COLUMN STUDY OF THE ADSORPTION OF PHOSPHATE BY USING DRINKING WATER TREATMENT SLUDGE AND RED MUD

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1 International Journal of Civil Engineering and Technology (IJCIET) Volume 6, Issue 9, Sep 215, pp. 8-19, Article ID: IJCIET_6_9_2 Available online at ISSN Print: and ISSN Online: IAEME Publication COLUMN STUDY OF THE ADSORPTION OF PHOSPHATE BY USING DRINKING WATER TREATMENT SLUDGE AND RED MUD Prof. Dr. Alaa Hussein Al-Fatlawi College of Engineering / Babylon University/Iraq Mena Muwafaq Neamah College of Engineering / Babylon University/Iraq ABSTRACT The present study investigates the efficiency of phosphate removal from wastewater by the Drinking Water Treatment Sludge (DWTS), and Red Mud (RM) sorbent. Wastewater was taken from the effluent channel of Almuamirah wastewater treatment plantin at Al-Hilla city/iraq. Drinking Water Treatment Sludge (DWTS), was taken from the sedimentation tanks of Al-Tayara drinking water treatment plant, in the same city. Column experiment was carried out to study the adsorption isotherm of phosphorus at 25±1⁰C and solution of different ph and adsorbent dosages. The effects of (DWTS) dose, bed height (H), contact time (T), agitation speed (S), hydrogen ion concentration (ph), (DWTS RM) ratio, were studied. All continuous experiments were conducted at constant conditions, bed depths 25 cm, initial phosphate concentration 4 mg/l, flow rate 5 ml/min, particle size (1mm) for (DWTS), and (.425mm) for (RM) and solution ph of 4. The results show that the use of (RM) reduces the operating time by about 21% compared to the use of (DWTS).Increasing (RM) ratio increasing the removal efficiency and decreasing the equilibrium time in about 57% and 38% for 5% and 33% (RM) ratio respectively. At the highest phosphate concentration of 4 mg/l, the (DWTS) bed was exhausted in the shortest time of less than 9 hours leading to the earliest breakthrough. Percent of phosphate removal decreased with the increase in initial concentration. Both the breakthrough and exhaustion time increased with increasing the bed height. The results show that a significant increase in the operating time is achieved by adding different ratios of (RM) to (DWTS). Adding 33%, and 5 % (RM) weight ratios to the (DWTS) bed decreases the operating time by about 18%, and 3% respectively. 8 editor@iaeme.com

2 Column Study of The Adsorption of Phosphate by Using Drinking Water Treatment Sludge and Red Mud Key words: Column Study, Adsorption, Drinking Water Treatment Sludge (DWTS), and Red Mud (RM), phosphate. Cite this Article: Prof. Dr. Alaa Hussein Al-Fatlawi and Mena Muwafaq Neamah. Investigating Column Study of The Adsorption of Phosphate by Using Drinking Water Treatment Sludge and Red Mud. International Journal of Civil Engineering and Technology, 6(9), 215, pp INTRODUCTION Phosphorus (P) is an essential nutrient for the growth of organisms in most ecosystems, but superfluous phosphorus can also cause eutrophication and hence deteriorate water quality. Phosphorus is released into aquatic environments in many ways, of which the most significant are human industrial, agricultural, and mining activities. Although phosphorus removal is required before discharging wastewater into bodies of water, phosphorus pollution is nevertheless increasing. Therefore, there is currently an urgent demand for improved phosphorus removal methods which can be applied before wastewater discharge. In wastewater treatment, enhanced biological phosphorus removal (EBPR) is becoming an increasingly popular alternative to chemical precipitation (CP) because of its lower costs and reduced sludge production. Much water treatment sludge is produced in the production of service water and drinking water. It is impossible to prevent the production of water treatment sludge. The water treatment sludge is liquid and solid and is regarded as a waste. Consequently, the water treatment sludge must be handled in accordance with regulations in forces. The quantity of the water treatment sludge is rather high. The water treatment sludge is placed mostly in landfills. In some countries, for instance in the Netherlands, about 25 per cent of the produced water treatment sludge is re-used, (Miroslav, 28). It is still an issue to choose a disposal or liquidation method for the water treatment sludge that would be reasonable in terms of technology and economy. According to environment protection regulations it is required to minimise the quantity of wastes produced. If possible, the wastes should be re-used or processed as secondary raw materials as much as possible. If this is not possible, the solid wastes should be put back in the environment where the space occupied should be as little as possible and minimum costs should be incurred, (Moldan et al., 199). Phosphorus removal from wastewater has been widely investigated and several techniques have been developed including adsorption methods, physical processes (settling, filtration), chemical precipitation (with aluminum, iron and calcium salts), and biological processes that rely on biomass growth (bacteria, algae, plants) or intracellular bacterial polyphosphates accumulation (de-bashan et al., 24). Recently, the removal of phosphate from aqueous solutions via adsorption has attracted much attention. The key problem for many phosphorus adsorption methods, however, is finding an efficient adsorbent. Several low-cost or easily available clays, waste materials and by-products. 9 editor@iaeme.com

