Wednesday, June 19, 2013

again about Reed Bed Treatment System in arid and warm climates: the United Arab Emirates examples

by this blog I have known many people that like treatment wetlands system because are involved in their design and construction or because they like green technologies.
One of the last I have meet is Wolfram Sievert working at Mizan Consult FZE.
With this article I want to share with the TWs blog network the experience of Worlfram in UAE. 
Some pictures of the works (click on the image to enlarge it):

Here below the list of his systems built in that really warm and arid zone:
  • Example 1: Domestic wastewater at a contractor head office is collected by separate gravity sewer lines for grey and blackwater. (i) Greywater: After settling in a 2-chamber tank, is pumped into two parallel vertical flow sand filter reed beds, each with an area of 250m2; (ii) Blackwater: This is passed through a 3-chamber septic tank for pre-treatment prior to treatment in a mechanical self-backwashing filter. Final disposal is via subsurface drip irrigation; (iii) The settled solids from the pre-treatment units of greywater and blackwater (settlement tanks) are pumped every 3 months into 200m2 sludge dewatering reed bed for mineralisation.
  • Example 2: Car washing wastewater from Waagner Biro Gulf workshop is collected through gravity sewer to the pre-treatment: (i) 3 chamber oil separator without chemicals; (ii) 20m2 horizontal flow sand filter reed bed; (iii) final treatment in the reed bed for greywater treatment.
  •  Example 3: Domestic wastewater of SAMA Dubai site office: (i) 3-chamber septic tank and 100 m² vertical flow sand filter reed bed treatment for toilet blackwater; (ii) 2-chamber settlement tank and 40 m² separate vertical flow sand filter reed bed treatment for greywater; (iii) 20 m² sludge dewatering reed bed (reed-planted sand filter bed) for mineralization of septic tank sludge. Treated water is reused for landscape irrigation.
  • Example 4: Conversion of conventional septic tank with soak away at Dubai Municipality Jaddaf: The septic tank is used as pre-treatment system. The pre-treated water is pumped to a vertical flow sand filter reed bed for biological and tertiary treatment. The treated effluent is then used for irrigation.
  •  Example 5: Raw sewage double stage vertical flow reed bed system for treatment of up to 250 m³/day sewage from a Hotel complex (TDIC) on Sir Bani Yas Island, Abu Dhabi. The raw sewage from the Hotel and the laundry water is pumped through a grinder pump directly onto a vertical flow Stage A reed bed for sludge filtration and mineralization. After this pre-treatment the sewage is pumped onto a second vertical flow reed bed (Stage B) for final treatment. The outflow is used directly for irrigation.
  • Example 6: Raw sewage double stage vertical flow reed bed system for treatment of up to 30 m³/day for a labour accommodation in Mirfa. The raw sewage is pumped through a grinder pump directly onto a vertical flow Stage A reed bed for sludge filtration and mineralization. A stage B reed bed is doing the final treatment and final effluent is used for irrigation. 
And what about the lesson learned:
·          The double stage raw sewage vertical flow reed planted sand filter (French System) perform perfect under hot climate conditions and achieves results complying with all ME irrigation standards in the treatment of all kinds of sewage (grey, raw, black, tanker, oil), proven by > 20 systems currently operation in the ME.
·          Direct treatment of raw sewage in a double stage reed bed has the lowest operation and maintenance requirements and is therefore the most appropriate reed bed technology for remote treatment of sewage in the ME.
·          Seperation of grey and black water has no positive effect on the treatment performance.
·          The investment costs for reed beds are equal or even higher compared to conventional low cost/quality package plants, but the operation and maintenance costs are much lower; after 5-7 years the reed bed system becomes financially viable in comparison to conventional package plants, after 20 years the total life cycle costs are 50% of a conventional system.
·         The reed bed system does consume only little energy (max. 0.3 kWh/m³) and produces a biomass which is a valuable by-product, which serves as biotope.
·         Depending on the type of reed bed system used no sludge disposal is required for 15 years as sludge gets directly mineralized in the system.
·         The reed bed technology provides a long lasting, low-maintenance, easy to operate and high performance, robust sustainable waste water treatment solution.

The reed bed technology is not a low cost solution for short term projects.

After more than 8 years of continuous persuading of governmental and private organizations with countless presentations, workshops and discussions and construction of more than 20 reed bed systems, mainly financed by private contractors, the reed bed technology starts to play a role in the decentralized treatment of sewage in the U.A.E., Qatar and Oman. The first tenders were released in the U.A.E. from governmental organizations and private developers to implement the reed bed technology for remote areas and sustainable projects proving that this technology finally got accepted and approved in the region and will take its place in the treatment of sewage in the U.A.E. as alternative green and sustainable alternative to conventional waste water treatment.  

Thank you Wolfram to give us something about your experience!

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