Locally Produced Transportation Biofuels: Biodiesel from Sewage Effluent.
First designed at home-farm-ranch scale a photo-bioreactor cube 1/2m on a side full of glass plates with light, air, temp control that stack to conserve heat takes 4-6 units per adult to handle capacity. Algae take 2.5-days to clean water with these growing is 24x7 it scales to big city.
Test case Phoenix, AZ, 10M-gallons/day of secondary effluent normally the treatment plant uses floccing chemicals to remove the dissolved solids, aka algae food as treatment plants are there to prevent algae blooms, eh?
This is a lot of nutrients worth about 2-gallons/person/day on the system for Phoenix some 3M-gallons/day of biodiesel at one of three plants in the basin 9M-gal/day.
For atmospherics this removes CO2 adds O2 and the reverse when burned low in the atmosphere and on a continuing roll-over so should slow down migration of the gases to the troposphere where they do the damage.
Soot is the biggie to remove to scale, consider using a low-power, high-frequency plasma for that by mfg's.
The biodiesel industry is robust yet lacks an outlet to transportation being mainly small operators so no gas-stations, they usually have pumps around $2/gal at the plant, most of the biodiesel used for home heating oils; about 1/3 of producers use wastewater for a feedstock.
Consider running any IC-engine this way for the zillions of them, and for much of the world a heating & cooking oil and because algae clean so well easy to fully purify and recycle the water.
I don't understand this: So they are making biodiesel from waster by growing algae? The math simply does not add up. It's 125 lt of volume. the algae does not live typically past 1%, so you are looking at 1.25 liters of algae per 2.5 days. Extracting the oil is probably going to require a hand press, and you will get maybe 20% of that mass as oil. That's going to be 0.25 liters of oil every 2.5 days, so 0.1 liters. That has to be converted to biodiesel, requiring collection, Every year you can make perhaps 35 liters of fuel, if there are no other loses in the system. Sorry for the back of the envelope math.. I am using 1g/cm3 for water/oil mass. Oil is typically 0.85 g/cm3.
Solyazme are the most advanced of trying to make fuel from algea, and they have concluded that it's best to have a main product (such as proteins) rather than grow for food Their stock price is a good indicator of their success.
The comment on biodiesel is actually completely wrong. The biodiesel market is huge and is LARGELY used for transportation. ADM is the largest in America, with 450m gallons or so of capacity. Note also that the outlet is in diesel wholesale rack which is often blended at 5% with biodiesel. Pretty much every gallon of diesel fuel bought in California has been blended with biodiesel. The total production in the US is 2 billion gallons or so, with 3.5 billion gallons of total capacity. Biodiesel is small compared to the petroleum industry, but the industry itself has close to 8b in gross revenue. Only a small fraction goes to heating oil as you cannot claim RIN or LCFS credits if it does. You can claim a D5 RIN for home heating but you have to jump through hoops with the EPA to make sure you are auditable.
SOOT is not an issue with burning biodiesel, it actually reduces PM emissions over ULSD. As it is burnt as transportation fuel it is typically passed through a DPF before release, to reduce particle emissions to a minimum.
RE: "So they are making biodiesel from waster by growing algae? "; Yes for decades from wastewater effluent solids removed.
RE: Grow-rates; my figures are based upon lab work & the ASU library that put the first commercial jet on biodiesel into the air, most growth data is actually from CO2 sequestration by the coal companies since the late 60's I had to interpolate, prior to WW2 50% oil species were hybridized.
The largest influence on growth-rate is distance from the lighting source not nutrients the reason for the glass plates which provide light equal to the top 1/4" of a pond, which squeegee well during harvest.
A main issue with me is to fully recycle the water, done at Lake Tahoe since the late 70's using algae makes it cheaper by having a revenue stream and an alternative to chemical precipitation of dissolved solids.
Solyazme use bioreactors, just huge ones and most are sushine growing not illuminated for 24x7 growing mainly in big tubes and the send cleaners down them. Harvesting was once the greatest challenge not growing now EMF is used to break apart the cell walls, this technique used by OriginOil, they can purify fracking wastewater with their system the only one with a production prototype.
Also pretty certain they do a lot of volume in refined used oils as well via subsidiaries as that's where most volume is coming from afaik.
These are expensive, at a sewage treatment plant the feedstock comes at you at 1000-gallons/hour from existing infrastructure & these units plug into that system by simply valving the effluent to the racks, this give emergency capacity when someone flushes a meth lab before they have to release it.
Keeping that kind of inflow kills the biology and all sewage plants use natural bacteria to break down wastes this helps operators decide to try it, nobody can afford to build tanks just for that.
RE: ". The biodiesel market is huge and is LARGELY used for transportation. ADM is the largest in America, with 450m gallons or so of capacity."
Forgive the confusion they don't use wastewater as the feedstock for nearly all of that volume I'm only referring to companies, usually small operators that do. Afaik a first airline using ONLY biodiesel has a good enough supply-chain to fly, I wouldn't call that being used "largely for transportation" yet.
If you go to sources they list "alternative" for wastewater as a feedstock, most are reprocessing used oils from food crops so not a "green" feedstock although they call it that, worthy of doing regardless just pointing out a big difference to algae growers and where most volume right now comes from.
So in 10-million gallons of effluent it's half in weight of dissolved solids, over 20,000-tons per day if you had to buy it as fertilizer at $400/ton that's a cool $8-million a day saved over being a 2nd party to get that many nutrient to grow with.
Nobody but treatment plants can afford it, the small timers using it mainly are helping treatment plants not have to add capacity and avoid using farmer's fields which is becoming restricted.
Next is to put the concept into a global perspective, most people will use the biodiesel for cooking and home heating, most people don't own a bicycle on the planet.
All cities have trouble processing their sewage and it's expensive, this uses a non-food feedstock to be a primary producer of biodiesel that creates a revenue-stream to pay for tertiary purification and all water is recycled, also something a lot of cities deal with.
Therefore, this isn't simply a way to make biofuel, it's a way to turn sewage treatment into a large asset instead of an expense, recycling a lot of water, producing a transportation, heating and cooking biofuel.
Mainly, I don't see where you address the whole issue of sewage-water-biofuel as integrated and ready-to-go just needing awareness & education.
And finally, my units are made for homes to allow people to DIY biodiesel from their own waste cutting out the fuel companies entirely; for a dairy farm it'll run the whole operation on wash-down with few solids to deal with a consistent input an example of distributing the system at that scale.