3 Prof. Dr. Alaa Hussein Al-Fatlawi and Mena Muwafaq Neamah 2. MATERIAL AND METHODS 2.1 Adsorbate Phosphate was selected as a representative of a contaminant because the it is the main nutrient for the growth of aquatic microorganisms like algae but the excess content of phosphorus in receiving waters leads to extensive algae growth (eutrophication). The samples was collected from the effluent channel of Almuamirah wastewater treatment plant in Al-Hilla city, Iraq. These samples were immediately transported to the laboratory for processing. The total amount of plant nutrients and other pollutants present in a sewage plant effluent is subjected to seasonal, daily, and hourly variation. Table 1 summarizes the composition and variability of the effluent under study. The wastewater sample was used as stock solution to provide the specific value of phosphate concentration. Where necessary, ph adjustment was made on each sample by addition of.1 M HNO 3 and NaOH solutions using a HACH-pH meter. Table 1 Physico-chemical analysis of secondary wastewater effluent sample, (Almuamirah wastewater treatment plant, 214) parameters Quantitative composition E.C, µs/cm 3.5 T.D.S, mg/l 1288 Salinity, mg/l 2.18 Total hardness, as CaCo 3, mg/l 12 ph 7.9 Mg, mg/l Ca, mg/l 16.3 So 4, mg/l Cl, mg/l Po 4, mg/l 2.7 No 3, mg/l.46 T.S.S, mg/l 4 BOD 5, mg/l 32 COD, mg/l 54 DO, mg/l 2.3 Fecal coliform, mpn/1 ml 12 Total coliform, mpn/1 ml Adsorbent Two types of adsorbent were used in the present study for adsorption of phosphate from secondary effluents of wastewater treatment plant they are: 1. Drinking Water Treatment Sludge (DWTS), 2. Red Mud (RM) Drinking Water Treatment Sludge (DWTS) The composition and properties of the water treatment sludge depends typically on the quality of treated water as well as on types and doses of chemicals used during the 1 editor@iaeme.com

4 % of cumulative passing Column Study of The Adsorption of Phosphate by Using Drinking Water Treatment Sludge and Red Mud water treatment. Depending on the quality of the treated water, the water treatment sludge contains suspensions of inorganic and organic substances. The (DWTS) used in this study was taken from the sedimentation tanks of Al- Tayara drinking water treatment plant, in Al-Hilla city, Iraq. This sludge was dried at atmospheric temperature for 5 days, and then sieved on 2 mm mesh to achieve satisfactory uniformity. The sludge had a particle size distribution ranged from 15 μm to 1 mm (Fig. 1) with an effective grain size, d 1, of 25 μm, a median grain size, d 5, of 46 μm and a uniformity coefficient, C u = d 6 /d 1, of Partical size (diameter, mm) Figure 1 Gradation curve for (DWTS) used in the present study. The geometric mean diameter (1.19) is given by where d 1 is the diameter of lower sieve on which the particles are retained and d 2 is the diameter of the upper sieve through which the particles pass (Alexander and Zayas, 1989). Table 2 presents the physical and chemical characteristics of this (DWTS). Table 2 Physical and chemical characteristics of DWTS Element Quantitative composition T.O.C, mg/l 4.29 E.C, µs/cm 62 T.D.S, mg/l 312 Salinity, mg/l.2 ph 8.1 L.O.I, mg/l Fe 2 O 3, mg/l 3.6 CaO, mg/l SO 3, mg/l.63 MgO, mg/l 3.66 Al 2 O 3, mg/l R 2 O 3, mg/l SiO 2, mg/l Red Mud (RM) The Red Mud (RM) used in this study was supplied by the Iraqi commercial markets. It is a solid waste produced in the process of alumina production from bauxite following the Bayer process. Red mud, as the name suggests, is brick red in colour and slimy, having an average particle size of <1μm. A few particles greater than 11 editor@iaeme.com

