Since the launch of the "Reinvent the Toilet Challenge", more than a dozen research teams, mainly at universities in the U.S., Europe, India, China and South Africa, have received grants to develop innovative on-site and off-site waste treatment solutions for the urban poor. The grants were in the order of 400,000 USD for their first phase, followed by typically 1-3 million USD for their second phase; many of them investigated resource recovery or processing technologies for excreta or fecal sludge.
If it is possible to answer this question, answer it for me (else, reply "unanswerable"): What did many investigate
many of them investigated resource recovery or processing technologies for excreta or fecal sludge.