I want to know the answer to the following question:
What did many investigate
All the background I'm provided with is that "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.". Is that enough to answer the question?
Answer: no