Optimizing Aeration Rates for Minimizing Membrane Fouling and Its Effect on Sludge Characteristics in a Moving Bed Membrane Bioreactor
Authors: Yousef Rahimi, Ali Torabian, Naser Mehrdadi, Mehran Habibi-Rezaie, Hamid Pezeshk, Gholam-Reza Nabi-Bidhendi
Journal of Hazardous Materials (2010), doi:10.1016/j.jhazmat.2010.11.117
In MBR processes, sufficient aeration is necessary to maintain sustainable flux and to retard membrane fouling. Membrane permeability, sludge characteristics, nutrient removal and biomass growth at various air flow rates in the membrane and moving bed biofilm reactor (MBBR) compartments were studied in a pilot plant. The highest nitrogen and phosphorous removal rates were found at MBBR aeration rates of 151 & 85 L∙h-1 and a specific aeration demand per membrane area (SADm) of 1.2 & 0.4 m3air∙m-2∙h-1 respectively. A linear correlation was found between the amount of attached biofilm and the nutrient removal rate. The aeration rate in the MBBR compartment and SADm significantly influenced the sludge characteristics and membrane permeability. The optimum combination of the aeration rate in the MBBR compartment and SADm were 151 L∙h-1 and 0.8-1.2m3air∙m-2membrane∙h-1, respectively.
Simultaneous nitrification–denitrification and phosphorus removal in a fixed bed sequencing batch reactor (FBSBR)
Authors: Yousef Rahimi, Ali Torabian, Naser Mehrdadi, Behzad Shahmoradi
Journal of Hazardous Materials 185 (2011) 852–857
Biological nutrient removal (BNR) was investigated in a fixed bed sequencing batch reactor (FBSBR) in which instead of activated sludge polypropylene carriers were used. The FBSBR performance on carbon and nitrogen removal at different loading rates was significant. COD, TN, and phosphorus removal efficiencies were at range of 90–96%, 60–88%, and 76–90% respectively while these values at SBR reactor were 85–95%, 38–60%, and 20–79% respectively. These results show that the simultaneous nitrification–denitrification (SND) is significantly higher than conventional SBR reactor. The higher total phosphorus (TP) removal in FBSBR correlates with oxygen gradient in biofilm layer. The influence of fixed media on biomass production yield was assessed by monitoring the MLSS concentrations versus COD removal for both reactors and results revealed that the sludge production yield (Yobs) is significantly less in FBSBR reactors compared with SBR reactor. The FBSBR was more efficient in SND and phosphorus removal. Moreover, it produced less excess sludge but higher in nutrient content and stabilization ratio (less VSS/TSS ratio).
Assessment and Upgrading of Khoy Wastewater Treatment Plant
Authors: Amir Hossein Mahvi, YousefRahimi and A.R. Mesdaghinia
Pakistan Journal of Biological Sciences 9 (7): 1276-1281,2006
This research contains assessment and analysis of the operation data for 30 months, analysis of 540 checklists results to determine design parameters, redesigning the WWTP to determine the problem agents and upgrading requirements, designing the various processes for upgrading and evaluating them by multicriteria decision and selecting the most proper alternative. The results show that the main true design parameters such as BODs and TSS are 50 and 57 g/capita-day, respectively. The water consumption and wastewater production per capita per were 220 and 187, respectively. Using these Design criteria to come up with the best alternative for upgrading of wastewater treatment plant a number of remarks such as: ease of 0 and M, low operational costs, low maintenance costs, low capital costs short implementation period, potential to remove N and P, reliability of performance, innovation, pollution prevention, maximum use of facilities, long useful life and minimal plant disruptions were considered. All of the alternatives were evaluated by multi-criteria decision method. The score earned by various alternatives are: Use of rock filter in maturation pond effluent (-59), Use of micro strainers for filtration the emuent (-38), Dual powered aerated logoon (-65), Activated Sludge with digest and store excess sludge cOlmtercurrent with part of influent wastewater about 8500 m3 day-l in available lagoons (196), Commutation of No. 1 lagoon to aeration tank and built the sedimentation tanks, invert it to extended aeration tank and use the No.2 and 3 lagoons for sludge storing (241), Biolac Process (201), Facultative aerated lagoon in 3 modules (-107). At last the alternative with highest score was selected.
Ev Aluation of Chronological Aspects of Collection and Transportation of Municipal Solid Waste System in Urmia
Authors: A. Jalilzadeh, Iy. Rahimi ,A. Parvaresh
Iran. 1. Environ. Health. Sci. Eng ., 2005. Vol. 1. No.4. pp.167-272
Municipal solid waste (MSW) is a serious environmental hazard and social problem in Iran. Currently a high volume of solid waste is generated every day in the district towns of Iran and unfortunately solid waste management is being deteriorated due to the limited resources to handle the increasing rate of generated waste. Due to this fact that more than 60% of solid waste management cost is usually allocated for purpose collection and transportation of generated solid waste in the city. Analysis of this section and understanding of its effect on the management system could have a great role in reduction the costs and solving many of exist problems. This study illustrate the effectiveness of timing managing an MSW economy and that has been carried out as a case study in Urmia. Results of this research illustrsate that 58.3% in Neisan. 68.7% in Khavar. 61.5% in Benz. 81.3% in Compactor and 59.3% in FAUN Of each cycle time is pickup time. Mean of traveling speed for Van . Mini-truck. Truck. FAUN and Compactor was 35,46,41 ,38 and 42 kilometer per hour respectively. Total spent time for collection and transportation of solid waste were I :21 hour with Van, I :23 hour with Mini-trucck, I :29 hour with Truck, 17 minutes with FAUN and 57 minutes with Compactor. Result of this study illustrated Van is the most economic vehicle for solid waste collection system in Urmia city. Generally, priority to usage of sol id waste collection vehicles illustrate in below: Truck < Mini-truck < Compactor < Van < FAUN