Black water recycling is a long-established practice used for irrigation, especially in arid or semi-arid countries like South Africa. Reusing wastewater is part of sustainable water management and is an alternative water source. Recycling blackwater reduces water scarcity and alleviates pressures on groundwater and other natural water bodies.

When greywater is mixed with toilet wastewater and/or kitchen sinks, it is called sewage or blackwater and is treated onsite sewage facility (septic system).  Water from kitchen sinks and/or dishwashers contains fats, oils and grease. It undergoes preliminary treatment to remove these substances before discharging it into a grey water tank.

Blackwater Recycling for Irrigation:

Sometimes it is not viable to separate greywater outlets from blackwater outlets/sewer. Although it is easier and cheaper to treat and recycle greywater than blackwater (sewage), because of lower levels of contaminants, it is not impossible. Blackwater reuse is a long-established practice used for irrigation, especially countries prone to drought like South Africa. 

The treatment process is purely the biological breakdown of organic solids entering the treatment plant. This process incorporates the advantages of fixed film technologies and combines it with fine bubble diffused aeration techniques. Its main components: the bio media and fine bubble diffused aeration grid.

The Biological Breakdown Process:

• Primary treatment takes place in septic tanks/anaerobic reactors. The septic tank size is determined by the number of people in the household. This process requires at least 24hrs but should be retained for at least 48hrs. The longer retention time, the higher quality effluent. It then flows into the biological reactor for secondary treatment.
• Secondary treatment is done in the Aerobic Biological Reactor. Here air (oxygen) is pumped into the reactor to mix and supply air to the wastewater. This allows the wastewater to circulate between an aerobic zone and an anoxic zone to facilitate the de-nitrification process. Fixed film (specifically designed for wastewater treatment) process is when immobilised media has been provided for microorganisms to attach and grow on.
• The last, Tertiary treatment process is a disinfectant/sterilising process as a precaution against pathogens that may have passed on from the second stage. Contact period should be at least 30 minutes.

Blackwater recycling provides water for your garden all year round; 24/7, 365 days a year. This is saving water at its best without you having to change your lifestyle in any way whatsoever.