RP2017: Energy Benchmarking for Efficient, Low-Carbon Water Recycling Operations

Peer Reviewed Research Publications

RP2017: Journal Article: Comparing the performance of aerobic granular sludge versus conventional activated sludge for microbial log removal and effluent quality: Implications for water reuse

The application of aerobic granular sludge (AGS) technology has increased in popularity, largely due to the smaller physical footprint, enhanced biological nutrient removal performance and ability to perform with a more stable operation when compared to conventional activated sludge (CAS) systems. To date, the ability of AGS to remove microbial pathogens such as; Escherichia coli, Giardia, and Cryptosporidium has not been reported.

This study compared the log10 removal performance of commonly used pathogen surrogates (sulfite-reducing clostridiaspores, f-RNA bacteriophage, E. coli and total coliforms) by AGS and CAS during the start-up phase, through to maturation.

Results showed that AGS performed as well as CAS for the log10 removal performance of all microbial surrogates, except for spores which were removed more effectively by AGS most likely due to greater adherence of spores to the AGS biomass compared to CAS mixed liquor. Results suggest that AGS is capable of meeting or exceeding CAS-equivalent health-based targets for pathogen removal in the context of water recycling as well as not adversely affecting the secondary effluent water quality (suspended solids, turbidityand particle size) in terms of ultraviolet light transmissivity (254 nm). These findings confirmed for the first time that the adoption of AGS operation would not adversely impact downstream tertiary disinfection processes from altered water quality, nor would it require further pathogen treatment interventions in addition to what is already required for CAS systems.

Read the article HERE.

RP2017: Journal Article: Survey of the effect of odour impact on communities

In the context of environmental malodour, surveys are valuable as they allow for the relatively detailed analysis of multiple factors pertaining to odour perception and subsequent reaction. However, the causes for an individual to experience odour impact while a neighbour will not are still not understood.

The goal of this current survey design was to consolidate varying research paths for surveys within the environmental odour research space. This survey investigated the area of effect for wastewater treatment plants by using stratified random sampling techniques that radiated from the industrial areas. Additionally, this survey provided a “non-alerted” response to environmental malodour that represents a step forward for ecological validity.

We found a small number of items relating to odour annoyance and home ownership that can be used in order to predict odour impact for individual community members. However, we also did not find any relationship with odour impact and perceived control. This survey design and analysis reconciles the varied approaches towards community surveys administered in prior literature, as well as providing information to improve future community engagement policies.

Read the article HERE.

RP2017: Journal Article: Ecology and performance of aerobic granular sludge treating high-saline municipal wastewater

The successful development of aerobic granular sludge (AGS) for secondary wastewater treatment has been linked to a dedicated anaerobic feeding phase, which enables key microbes such as poly-phosphate-accumulating organisms (PAOs) and glycogen-accumulating organisms to gain a competitive advantage over floc-forming organisms. The application of AGS to treat high-saline sewage and its subsequent impacts on microbial ecology, however, are less well understood.

In this study, the impacts of high-saline sewage on AGS development, performance and ecology were investigated using molecular microbiology methods. Two feeding strategies were compared at pilot scale: a full (100%) anaerobic feed; and a partial (33%) anaerobic feed.

The results were compared to a neighbouring full-scale conventional activated sludge (CAS) system (100% aerobic). We observed that AGS developed under decreased anaerobic contact showed a comparable formation, stability and nitrogen removal performance to the 100% anaerobically fed system. Analysis of the microbial ecology showed that the altered anaerobic contact had minimal effect on the abundances of the functional nitrifying and denitrifying bacteria and Archaea; however, there were notable ecological differences when comparing different sized granules. In contrast to previous work, a large enrichment in PAOs in AGS was not observed in high-saline wastewater, which coincided with poor observed phosphate removal performance. Instead, AGS exhibited a substantial enrichment in sulfide-oxidising bacteria, which was complemented by elemental analysis that identified the presence of elemental sulfur precipitation. The potential role for these organisms in AGS treating high-saline wastewater is discussed.

View the article HERE

RP2017: Journal Article: Comparison of an anaerobic feed and split anaerobic-aerobic feed on granular sludge development, performance and ecology

The retrofitting of existing wastewater sequencing batch reactors (SBRs) to select for rapid-settling aerobic granular sludge (AGS) over floc-based conventional activated sludge (CAS), could be a viable option to decrease reactor cycle time and increase hydraulic capacity. Successful CAS-to-AGS conversion has previously been shown to be highly dependent on having a dedicated anaerobic feed, which presents additional engineering challenges when retrofitting SBRs.

