Tereftalik asit fabrikası atıksularının arıtılmasında ileri oksidasyon ve yeni biyolojik yöntemlerin uygulanması

In this study, treatment of terephthalic acid wastewater by various advanced oxidation methods and biological oxidation using walnut shells based catalysts has been studied. The target compounds to represent terephthalic acid wastewater were selected as terephthalic acid (TPA), benzoic acid (BA) and p-toluic acid (p-Tol). Degradation of BA by various advanced oxidation methods such as Fenton-like oxidation, catalytic wet air oxidation, photocatalytic oxidation, photo-Fenton-like oxidation and by biological oxidation was investigated. Degradation of terephthalic acid and p-toluic acid by photocatalytic and photo-Fenton-like oxidation were also investigated. The first part was preparation and characterization of metal doped walnut shells based catalysts. Iron (Fe) or iron-titanium dioxide (Fe-TiO2 (1:99)) with a weight ratio of 10 % were doped to the activated carbon (AC) prepared from walnut shells by physical and different chemical activation methods such as acidic, neutral and basic activation. After metal doping Fe/AC and Fe-TiO2/AC catalysts were obtained. In the second part of the study, first catalyst screening experiments were performed to each target compound for methods applied to determine the most efficient catalyst. Then parametric studies were performed to determine optimum values of operating conditions. Initial concentration was kept constant as 50 mg/L for each target compound. For benzoic acid, neutral Fe-TiO2/AC catalyst was selected for photocatalytic and photo-Fenton-like oxidation and highest degradation efficiency for BA, % 95 degradation was accomplished by photo-Fenton-like oxidation in 80 minutes at optimum operating conditions. For terephthalic acid, neutral Fe-TiO2/AC catalyst was determined from catalyst screening experiments for photocatalytic and photo-Fenton-like oxidation and highest degradation efficiency for TPA in the presence of this catalyst was accomplished with a degradation efficiency of 90 % in 120 minutes at optimum operating conditions. For p-toluic acid, neutral Fe-TiO2/AC catalyst same as other target compounds was determined for photocatalytic and photo-Fenton-like oxidation. Highest degradation efficiency for p-Tol in the presence of this catalyst was accomplished with a degradation efficiency of 70 % in 60 minutes at optimum operating conditions. In the third part of the study, biological oxidation of benzoic acid in the presence of biocatalysts based on walnut shells was investigated. P.chrysosporium and T.versicolor were selected as microorganisms and immobilized on walnut shells. P.chrysosporium immobilized on walnut shells were determined as more successful in biocatalyst screening experiments and in presence of this biocatalyst, up to 90 % degradation was achieved at optimum conditions in 4 days. As a conclusion, neutral and basic activation were considered as more successful than physical and acidic activation based on catalytic performances. Photocatalytic oxidation and photo-Fenton-like oxidations were determined as the most promising methods with higher degradation efficiencies and degradation rates for all target compounds. Comparing biological oxidation, photocatalytic oxidation, and photo-Fenton-like oxidation of BA in which highest degradation efficiencies were obtained for BA, the same degradation efficiency (90–95 %) was achieved in two hours by photocatalytic oxidation and photo-Fenton-like oxidation where it was achieved in four days by biological oxidation.