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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.

The main object of this research is to assess the water quality of Shatt Al-Arab River and its suitability for various purposes near power plants (Hartha and Najibia) through physical and chemical analysis [temperature, pH, EC

In understanding the hydraulic characteristics of river system flow, the hydraulic simulation models are essential tools. This study submits the results of the proposition of a hydraulic model in order to determine the roughness coefficient (Manning’s coefficient n) of the Tigris River along 3.5 km within the Maysan Governorate, south of Iraq. HEC-RAS software was the simulation tool used in this study. The HEC-RAS model was adopted, calibrated, and validated in adopting two sets of observed water levels. Graphical and statistical approaches were used for model calibration and verification. Results from this investigation showed that a value of Manning’s coefficient of 0.025 gave an acceptable agreement between observed and simulated values of water levels.

The aim of present study was to design and construct an continuous up-flow pilot scale Moving Bed Biofilm Reactor (MBBR) which is consists of combined cylindrical Anoxic/Aerobic MBBR in nested form with anoxic/aerobic volume ratio equal to 0.16 to treated 4 m 3 /days 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). Kaldnes (K1) media was used as a carrier in both reactors at a media fill ratio equal to 50%. The reactors was operated under the Anoxic/Oxic (An/O) process which must meet stringent TN limits without sludge returning into the system and only an internal recycling was performed from aerobic to anoxic reactor. After developing the biofilm on the media, reactor was operated at 3 different Hydraulic Residence Time (HRT) ranging from 4.95 to 8.25 h. During operation the internal recycle ratio to eliminate nitrogen compounds were 100% of inflow rate and the average Dissolved Oxygen concentration (DO) in aerobic and anoxic MBBRs were 4.49 and 0.16 mg/L, respectively. The obtained results showed that the HRT of 6.2 h was suitable for simultaneous removal of COD, NH 4 + -N, TN and TP. In this HRT the average removal efficiencies were 93.15, 98.06, 71.67 and 90.88% for COD, NH 4 + -N, TN and TP, respectively.