Use of Some Natural Materials to Reduce Concentrations of some Heavy Metals in Polluted Water and Possibility of Using Them for Irrigation in Calcareous Agricultural Soils
Authors: Hameed Dhiaa Zahim , Naser Kadhim Makki 
Published: November 2023

Abstract
To evaluate efficiency of some natural materials in using them as filters to reduce concentrations of some heavy elements in polluted water, and possibility of using them for irrigation in calcareous agricultural soils, two experiments were conducted, first is laboratory, which is treatment of various polluted waters, namely industrial water, gray water, and river water using three natural treatment materials as filters, which are activated charcoal, Eichhornia crassipes plant powder, Ceratophyllum plant powder. Poles made of polyethylene were used with a length of 100 cm and a diameter of 10 cm equipped with a tap from bottom, a layer of glass wool was placed at bottom, and then treatment materials were placed on top of it at a height of 50 cm. A piece of gauze cloth was placed over it for filter polluted water from solids. Polluted water was passed after filtering from top of column and left for 24 hours for equilibrium, then filtrate was collected from bottom of column. Second experiment, it is biology, as an experiment was conducted in pots of 20 kg capacity, using calcareous soil with a Loamy texture, and Dodonaea seedlings (one of fence plants) were planted. NPK fertilizers were added to it according to fertilizer recommendation, and irrigation was done with tap water after 50% of available water was depleted by gravimetric method. Results showed the following: 1-High concentrations of heavy metals, each of Lead, Ccadmium, Zinc and Nickel in industrial water, where they reached 5.190, 0.043, 3.727 and 0.371 mg L-1, respectively, exceeding limits allowed by World Food and Health Organization for each of Cadmium, Zinc and Nickel, while concentrations of Lead is within internationally permitted limits. As for gray water, Cadmium concentrations exceeded internationally permitted limits, while concentrations of Lead, Zinc and Nickel were within internationally permitted limits. In river water, they were within internationally permitted limits. 2. Decreased concentrations of heavy metals in polluted water treated with various natural treatment materials compared to their concentrations before treatment. The materials used in treatment can be arranged according to their efficiency in adsorption of heavy metals from industrial and gray water as follows: -activated charcoal > Eichhornia crassipes powder > Ceratophyllum powder > Arundo donax plant_powder. 3-High available concentrations of heavy metals in soils passed through polluted water compared to soils irrigated with treated water. Total concentrations were 34.436, 18.227, 8.064 mg kg-1 soil, 31.064, 16.884, 6.190 mg kg-1 soil, 32.860, 12.670, 4.930 mg kg-1 soil, 0.465, 3.680, and 0.590 mg kg-1 soil for Lead and Cadmium elements and Zinc and Nickel in succession and industrial water and gray water and river water successively, after 100 days of cultivation. 4-High concentrations of heavy metals in plants irrigated with different polluted water compared to plants irrigated with different treated water after 100 days of cultivation. Plants irrigated with polluted and treated water can be arranged according to concentration of heavy metals in them as follows: - industrial water > gray water > river water.