Floating Bioreactors.

The carbon dioxide gas from the off shore methane digester can be pumped into clear plastic tubes to cause them to float on the surface of the sea. Wave action will stir the contents and help the fluid in the bioreactors absorb the gas. Sea water can be mixed with nutrient rich water exiting the methane digester to supply nutrients for the algae in the bioreactors. At the end of the tubes, the algae can be separated from the sea water. The algae is pressed to separate fluids from solids. The pressed fluid is further separated into oils and nutrient solution. The oil is used for fuel, the nutrient solution is used as fertilizer in the greenhouse, the press cake is used as animal food.

The advantage of this system is that no land has to be prepared, if more area is needed more tube is floated. There is plenty of unused area offshore. As the tube needs to be clear and the solution will be relatively thin, a good bit of light can get through and the environmental impact to the local area is minimal. However, there is much less chance of triggering a dead zone with the dumping of municipal BOD and there is a recovery of nutrients and energy.

Note that the brine from the reverse osmosis unit is mixed with the output from the methane digester bringing it back toward typical concentration for sea water. Make big circles.