Wastewater recovery

When considering wastewater treatment, two categories present themselves: centralized and decentralized. "Centralized" is a single wastewater treatment system serving several or many end users. A municipal sewage treatment system is one such example. "Decentralized" refers to a particular facility (residence, manufacturing plant, etc.) treating its own wastewater for reuse, usually within the facility. Either type of operation can employ a range of physical, chemical and biological treatment processes designed with an explicit focus on co-recovery of value-added resources.

Treating wastewater for reuse may present significant challenges. The plant personnel responsible for making decisions and taking action are often unaware of which technologies can be used for this purpose. Also, they may have negative views such as:

1. Our freshwater supply is sufficient in both quantity and quality. That may be the situation now, but as supplies diminish and become more contaminated, this could change drastically, and the cost of this water (both incoming and outgoing) will certainly continue to increase.
2. A treatment system will cost too much. As more and more wastewater recovery and reuse systems are designed and installed, new and existing technologies become more widely employed and competitive in price. The recovery of valuable solute may also provide sufficient economic incentive.
3. We don't have the engineering knowledge to tackle this. There are many competent consulting engineering firms and academics with expertise in designing complete treatment systems for wastewater reuse.
4. Will it make a difference to our customers? As the public becomes more aware of the looming water shortages associated with climate change, manufacturers of consumer products are discovering that being able to make recovery and reuse claims has excellent public relations value. “Sustainability” has become today’s buzzword.

There are technologies that can treat virtually any wastewater stream for reuse in any application. The increasing acceptance of treated municipal sewage for drinking water provides testimony.

The "Poster Child" for this is the Groundwater Replenishment System (GWRS) located in Orange County, California. It generates over 100 million gallons per day of potable quality drinking water from secondary treated sewage. This treated water meets the potable water requirements for over 850,000 residents.

Because sewage all over the world has similar kinds and concentrations of contaminants, it is possible to design similar treatment trains for virtually any location, often without pilot testing.     (责任编辑：Alice Lee)