for energy efficiency measures: € 2,800,000
Origin funds: own funds (credit) € 3,420,000; € 580,000, Federal Ministry for the Environment
Savings: ca. € 263,000/y, Amortization: ca. 17 years (interest 2.5%, increase energy costs 4%/y)
Evidence of success
During monitoring, approx. 294,560 kWh/a of electricity were produced using cogeneration (CHP). Additionally power was generated from PV: 1,814 kWh/y. Consumption 447.982,2 kWh/y ( - 32,000 kWh/y despite additional consumers) . 72.2% of energy demand covered with own production. Heat: 100%, no external energy source.
Reduction of dry sludge to be deposited: 35.8%
CO2 savings: 181,4 tons/y
Reduction of dry sludge to be deposited: 35.8%
CO2 savings: 181,4 tons/y
Potential for learning or transfer
High potential for savings (emissions, energy, costs). Sewage collection and treatment is usually a municipal task and sewage treatment plants are major energy consumers. Potential saving of energy demand of municipal sewage treatment plants: 30%. In Rhineland-Palatinate a few municipalities already invested in energy efficiency measures in sewage plants and are able to show that is economically efficient, e.g. Pirmasens (40,000 inhabitants, cost savings/year: 162,000 €) and Wörrstadt (7900 inhabitants, cost savings/year 89,000 €). In Germany one out of eight sewage plants installed a CHP to use sewage gas for their own energy supply.
Sewage plants can be found in municipalities all over Europe. If energy efficiency measure are combined with making use of sewage gas the emission savings effects are even higher. The municipality of Weilerbach did both and this is why this practice has great potential for transfer and learning.
Sewage plants can be found in municipalities all over Europe. If energy efficiency measure are combined with making use of sewage gas the emission savings effects are even higher. The municipality of Weilerbach did both and this is why this practice has great potential for transfer and learning.
Further information
Website
Good practice owner
You can contact the good practice owner below for more detailed information.
Organisation
Verbandsgemeinde Weilerbach
Germany
Arnsberg
Contact
National coordinator