Cleaning up Guanabara Bay - Could it Be possible?

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I was asked if, based on the video from BBC http://www.bbc.com/news/world-latin-america-25635140, the idea to try to clean up the bay with boats is feasible until the Olympic games? So I carried together a few assumptions to make a rough estimate. Please do not take this for granted as it is based on very little available information.

I hope that other measures are additionally taken on land to reduce the litter entering the water body but this might take longer time than hitting the target 2016 to have a clean bay. Just cleaning alone will not create a sustaining improvement. 

I made just some rough assumptions based on technical economical point of view and based on the BBC video (click more to read). I can't make any remarks concerning impact on the environment.

The info which I got from the video:

• 6 small ships
• 1 large barge
• and the one shown in the video (large/small ??)

• The Bay surface coverage 412 sqkm (Wikipedia)
  
• 840 Million for the cleanup and sewage system (I read somewhere that this budget has been reduced).
  
• 842 USD per day per unit incl. staff. (and fuel???) 
  
• 3.5 square meter collection surface (just an assumption).
  
• Skimming depth 45 cm below surface
  
• 3.5 meter skimming width. (rough guessing from the video)
  
• ( Speed: 4km/h = 4000 m/h ) ASSUMPTION
  
• Working time effective 8 hours per day. ASSUMPTION
  
• 8 * 4000m = 32 000 m
  
• 3,5m x 32 000 m = 112 000 square meter per day per unit. = 0.112 sqKM per day
  

• 10 units = 1,12 = 368 days surface coverage (220 working days per year = 1,67 years = 20 months) = 1st March 2014 start 1.Nov.2015 end 
  
• 10 units = 8420 dollar per day 
  
• 8420 USD * 368 = 3.097.357 USD
  
• Running Cost per ship per year (220 working days) = 185240 USD
  

Conclusion: If such a venture focuses on the hot spots and would drive with the small units systematically along the shore and focus on hot spots plus using the bigger one to drive in a ZIG ZAG manner across the bay it can work and before 2016. With total cost of around 3 to 4 million it seems to fit into the 840 million total budget below the 5% line which might make sense for something that is for fixing the effects but not to cure the source. The system needs good navigation to stay effective (GPS tracking to record surface coverage + fluid particle simulation + a few fast boats to monitor and identify hot spots). As the water is in constant movement it is hard to clean an area. But this is true for every solution. And at the given traffic in the bay a big solution is not handy. A river mouth solutions could change that.