What’s a Root Zone Waste Water Treatment

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Author: Saudamini Sharma

The sight of filthy sewage flowing unrestricted into our rivers is not new. Our government spends humungous amount of public funds for treating sewage water before it is discharged into the rivers. However, the sad state of our rivers indicates that a lot is left to be desired.

High maintenance cost is the main deterrent for people from having a sewage treatment plant installed in their industry or residential area. So, they completely depend on state managed and operated Sewage Treatment Plants (STPs), which often malfunction due to overload.

While every large city in India has large-scale conventional STPs, they usually fall into disuse due to their high operating costs, equipment corrosion and lack of skilled operating personnel. If sewage is treated at each industry and residential colony, a major portion of the problem can be mitigated.

Approximately 70% of domestic water is released as wastewater, most of which can be recovered if it is properly treated. Hence, wastewater should be seen as a resource rather than waste. Wastewater can be mainly classified into two categories:

  • Grey water – wastewater generated from kitchens, laundry, bathrooms, etc.
  • Black water – wastewater from toilets containing faecal matter and urine, which is also called as “sewage”

Both grey water and black water can be suitably treated by root zone wastewater treatment and reused for non-potable applications such as toilet flushing and kitchen gardening. Among the many types of STPs, Root Zone Wastewater Treatment (RZWT) is the most innovative and eco-friendly. The Root Zone Waste Water Treatment system is a low cost, virtually zero energy and maintenance-free plant. What’s more, it is pretty good looking too!!!

Root Zone Waste Water Spot the STP here!
Root Zone Waste Water Spot the STP here!

What is Root Zone Wastewater Treatment?

‘Root Zone’ is a scientific term used to cover all the biological activity among different types of microbes, the roots of plants, water soil and the sun. It consists planted filter-beds containing gravel, sand and soil. The RZWT system utilises nature’s way of biologically processing domestic & industrial effluents. This effective technology called Decentralised Wastewater Systems (DEWATS) was developed in 1970s in Germany and has been successfully implemented in different countries mainly in Europe and America.

The root zone wastewater treatment system makes use of biological and physical-treatment processes to remove pollutants from wastewater. Due to its natural process, there is no need to add any input such as chemicals, mechanical pumps or external energy. This reduces both the maintenance and energy costs.

To accomplish this, the root zone wastewater treatment undertakes the following steps:

  1. Pre-treatment done in a Settler – a device that separates the liquid from the solid
  2. First treatment takes place in a Anaerobic Baffled Reactor – a device with several identical chambers through which the effluent moves from top to bottom.
  3. Second treatment happens in an Anaerobic Filter – a device filled with a filter material (cinder), through which the effluent moves from top to bottom.
  4. Third treatment takes place in a Planted Gravel Filter – a structure filled with gravel material and planted with water-resistant reed plants, which provide oxygen to the passing effluent.
biological wastewater treatment
Main DEWATS modules for physical and biological wastewater treatment

1. Settler | 2. Anaerobic Baffled Reactor | 3. Anaerobic Filter | 4. Planted Gravel Filter
Source: BORDA Germany

The Root Zone Waste Water Treatment system takes into account the natural slope of the ground, so that water flows from one device to another without any external energy input such as motor pump. Once the reed plants create an established stand, usually after the first growing season, the reed bed requires little or no maintenance. The plant foliage will soon blend naturally into the landscape, ever changing with the seasons and creating a pleasing sight as well!

Conventional Water Treatment PlantRoot Zone Treatment Plant
A lot of sewage aeration tanks powered with mechanical energy do not work because of power cuts, technical problems and poor maintenanceBy its treatment and construction features DEWATS is designed to limit operation and maintenance requirements and in the same to ensure high treatment standards even for shock loads
Requires lot of external energyMinimal need for external energy
Pumps neededUsing gravity instead of pumps, avoiding valves
Regular maintenance requiredZero maintenance
High operating costsLow operating costs
 

Rootzone waste water
RZWT system at Aravind Eye Hospital

In India, this project was first executed by Bremen Overseas Research and Development Association (BORDA) in the Auroville global community. Since the last 15 years, Auroville located in South India near Pondicherry has been experimenting with such natural wastewater recycling systems. Auroville has now become a pioneer in the Root Zone Wastewater Treatment System and has enabled many such plants across India. One such treatment plant is now implemented in Aravind Eye Hospital, Pondicherry.

Factfile –

http://www.auroville.org
http://www.borda-net.org/
http://www.borda-net.org
Ascenso Management & Consulting Services Pvt. Ltd.
http://www.amcgroup.co.in/environment.aspx
http://www.ecohousingindia.org

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Ecoideaz is hell bent on proving that sensible green ideas do emerge from India. It is eager to build a comprehensive portfolio of all eco-friendly ideas developed in India and create a repository for innovative green ideas both from the investor and consumer perspective.

14 COMMENTS

  1. Hi
    I am a consultant promoting eco friendly treatment options for waste water in south india more specifically in Tamil Nadu.
    I am very interested in your Rot Zone Treatment Process
    Kindly let me know how we can work together to save environment.
    Thanks
    Prosper

  2. Hi, i am vinod patil from Maharashtra i have working last five year in wastewater treatment and i am interested for your treatment process .please can we work together in our region.inform me .
    Thanks….

  3. Hi. This is a very good article and I find it a brilliant idea. But sadly, that’s all it is sir. An idea. We hear about it happening in auroville but I want to start it in my own property. And encourage others to do the same. But how do I know where to get the equipment from? What specifics like size etc… to use when designing it? which plants exactly. Some more specific details would indeed be very helpful and practical to make this planet a lot greener. There are many of us who want to be green but don’t know how.

    • Hi Ninoschka,
      Its not just an idea. It is a viable option that we have ourselves implemented. The first photograph in this article is of our project that we have done for a resort. All designing aspects like size etc depends on the area of project and amount of waste water generated etc. Commonly Canna plant is used as you can see in the photo. We would advise to get the plant designed and erected by an agency which does it and then handle the maintenance yourself, as for maintenance only a mali is required!!! There are no machinery or power required for this project. Send us an email on saudamini@amcgroup.co.in, so that we can take it further if you wish to install this plant. Regards

  4. We run a residential school with 400 students. Hitherto, both grey water and black water was being sent to septic tank. We are now separating grey water allowing it to flow into the lake adjoining our premises. We are planning to set up a system to treat grey water before it enters lake. Hence, we request assistance to deploy root zone treatment. Can you help us?

  5. Hi sir, I’m student of microbiology & i think this article really innovative, helpful to all microbiology student.thank u

  6. Hello sir/mam
    I am student of civil engineering from university of pune. Currently in final year, My area of interest is water purification and disposal of sewage .I am working on RZTS as project point of view. I studied whole RZTS technology. And interested in using plants or species surviving in low sunlight for RZT indoor system.
    So kindly tell me list of plants which can be used for indoor RZTS .
    Thanking you

    • Dear Vishal,
      RZTS uses natural slope for flow of water, hence mostly we have made such systems outdoor. At present, we have not installed any indoor RZTS, but surely its an interesting idea. I would try to get some information on the types of indoor plants for such project and update you.

      Thanks and regards
      Saudamini

  7. Great blog. It has explained a lot regarding the aspects of water treatment solutions. Thanks a lot and thanks for explaining the things regarding the different kind of waste water solutions.

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