Greywater treatment using vertical subsurface flow constructed wetland system

Wastewater (specifically greywater) treatment methods are vital especially in areas facing water shortage pro-blems with arid climates. Constructed wetlands could play a strategic role in wastewater reclamation in arid regions. On one hand, the reliability is not high since its efficiency and the nutrients removal is low. On the other hand, the efficiency in removing the chemical oxygen demand is high. (Chemical Oxygen Demand, Dissolved Oxygen, Total Nitrogen, and Phosphate) were analyzed to study the effect on the removal efficiency if different substrates and hydraulic retention time (HRT) were varied. The systems were roughly identical except the main substrate in each was modified to be soil, gravel, or random packing. The best system, which is the system with soil substrate, resulted in a final average percent removal of 93% and 74% for chemical oxygen demand and total nitrogen, respectively. However, resulted in low percent removal for the orthophosphate. This system also gave the highest efficiency when the aeration period was the longest. The longer the aeration period the more oxygen is supplied and by this, microorganisms will be highly active and decompose the organic matter. While system three with random packing substrate had the least removal efficiency; yet operated the best for the removal of phosphorus. Generally, all the systems achieved the highest percent removal when the HRT for the wastewater spent inside the system was the shortest and aeration was the longest.