Removal of Ammonium and Phosphate from Fertilizer Industry Wastewater Using Struvite Precipitation Method

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1 J. Appl. Environ. Biol. Sci., 7(2) , , TextRoad Publication ISSN: Journal of Applied Environmental and Biological Sciences Removal of Ammonium and Phosphate from Fertilizer Industry Wastewater Using Struvite Precipitation Method Nurani Ikhlas* and Warmadewanthi Department of Environmental Engineering, Faculty of Civil Engineering and Planning, Sepuluh NopemberInstitute of Technology (ITS) Surabaya, 6111, Indonesia ABSTRACT Received: October 1, 216 Accepted: December 24, 216 This research investigated the effect of and molar ratio [Mg 2+ ]:[NH 4+ ]:[PO4 ]on struvite precipitation method for wastewater treatment from fertilizer industry. Struvite precipitation conducted in batch reactors, MgCl 2 as precipitant and mechanically agitated for 158 rpm. Results show that optimum is 9 and molar ratio [Mg 2+ ]:[NH 4+ ]:[PO4 ] optimum is molar ratio of 3:1:1 with removal efficiency of ammonium and phosphate reached 99%. KEYWORDS: ammonium, molar ratio,, phosphate, struvite INTRODUCTION Wastewater from fertilizer industry has contribution to water pollution because of high concentration of ammonium and phosphate.pt Petrokimia Gresik is one of fertilizer industry which has done to treat wastewater both in physic and chemical using precipitation method. This kind of treatment is not optimum because residual levels of phosphate and ammonia in wastewater treatment effluent exceeding quality standard effluent treatment [1]. High concentration of ammonium and phosphate was produced in wastewater treatment.the concentration of ammonium and phosphate from Production Unit I and III are mg/l and mg/l [1]. Struvite precipitation is white crystal consist of magnesium, ammonium, and phosphate in same molar concentration [2] and was used to supply Mgwhich act as an agent of precipitant.mgcl 2 has been used because of good solubility and more effective precipitation process[3]. Another parameter that must be considered onstruvite precipitation are, molar ratio [Mg 2+ ]:[NH 4+ ]:[PO4 ] [2]. Increasing the from 8 to 1 can increase 8-9%phosphate allowance. Research conducted by Anggrainy et al. [4]with a variation of 7, 8, and 9 for 15 minutes while stirring with a stirring speed of 1 rpm can be set aside phosphate reaches 91%.Another factor that can influence struvite precipitation is molar ratio of Mg 2+ : NH 4+ : PO 4 [5]. Based on Pratama[1] researchoptimal precipitation occurs at a molar ratio [Mg 2+ ]: [NH 4 + ]: [PO 4 ] 2: 1: 1.Total 3.74% and 99.75%ammonium phosphate can be excluded with a stirring speed of 2 rpm. MATERIALS AND METHODS Wastewater used in the research was mixed from wastewater treatment plant (Point L) and Production Unit III PT Petrokimia Gresik. Wastewater from Production Unit III as phosphate source mixed with wastewater from inlet of wastewater treatment plant (Point L) in order to get molar ratio [NH 4+ ]:[PO 4 ] which is desired 1:1. The next step is prediction of variation, molar ratio [Mg 2+ ]:[NH 4 + ]:[PO 4 ]using Visual MINTEQ application (version 3.). Table 1 Wastewater Treatment Characteristics Parameter Method Results SNI Magnesium AAS mg/l Phosphate Tin Chloride mg/l Ammonium Nessler mg/l Silicate Molybdosilicate Method mg/l Calcium Titrimetri EDTA 576. mg/l Fluoride SPADNS 1.28 mg/l Turbidity Turbidity meter 59.7 NTU Table 1 shows that the results of mixed wastewater obtained concentration of phosphate and ammonium were mg/l and mg/l with molar ratio [NH 4+ ]:[PO 4 ] 1:1.6. Molar ratio [Mg 2+ ]: [NH 4+ ]:[PO 4 ] *Corresponding author: Nurani Ikhlas, Department of Environmental Engineering, Faculty of Civil Engineering and Planning, Sepuluh Nopember Institute of Technology, Surabaya, 6111, Indonesia. nurani.ikhlas@gmail.com 158

