Search

Browse

• Communities
• Authors
• Year
• Titles
• Subjects

My Space

• Login

Contemporary energy saving technologies in municipal wastewater treatment plants

Kontogiannis Konstantinos

Full record

---

Summary

In recent years there has been increasing pressure on the wastewater treatment sector. Conventional treatment methods require significant amounts of energy, leading to higher operating costs for Wastewater Treatment Plants (WWTPs) and contributing to global warming potential through high greenhouse gas emissions. The scope of this thesis is to describe and evaluate innovative wastewater treatment technologies which have the main objective of mitigating energy consumption and consequently reducing greenhouse gas emissions in WWTPs. In this thesis, energy saving technologies concerning primary, secondary treatment of wastewater as well as sludge treatment were studied. An alternative of primary treatment of wastewater process is the application of Chemical Enhanced Primary Treatment (CEPT) which aims to high reduction of suspended solids (60-90%) in wastewater using chemicals, resulting in a reduction of energy consumption during the aeration process along with increased energy production during anaerobic digestion. The energy consumption per cubic meter of wastewater in a CEPT ranges from 0.07 to 0.13 kWh/m3. Microsieving is considered an attractive technology as it requires small amounts of energy (0.04-0.4 kWh/m3), requires less than 5% of the space occupied by conventional treatment and usually produces similar or even better effluent quality in comparison to primary clarification. The activated sludge process is the largest energy consuming process in a WWTP (0.3-0.65 kWh/m3). Anaerobic ammonium oxidation is an alternative energy-saving process as it requires up to 60% less aeration requirements than conventional activated sludge treatment. Microbial Fuel Cells (MFCs) are a promising technology as they offer the possibility of generating electricity directly alongside treating wastewater. The main drawback of the MFCs is the cost of electrodes and the ion exchange membrane. Treating wastewater with microalgae also consumes small amounts of energy due to the fact that it does not require air supply given that these types of systems utilize the environmental conditions. Trickling Filters (TFs) are considered a low energy technology (0.18-0.42 kWh/m3) which shows the highest technological maturity compared to the other technologies studied. Regarding sludge treatment, the application of anaerobic treatment processes, sludge co-digestion with organic waste and sludge pre-treatment prior to anaerobic digestion achieves more than 50% increase in methane production compared to conventional anaerobic digestion. Finally, sludge gasification shows a lot of potential for development in the wastewater sector as large amounts of thermal and electrical energy can be recovered through syngas.

Available Files

Services