Coming Full Circle: Moving Wastewater Treatment Plants Towards Energy Neutrality

Achieving energy neutrality in wastewater treatment plants through energy savings and enhancing renewable energy production

“…Energy is most often among top three most expensive items in a wastewater utility's operation and management budget. Reducing the purchased energy not only benefits lowering the potential costs, but also results in decreasing the carbon footprint and increasing the sustainability of the operations (Horne et al 2013;Moss et al 2013). Methods of minimizing the electricity consumption can be divided into two major categories.…”

“…Shizas and Bagley (2004) determined the energy content of organics in municipal wastewater, using a bomb calorimetry method. Results of those experiments revealed that the organic energy in wastewater is approximately 10 times greater than the electric energy required to treat it (Horne et al 2013;Moss et al 2013). On the contrary, Parry (2014) challenged this argument by showing that not all the potential energy can be used for energy neutrality or even positive effect in WWTPs due to low-grade heat that has low energy quality for production.…”

“…6 Examples of case studies and projects on energy neutral/positive WWTPs Currently, only a small subset of wastewater treatment facilities is operating in a manner that allows them to be considered totally or nearly energy neutral (Horne et al 2013). Case studies which applied modifications to improve the energy balance are presented in Table 9. 6.1 Case studies on energy neutrality of WWTPs Wang et al (2016) compared the electricity intensity and associated carbon emissions of WWTPs in four countries, including the US, Germany, China, and South Africa.…”

“…As nutrient limits continue to ratchet downward and electricity costs creep upward, and with an increased focus on carbon footprint, climate change, and GHG emissions, all consumers are becoming more cognizant of the impacts of their activities on the social, environmental, and financial bottom lines. This triple bottom line approach also refers to the wastewater industry (Horne et al 2013). According to a new paradigm in wastewater treatment, WWTPs should be designed considering maximization of the resource and energy recovery.…”

Novel A-B processes for energy-efficient municipal wastewater reclamation with minimized sludge production

“…Typically, about 65-90% of COD in real municipal wastewater could be removed anaerobically, while the sludge production is about 3 to 20 times lower than that produced in the CAS process (Bitton, 2005, Seghezzo et al, 1998. In addition, the produced biogas is helpful for offsetting the total in-plant energy consumptions (Van Horne et al, 2012). However, it was found that a substantial amount of methane gas was dissolved in the effluent in anaerobic treatment of municipal wastewater due to high methane solubility in water, i.e.…”