Wastewater plants extract nutrients from sewage_美文

Wastewater plants extract nutrients from sewage

Pramanik says the digester project under construction will help reduce waste that now flows largely into open pits or landfills. He says project managers hope it will also generate useful and commercially valuable by-products such as nutrient-rich soil additives, bio-diesel fuel and methane gas.

“Can you recover that gas and can you use that either for heating or cooking and so on?" he says. "Can you grow food crops with this? Can you recover the nitrogen and phosphorus and increase agricultural yields?”

Economically and environmentally sound

What’s attractive to the local community, Pramanik says, is the payback.

He says the model could be adopted anywhere that waste can be marketed as a profitable community resource. “So if you can get the community involved from the beginning and see that the community is benefiting from it, and the community sees that, they will take ownership.”

Pramanik says these new green factories make good sense for the local economy, for public health and for the environment.

Costly old infrastructure

George Hawkins at the Washington Water and Sewer Authority agrees, however he and other waste water managers in the United are faced with many challenges to put such new green factories in place. First, he says, their current system of pipes and pumping stations is old and requires on-going maintenance. “In most cities the system was put in at the turn of the century of the last century when cities were being formed. And, he adds, the fact is that we need a lot of revenue from our rate-payers to bring it back up to date.”