5 % of cumulative passing Prof. Dr. Alaa Hussein Al-Fatlawi and Mena Muwafaq Neamah 2μm are also available [Liu et al., 211].The mesh size of red mud used in the study was of 1mm. This size was obtained by sieving analysis using the American Sieve Standards in the building of Materials Engineering laboratory at the University of Babylon. Its composition, property and phase vary with the type of the bauxite and the alumina production process, and also change over time. The chemical composition of the red mud is given in Table 3. As a pre-treatment, (RM) was crushed and sieved to get granular (RM)with particle size of.425 mm to be used in present experiments as shown in Fig. 2.The granular (RM) was firstly washed with distilled water and then dried in an electric oven at 12⁰C, overnight. This time was usually enough to remove any undesired moisture within the particles. It was then placed in desiccators for cooling Partical size (diameter, mm) Figure 2 Gradation curve for (RM) used in the present study. Table 3 The main chemical constituents of (RM), (Ping and Dong, 212) Chemical constituent Quantitative composition, % Fe 2 O Al 2 O SiO CaO Na 2 O 4.75 TiO K 2 O.68 Sc 2 O 3.76 V 2 O 5.34 Nb 2 O 5.8 TREO.12 Loss editor@iaeme.com

6 Column Study of The Adsorption of Phosphate by Using Drinking Water Treatment Sludge and Red Mud 3. PREPARATION OF SAMPLES WITH DIFFERENT (DWTS) AND (RM) RATIOS Two different (DWTS) and (RM) weight and ratios of (DWTS) to (RM) were used starting with %, 33% and then 5%. The added (DWTS) was with a size of 1mm while the size of (RM) was of.425mm. Each sample was mixed by shaking using a shaker for 1 hour. The % ratio was first prepared and used in the experiments. When an increase in the operating time was achieved, the addition ratio was raised to 5%. 4. EXPERIMENTAL PROCEDURES The reactor setup (Fig. 3) used in the present study is constructed of pyrex glass tube of (1 cm) height, and (7.5 cm) internal diameter. The column was made in a methacrylate cylinder, thus allowing for visual examination of the progress of the wetting front and detection of preferential flow channels along the column walls. The column dimensions were defined to minimize the occurrence of channeling by making the column diameter at least 3 times the maximum particle size found in the material used. The column dimensions also met the minimum length-to-diameter requirement (Relyea, 1982). This means the column length (1 cm) must be four times greater than its diameter (7.5 cm). Attached to the lower part of the column was a plastic funnel, inside which a perforated fiberglass plate was installed to support the column s methacrylate structure. The plate was covered by a mesh to act as a filter and to retain the porous medium. The entire device was mounted on top of a metal structure that allowed its height above the surface and the verticality of the column to be regulated (Fig. 3). The column was packed with (DWTS) and (RM) in different ratios as filter. Fluid entered the column, previously saturated with the wastewater. Contaminant up gradient wastewater (Table 1) was used to flow through the layer of packed materials. A constant-head reservoir of 5 liter volume polyethylene container was used to deliver influent wastewater at a flow rate of 5 ml/min. The sample was collected as a function of time at the bottom of the column through a 3 liter polyethylene container to collect the effluent solution. Two valves were used to control the desired flow rate through the adsorption column. The first sample, corresponding to time, was taken when water started to flow from the lower part of the column. Samples were filtered through.45µm cellulose acetate filters. Figure 3 Experimental set-up of column test used in the present study. Monitoring of phosphate concentrations in the effluent was conducted for a period of 12 hr. Samples were taken regularly (after different periods) from the effluent. The water samples were immediately introduced in glass vials and then analyzed by AAS editor@iaeme.com

