During the Thailand flooding last year there were many events organized for volunteers to make EM balls for treatment of stagnant flood waters. At the time I was following a lot of action about the flooding on Twitter and kept seeing tweets about people joining the EM ball making parties. I have previously experimented with EM and had read about the use of EM balls for stagnant water treatment so I already knew it was bogus. But few Thais knew anything other than what organizers told them and besides they like to feel like they are doing something to help regardless of whether it actually helps. So thousands of EM balls were produced and tossed into areas where flood waters were trapped and beginning to turn black, rotten and smelly.
The searches I did at that time turned up several independent studies in which EM had been used to treat several types of stagnant water. In all cases the EM actually made the water worse because it depelted dissovled oxygen, resulting in more anerobic decay and worse water quality. One of those studies had been done in Thailand and had been publised but that didn’t stop the Thai government from going ahead with the EM ball parties.
The day before yesterday Chulalongkorn University in Bangkok held a press conference and presented the results of a new study they did. The researchers took water samples from Rangsit and Pathumthani where there were large volumes of trapped flood waters that were terribly stagnant and disgusting. They treated the samples with EM balls. The results were decreased levels of dissolved oxygen and worse water clarity than untreated samples. Basically they confirmed what earlier studies had shown.
The only studies I have found that support the claims that EM can be used to improve the quality of flood waters were done by they manufacturer of EM or people selling the product. All independent studies I know of show it actually makes the water quality worse.