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Blogs under tag Wastewater Treatment

Report Says, Algal Biofuels May Not Cut Carbon Emissions Posted by Mathumitha on Wed April 07 2010 03:24:05 AM 1

Algae- based biofuel production and carbon capture are the hot-topics of research all over the world. On the other hand, a new study published in American Chemical Society journal, Environmental Science and Technology, suggests that the overall CO2 emissions to produce biofuel from algae may be worse than those from first and second generation biofuel feedstocks such as corn, canola (rape-seed) or switch grass.The report says though the algae-based biofuel production is advantageous than the above mentioned land-based crops when we grow algae in wastewater or near powerplants, algal fuels could cause an overall increase in carbon emissions when we grow them in freshwater(using additional nutrients and compressed CO2 source).

On closer inspection, the report is in fact very positive about growing algae. Read positively, the data are only in opposition to making fuel from algae if nitrogen and phosphorus nutrients are added in their mineral forms, and if the CO2 has to be injected into the system (transported as a compressed gas) as made mainly by the process of steam reforming methane, along with most of the world's available hydrogen:

(Overall) CH4 2H2O --> CO2 4H2.

That H2 is used to make nitrogen (ammonium sulphate and nitrate) fertilizer by reacting it with N2 via the Haber Bosch process to make ammonia (NH3), and so there is in a way a symbiosis between the production of CO2 and NH3. The phosphorus would likely come from mining "rock phosphate", which requires energy too.

The US Algal Biomass Organisation has claimed that the study contained "faulty assumptions" and was based on "grossly outdated data". Even if there remains some dispute over the exact figures used, what the study does highlight is the importance of developing an integrated paradigm of production and recycling for algal fuel production.

Source: http://ergobalance.blogspot.com/2010/04/report-says-algal-biofuels-may-not-cut.html

Green Algae + Human Waste = Green Power Posted by Mathumitha on Tue April 06 2010 03:24:09 AM 2

An algae-based wastewater treatment project is planned to be started in May, at Laguna wastewater treatment plant in the city of Santa Rosa, California.The pilot plant relies on native algae and marsh plants to purify sewage and produce methane.The methane gas will run a generator that charges a fleet of four electric maintenance vehicles.

The project is co-ordinated by Sonoma State University biologists. They have constructed six algae ponds at Laguna to clean a small portion of the wastewater stream, meeting state standards for nitrates and phosphates.Laguna serves a population of 250,000 people, and it would require more than 100 acres of algae ponds to purify the entire waste stream of nitrates.The current project measures only 800 square feet. Treddinick, the project development manager for the city's Utilities Department, plans to scale up the project to an acre.

Michael Cohen, the Sonoma State biologist who oversees the algae operation said they planned to extract oil from the algae, though they are aware of the fact that extracting oil from algae is a tough process. This is because of the variation in oil content of algae species and difficulty in extracting oil due the tough cellwalls of algae.

"We knew going in that we were going to be fighting a losing battle, but we thought we would see if we could make it work", said Hare, who is Cohen?s student at Sonoma State.

Source: http://www.miller-mccune.com/science-environment/when-sewage-is-not-a-dirty-word-12563/

Algae as Bio-accumulative Agents for Hazardous Pollutants Posted by Mathumitha on Sat April 03 2010 04:15:33 AM 1

Recent studies show that using biological systems to remove trace hazardous pollutants from wastewater is a high-performing and low-cost method than other conventional treatment systems.This is because of the fact that the conventional treatment systems fail to treat the trace hazardous materials in wastewater. I came across an interesting article in which they tried to show the bio-accumulation potential of algae.

According to the study (M.A. Coogan and R.E.Edziyiea, 2007), algae have the potential to bio-accumulate the hazardous contaminants.The potential of algal bio-accumulation was tested by using three common antimicrobial agents(triclocarban, triclosan, and methyl-triclosan)in a wastewater treatment plant receiving stream in North Texas. The waste water comprised of filamentous algae, especially Cladophorea spp., and some diatoms.The study revealed that filamentous algal species typically occurring in waste water treatment plant has the bio-accumulative potential for these contaminants. This phenomenon is due to the lipid content of algae,which have the capacity to act as an entry point of lipophilic organic compounds.

There are many other research articles showcasing the potential of algae as bio-accumulative agents. Hence, it may be possible to use algal biofilm in wastewater treatment to remove hazardous organic chemicals, which cannot be treated by the conventional treatment plants.