7 Ce /C₀ Prof. Dr. Alaa Hussein Al-Fatlawi and Mena Muwafaq Neamah The filling material in the column was assumed to be homogeneous and incompressible, and constant over time for water-filled porosity. The volumetric water discharge through the column cross section was constant over time and set as the experimental values. The pollutant inlet concentration was set constant. All tubing and fitting for the influent and effluent lines should be composed of an inert material. Information from the column study can be used along with the site characterization and modeling to help in designs the field-scale (DWTS). 5. RESULTS AND DISCUSSIONS The adsorption experiments were carried out in columns that were equipped with a stopper for controlling the column flow rate. This experiment is useful in understanding and predicting the behavior of the process. The sample solution was passed through the adsorption column with a known amount of (DWTS) at a flow rate of 5mL/min by gravity. The flow rate was kept constant by controlling the stopper valve. The concentration of phosphate residual in the sorption medium was determined using fully automated PC-controlled true double-beam AAS with fast sequential operation (Varian AA5 FS, Australia) for fast multielement flame AA determinations with features 4 lamp positions and automatic lamp selection. The results of phosphate adsorption onto different adsorption fixed beds using a continuous system were presented in the form of breakthrough curves which showed the loading behaviors of phosphate to be adsorbed from the solution expressed in terms of relative concentration defined as the ratio of the outlet phosphate concentration to the inlet phosphate concentration as a function of time (C e /C₀ vs. time) Breakthrough Curves of the Different Adsorbents Two continuous flow adsorption experiments were conducted to study the adsorption behavior of fixed beds of (DWTS), and (RM). All the experiments were conducted at constant conditions, bed depths 25 cm, initial phosphate concentration 4 mg/l, flow rate 5 ml/min, particle size (1mm) for (DWTS), and (.425mm) for (RM) and solution ph of 4. The breakthrough curves of the experiments are presented in Fig. 4 in terms of C e /C₀ versus time in minutes DWTS RM Time, min. Figure 4 Experimental breakthrough curves for adsorption of phosphate onto DWTS and RM at C₀=4 mg/l, ph=4, Temp. = 25 ⁰C, H= 25 cm editor@iaeme.com

8 Cₑ /C₀ Column Study of The Adsorption of Phosphate by Using Drinking Water Treatment Sludge and Red Mud Fig. 4 shows that the two adsorbents used in present study are efficient in the removal of phosphate. The use of (RM) reduces the operating time by about 21% compared to the use of (DWTS). It is obvious from this figure that the breakthrough curves for the two adsorbents used are of S shape Effect of Initial phosphate Concentration The effect of changing of phosphate concentration from 2.7 mg/l to 4 mg/l with constant bed height of (DWTS) of 25 cm, flow rate of 5 ml/min, and solution ph of 4 is shown by the breakthrough curves presented in Fig. 5. At the highest phosphate concentration of 4 mg/l, the (DWTS) bed was exhausted in the shortest time of less than 9 hours while its 5 hours for (RM).Leading to the earliest breakthrough. The breakpoint time decreased with increasing the initial concentration as the binding sites became more quickly saturated in the column. This indicated that an increase in the concentration could modify the adsorption rate through the bed. A decrease in the phosphate concentration gave an extended breakthrough curve indicating that a higher volume of the solution could be treated. This was due to the fact that a lower concentration gradient caused a slower transport due to a decrease in the diffusion coefficient or mass transfer coefficient. The effect of initial phosphate concentration onto (DWTS) and (RM) are shown here (Fig. 5 and 6). It could be seen that the percent of phosphate removal decreased with the increase in initial concentration. This means that the amount of these phosphate sorbed per unit mass of sorbent increased with the increase in initial concentration. This plateau represents saturation of the active sites available on the (DWTS) samples for interaction with contaminants, indicating that less favorable sites became involved in the process with increasing concentration C=2.7 mg/l C=4 mg/l Time, min. Figure 5 Experimental breakthrough curves for adsorption of phosphorus onto DWTS at different initial concentrations, ph=4, H=25 cm, Temp.=25 ⁰C editor@iaeme.com

