Study Of the Optimum Conditions for Removing Phosphate from House Water in City of Mosul Using Some Local Clays

ABSTRACT


Introduction
Many local clays and soils have ability to exchange or absorb cations and anions.Thus, it contains on its surface such as (H + , Mg 2+ , Na + , Ca 2+ , NO3 -PO4 -3 and SO4 2-), which can be exchanged without change the geometry, which has a large surface area (Bergaya and Lagaly, 2006).They easily absorb dyes, heavy metals and organic matter from pollution, electrical conductivity (EC) and (pH).Bentonite shows the best removal efficiency of calcium and magnesium Phosphate, Nitrate, followed by Ninavite and Kaoline respectively.Removal of (COD) gives for (BOD5) at optimum doses (Nabeel and Abid, 2009).Phosphate concentration shows five times in the of the Al-Khosar River, (BOD) and (COD) increase by (1.5, 1.48) times respectively compared to the Iraqi standard No. (25-B1) of the conservation of water supply according to the load of organics (Hazim, 2009).Phosphate is essential for life, developed a sophisticated system to regulate the phosphate of evolution.
Also it has a critical factor in the pathogenesis of bone disorders and mineral associated with chronic kidney ( Komaba and Fukagawa, 2016), phosphorus is released to the soil water, and so phosphorus pollution is reaching dangerous levels in the rivers and others, hoping to use bacteria in the soil to overcome the unused phosphorus, boosting crop growth (Paul Simons, 2018).Pollution of water caused by human activities and industrial is one of the major problems in the world, as it is the leading cause of 80% of diseases worldwide, there is almost (1.1) billion people that cannot get portable water (Al-Hayani et al., 2022).In the aquatic environment, phosphate is found in wastewater as a result of agricultural phosphate fertilizers, household detergents and organic waste, knowing that its high concentrations in drinking water have health problems, including osteoporosis (Lanjwani et al., 2020) aquatic plants and plants due to the increase in the proportions of green algae known for their toxicity.This leads to a decrease in the amount of dissolved oxygen in the water, factors resulting from weighting, water springs, tourism in the adjacent soil (0.3-3) mg.kg -1 (Mustafa et al., 2019).

Location
Water samples are collected from five pumping stations in geographical locations with latitudes and longitudes shown in Table (1).Water samples are collected for laboratory measurements and biological analyses using clean glass bottles that are well washed with distilled water several times.As for the samples related to the determination of dissolved oxygen (DO) and the requirement of Bio-oxygen BOD5 is used to collect special bottles of 500 ml without creating air bubbles as much as possible, refrigerated boxes away from light for the purpose of preserving samples until reaching the laboratory at 4ºC, and a special iron canister tied with a rope for the purpose of collecting the sample from the basins of the lifting stations with special gloves for sample collection.The location address, date of sampling, weather conditions, the pH and electrical conductivity are calculated in the field at the studied sites.

Laboratory analysis
Turbidity, phosphate, chloride, nitrate, nitrite, COD, BOD, sulphate, hardness, Ca, Mg, Na, K, E.C and pH, are analyzed according to standard method for examination of water and waste water (APHA, 1998).

Materials Adsorbent
Bentonite, Tulkeef and Al-Qobah clays, which are locally available in large quantities are used as an inexpensive raw material.They are available in the environment areas.After collecting them, the samples are crushed and sieved with a grain open size of 175 micron and kept inside a plastic container for measurement (Khan, 2020).A mass of (2.5 g) of absorbent materials is separately used (batch and column) techniques.The volume of stock solution 25 ml at different concentrations (7.5, 15, 22.5, 30, 37.5) ppm of PO4 -as KH2PO4 are added, then standing time for (15 min) with stirring in batch technique, and the other used 1.5 ml/min flow rate for column (see schematic 1), finally absorbance is read of phosphate according to ammonium molybdate-meta vanadate mixture (Tandon et al., 1968) spectro-photometrically at maximum wavelength 400 n.m.
Then phosphate is calculated before adsorbed according to equations: Where: PO4-ad: phosphate adsorbed in ppm, V: the quantity of phosphate in ml, W: weigh of dry material in gram.The equilibrium concentrations of the phosphate according to Langmuir single-surface equation are determined to get free energy, binding capacity preference factor, and maximum adsorption capacity. Where: X: the quantity of phosphate adsorbed in µg g-dry clay, K: the binding factor of the phosphate on the clay surface.energy coefficient in ml µg-unit, b: maximum adsorption in µg.g -1 , C: phosphate concentration in the equilibrium in µg.ml -1 , and the values of constants are calculated after plotting the relationship between C/X values and C values to get a straight line, so the slope of the line is 1/b, and the intersection with the y-axis Intercept is 1/Kb.

Maximum Buffering Capacity (MBC)
This value is expressed mathematically by multiplying the binding energy K in the maximum adsorption capacity of the surface Xm of the Langmuir equation, which is a specify of ion adsorption.The Langmuir equation, as noted by Yassen and Fakher, 2016;Al-Hassoon et al., 2019) is as follows: The samples were collected once in month starting from July 2021.

Composition of clay and soils:
A property of natural adsorbents (bentonite, Tulkeef and Qobah) clays are used as listed in tables (2 and 3).

Analysis of house water
After collection of water from lift pump station, many chemical parameters and biological were examined, all value listed in table 5 were with permissible limit, except phosphate.The relative increase in the concentration of orthophosphate ions (6.8 ppm) in Bab Sinjar station, and this is due to the increase in the use of detergents rich in phosphorus compounds, as well as agricultural waste containing pesticides and fertilizers through the disposal of outfall water thrown to the river.

Optimum condition for adsorption of clays
In the beginning, three clays (2.5 gram) of (bentonite, tulkeef and Qobah) are selected in order to make a comparison between them to choose the best, where five duplicate concentrations of phosphate (25 ml ) are prepared, the first is placed in five glass beakers for a period of a quarter of an hour, while the second concentrations are passed on columns with a diameter of 1 cm at a flow rate of 2 ml/min and the samples are collected for the determination of phosphate by colorimetric analysis (see Table 5, Fig. 2).
From above table 5 choice Al-Qobah clay in Subsequent experiments which are of more efficiency and cheaply available comparing to others.After optimum condition for different adsorbe material, select Al-Qobah in next application, firstly study the quantity of soil (Table 6):

5-Study the phosphate concentration on adsorption:
Other parameter was study, the quantity of phosphate adsorbed (see Table 10).From Table ( 11), the adsorption reactions are spontaneous with different clays and that the reaction are negative and that these values are in line with the values of the preference factor (separation coefficient, R 2 ) with negative free energy value (Yassen and Fakher, 2016).

Conclusion
1-We conclude that the water of the houses exposed to the river through the pumping stations is higher than the surveyed limit.
2-The deterioration of the waste water requires treatment, and for this reason we have prompted us to carry out the treatment process.
3-Soil of Tulkeef region was the best compared to the bentonite clays and Al-Qobah regions in terms of adsorption efficiency.

Fig. 3 .
Fig. 3. Capacity adsorbed of different clays; (A):by batch technique (B):by column From Figure (3)., the adsorption capacity of phosphates in the column technique was better than the batches, especially bentonite clays, but choice the more availability Al-Qobah soil.Study the condition parameters of adsorption on Al-Qobah soil: 1-Study the quantity of Al-Qobah soil:

Fig. 4 .
Fig. 4. Diagram for Phosphate removal efficiency and percentage by column and meal technique using (Qobah, Tulkeef and Bentonite soil).