ISSST 2015

The International Symposium on Sustainable Systems and Technology was held May 18-20 this year in Dearborn, Michigan. What started as the International Symposium on Electronics and the Environment, put on by the Institute of Electrical and Electronics Engineers (IEEE), in the ’90s has changed over the years into a very diverse conference with sessions that cover transportation, food systems, renewable energy, water systems, and much more. There is a strong focus on sustainability as a whole, and life cycle assessment was one of the main unifying themes for most of the research presented.

I presented a poster (Toward sustainability in wastewater treatment: Comparing life cycle impacts of algaculture and conventional systems) in the student competition and came in first place! Presenting the poster to such a diverse audience was a fun experience because I got questions and feedback from other perspectives than the usual algae- and water/wastewater-focused researchers and professionals. The experience helped me work on my science communication skills,  another theme at the conference, and as a result I thought my spiel would make for good blog-post material. So here it is (as best as I can do without pointing to the poster itself):

My research focuses on comparing algae-based and conventional wastewater treatment systems. The motivations for my work are two-fold: (1) Many aging wastewater treatment systems are mainly designed to treat organics, leaving an excess of nutrients in the effluent. As limits are being lowered to protect water quality, many plants are in need of upgrades to achieve nutrient removal. Conventional upgrades often result in increased chemical and/or energy use, more pumping, and larger plants. So I look at how existing systems can be retrofitted with algaculture to treat nutrients. (2) There is also a push for using algal biomass as a feedstock for biofuels or other bio-manufacturing applications, but life cycle assessment of these systems have shown that growing algae using fertilizers does not result in a net-positive energy balance, thus wastewater nutrients have been proposed as a means of replacing fertilizers.

In my research, I use a combination of process modeling and lab- and pilot-scale data to perform comparative life cycle assessment of algaculture and conventional systems for nutrient removal at wastewater treatment plants. My first publication was a process modeling study that showed that both primary and tertiary algae systems have the potential to remove effluent nutrients comparable to conventional systems, and that primary algal nutrient removal can reduce energy use at existing activated sludge plants, but that land use will be a limiting factor in implementation of these systems.

Therefore, I am now looking at using algaculture to upgrade existing lagoon systems (which already use a lot of land), like the one in Logan, Utah, for which I am using pilot-scale data on rotating algal biofilm reactors (RABRs) to model how they would perform when scaled up. So far, my results are showing that these RABRs can treat nutrients with comparatively lower chemical and energy use than would be required if Logan upgraded to a biological nutrient removal activated sludge system (BNR-AS). My next steps include performing life cycle assessment to include the impacts from construction stage for RABRs and BNR-AS, as well as performing system expansion to quantify the impacts that could potentially be offset by using the algal biomass produced for other end uses.

I had a great time at ISSST, and I hope to attend again in the future!