What's best landfill or litter dispersal?


I have just been interviewed by a journalist writing for the RYA’s Blue Green initiative which is being spearheaded by Mike Golding. He wanted to know what changes I was going to make in my sailing life for the good of the planet.
I had to confess spreading a rainbow-coloured patina of oil across the waters of St Katherine’s Dock a while back after pumping the bilge of my Contessa 32 unthinkingly – but perfectly naturally after a passage. Liberal doses of washing up liquid surreptiously pumped through the galley sink eventually dispersed the rogue slick. The story prompted my inquistor to ask if I had considered a bilge filter. And this got me thinking.
OK, so I fit a bilge filter. What then happens to the oily muck it collects? It finds its way into a large reservoir of used oil. It’s the same with rubbish. We carefully bag all our trash on passage and angelically dump it in the wheely bins at the marina. What happens to it next? It goes to a landfill site, or what used to be called a rubbish dump.
Some say the agents used to break up oil spills from wrecked supertankers are more damaging to the environment than the oil itself which eventually breaks down and becomes nuetral: perhaps the grey mullet swimming in St Katharine’s Dock would have preferred the oil to the detergent? Perhaps thinly spreading tin cans and sinkable organic matter across the world’s seabed is better than concentrating it in water table- breaching landfill sites?