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June 7, 2008 / Mridul

Biofuels From Industrial/Domestic Wastewater

Biofuels turned from being the solution of world’s rising carbon emissions to the cause of a global food crisis which seems to be worsening day by day. Record demand and subsidies amounting for billions of dollars made the farmers dump the traditional food crops and grow biofuel crops like corn, maize and palm; millions of acres of forests were cleared away to make way for biofuels crops plantations. The way these biofuels are being produced is highly unsustainable since it results in more carbon emissions and shortage of food crops.

Scientists who believe that biofuels can still play an important roll in mankind’s transition to clean fuels are trying to find new, eco-friendly methods of their production. One important breakthrough came when Jim Sears of Sulix Biofuels produced biodiesel using algae. The principle behind the technology is simple:

Algae need water, sunlight and carbon dioxide to grow. The oil they produce can then be harvested and converted into biodiesel; the algae’s carbohydrate content can be fermented into ethanol. Both are much cleaner-burning fuels than petroleum-based diesel or gas.

Although the technology is still bit expensive it presents a possible solution to land abuse caused by excessive production of biofuel crops. Yet another possible solution which holds great promise is the use of seaweeds (macro-algae) for the production of biofuels. The advocates of the technology claim that

Less than three per cent of the world’s oceans — that’s about 20 per cent of the land area currently used in agriculture — would be needed to fully substitute for fossil fuels. A small fraction of that sea area would be enough to fully substitute for biofuel production on land.

However this process has its own problems, a small part of which has been discussed in this link on Newsvine.

Farming seaweed requires an incredible amount of energy (powering boats, dropping nets, drying, transport, etc). It requires 0.8 gallons of petroleum to create 1 gallon of ethanol (which takes a car about as far as 0.8 gallons of petroleum), so I’m gonna guess that it takes even more petroleum to make a gallon of seaweed biofuel. In the end, it’s likely to be false economy.

So this technology faces significant trouble in going carbon-neutral.

However there is another option which is currently being research at the Woods Hole Oceanographic Institution and the Harbor Branch Oceanographic Institution – use of wastewater for breeding algae. The wastewater form domestic and industrial sources contain rich organic compounds which accelerate the growth of algae.

Using untreated or even treated wastewater can aid the process of ‘in-house’ biofuel production. Instead of using oceans water treatment plants can be used as the breeding grounds for these algae. The incoming wastewater is put into the equalization tanks after its collection and screening. The anchored floating lines which might be used for ocean cultivation could be used in these equalization tanks for ‘tying’ the seaweeds.

There are various advantages of cultivating these algae in treatments plants:

  • No major additional infrastructure is required. Transportation facility is already in place the only thing required is the installation of floating lines in the tanks.
  • The same pipeline system maybe modified so as to transport the raw biofuel to a refinery or an enrichment plant.
  • It would reduce the pressure on the rest of the treatment process since the algae would effectively treat the water by taking up most of the organic matter thus making the disposal of final effluent easier.
  • It is safer than ocean cultivation since it posses no danger to the marine ecology.

Using this method countries can become self-sufficient in the production of biofuels since they won’t have to depend on coastal countries or the ones with surplus land for biofuel crop cultivation. Wastewater is a highly mismanaged asset from which when used efficiently can yield profitable and environment-friendly solutions to some of our energy problems.

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