Design of an Airlift Column Photo-Bioreactor that Increases Remediation Rates of Reverse Osmosis Permeate Jose St Louis 2012 BioEnergy and Sustainability School August 7, 2012 Landfill Leachate  A liquid solution resulting from the extraction of soluble constituents from waste in landfills by downward percolating water.  Analogous to the liquid that sometimes collects at the bottom of trash cans  Why is it important?  Landfill leachate has a very high pollution potential  Landfills are required by law to manage leachate  How is it handled?  Widely trucked to waste water treatment plants Alachua County Southwest Landfill (ACSWL)  Experimenting with reverse osmosis (RO) system to remediate leachate  Advantages  Quickly removes most of the contaminants from the leachate  Disadvantages  Energy intensive  Inefficient at ammonium removal  Requires multiple run-throughs to remediate the leachate to dischargeable levels ACSWL -BEST Project  BEST and the ACSWL partnered to create a combined algal/RO remediation system  Algae remediate ammonium after single stage RO  Permeate (the result of single RO run) is a nitrogen source for algae  Advantages  Less energy intensive because the sun powers the algal remediation  Remediates permeate to dischargeable levels  Disadvantages  Takes a longer time for remediation to occur Objective  Design a photo-bioreactor capable of increasing the algal remediation rates of reverse osmosis permeate Types of Photo-bioreactors  What is a photo-  Types of photo- bioreactor? bioreactors:  Flat plate reactors  Tubular reactors  Bubble column reactors  Airlift reactors Airlift Reactors  Modified bubble column reactor  Very defined flow Modifications  Focused on increasing mixing within the system  Mixing increases mass transfer rates and light/dark cycles (Posten 2009) Methodology  Three bioreactors were constructed out of identical containers  1 bubble column, 1 airlift, 1 airlift modified with static mixers  Identical lighting, air, and CO supply 2  pH controlled CO delivery 2 Methodology (cont.)  Bioreactors inoculated with 91% algae and 9% permeate  Supplemented with required elemental nutrients (based on Adrian Brene’s experimentation)  Samples taken roughly every two hours  Measured:  pH  Optical density  Ammonia  Ammonia volatilization controlled by low pH (6.5-6.7)