A non-executive director of Hydrodec, the "clean" oil re-refining group, has purchased one million shares in the AIM-listed firm. Andrew Black bought the shares at 14.38p for a total of £143,700, taking his total number of shares to over 57m. The purchase came just one day after the firm announced that revenues for 2011 will come in significantly ahead of 2010. Sales of the branded Superfine oil rose 12% in the second half of 2011 versus the first six months of the year, giving some indication of the acceleration the company is currently seeing.There has been encouraging news from the US where Hydrodec has received a draft approval from the US Environmental Protection Agency (EPA) to treat polychlorinated biphenyl (PCB) contaminated used oil.There are still some loose ends to tie up with the EPA but the company is confident it will soon become a "one-stop shop" for companies to dispose of their used transformer oil. Top Director BuysHydroDec Group (HYR) Director name: Mr Andrew BlackAmount purchased: 1,000,000 @ 14.38p Value: £143,700Thorntons (THT) Director name: Mr John Von SpreckelsenAmount purchased: 402,301 @ 19.68p Value: £79,173Intercede Group (IGP) Director name: Mr Richard Arthur ParrisAmount purchased: 67,646 @ 73.50p Value: £49,720Braemar Shipping Services (BMS) Director name: Mr Alan MarshAmount purchased: 7,176 @ 338.14p Value: £24,265Dixons Retail (DXNS) Director name: Mr John AllanAmount purchased: 150,000 @ 13.99p Value: £20,985Thorntons (THT) Director name: Mr Jonathan HartAmount purchased: 75,431 @ 19.68p Value: £14,845Dixons Retail (DXNS) Director name: Mr John AllanAmount purchased: 100,000 @ 14.08p Value: £14,080Frontera Resources Corporation (DI) (FRR) Director name: Mr Steve C NicandrosAmount purchased: 1,230,000 @ 1.07p Value: £13,161Top Director SellsStarvest (SVE) Director name: Mr Anthony C R ScuttAmount sold: 125,000 @ 9.50p Value: £11,875