Treatment of wastewater by infiltration and its effect on the engineering properties of natural soils

Recently, treatment and recovery of wastewater play an important role in the world. Generally, wastewater treatment involves collecting wastewater in a place transported by the central sewage system and treating wastewater according to its type. However, in rural settlements that do not have a central sewage system, the removal of wastewater can only be achieved with onsite treatment systems. Soil takes an important part in onsite wastewater treatment. Soil can provide contaminants in the waste water to be removed from the water. On the other hand, as is known wastewater contains many organic, inorganic substances and microscopic contaminants. As a result of the interaction of the soil with these contaminants, physical, chemical and mechanical properties may change. This change in soil structure can change the properties of the infiltration areas originally designed and thus it can also affect the efficiency of wastewater treatment. For this reason, the effects of onsite wastewater treatment systems on both wastewater treatment performances and geotechnical properties of natural soils were examined in this study. Wastewater was treated with the infiltration areas developed by simulating with a natural soil column. Wastewater which was taken from the influent water of GASKI Kızılhisar Wastewater Treatment Plant was first passed through the pre-sedimentation tank and then leaked into the soils in the plexiglass pipe with a diameter of 20 cm and a height of 100 cm. Natural soils were taken from 4 different types of field conditions were used for filtration. Columns were constructed for each soil type with different hydraulic loading rates by 9, 18 and 36 L/day. These columns were fed with continuous flow for 23 days. Laboratory and field-scale studies were conducted to determine the properties of natural soils and wastewater before and after leakage. The results of these studies indicated that while soil filtration improves wastewater quality, it can change the engineering properties of soils.