9 Cₑ/C₀ Prof. Dr. Alaa Hussein Al-Fatlawi and Mena Muwafaq Neamah C=2.7 mg/l C=4 mg/l Time, min. Figure 6 Experimental breakthrough curves for adsorption of phosphorus onto RM at different initial concentrations, ph=4, H=25 cm, Temp.=25 ⁰C Effect of Adsorbent Bed Height The effect of bed height was investigated for phosphorus adsorption onto (DWTS); the experimental breakthrough curves are presented in Fig. 7. This Fig. shows the breakthrough curves obtained for phosphate adsorption on the (DWTS) for five different bed heights of (5, 1, 15, 2, and 25 cm), at a constant flow rate of 5 ml/min, phosphate initial concentration of 4 mg/l, and solution ph of 4.It is clear that the increase in bed depth increases the breakthrough time and the residence time of the solute in the column. Both the breakthrough and exhaustion time increased with increasing the bed height. A higher phosphate uptake was also expected at a higher bed height due to the increase in the specific surface of the (DWTS) which provides more fixation binding sites for the phosphate to adsorb. The increase in the adsorbent mass in a higher bed provided a greater service area which would lead to an increase in the volume of the solution treated. (Gupta et al., 21) reported in their works that when the bed height is reduced, axial dispersion phenomena predominates in the mass transfer and reduces the diffusion of the solute, and therefore, the solute has not enough time to diffuse into the whole of the adsorbent mass. The effect of bed depth on the adsorption capacity of (DWTS) was shown in Fig.8, by plotting the capacity versus different bed depth. This Fig. shows that increasing bed depth would increase the capacity because additional spaces will be available for the wastewater molecules to be adsorbed on these unoccupied areas. Furthermore, increasing bed depth will give a sufficient contact time for these molecules to be adsorbed on the (DWTS) surface editor@iaeme.com

10 Adorption capacity, mg/g. Cₑ /C₀ Column Study of The Adsorption of Phosphate by Using Drinking Water Treatment Sludge and Red Mud H=25 cm H=2 cm H=15 cm H=1 cm H=5 cm Time, min. Figure 7 Experimental breakthrough curves for adsorption of phosphorus onto DWTS at different bed thickness C₀=4 mg/l, ph=4, Temp.=25 ⁰C Bed depth, cm. Figure 8 Effect of different bed depth on the adsorption capacity of DWTS (Q=5 ml/min, C₀=4 mg/l, ph=4, Temp=25 ⁰C) Effect of Different (DWTS) (RM) Ratios The effect of different (DWTS) (RM) weight ratios were investigated for phosphate adsorption onto (DWTS) by adding different weight ratios of (.425mm particle size) (RM) to the (DWTS) bed which was of (1 mm particle size). Three experiments were conducted using different weight ratios of (DWTS) (RM) (%, 33%, and 5%). All experiments were carried out at constant conditions, flow rate of 5 ml/min, initial phosphate concentration of 4 mg/l, (DWTS) bed height of 25 cm, and solution ph of 4. The experimental breakthrough curves are presented in Fig. 9. This Fig. shows that a significant decrease in the operating time is achieved by adding different ratios of (RM) to (DWTS). Adding 33%, and 5 % (RM) weight ratios to the (DWTS) bed decreases the operating time by about 18%, and 3% respectively. In the packed bed of the (DWTS) column, the contact points between the 17 editor@iaeme.com

