By Elisha Musgraves, MQP in Israel: The ability to recycle agricultural wastewater is becoming imperative in desert regions, as freshwater sources are dwindling. At the experimental R&D farm on Kibbutz Yotvata, they run experiments with different salinities and fertilizer amounts to determine best practice for each crop. Currently, the wastewater for many of these experiments is dumped into septic, and eventually makes it way to the groundwater. Alternative wastewater recycling practices utilizing microbial mats to denitrify fish effluent (high in nitrates) have shown success in lab experiments. However, the CO2 gas necessary to “feed” the autotrophic organisms that comprise a microbial mat represents a large, often prohibitive, expense for many applications. I am experimenting with HCO3 as a replacement for CO2 for microbial mat wastewater treatment to try to provide a low-cost alternative for kibbutzim in the region. I plan on taking the results from my current experiment and designing a wastewater recycling system that takes into account the various limitations of the desert, the microbial mats, and the desired applications.