Oliver Saavedra

Assessment of the performance of a down-flow hanging sponge system for treatment of agricultural drainage water

AbstractThe performance of down-flow hanging sponge (DHS) system for the treatment of agricultural drainage water has been investigated for six months. The reactor was operated at a hydraulic retention time (HRT) of 2.0u2009h, sludge residence time of 88.5u2009d, and food to micro-organism ratio of 0.24u2009kgu2009COD/kgu2009MLVSS/d. The results obtained showed that the average total chemical oxygen demand (CODtot) and biochemical oxygen demand (BOD5) concentrations measured in the final effluent of the system were 62.4 and 17.1u2009mg/l, respectively, corresponding to the overall removal efficiency of 73.1% for CODtot and 86.7% for BOD5. The reactor provided a final effluent containing a low concentration of 14.7u2009mg/l for total suspended solids (TSS). Moreover, 84% of ammonia–nitrogen was eliminated at organic loading rate (OLR) of 3.0u2009kgu2009COD/m3u2009d. The calculated nitrification rate of the DHS system according to the nitrate and nitrite production amounted to 0.16u2009kgu2009NH4–N/m3u2009d. Based on these results, the reactor achieved an ef...

Towards a Sustainable Stability of Coastal Zone at Rosetta Promontory/Mouth, Egypt

Rosetta promontory/mouth where Rosetta branch of the Nile River meets the Mediterranean sea suffers from several severe environmental problems which began to take place since the beginning of the 20th century along Rosetta area, and increased dramatically since the construction of the Aswan High Dam (AHD) in 1964. It suffers from coastline erosion and sedimentation inside the inlet. The shoaling of the inlet leads to hindering the navigation process of fishing boats, negative impacts to estuarine and salt marsh habitat and decreases the efficiency of the cross section to transferring the flood flow to the sea. Many attempts to solve the erosion, and sedimentation problem were performed. Although, hard protection (and dredging) works have been implemented since 1989 including seawalls on the tip of the promontory and several groins along the eastern and western shores of the promontory, the problems still existing. This paper presents the results of testing a huge number of proposed alternative solutions to sustain the stable conditions of the Rosetta promontory/mouth. Hard structures, soft measures, combination of hard structures and soft measures were tested with and without nourishments of predetermined. The utilized Coastal Modeling System in testing the suggested measures was calibrated using collected field data from Ministry of Water Resources and Irrigation authorities and research institutes. The results indicated using only hard structures or soft measures without nourishment is not capable of keeping the Rosetta promontory/outlet stable. Only combination of both hard structures and soft measures with application of nourishment can improve the situation towards sustainable stable conditions but absolutely not the original stable conditions that were there before the construction of AHD.