Quantifying the benefits of integrated resource recovery from sanitation provision in a developing country setting

So, we know that reclaiming water from sewage can help offset the local demand for freshwater and divert nutrient loads from entering waterbodies, and reclaiming biogas from sewage treated anaerobically can help offset the energy costs of wastewater treatment. But what is the combined benefit of integrated resource recovery and how do we quantify it?

USF Reclaim is setting out to answer that very question. Ph.D. candidate Pablo Cornejo and professors Qiong Zhang and James Mihelcic from the University of South Florida are authors of a new study published in the Journal of Environmental Management. The team uses Life Cycle Assessment (LCA) to quantify the benefits of resource recovery in a developing country setting. Specifically, they estimate the embodied energy, carbon footprint, and eutrophication potential of two distinct technologies: an upflow anaerobic sludge blanket (UASB) reactor followed by polishing ponds, and a system consisting of three stabilization ponds in series.

Stabilization Pond System

The carbon footprint of wastewater treatment pond systems in Bolivia is dominated by direct methane emissions. The carbon footprint of wastewater treatment systems consisting of ponds can be reduced by recovering biogas in an anaerobic reactor that precedes the ponds. (Photo credit: Pablo K. Cornejo)

One major finding was that the bathroom and collection infrastructure in these two towns had a higher embodied energy intensity than the actual wastewater treatment processes! Also, the primary contributor to the carbon footprint of the two systems were direct methane emissions.

The team evaluated several resource recovery scenarios to evaluate their impact on embodied energy, carbon footprint, and eutrophication potential. Reclaiming the treated effluent for irrigation would greatly reduce the eutrophication potential for both systems by offsetting phosphorus and nitrogen discharged to receiving waters. Recovering biogas from the UASB reactor system to reclaim energy would provide a 19% reduction in embodied energy and a 57% reduction in carbon footprint. The combination of water reuse and energy recovery for the UASB-Pond system in particular would reduce the eutrophication potential, embodied energy and carbon footprint simultaneously.

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UASB reactor treating domestic wastewater in Irupana, Bolivia (Photo Credit: Pablo K. Cornejo)

The results of this study highlight the benefits of integrated resource recovery, and provide insight about the environmental footprint of wastewater treatment in a small town, developing country setting. The full article can be found at Cornejo, P.K., Zhang, Q., Mihelcic, J.R. 2013. Quantifying benefits of resource recovery from sanitation provision in a developing world setting. Journal of Environmental Management, Vol. 131, pg. 7-15. http://www.sciencedirect.com/science/article/pii/S0301479713006439#

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