2 Ikhlas and Warmadewanthi, 217 and prediction used Visual MINTEQ (version 3.) application (US Environmental Protection Agency). Variation of values between 7 to 1 with increase.5. Data was entered in Visual MINTEQ and taken 3 variation values of optimum results as variable. Molar ratio was using 3 optimum results values from molar ratio[mg 2+ ]:[NH 4+ ]:[PO 4 ] 1:1:1 to 5:1:1 and the amount increase molar Mg 2+ was 1. Whereas for gradients agitated speed was determined from previous research Fitriana, 216 [6] by using 158 rpm and agitating duration was 6 minutes to remove ammonium and phosphate from PTPetrokimia Gresik wastewater Production Unit II and III with struvite precipitation. Variation of was chosen from optimum in the results of Visual MINTEQ application model. Adjustment of is done by adding crystals caustic soda or H 2SO 44N. This research varying magnesium in molar ratio[mg 2+ ]:[NH 4+ ]:[PO 4 ] with magnesium based on ammonium and phosphate concentration based on ammonium existing in wastewater. Magnesium are coming frommgcl 2 and phosphate taken from wastewater in PT Petrokimia Gresik Production Unit III. Based on Fitriana, 216[6] research, if magnesium ratio was increased, the amount of Mg 2+ which bonded with PO 4 is also increased so phosphate removal ability will be higher. The main research consist of research implementation and parametersmeasurement. Explanation of each steps is as follows. a. Implementation of research Precipitation processes are using batch reactor. MgCl 2 precipitant was added to.5 L wastewater according with the variation of molar ratio which has been set. The solution was adjusted to added crystals caustic soda or H 2SO 4 4N and homogenized. The solution was stirred by using jartest in 158 rpm for 6 minutes and allowed to stand for 3 minutes to sedimentation process. b. Measurement of parameters Parameters tested are ammonium, phosphate, Si 2+, Ca 2+, and F -. The measurement of was using meter, Ca 2+ concentration using AAS instrument according to APHA standard method, 198 [7], Si 2+ concentration using Molybdosilicate method, whereas F - was using SPADNS method. The measurement of ammonium and phosphate was using Nessler method and Tin Chloride method. Precipitate analysis that has been conducted are composition analysis, morphology, and structure. Precipitate (struvite) composition analysis was conducted with the following steps. Precipitate was separated from supernatant with a filter by using Watman filter paper then was dried in room temperature for 48 hours [3] and be pondered until getting constant weight. The drying process was using oven because it would causes the structure of precipitate changed effect due to evaporation effect of ammonium bonds or hydrate[6]. Precipitate analysis was conducted by using SEM-EDX in Integrated Central Laboratory Diponegoro University Semarang. EDX analysis was usedfor determining the micro analysis elements forming precipitate. RESULTS AND DISCUSSION a. Results Prediction on and Molar Ratio [Mg 2+ ]:[NH 4+ ]:[PO 4 ] Variation Prediction of and molar ratio [Mg 2+ ]:[NH 4+ ]:[PO 4 ] variation was using Visual MINTEQ v3. application and determined by looking precipitate prediction. This prediction was conducted with entering value range 7-1 and ratio [Mg 2+ ]:[NH 4+ ]:[PO 4 ] with increase.5. Data input consist of magnesium concentration, ammonium, and phosphate according to molar ratio [Mg 2+ ]:[NH 4 + ]:[PO 4 ] in range 1:1:1-5:1:1.Ions impurities concentration such as calcium, silicate, and fluoride was also added with wastewater. The results of precipitate prediction will be considered for determining variation that used in this research. Based on precipitate prediction, determination of variation in this research were 8, 9, and 1 because more struvite formed when 8 and 9 than 7 and 7.5. The determination