With water conservation becoming a concern, many people are turning to graywater recycling - the practice of reusing shower, dish, and other water for irrigation and other non-food uses.  However, did you know that you can recycle more than just graywater?  Blackwater - sewage and other contaminated water - can also be recycled.  It’s becoming much more popular in areas suffering from serious drought, including Australia, and it’s viable for many others.  Let’s take a look at blackwater recycling and how it works.

In a blackwater recycling system, all household water is routed into a tank using gravity.  Then, the blackwater is given enough time to settle and bacteria works on it for twenty-four hours.  This works in a similar way to the anaerobic environment in many septic tanks.  Once this process has finished, the blackwater is diverted into a secondary treatment tank.  This is divided up into three chambers, which are aeration, settling and irrigation.

The aeration stage injects water and air into the chamber at carefully timed intervals.  This causes the tank contents to churn, encouraging the growth of bacteria.  These organisms proceed to pull nutrients from the sludge, breaking it down further.  In the settling chamber, that sludge sinks to the bottom.  Any partially treated water goes upwards.  It passes through a mechanism covered in bacteria biomass, which consumes the rest of the oxygen and breaks down the rest of the solids.

After that, what’s left of the blackwater goes into the irrigation chamber.  It’s clarified, and in some cases chlorinated, depending on local health regulations.  At this point, treatment is done, and the water is safe for use in lawn or garden irrigation, though not on vegetable gardens.  This water remains relatively rich in nutrients, but doesn’t have the risk of pathogen spread that untreated blackwater does.  There is no smell, either sewage or chlorine, and it’s not possible for the treatment tanks to be contaminated with raw sewage.

Periodically, settled sludge will be pumped back to the primary tank for the bacteria to work on it.  This makes the system more efficient and reduces sludge build up.  Generally, a system of this type will require servicing by the installation company every few months, and it does mean you have to watch what goes down the drain.  Antibacterial soaps will really mess up the system.  However, this encourages you to use products that are more environmentally friendly.  A blackwater treatment system can really help you reduce the use of water for irrigation purposes, and help you avoid taxing the water system even more.