Sorry, but I must disagree. In the early days he was well known for one of the most ruthless and dishonest businessmen in his field. He ruined many careers simply based upon his personal greed. This isn't to say that he didn't do a lot of good; the consolidation of system parameters eliminated a good deal of software issues that existed between programs and platforms.
One of the more classical examples was when he directed John Scully of Apple to surrender MAC Basic and threatened to withdraw all of Apple's other OS programs that were Microsoft simply because he was afraid of a little competition. There was no alternative and he wouldn't even agree to pay Apple even a penny for the program.
In reference to the article, every sewage treatment facility has a certain degree of odor. The odor is primarily from the action of bacterial digestion of the organic materials. Without it, the solids would not break down. Even if the odor was 1:1 with present plants, to have such efficiency not only greatly enhances the capabilities but produces a positive product in the form of electric, clean water and reduction of solid waste. Several cities on the West coast are going to a "sewer to tap" processing system now because of the area's water shortages. Simply put, this plant not only does the same, but generates enough power to be operationally sustainable. I have built many treatment plants and water plants over my 40 years in the field and I can guarantee you that this design application is the best we have seen. Now if you want to know the real question? What does it cost? What is the ROI and can it be developed more into a package unit that can be easily built, shipped, and set up "as needed" so it can do the most good? With that high efficiency burner, it has a great potential for processing many hazardous wastes that are being land-filled, which is another win/win that hasen't even been explored yet.
So, like I said, Mr. Gates is making headway. Like many of the philanthropists of the past two centuries, he is devoting much of his wealth to improvement for the masses. The question now is how the historians will see this and will he manage to do enough. Only time will tell.