RESUMEN
One of the complete treatment processes for industrial and municipal wastewater treatment is membrane bioreactor process which has dominant potential in process and operation sections. This study was conducted to compare the performance of extended aeration activated sludge [EAAS] with submerged membrane bioreactor [SMBR] systems in the treatment of strength wastewater, in the same condition. The initial activated sludge was brought from the Plascokar Saipa wastewater plant. The Plexiglas reactor with effective volume of 758 L was separated by a baffle into the aeration and secondary sedimentation parts with effective volumes of 433 L and 325 L, respectively. The chemical oxygen demand [COD] concentration of the influent wastewater of the EAAS and SMBR systems were between 500-2700 and 500-5000 mg/L, respectively. Results showed that the SMBR system produced a much better quality effluent than EAAS system in terms of COD, biochemical oxygen demand [BOD5], total suspended solids [TSS] and ammonium. By increasing the COD concentration, the concentration of mixed liquor suspended solids [MLSS] and the removal efficiency of organic matter in the SMBR system, were increased regularly, however the removal efficiency of COD in the EAAS system was irregular. The average BOD5/COD ratio of effluent in the EAAS and SMBR systems were 0.708 +/- 0.18 and 0.537 +/- 0.106, respectively. These show that the organic matters in the effluent of the SMBR system was less degradable and thereupon more biological treatment was achieved. Nitrification process was completely done in the SMBR system while the EAAS system could not achieve to complete nitrification
RESUMEN
Nitrate contamination in drinking water can cause methemoglobinemia, which is especially detrimental to infants and nursing mothers. Batch experiments in two units for catalytic reduction of nitrate from groundwater with Zn catalyst and sulfamic acid were conducted. The system includes chemical denitriphication [ChemDen reactor] and electrolytic recovery reactoers. A batch study was conducted to optimize parameters like pH, sulfamic acid concentration, Zn concentration, temperature and reaction time governing the ChemDen process. The concentrations of remained nitrate and Zn were measured at the end of the reactions. Results showed that near to 100% of nitrate decreased and the quantity of remained nitrate was <1 mg/L. pH and agitation had great effect on denitrification, and the nitrate removal rate changed rapidly when pH value ranged between 3-4. Two water quality parameters which limit this process were sulfate and chloride ions concentrations in nitrate contaminated water
RESUMEN
Advanced oxidation processes such as Fenton reagent generates highly reactive hydroxyl free radicals to oxidize various compounds in the water and wastewater. The efficiency of different Fenton-related oxidative processes such as Fenton, solar-Fenton, UV-Fenton and Fenton reactions in different batch reactors was examined using benzene as pollutant in aqueous solutions. A batch study was conducted to optimize parameters like pH, hydrogen peroxide concentration, temperature, reaction time and ferrous ion concentration governing the Fenton process. The concentrations of produced phenol were measured at the end of the reactions. The role of sequence reaction was tested for decreasing phenol formation during benzene conversion. At optimum conditions, different Fenton-related processes were compared for the degradation of benzene. Increased degradation efficiency was observed in photo-Fenton processes as compared to conventional Fenton process. The formation of phenol in Fenton reaction depended on reaction time, sequence in reaction, purity of hydrogen peroxide and other compounds such as alcohols that contributed into the reaction. In the Fenton process, carboxylic acids like acetic acid and oxalic acid were formed as the end products during the complete degradation of benzene. With the increase in mono-valence, two-valence ions and hardness, Fenton's efficiency decreased, respectively. Sequence Fenton reaction produced less phenol and its end products had smaller COD as compared to conventional Fenton process