of 1 was because the highest struvite content formed at 1. Basically in alkaline condition,precipitate were found in many forms such as brucite (Mg(OH) 2), hydroxyapatite (Ca 1(PO 4) 6(OH) 2), chrysotile (Mg 3(Si 2O 5)(OH) 4), sepiolite (Mg 4(Si 6O 15)(OH) 4), and cristobalite. Precipitates could be formed because of Ca 2+, Si 2+, F - presence in wastewater existing that was included in modelling due to determine ions impurities effect on struvite formation. Precipitate prediction was used to determine variation in this research. Molar ratio [Mg 2+ ]:[NH 4+ ]:[PO 4 ] that has been selected were molar ratio 1:1:1, 2:1:1, and 3:1:1.Molar ratio 4:1:1 and 5:1:1 unselected because there were brucite and hydroxyapatite precipitate which can damage struvite structure and need more magnesium sources (MgCl 2). b. Determination of and Molar Ratio Optimum on Struvite Precipitation MgCl 2 addition as magnesium source for molar ratio [Mg 2+ ]:[NH 4+ ]:[PO 43 ] 1:1:1, 2:1:1, and 3:1:1was used because it has highest solubility and more effective precipitation [3]. Acidity or was precipitation factor and an important role in struvite precipitate. The range for forming struvite was [8]. 159

3 J. Appl. Environ. Biol. Sci., 7(2) , Residual ammonium modelling (mg/l) 8, 8,5 9, 9,5 1, 4 Figure 1: Effect of in Molar Ratio 1:1:1 4 Residual ammonium modelling (mg/l) 4 8, 8,5 9, 9,5 1, Figure 2: Effect of in Molar Ratio 2:1:1 4 Residual ammonium modelling(mg/l) 4 8, 8,5 9, 9,5 1, Figure 3: Effect of in Molar Ratio 3:1:1 16

4 Ikhlas and Warmadewanthi, 217 Figure 1 to 3 shows that can affect in decrease of phosphate concentration [9]. The results in 8 to 9 was decreased phosphate concentration in molar ratio [Mg 2+ ]:[NH 4+ ]:[PO 4 ]. The highest decreasing value of phosphate concentration in 9 was 4.26 mg/l from mg/l of initial concentration with 99.9% of removal efficiency. Kim et al., 27 [1] research indicated the highest removal efficiency of phosphate in precipitate occurs to 9.The results shows that the highest efficiency in 9. However, 1 decreased phosphate concentration because decreasing of ions activity[3], furthermore there was another factors such as the presence of interfering ions decreasing phosphate removal. Effect of against ammonium residual indicates that higher value, higher decreasing ammonium value. Figure 3 shows that 8 to 1 has ammonium residual 7.81 mg/l from initial concentration mg/l with removal efficiency was 99.9%. That caused partial of ammonium have been volatilization. The higher value could move ammonium equilibrium to be ammonia aqueous (NH 3(aq)) which was volatile [11]. Based on Figure 1, 2, and 3 indicated the influence of molar ratio variation [Mg 2+ ]:[NH 4+ ]:[PO 4 ] were ratio 1:1:1, 2:1:1, and 3:1:1. Molar ratio variation conducted by varying magnesium concentration which was MgCl 2 addition. MgCl 2act as magnesium sources. MgCl 2requirementformolar ratio variation 1:1:1, 2:1:1, and 3:1:1 are 3.6 gram, 7.92 gram, and gram. The results from phosphate and ammonium residual in 9 as optimum with molar ratio [Mg 2+ ]:[NH 4+ ]:[PO 4 ] 1:1:1, 2:1:1, and 3:1:1 was compared with the result of modelling phosphate and ammonium removal to determined optimum molar ratio. Based on optimum condition ( 9) occurred significant decrease with molar ratio [Mg 2+ ]:[NH 4+ ]:[PO 43 ] 3:1:1. It caused molar ratio greater so phosphate percentage will increase [6]. This research shows that the highest percentage phosphate removal in 9 with molar ratio [Mg 2+ ]:[NH 4+ ]:[PO 4 ] 3:1:1 was 99.9% that indicated 9 as optimum and ratio 3:1:1 was optimum. Molar ratio Mg 2+ addition could increasing phosphate removal efficiency, its according from the results Warmadewanthi and Liu [3] that phosphate removal efficiency could increase along with increasing molar ratio. c. Struvite and Mineral Impurities