MicroAlgae harvesting from wastewater treatment plant for use in biofuel production is still considered a relatively new field that has not yet been fully explored. Although countless research papers were written on this subject, the whole concept has not yet been put into practise and applied full-scale in actual plant scenario. Just like wastewater sludge which undergoes anaerobic digestion in a digester to release methane gas, similarly algae biomass can also be collected for use with the same purpose. Furthermore with large capacity measuring million of gallons present in typical wastewater systems, coupled with the high biomass regeneration rate of the microalgae, this could easily translate to viable alternative energy options that can be utilized to replace fossil fuel.
The scientific explanation behind the use of microalgae for biofuel production generally revolves around two different possibilities. As mentioned earlier, the energy can be harvested in the form of methane using anaerobic digestion process while another possibility is by using lipid extraction methods whereby the single cell microorganisms were subjected to either mechanical or chemical means of separating out the oil from the cell walls. There are few ways to achieve this if one chooses the lipid extraction route and the most common approach right now is by using solvent extraction although this is considered to be less efficient process due to the escalating high cost of fuel and then factored in the losses coming from the recovery process of hexane. Furthermore, the solvent itself used in the extraction process is also derived from petroleum, thus making the whole idea unwarranted since it still goes back to the subject on relying on fossil fuel to make it work. Most recent method which is still currently in the development stage is by using osmotic pressure to rupture the cell walls and the whole idea to get algae oil basically still needs to be studied in details before it can be commercialized and applied fully in operation.
In order to achieve the objective of large scale energy production, the source for biomass production needs to be established and thus comes the need for microalgae farming to be carried out. Usually retention ponds are built and constructed for the purpose but since this requires large land area and manpower resource to handle it and without serving any other secondary purpose, this will escalate the overall cost of making the whole idea feasible. Several companies in the private sector sponsored by governmental agencies have so far undertook the project of overseeing and conduct a study on whether it can be commercialized but so far, the results on feasibility aspect has not been encouraging. Thus when it dwells into the idea of using wastewater treatment plants as microalgae source, the whole idea starts to fit into the picture nicely and since the treatment setup has already been utilized to serve other purpose and fulfill the needs to treat and produce clean water discharge, it does not require any other additional cost allocation. Furthermore with the huge capacity and with the readily available nutrient coming from the effluent itself, this makes the whole approach for biofuel production using wastewater source to become more viable in the long run.
Apart from that, since complications and environmental impact arising from algae present in wastewater discharge remains a very big concern leading to tight regulatory requirement, harvesting of algae for oil and energy production will also mean high possibility of eliminating the problem on algae control once and for all. If you consider other aspects that all these operate within a controlled environment such as in the wastewater treatment systems, it is also possible that microalgae production facility can also be set up to run concurrently with sludge biomass production. Both of these can actually be combined together into one single unit to harvest methane gas and this in turn maximizes the potential return in the long run. In other words, the sludge will become the co-digestion feedstock for the microalgae in the digester and overall the possibilities on how to make full use of it are endless. However, a single problem that remains a big question mark here is on how to effective harvest and get a full concentrated algae biomass and so far the old techniques of mechanical filtration and sedimentation do not present a good solution.
Finally, although there are still several aspects to overcome become making it into a full-scale biofuel production, overall the benefits that it offers is worth all the time and effort. In totality, microalgae is looked upon not only as the solution to overcome the current escalating energy crisis but other environmental-friendly benefits include playing a major role for carbon dioxide bioremediation process that releases oxygen back to the environment.