11 Cₑ/C₀ Prof. Dr. Alaa Hussein Al-Fatlawi and Mena Muwafaq Neamah (DWTS) particles represent dead zones because they don t contribute in the adsorption process. So, adding a specific ratio of (RM) to the bed with a smaller particle size fills the dead zones between the particles and increases the total specific surface area of the bed leading an increase in the adsorption capacity and the operating time. Increasing the (RM) ratio to 5% caused the operating time to decrease as compared to 33% ratio, but the bed was still achieving slightly higher operating time and removal efficiency than the pure (% ratio) (DWTS) bed. In fact, the (RM) has higher adsorption capacity and higher porosity than (DWTS). Therefore; increasing the (RM) ratio to 5% causes an increase in the available adsorption sites and the total adsorption capacity of the bed, and this leads to a decrease in the operating time DWTS 33% RM 5% RM Time, min. Figure.9 Experimental breakthrough curves for adsorption of phosphate onto different (RM) ratios, (C₀ =4 mg/l, ph=4, H=25 cm, Temp=25 ⁰C). 6. CONCLUSIONS The following Conclusions were obtain from this study:- (DWTS) seems suitable for use as filler for remediation of wastewater contaminated by phosphate. The laboratory column experiment show the possibility decrease of contaminants in treated wastewater. The use of (DWTS) as a reactive medium for the treatment of wastewater ensures that significant rates of reduction of phosphate are achieved, particularly in cases in which there is initially a high concentration. Results from the column study showed that higher initial concentration resulted in shorter column saturation. (DWTS) is environment friendly, cost- effective, and locally available adsorbent for the adsorption of phosphate ions from secondary wastewater effluents. The effect of different (DWTS) (RM) weight ratios shows that a significant decrease in the operating time is achieved by adding different ratios of (RM) to (DWTS). Adding 33 %, and 5 % (RM) weight ratios to the (DWTS) bed decreases the operating time by about 18%, and 3% respectively. Increasing the (RM) ratio to 5% caused the operating time to decrease as compared to 33% ratio. Increasing (RM) ratio increasing the removal efficiency and decreasing the equilibrium time in about 57% and 38% for 5% and 33% (RM) ratio respectively editor@iaeme.com

12 Column Study of The Adsorption of Phosphate by Using Drinking Water Treatment Sludge and Red Mud One of the important aspects of the present study is represented by considering the (DWTS) as reactive medium, i.e. not inert. The utilization of these conditions is logic because the (DWTS) and (RM) may be worked together under the same field conditions of the continuous flow. REFERENCES [1] Almuamirah wastewater treatment plant, 214. [2] Alexander, P.M., Zayas, I. Particle size and shape Effects on adsorption rate parameters. Environ, Eng., 115(1), 1989, pp [3] De-Bashan, L.E., Bashan, Y., 24, Recent advances in removing phosphorus from wastewater and its future use as fertilizer ( ). Water Research 38, [4] Gupta, V.K., Gupta, M., Sharma, S., 21. Process development for the removal of lead and chromium from aqueous solutions using red mud-an aluminum industry waste, Water Res. 35(5), [5] Liu, W., Zhang, X., Jiang, W., 211, Study on particle- size separation pretreatment of Bayer red mud, Chin. J. Environ. Eng, 5, pp [6] Miroslav KYNCL, 28, Opportunities For Water Treatment Sludge Re-Use. Volume LIV, No.1, GeoScience Engineering, ISSN , pp [7] Moldan, B., 199, Životníprostředí Českérepubliky. 1.vydání. Praha: Academia, 228 s. ISBN (Environment of the Czech Republic). [8] Relyea, J.F., 1982, Theoretical and experimental considerations for the use of the column method for determining retardation factors, Radioactive Waste Management and the Nuclear Fuel Cycle 3, No. 2: pp [9] Rodhan Abdullah Salih. Evaluation of the Drinking Water Quality and the Efficiency of Al-Hawija Water Treatment Plant: A Case Study in Iraq. International Journal of Civil Engineering and Technology, 5(6), 215, pp [1] Kadhim Naief Kadhim Al-Taee, Thair Jabbar Mizhir Al-Fatlawi and Zainab Falah Hussein Al-Barrak. Lowering Groundwater in the Archaelogical Babylon City Using Underground Dams. International Journal of Civil Engineering and Technology, 6(4), 215, pp editor@iaeme.com