Identification Using SEM-EDX Analysis Scanning Electron Microscope (SEM) was conducted to determine morphology characteristic and crystals structure. Energy Dispersive X-ray Spectroscopy (EDX) was conducted to determine the chemical components contained in crystals. Analysis were performed at the Integrated Central Laboratory of Diponegoro University in Semarang. SEM analysis performed with magnification of x. According to Liu et al. [12] forms of struvite crystals can be prismatic, pyramid, needle, tapered, and irregular. Figure 4 shows SEM results from the control sample (ratio [Mg 2+ ]: [NH 4+ ]: [PO 4 ] optimum 3: 1: 1 with a of 9 elliptical-shaped crystals). Figure 4. Sampel Struvite Crystal in Ratio[Mg 2+ ]:[NH4 + ]:[PO4 ] 3:1:1 Figure 5. EDX Microanalys in Ratio[Mg 2+ ]:[NH4 + ]:[PO4 ] 3:1:1 Figure 4 and 5 shows that some ion impurities contained in precipitates: calcium, fluoride, Na, Cl, and silicate. Na ions can be foundin precipitates because caustic soda crystals in precipitates lead to value raise. While Cl ions from magnesium sources used in the form of MgCl 2.Struvite crystals formed into a long round with a rough surface due impurity ions contained in the wastewater causes damage to struvitesurface. 161

5 J. Appl. Environ. Biol. Sci., 7(2) , 217 CONCLUSION Result showsthat optimum is on 9 with 4.25 mg/l phosphate residual and mg/l ammonium residual using MgCl 2precipitant (magnesium sources). Molar ratio [Mg 2+ ]:[NH 4+ ]:[PO 4 ]optimum on ratio 3: 1: 1 with 99.9% of phosphate removal efficiency reached.struvite precipitation in the sample molar ratio [Mg 2+ ]:[NH 4 + ]:[PO 4 ]3: 1: 1 had a crystal form elliptical but had impurities that damage the surface of struvite. REFERENCES [1] Pratama, R.R.P. Recovery of ammonium and phosphate from PT Petrokimia Gresik wastewater using magnesium addition. Environmental Engineering. Surabaya [2] Khai, N. M. and Hoang, T. Q. T. Chemical precipitation of ammonia and phosphate from Nam Son landfill leachate, Hanoi.Iranica Journal of Energy & Environment 3 (Special Issue on Environmental Technology) ; [3] Warmadewanthi and Liu, J.C.. Recovery of phosphate and ammonium as struvite from semiconductor wastewater. Separation and Purification Technology ; [4] Anggrainy, A. D., Bagastyo, A. Y., and Hermana, Joni. Effect of and stirring speed crystallization process against low phosphate concentrate in wastewater. National ConferencesEnvironmental Engineering XI [5] Kumar, R. and Pal, P. Turning Hazardous Waste into Value Added Products: Production and Characteristization of Struvite Ammonical Waste with New Approaches. Journal of Cleaner Production ;14;59-7. [6] Fitriana, Rodliya. Removal of ammonium and phosphate from wastewater from production unit II and III of PT Petrokimia Gresik with precipitation struvite method. Environmental Engineering. Surabaya [7] APHA. Standards Methods for the Examination of water and wastewater. 2th ed. APHA, AWWA, WPCF, American Public Health Association. Washington DC [8] Bowers, K. E. Development of a Struvite crystallizer for reducing phosphorus in effluent from livestock waste lagoons. PhD. North Carolina State University. 24. [9] Su udi, Misbahul. Removal of phosphate from PT Petrokimia Gresik wastewater using gypsum waste. Environmental Engineering. Surabaya [1] Kim, D., Kim, J., Ryu, H.-D., and Lee, S.-I. Effect of mixing on spontaneous struvite precipitation from semiconductor wastewater. Journal of Bioresource Technology. 27 b. 1; [11] Chimenos, J. M., Fernandez, A. I., Hernandez, A., Haurie, L., Espiell, F., and Ayora, C. Optimization of phosphate removal in anodizing aluminium wastewater. Water Research ; [12] Liu b., Giannis A., Zhang J., Chang V., and Wang JY. Characterization of induced Struvite formation from source-separated urine using seawater and brine as magnesium sources. Journal of Chemosphere ;