Simulation Study on Constructed Wetland Treatment on Villages and Small Towns´ Sewage

Constructed wetland, one of technologies of wastewater treatment, is developing recently. There are many advantages for this technology: high removal capacity, simple technology of construction operation and maintenance, and low costs in investment, maintenance and operation. Therefore it is adapted to sewage treatment of village and small town short of fund and technician. In this paper, the effective specific surface area (alpha_S) and area factor (delta) of constructed wetland with different depths are calculated to study the location of aerobic microorganism according to the slab geometry theory. The simulation results indicated that alpha_s in different depths of wetland is different, that is, alpha_s of the upper layer is threefold as the wetland bed. The contamination is removed mainly in the upper 25 cm where microorganism is active.