Implementation
- Nutrient pollution is an immense global problem that impacts many large coastal waterways and the ecosystems that occupy them. On a large scale, nutrient pollution collects in estuaries, however nutrients leech from a variety of sources. These sources are mainly agricultural, with most of the pollution coming from large, industrial farms. Smaller, family-run farms also leech nutrients into the environment, but in a way that is dynamically unique from other polluters.
- The system that UMaryland iGEM proposes includes scalability that will allow for a bioremediation strategy that is helpful for many types of pollutants. The vessel of the bioreactor can be sized according to the needs of the end-user. For a small farm that diverts their water into a local stream, a 250 gallon bioreactor will most likely suffice. For an industrial farm that feeds runoff into a larger body like the Potomac River, a 1000-2000 gallon vessel would be more appropriate. To determine the needs of each polluter, the flowrate of water, basal nutrient level, and the number of polluters sharing a body of water should all be considered. Differences in scale means that installation of the technology can vary between sites. The NNBS should be implemented alongside the local, state, and federal government as needed.
- While vessel volume may vary between sites, the overall function of the system remains the same. The Nitrate Neutralizer Bioreactor is situated along the side of a body of moving water, with an inlet taking in polluted water, and a downstream outlet expelling remediated water. The vessel itself is installed underground, on an excavated foundation. This is done in order to reduce the amount of land area that is being occupied by the NNBS. Silica gel coated E. Coli beads are housed in the bioreactor vessel, and they are the mechanism by which nutrients are removed from polluted water. In order to prevent E. Coli from leaking into the environment, in and outflows are gated by semipermeable membranes. These membranes allow for passage of water and small molecules into and out of the reactor, while the E. Coli beads remained trapped inside.
- The NNBS is a passive system, however it does require upkeep. As time goes on and the E. Coli accumulate nutrients from the water, they eventually die. This means that the NNBS ability to accumulate nitrates diminishes and that the bacteria needs to be replenished. The end user will utilize a monitoring system (described below) that indicates when the beads should be retrieved from the vessel and replenished. Ideally, replenishing the NNBS and reclaiming fertilizer should be facilitated by a commercial organization, company, or interested third party. This would allow for farmers to buy their E. Coli beads from a supplier, just like they would for any other farm related expenditure. This entity would also pick up the used beads from farmers, lyse the cells, and chemically process the nitrogenous material back into a usable fertilizer. Hopefully, this entity can then redistribute the reclaimed fertilizer at a reduced cost, providing a sustainable and affordable alternative to the current farm-ocean nitrate cycle.
Monitoring System
In order to monitor the real time impact of the NNBS, the BlueLab TRUNV2 Truncheon Nutrient Meter will be utilized. This sensor is a low cost device that allows the user to continuously quantify the amount and type of nutrients in water. For each NNBS site, two TRUNV2 meters will be used. The first is placed upstream of the reactor inlet, towards the water source. The second sensor is integrated directly into the outlet of the bioreactor in such a way it is only exposed to remediated water exiting the vessel. This dual sensor system will allow the end user to gauge the quantity of nutrients in their runoff, how effective the NNBS is at removing nitrates currently, and if the E. Coli beads need to be replaced. When the measurement on the second sensor approaches the value on the first sensor, it is indicated that the beads in the reactor vessel need to be replenished.