The effect of waste water on physical and chemical features of soil

Subject Areas : environmental management

Vahid Yazdanee ¹ , Bijan Ghahreman ² , Kamran Davudee ³ , Ebrahim Fazeli ⁴

1 - student of PHDof water engineering department of Ferdowsi University
2 - professor of water engineering department of Ferdowsi University
3 - associate professor of water engineering department of Ferdowsi University
4 - MS student of water engineering of Ferdows Azad university

Received: 2010-12-31 Accepted : 2011-06-08 Published : 2014-12-22

Keywords: irrigation, features of the soil, water of the well, Wastewater, concentric cylinders,

Abstract :

Field and purpose According to huge utilization of domestic and urban wastewaters in planting and agricultural fields around big cities, now a days local researches about this field and observing different outcomes from irrigation by waste water, has got a great importance. Procedure In this research we have used discharging waste water of filtration plant of Parkand Abad of Mashhad (BOD=169.5 & TSS=138 & SAR=14.6) and water of the well (EC=740 micro M per second) as samples. Irrigation and experiments were performed in fields of 4 square meters, which were surrounded by the soil of farm. With waste water and water of the well, fields were irrigated one to five times and every time the amount of irrigation was 150 mm. After that, by using concentric cylinders, absorption potentiality and full hydraulic conduction was estimated. The other chemical and physical parameters of the soil in the fields are presented in standard book of measuring methods. Findings Irrigation with wastewater effects density of the soil and decreases the amount of it. So much so that with 1, 2, 3, 4 and 5 times increase of wastewater irrigation, relatively we had 2, 6.6, 4, 15.7 and 17.6 percent decrease in density of the soil. Also with increase of irrigation times by wastewater, ions of sodium, phosphorus, nitrates and nickel were increased as well. The maximum increase was seen in nitrates ions (38%) and sodium (84%). The amount of absorption potentiality in irrigated fields with water and wastewater was less than the fields which were not irrigated at all. Besides this absorption was even less in the fields which were irrigated by wastewater. Also from the second irrigation on, because of formation a seleh layer, absorption was suddenly reached to its maximum rate (0.34 mm per minute), which absorption was controlled by this seleh layer. One of the most important reasons of seleh layer formation was existence of sodium particles in wastewater which were absorbed in the soil. It seems that sodium ion causes scattering particles of soil, so due to these fact small particles fills the pores and prevent absorption of water in the soil.