Suspended Growth Bio-Treatment : Activated Sludge Process for BOD Removal & Nitrification

Abstract Clean water and renewable energy are essential requirements to build resilience towards the adverse effects of climate change and global warming. Advanced wastewater treatment options may provide a unique opportunity to recover various useful resources such as energy (biogas), fertilizers, minerals, and metals embedded in the wastewater stream. However, considerable challenges remain when it comes to designing and planning sustainable wastewater treatment systems. This thesis focuses on the avenues of energy recovery from wastewater treatment plants (WWTP), by evaluating the potential for biogas recovery from wastewater and sewage sludge treatment in WWTPs. Various available technologies for biogas recovery are examined and evaluated to understand their viability in different applications and relative performance. Further, the methodologies and tools employed to assess such energy recovery systems are evaluated, covering the technical, economic, and environmental performance aspects. A sustainability assessment framework is then developed, using appropriate sustainability indicators to assess performance. The framework is applied to a case study of a WWTP in the emerging city of Tbilisi, Georgia. A spreadsheet tool is also developed to aid the sustainability (techno-economic and environmental) assessments for the case study. The case study results reveal a significant biogas recovery potential, with an annual energy generation potential of 130 GWh from combined heat and power (CHP) recovery, and a potential to avoid 28,200 tCO2eq emissions every year when biogas is recovered only from the wastewater. The recovery potential increases when biogas is recovered from both wastewater and sewage sludge. Further, the contribution of overall resource (energy and nutrient) recovery in WWTPs to the Sustainable Development Goals is examined. By studying the linkage of various benefits to the different SDGs, the multilateral and cross-cutting nature of benefits from resource recovery is clearly illustrated. The thesis concludes with a discussion of possible future technologies and perspectives that can enhance the sustainability of WWTPs and help transform them into Wastewater Resource Recovery Facilities (WRRFs).

INTRODUCTION Odors remain at the top of air pollution complaints to regulators and government bodies around the U.S. and internationally. Ambient air holds a mixture of chemicals from everyday activities of industrial and commercial enterprises. A person’s olfactory sense, the sense of smell, gives a person the ability to detect the presence of some chemicals in the ambient air. Not all chemicals are odorants, but when they are, a person may be able to detect their presence. Therefore, an odor perceived by a person’s olfactory sense can be an early warning or may simply be a marker for the presence of air emissions from a facility. For whatever reason, it is a person’s sense of smell that can lead to a complaint. When facility odors affect air quality and cause citizen complaints, an investigation of those odors may require that specific odorants be measured and that odorous air be measured using standardized scientific methods. Point emission sources, area emission sources, and volume emission sources can be sampled and the samples sent to an odor laboratory for testing of odor parameters, such as odor concentration, odor intensity, odor persistence, and odor characterization. Odor can also be measured and quantified directly in the ambient air, at the property line and in the community, using standard field olfactometry practices, e.g. odor intensity referencing scales and field olfactometers.

. Ultimate Goal: Transform negative-value or low-value biosolids into high-energy-density, fungible hydrocarbon precursors. .Enables sustainable production of biogas that is considered as a cellulosic biofuel under new RFS2 (EPA, July 2014). .Addresses DOE's goals of development of cost-competitive and sustainable biofuels by advancing efficient production strategies for drop-in biofuels.