Recovery Fosfat dari Limbah Cair Industri Pupuk Menggunakan Teknik Presipitasi dan Penambahan Aerasi

Iswarani, Widya Prihesti (2018) Recovery Fosfat dari Limbah Cair Industri Pupuk Menggunakan Teknik Presipitasi dan Penambahan Aerasi. Undergraduate thesis, Institut Teknologi Sepuluh Nopember.

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Abstract

Limbah cair PT Petrokimia Gresik yang mengandung fosfat dan amonium dengan konsentrasi tinggi dapat diolah menggunakan teknik presipitasi untuk mendapatkan struvite. Struvite adalah pupuk yang dapat menjadi sumber alternatif pupuk fosfat. Struvite terbentuk apabila larutan yang mengandung ion-ion fosfat bereaksi dengan magnesium dan amonium dalam kondisi alkali. Tujuan dari penelitian ini adalah menentukan kemampuan teknik presipitasi dan penambahan aerasi untuk recovery fosfat dalam bentuk struvite, menentukan laju aerasi optimum pada recovery fosfat, dan menganalisis pengaruh laju aerasi terhadap pH dan rasio molar [Mg2+]:[NH4+]:[PO43-] optimum pada pembentukan struvite. Nilai variasi laju aerasi akan disesuaikan dengan pH optimum hasil permodelan dengan mengacu hasil penelitian terdahulu. Variasi pH dan rasio molar [Mg2+]:[NH4+]:[PO43-] dipilih berdasarkan permodelan menggunakan aplikasi PHREEQC. Laju aerasi yang digunakan adalah 4, 16, dan 32 LL-1min-1 untuk mencapai pH 8; 8,5; dan 9. Rasio molar yang digunakan adalah 1,5:15:1; 2:15:1; 2,5:15:1; dan 3:15:1 dengan presipitan MgCl2. Pengoperasian reaktor dilakukan dengan sistem batch. Sampel akan diaerasi menggunakan aerator air pump hingga tercapai pH optimum sesuai hasil permodelan. Running presipitasi dilakukan dengan kecepatan pengadukan 158 rpm selama 60 menit dan dilanjutkan dengan sedimentasi selama 30 menit. Selama proses presipitasi berlangsung, pH akan terus dipantau menggunakan pH meter. Parameter yang diuji adalah pH, residual amonium, residual fosfat, DO, dan karakteristik presipitat menggunakan SEM, EDX, dan XRD. Hasil penelitian menunjukkan bahwa teknik presipitasi dapat digunakan untuk recovery fosfat dan penambahan aerasi dapat meningkatkan pH hingga mendekati pH optimum presipitasi struvite. Laju aerasi optimum pada recovery fosfat adalah 16 LL-1min-1. Recovery fosfat yang diperoleh dari teknik ini adalah 99,9%. Pada laju aerasi optimum, maka pH yang dapat dicapai adalah 8,5±0,2 dengan rasio molar [Mg2+]:[NH4+]:[PO43-] untuk pembentukan struvite optimum adalah 1,5:15:1. Konsentrasi awal amonium adalah 12.282,60 mg/L dan residual amonium adalah 8.215,28 mg/L. Konsentrasi awal fosfat adalah 4.180,33 mg/L dan residual fosfat adalah 1,90 mg/L. Analisis SEM-EDX menunjukkan presipitat berbentuk batang panjang dengan unsur utama penyusun berupa Mg, P, N, dan O. Hasil analisis XRD yang dicocokan dengan aplikasi Match! menunjukkan bahwa presipitat yang terbentuk adalah struvite yang memiliki rumus kimia MgNH4PO4.6H2O. ====== PT Petrokimia Gresik wastewater contains high amount of phosphate and ammonium which make it feasible to be treated with precipitation technology to form struvite. Struvite is an alternative source for phosphate fertilizer. Struvite is formed when solution containing phosphate ions reacts with magnesium and ammonium within alkaline condition. The aims of this research were to determine the ability of precipitation and aeration techniques to recover phosphate in the form of struvite, to determine the optimum aeration flow rate on phosphate recovery, and to analyze the effects of aeration flow rate on the optimum pH and molar ratio of [Mg2+]:[NH4+]:[PO43-] in the formation of struvite. Variations of aeration flow rate were adjusted with the optimum pH which were obtained from modelling and referring to the previous research. Variations of pH and molar ratio of [Mg2+]:[NH4+]:[PO43-] were chosen from modelling using PHREEQC. Aeration flow rates were 4, 16, and 32 LL-1min-1 to raise the pH until 8; 8,5; and 9. Molar ratio variations of [Mg2+]:[NH4+]:[PO43-] were 1,5:15:1; 2:15:1; 2,5:15:1; and 3:15:1 with precipitating agent of MgCl2. Reactors were operated in batch system. Samples were aerated using air pump aerator until it reached the optimum pH according to the modeling result. The precipitation was performed at a mixing rate of 158 rpm for 60 minutes and continued with 30 minutes for sedimentation. During the precipitation process, pH was monitored continuously using pH meter. The parameters observed on this study were pH, residual of ammonium, residual of phosphate, DO, and the characteristics of precipitates using SEM, EDX, and XRD. Results of this experiment showed that precipitation technique was capable to recover phosphate and aeration was capable to raise the pH near the optimum pH of struvite precipitation. The optimum aeration flow rate was 16 LL-1min-1. The percentage of phosphate recovery was 99,9%. Over the optimum aeration flow rate, the optimum pH was 8,5±0,2 and molar ratio of [Mg2+]:[NH4+]:[PO43-] to form struvite was 1,5:15:1. Initial concentration of ammonium was 12.282,60 mg/L and residual of ammonium was 8.215,28 mg/L. Initial concentration of phosphate was 4.180,33 mg/L and residual of phosphate was 1,90 mg/L. SEM-EDX analysis showed that the precipitates were long and rod-alike with the main component of Mg, P, N, and O. XRD analysis which was matched with Match! software showed that the precipitate formed was struvite with the chemical formula of MgNH4PO4.6H2O.

Item Type: Thesis (Undergraduate)
Additional Information: RSL Isw r
Uncontrolled Keywords: aerasi, amonium, fosfat, presipitasi, struvite
Subjects: T Technology > TD Environmental technology. Sanitary engineering > TD646 Sewage--Purification
T Technology > TP Chemical technology > TP156 Crystallization. Extraction (Chemistry). Fermentation. Distillation
Divisions: Faculty of Civil Engineering and Planning > Environment Engineering > (S1) Undergraduate Theses
Depositing User: Widya Prihesti Iswarani
Date Deposited: 05 Mar 2018 04:23
Last Modified: 05 Mar 2018 04:23
URI: http://repository.its.ac.id/id/eprint/49844

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