BACKGROUND High SO42‐, COD, and nitrogen‐containing wastewater treatment requires different bacterial groups and environmental conditions, which can be achieved by sequential separate processes. This study examined the simultaneous removal of SO42‐, COD and nitrogen in a four‐compartment ABR, which allowed enrichment of different group of bacteria in each compartment. Feed COD and SO42‐ concentrations were kept constant at 1200 and 1500 mg L‐1, corresponding to COD/SO4‐2 ratio of 0.8. Initially, ABR was tested at varying influent ammonium concentrations (25–1500 mg NH4+‐N/L). Further, the third compartment of ABR was supplemented with nitrate under varying loading rates (60–300 mgNO3‐N L‐1 d‐1) for autotrophic denitrification with the sulfide produced in the previous compartments. This kind of application mimicked the internal recirculation of nitrate, which can be generated via nitrification of ABR effluent. RESULTS High sulfate reduction efficiencies (over 86%) were observed up to 1000 mg L‐1 NH4+‐N, however, 1500 mg L‐1 NH4+‐N caused decrease in reduction efficiency. Optimum nitrate loading rate was determined as 146 mgNO3‐N L‐1 d‐1 at molar N/S ratio of 0.42, corresponding with 100% nitrate, 83% sulfate, and 79% COD removals. Nitrate removal decreased at higher nitrate loadings and high sulfate generation arising from sulfide oxidation was observed. CONCLUSION Sulfate and COD removals together with efficient sulfide‐based autotrophic denitrification succeeded in a single reactor configuration at S/N ratio of 0.42. The developed process has the potential to be used in lab‐scale applications. © 2017 Society of Chemical Industry

The aim of this study was to investigate the applicability of Fenton process and combined ozone/Fenton process to remove color, soluble chemical oxygen demand (CODs), phenol, and dissolved organic carbon (DOC) from real olive mill wastewater (OMW). The treatability of OMW was investigated in three different study parts. Initially, Fenton process was optimized under varying H2O2/Fe 2+ molar ratios ranging between 10 and 20 at the constant H2O2 concentration of 0.5 mM. The H2O2/Fe 2+ molar ratio of 10 was found optimum providing high color (51.6 %), CODs (58%), DOC (27.9%) and phenol removals (93.9%). Further, combined ozone/Fenton process was applied under gradually increasing dosages of Fe 2+ and H2O2 reagents at constant H2O2/Fe 2+ molar ratio of 10. The high color removal efficiency (51.6% color removal for Pt-Co) was obtained at the H2O2 and Fe 2+ molar ratio of 0.5/0.05. Additionally, CODs, color, DOC and phenol removal efficiencies improved at increasing reagents concentrations. However, the color removal efficiency was adversely affected while no significant difference on CODs and phenol removal was observed at higher concentrations of molar concentrations above 0.5/0.05. Additionally, the results indicated that combined process enhanced treatment performance of OMW by 21%, 49% and 22% in terms of color, DOC and CODs removals, respectively, compared to only-Fenton process. In the rest of this study, combined ozone/Fenton process was optimized under varying ozonation time (60-120 min) at the optimum H2O2 and Fe 2+ molar dosage of 0.5/0.05 obtained from previous parts. Ozonation time significantly affected the treatment performance, and optimum the reaction time was determined as 90 minute in terms of the high treatment productivity and low operating cost resulted from minimum ozone consumption and short reaction time.

No abstract

Landfill leachates are complex wastewater which has high pollution and their biological degradability is also difficult. Landfill leachate with high concentrations of contaminants must be pretreated. For this reason, the ammonium stripping process is an effective method for ammonium removal, especially for landfill leachate. With the ammonium stripping process, the ammonium and organic matter removal increases. This study aimed to investigate the applicability of the ammonium stripping process as remove ammonium (NH4 + ) and chemical oxygen demand (COD) from raw leachate. A new system has been designed which is called ammonium stripping tower. During this study, the ammonium stripping process was operated temperature (30-40-60 o C), aeration rate (HH, HL, LL m 3 air/min), and hydraulic retention times (6-12-24-48 h). System performance was evaluated by ammonium, and COD parameters. The optimum conditions of the ammonium stripping process were determined at 60 0 C temperature, HH(1m 3 air/min aeration rate), and hydraulic retention time (48h). The corresponding ammonium and COD removal efficiencies were about 88% and 79% respectively. The results of this study suggest that the use of an ammonium stripping process is an effective way to remove ammonium and COD concentration from raw landfill leachate.

No abstract