Actually, they put a kind of medicine made of ‘Polyglutamic acid‘ from natto. Then, they skimmed the scum. When I read this news I thought that it had gone by natural decomposition. If so, I think it’s great! But you have to skim….Is it worth gathering scum by that medicine? Mmmm…I don’t know but at least, they say that it doesn’t make any harm to the environment and there are a lot of place where need clean water, so I hope this study would continue and be improved further!