In this study the authors compared the performance of a split anaerobic-aerobic (An-Aer) feed with that of a traditional dedicated anaerobic feed regarding AGS formation and stability, nitrogen removal performance and microbial ecology.

Using pilot trials, the authors showed that AGS could be established and maintained when using a split An-Aer feed at low organic loading rates analogous to that of a parallel full-scale conventional SBR. Additionally, the authors showed that AGS start-up time and nitrogen removal performance were comparable under a split An-Aer feed and dedicated anaerobic feed. Microbial ecology characterisations based on whole-of-community 16S rRNA profiles and targeted analysis of functional genes specific for nitrifying and denitrifying microorganisms, showed that the two different feed strategies had only subtle impacts on both the overall community composition and functional ecology. A much greater divergence in microbial ecology was seen when comparing AGS with CAS.

Data presented here will be of value to those planning to retrofit existing CAS-based SBRs to operate with AGS and demonstrates the viability of using a more cost-effective split An-Aer feed configuration over a dedicated anaerobic feed.

Read the paper HERE.

RP2017: Journal Article: Benchmarking the energy-health nexus for more efficient water recycling operations

This paper reports on the findings of a 12-month study, undertaken at SA Water and supported by the Australian Water Recycling Centre of Excellence and UniSA, which set out to explore and develop a new approach to energy benchmark and optimise water recycling systems - so-called 'energy-health' benchmarking. The project also made the first steps toward developing a new suite of energy benchmarks for a range of advanced water recycling processes. Several South Australian recycling schemes were selected to 'road test' the new benchmarking approach, with the results of these investigations presented for two of the case studies.

Following an extensive literature review of specific energy data for a range of recycling processes, preliminary benchmarks for water recycling processes were developed for so-called Guide (50th %ile) and Target (20th %ile) performance values. Detailed processlevel energy benchmarking was then undertaken at each of the case study sites using the newly-developed Guide and Target performance benchmarks. Health-based process performance criteria (i.e. pathogen log reduction values) were then integrated into the process benchmarking and optimisation approach to identify optimisation and energy efficiency opportunities at the process level. Overall, the study provides the first known set of indicative energy benchmarks for a range of advanced water recycling processes and has made the first steps toward developing a new approach for the Aust ralian water industry to use in future water recycling process optimisations.

Read the paper HERE.

Value-Added Products Derived from Waste Activated Sludge: A Biorefinery Perspective

Substantial research has been carried out on sustainable waste activated sludge (WAS) management in the last decade. In addition to the traditional approach to reduce its production volume, considering WAS as a feedstock to produce bio-products such as amino acids, proteins, short chain fatty acids, enzymes, bio-pesticides, bio-plastics, bio-flocculants and bio-surfactants represents a key component in the transformation of wastewater treatment plants into biorefineries.

The quality of these bio-products is a key factor with respect to the feasibility of non-conventional WAS-based production processes. This review provides a critical assessment of the production process routes of a wide range of value-added products from WAS, their current limitations, and recommendations for future research to help promote more sustainable management of this under-utilised and ever-growing waste stream.

Read the full article HERE

doi:10.3390/w10050545

RP2017: Final Report: Energy Benchmarking for Efficient, Low-Carbon Water Recycling Operations

The objective of this research project is to provide the water industry with new and improved information to facilitate more energy-efficient, cost-effective and environmentally-benign wastewater treatment operations into the future.

This project has undertaken research into two core areas of relevance to the Australian water industry:

1) Energy efficiency in wastewater treatment via energy benchmarking methodology; and
2) Investigating the performance of aerobic granular sludge technology for wastewater treatment.

Energy Benchmarking for Efficient, Low-Carbon Water Recycling Operations: Final Report (5346376 PDF)

RP2017: Conference Paper: Einfluss der Wassernutzung auf die Auslastung und den Energieverbrauch bei der Abwasserwiederverwendung (Impact of water demand on energy consumption during wastewater reuse)

Impact of water demand on energy consumption during wastewater reuse - paper from Proceedings of Aachen Conference on Water Technology.

krampe et al 2015 (2418213 PDF)

Fact sheets

RP2017 FACTSHEET: Reducing the energy intensity and carbon emissions of waste water treatment

Wastewater treatment plays an essential role in safeguarding public and environmental health within the built environment. However, wastewater treatment operations are among the most energy intensive activities carried out in our cities, with high levels of associated greenhouse gas emissions. This fact sheet outlines how to develop new, locally-relevant energy benchmarks for use by the Australian water sector.

RP2017 FACTSHEET: Reducing the energy intensity and carbon emissions of waste water treatment (933376 PDF)