Modified Oxidation Ditch Research Articles

Oxygen Uptake by Biological Processes inside Oxidation Ditch

Abstract. In order to provide a better understanding of the Orbal Biological System (OBS), as one type of a modified oxidation ditch, the research aims to develop a preliminary process model to visualize the oxygen uptake by biological processes inside the oxidation ditch. Fundamentally, the model can be used as initial study to get a clearer picture of the oxygen utilization rate inside the ditch. Based on the results, the outer channel takes the highest portion of the overall oxygen consumption which is 66 % compare to the middle channel with only 14 % and followed by the inner channel with 20 %. However, simplifying assumptions made for the preliminary process model development (e.g. constant values of HRT throughout each channel) may affect the accuracy of describing the real conditions of the system.

Nutrient Removal and Denitrifying Phosphate-Removal Bacteria Content in the Modified Oxidation Ditch

The flashboard was installed in the circulation compartment of the modified oxidation ditch in order to regulate the mixed reflux from aerobic zone to anoxic zone. The differences of the nutrient removal efficiencies and the phosphate-removal bacteria content were researched before and after flashboard installation. The results showed that the average removal efficiencies of COD, NH4+, TN, TP were 93.3%, 87.1%, 78.1% and 96.0% respectively, and the proportion of denitrifying phosphate-removal bacteria (DPB) to total phosphorus accumulating organisms were 46.1% after the flashboard installation. However, the average removal efficiencies of COD, NH4+, TN, TP were 91.2%, 82.7%, 67.2% and 86.4% respectively, and the proportion of denitrifying phosphate-removal bacteria to total phosphorus accumulating organisms were 17.54% before the flashboard installation. So, the modified oxidation ditch with flashboard could enrich denitrifying phosphate-removal bacteria and and improve the nutrient removal efficiencies.

Aerobic granulation in a modified oxidation ditch with an adjustable volume intraclarifier

A modified oxidation ditch (MOD) with an adjustable volume intraclarifier was proposed and used to achieve aerobic sludge granulation in continuous flow process. This MOD with working volume of 60L treated onsite wastewater from a town. Excellent aerobic granules with mean diameter of 600μm and sludge volume index (SVI) of 44mL/g were obtained in 120day. Bacterial community analysis revealed that most species from seed sludge were preserved in both MOD and granule SBR (G-SBR) except bacteria (Bacteroidetes) might be easily washed out during granulation. Some different bacterial communities were found in sludges from sequencing batch and continuous flow reactors. Presence of metal ions and inorganics in raw wastewater had positive effect on granule formation, but an adjustable volume intraclarifier for controlling selection pressure and deleting return sludge pump played a key role in aerobic sludge granulation.

Modeling and Simulation of Pollutants Removal in the Modified Oxidation Ditch

The kinetic models of COD removal and phosphorus release in anaerobic zone, and phosphorus uptake, nitrification, denitrification and COD removal in circulating corridors were established in this work, in order to provide the guidance on design and running of the modified oxidation ditch. At the same time, the coefficients of reaction rates were calculated. Using the kinetic models already been established and the coefficients already been calculated to simulate the experimental results, the results showed that the models can well simulate the removal effect of pollutants in the modified oxidation ditch.

A Modified Oxidation Ditch with Additional Internal Anoxic Zones for Enhanced Biological Nutrient Removal

A novel modified pilot scale anaerobic oxidation ditch with additional internal anoxic zones was operated experimentally, aiming to study the improvement of biological nitrogen and phosphorus removal and the effect of enhanced denitrifying phosphorus removal in the process. Under all experimental conditions, the anaerobic-oxidation ditch with additional internal anoxic zones and an internal recycle ratio of 200% had the highest nutrient removal efficiency. The effluent NH+4-N, total nitrogen (TN), PO3−4-P and total phosphorus (TP) contents were 1.2 mgL−1, 13 mgL−1, 0.3 mgL−1 and 0.4 mgL−1, respectively, all met the discharge standards in China. The TN and TP removal efficiencies were remarkably improved from 37% and 50% to 65% and 88% with the presence of additional internal anoxic zones and internal recycle ratio of 200%. The results indicated that additional internal anoxic zones can optimize the utilization of available carbon source from the anaerobic outflow for denitrification. It was also found that phosphorus removal via the denitrification process was stimulated in the additional internal anoxic zones, which was beneficial for biological nitrogen and phosphorus removal when treating wastewater with a limited carbon source. However, an excess internal recycle would cause nitrite to accumulate in the system. This seems to be harmful to biological phosphorus removal.

격벽에 의한 조분리와 내부반송을 이용한 산화구 시설의 고도처리개선에 관한 연구

This study was performed to assess the removal efficiency on nitrogen, phosphorus and organic carbon in wastewater by spatial separation and internal recycling in a modified oxidation ditch process (modified OD). The performances of the modified OD were evaluated via laboratory-scale experiments. The process was operated at hydraulic retention times of 6-48 hours and solid retention times of 17-38 days. We found that organic carbon removal efficiency increased after the modified OD operation period. T-N removal efficiency remained stable; average T-N concentration of effluent was 8.02 mg/l after modified OD operation. In contrast, T-P concentration of effluent was over 1 mg/l. Nitrogen and phosphorus removal efficiency of modified OD at HRT 12 hr were 83.1% and 74.1%, respectively. Also, maximum efficiency was found at SRTs from 20 to 30 days. T-N removal efficiency was 83.1% at a C/N ratio from 3.0 to 3.5. However, T-N removal efficiency decreased at C/N ratios over 3.5. Also, T-P removal efficiency increased with HRT at C/P ratios in the same condition. Maximum efficiency was 74.1% at a C/P ratio from 25 to 28. T-N removal efficiency was 79.2% and T-P removal efficiency was 65.3% after M4 mode operation (added to the internal recycle line connected to the anoxic reactor). The modified OD with spatial separation and internal recycling developed in this study is, therefore, believed to be an improvement for solving problems in the nutrient removal technologies.

A Mass-balance Analysis to Evaluate the Performance of Modified Oxidation Ditch (OD) System for Sludge Reduction

A Mass-balance Analysis to Evaluate the Performance of Modified Oxidation Ditch (OD) System for Sludge Reduction

A Mass-Balance Approach to Evaluate the Performance of Modified Oxidation Ditch (OD) System for Sludge-Reduction Operation

A Mass-Balance Approach to Evaluate the Performance of Modified Oxidation Ditch (OD) System for Sludge-Reduction Operation

Aeration, Water Quality, and Catfish Production

ABSTRACT EVALUATION of catfish pond aera-tion systems has shown that day-time aeration by algae overshadows me-chanical aeration and can reduce power requirements. The paddlewheel (modi-fied oxidation ditch rotor) appears as the most reliable system. Paddlewheel tests have evolved a Level Raceway Con-cept which promises several advantages over the conventional earthen raceway.