The method uses biogas, which is produced when waste water sludge is broken down by microbes in a process known as anaerobic digestion.

BBC: United Utilities turns human waste to energy at plant

The EPA's initial report concluded that there was a link with the waste-water produced by drilling for gas.

BBC: Fracking: Untangling fact from fiction

Now, companies with plants that use or produce chemicals on the list have to complete a long form (one form per chemical, per plant), which tells exactly how much of the chemical is used or produced and where it is going (air, water, recycling, waste treatment).

FORBES: Toxic Neighbors?

Brian figured that if he could solve the technology and logistics problems required to anchor a fish farm 10 or 20 miles offshore, where swift currents carry away and disperse the waste produced by concentrated fish stocks, it would allow the farmed fish to swim in the same fresh water as their wild cousins-the best of both worlds.

FORBES: Regulatory Uncertainty Drives A Fish Farmer To Foreign Waters