Effect of Gas/Water Ratio on the Performance of Combined Cylindrical Anoxic/Aerobic Moving Bed Biofilm Reactors for Biological Nutrients Removal from Domestic Wastewater by Fully Nitrification-Denitrification Processes

Abstract

In this research the continuously up-flow pilot scale Moving Bed Biofilm Reactor (MBBR) which was consists of combined cylindrical anoxic/aerobic MBBR in nested form with anoxic/aerobic volume ratio equal to 0.16 under fully nitrification-denitrification process were used to treated 4 m 3 /day of domestic wastewater in Chongqing city at Southwest China. The treatment must be satisfactory to meet with grade B of discharge standard of pollutants for municipal wastewater treatment plant in China (GB/T18918-2002). Both the anoxic and aerobic reactors were filled to 50% (v/v) with Kaldnes (K1) biofilm carriers to attach and retain biomass. The reactors was operated under fully nitrification-denitrification process without sludge returning into the system and only an internal recycling was performed from aerobic to anoxic reactor. After developing the biofilm on the carriers, the effect of gas/water ratio on biological nutrients removal from domestic wastewater was investigated by operated the reactors under 5 different gas/water ratio ranging from 5/1 to 24/1. During this operation mode, the favorite internal recycle ratio and Hydraulic Residence Time (HRT) to eliminate nitrogen compounds were 100% of inflow rate and 6.2 h, respectively. The experiment results showed that optimum value of the gas/water ratio for simultaneous organic carbon and nutrients removal was equal to 7/1. In this gas/water ratio, the average removal efficiencies were 92.67, 99.12, 71.37 and 90.49% for COD, NH 4 + -N, TN and TP, respectively, while the average Dissolved Oxygen concentration (DO) in aerobic and anoxic MBBRs were 4.49 and 0.16 mg/L, respectively.

Nutrients Removal from Domestic Wastewater in Basrah City (Southern Iraq) using Combined A2/O Bio Contact Oxidation Technology

“…Kaldnes polyethylene media (K1) with density equal to 0.93 g/cm 3 and effective specific area equal to 500 m 2 /m 3 was used in this study in order to achieve attached biofilm process with filling ratio equal to 30% for both anaerobic and anoxic MBBRS, and with filling ratio 50% for aerobic MBBR. Small sized sieve with opening diameter approximately equal to 2 mm was used in order to retain the media elements inside the reactors.…”

“…The head loss is small and there is no need for biomass recycling. There are many researchers interested in studying the technique of MBBR bases to treat different types of wastewater such as fish farming wastewater [25], landfill leachate [26], paper industry wastewater [27], cheese factory wastewater [11], dairy wastewater [15,28], and domestic wastewater [2,3,10,[29][30][31][32][33][34][35], all these researches presented the MBBR technique as the most useful and economical method to treating all the types of wastewater especially for nutrient removal.…”

“…NO2is not only an electronic acceptor for NH4 + -N oxidation, but it is also as an electronic acceptor for carbon dioxide reduction [48][49][50][51].Also part from the TP will removed in anaerobic and anoxic reactors under the process of Phosphate Denitrification, which the Denitrifying Phosphate Accumulating Organisms remove some of the phosphate by using nitrate as electronic acceptor and consumed some of the COD and NH4 + -N [2,3,52,53]. The dissolved oxygen in the aerobic reactor will be consumed by a competition between COD removal bacteria (Heterotrophic Organisms),TP removal bacteria (Phosphate Accumulating Organisms), and Nitrification bacteria (Autotrophic Organisms), while the COD will be consumed by a competition between both Phosphate Accumulating and Heterotrophic Organisms [2,3,39].…”

“…The increased of world population by each year, and urbanization, caused to increase the quantity of wastewater with decreasing in the available area to build additional wastewater treatment plants, also the limitation of discharge for various pollutants especially for nutrients ( TN, and TP) was became more stringently .So it's important to find alternative and new technology to treating the wastewater especially for nutrients such as nitrogen and phosphorus instead of conventional activated sludge processes which presented many shortcomings like the sludge rising, sludge bulking, higher retention time requirement, and end up to large reactors volume [1][2][3].…”

Performance of Combined A/O Moving-Bed Biofilm Reactors for Biological Nutrients Removal from Domestic Wastewater under Different Gas/Water Ratios

“…e process of Moving-Bed Biofilm (MBB) was presented to overcome the drawbacks identified in the process of conventional activated sludge [1][2][3][4]. Today, the technology of MBB became the most famous and alternative process for wastewater treatment under different conditions, especially for nitrogen and phosphorus removal from different kinds of wastewater such as landfill leachate [5], domestic wastewater [2,3,[6][7][8][9][10][11][12][13], dairy wastewater [14,15], cheese factory wastewater [16], paper industry wastewater [17], and fish farming wastewater [18]. Firstly, this technology was developed in Norway in 1990 and then introduced in United States in 1995; in 2009 more than 600 municipal and industrial wastewater treatment plants used the technology of MBB in 50 different countries all over the world [4,19].…”