Wastewater treatment Process

The wastewater is first collected in a holding tank after which it is pumped into a trapezoidal-shaped bioreactor. The bioreactor is constructed by excavation and made waterproof. The under drain is laid at the base. The tank is then filled with layers of media and culture. The surface of the bioreactor contains rows of plants. A network of perforated pipes is constructed on the surface that spreads the incoming wastewater evenly over the surface of the bioreactor. Another set of pipes is also laid vertically extending into the bioreactor for aeration.

Water is pumped over the bioreactor through the perforated pipe network and begins to trickle down the filtering media. The suspended solids in the wastewater are held back by the top media. As the water seeps through the rest of the layers, dissolved pollutants are removed, and finally treated water passes through an outlet at the bottom of the tank and is collected in a treated water storage tank constructed alongside.

If required, recirculation pumps can be added to transport the water back into the bioreactor. This creates a second round of purification, obtaining the desired hydraulic retention and improved output water quality to the desired level. Shrubs and trees are planted on top of the bioreactor to act as bio-indicators, organisms used to monitor the health of the environment. In this case the growth of these plants will determine their ecological health thereby indicating the quality of the recirculated water.

This entire treatment process can be operated on a batch or in continuous mode and is based around three fundamental reactions

(refer to Figure 1 for more detail):

a) Respiration

b) Mineral weathering

c) Photosynthesis