OPTIMIZATION OF STRUVITE PRECIPITATION IN POULTRY SLAUGHTERHOUSE EFFLUENT

SIENG, SREYVICH, Chandra Wahyu Purnomo, S.T., M.E., M.Eng., D.Eng.; Himawan Tri Bayu Murti Petrus, S.T., M.Eng., D.Eng.

2019 | Tesis | MAGISTER TEKNIK KIMIA

Due to population rapid growth, fertilizer industries have to increase the production to ensure food security causing faster non-renewable resource depletion. However, organic wastewater (cow urine) commonly contains high amount in NH4+ and PO43- is still underutilized and causing eutrophication and unpleasant odour problem. Struvite precipitation, a common technique using for nitrogen and phosphorus recovery from wastewater, is proposed to recover the organic and renewable nutrients sources. Struvite precipitation process for nutrients recovery/removal from waste sources is beneficial not only providing slow-releasing and high-quality fertilizer but also reducing soil and water pollution from rich-nutrients wastewater. This research aimed to utilize the cow urine wastes as the raw material for the struvite precipitation, to determine the influence of the PO43-: Mg2+ concentration, and input flowrate on a continuous reactor to the struvite formation. Struvite was made using continuous method with variation of the PO43-: Mg2+ concentrations ratio of 1:1; 1:2 and 1:4 and the inlet flowrate of 8.2 mL/s and 15.8 mL/s. The results of this study show that the increase of MgCl2 addition and the higher flow rate could increase the P removal efficiency of struvite in reactors. The optimum phosphate removal efficiency at the flow rate of 8.2 mL/s is obtained at 80 mins with the percentage of 54%, while at the flow rate of 15.8 mL/s, 43% of P removal is obtained at 70 mins. The results from the kinetic study in the input flowrate was found that the higher the concentration ratio of PO43- and Mg2+, the greater the value of the reaction rate constant. However, for molar ratio 1:1 of PO43-: Mg2+, the greater the input flow rate, the smaller value of the reaction rate constant was obtained. From this study, it is revealed that the molar ratio of PO43-: Mg2+ and aeration rate affect significantly the struvite precipitation.

Due to population rapid growth, fertilizer industries have to increase the production to ensure food security causing faster non-renewable resource depletion. Poultry slaughterhouse wastewater (PSW) commonly contains high amount in NH4+ and PO43- is still underutilized and causing eutrophication and unpleasant odor problem. Struvite precipitation, a common technique using for nitrogen and phosphorus recovery from wastewater, is proposed to recover the organic and renewable nutrients sources. The precipitation process is formed based on the equimolecular concentration of Mg2+, NH4+ and PO43- at a slightly alkaline condition. Three parameters in struvite precipitation will be observed in this study which are pH, temperature, and PO43-/Mg2+ molar ratio to determine the optimum conditions of struvite precipitates from PSW. Struvite precipitation process for nutrients recovery from waste sources is beneficial not only providing slow-releasing and high-quality fertilizer but also reducing soil and water pollution from rich-nutrients wastewater. The highest nutrient removal efficiency set up can be obtained by PO43-/Mg2+ ratio of 1:3, pH at 9; and temperature at 30�. However, the result of kinetics study is quite different due to the different conditions. As obtained by the simulation, the reaction rates for pH at 7.5 is 0.0408 L2/mol2.s, the 1:3 of PO43-/Mg2+ molar ratio provided the reaction rate 0.2961 L2/mol2.s and at the temperature of 40� provided 0.0541 L2/mol2.s. The obtained powder of struvite has been successfully confirmed by X-Ray diffraction (XRD) with expected impurity of MgCl2 due to the excess usage during struvite precipitation. In conclusion, the parameters such as pH, temperature and PO43-/Mg2+ molar ratio are affecting the removal efficiency of nutrients in wastewater and also the kinetic of struvite formation.

Kata Kunci : Struvite precipitation, removal efficiency, nutrients, kinetic study, and reaction rate constant.