scholarly journals A two-stage soil infiltration system incorporated with heterotrophic denitrification (TSISHD) for urban runoff treatment

2015 ◽  
Vol 47 (1) ◽  
pp. 128-136
Author(s):  
Lizhu Hou ◽  
Xue Xu ◽  
Yiran Song ◽  
Chuanping Feng
Keyword(s):  
Carbon Sources ◽  
Oxygen Demand ◽  
Urban Runoff ◽  
Quality Standard ◽  
Soil Infiltration ◽  
Class V ◽  
National Quality ◽  
Removal Efficiencies ◽  
Denitrification Process ◽  
Heterotrophic Denitrification

To enhance denitrification performance of soil infiltration, a soil infiltration system incorporated with heterotrophic denitrification (TSISHD) for urban runoff treatment was developed. Sawdust and grass powders were added in the anaerobic stage (ANS) to provide organic carbon sources for the denitrification process, and the reduction environment was improved by iron addition in the ANS. Aerobic respiration and nitrification primarily occurred in the upper aerobic stage (AES), which removed 86.68% of the chemical oxygen demand (COD) and 91.80% of the NH+4-N. Moreover, heterotrophic denitrification occurred in the bottom ANS when added sawdust and grass powders were used as a carbon source. Overall, the TSISHD showed remarkable removal efficiencies of 88.29%, 82.50%, 92.05%, and 78.10% for COD, NO−3-N, NH+4-N, and total phosphorus, respectively, and the corresponding effluent concentrations met the national quality standard of China for class V surface water. The removal efficiencies were significantly higher than those of the previous soil infiltration systems without inoculated microbes. The developed system has the potential to treat urban runoff.

Advanced nitrogen elimination by encapsulated nitrifiers

2003 ◽  
Vol 48 (8) ◽  
pp. 19-26 ◽  
Author(s):  
M. Sievers ◽  
K.-D. Vorlop ◽  
J. Hahne ◽  
M. Schlieker ◽  
S. Schäfer
Keyword(s):  
Hydraulic Retention Time ◽  
Carbon Sources ◽  
Oxygen Demand ◽  
Reaction Rates ◽  
Substantial Contribution ◽  
Reaction Volume ◽  
Nitrification Process ◽  
Soluble Chemical Oxygen Demand ◽  
Nitrogen Elimination ◽  
Denitrification Process

By introducing a mixed population of nitrifiers encapsulated in gel lens beads a more selective nitrification process was found in treatment of settled sewage in lab scale at a hydraulic retention time (HRT) of about 30 to 60 minutes. The reaction rates for oxidation of soluble chemical oxygen demand (SCOD) were found to vary between 25 to 150 mg/L·h while nitrification takes place around 50 mg nitrogen per hour and litre reaction volume. However, based on this SCOD removal in the nitrification step, a consequent post-denitrification process without nitrate recycle and dosage of external carbon sources has been proven to reach substantial nitrate elimination of up to 20 mg nitrogen per litre at COD/N-ratios of approx. 6 in settled sewage. At such COD/N-ratios, suitable nitrogen elimination seems to be possible, because the bioflocs of settled sewage, produced so far by SCOD oxidation and entrapment of particulate COD, are passing through the nitrification process having a substantial contribution to the denitrification rate additionally to the remaining SCOD.

Sulfate reduction and mixotrophic sulfide-utilization denitrification integrated biofilm process for sulfate-laden wastewater treatment and sulfur recovery

2015 ◽  
Vol 71 (12) ◽  
pp. 1852-1858 ◽  
Author(s):  
Wei Li ◽  
Xiao Liang ◽  
Jianguo Lin ◽  
Binxia Cao ◽  
Ping Guo ◽  
...  
Keyword(s):  
Sulfate Reduction ◽  
Nitrogen Compound ◽  
Electron Acceptors ◽  
Sulfur Recovery ◽  
Nitrogen Gas ◽  
Removal Efficiencies ◽  
Biofilm Process ◽  
Nitrate And Nitrite ◽  
Denitrification Process ◽  
Heterotrophic Denitrification

A novel and integrated biofilm process – the sulfate reduction (SR) and mixotrophic (MR) sulfide-utilization denitrification process (SMSD) – was recently proposed for sulfate treatment and sulfur recovery. The process consisted of two bioreactors: a 5.1 L anaerobic upflow reactor for SR, and a 3.5 L anaerobic upflow reactor for MR desulfurization–denitrification. The experiment was conducted for 370 days to evaluate the performance of SMSD at various sulfate concentrations and hydraulic retention times. The process successfully achieved sulfate, organics and nitrogen compound removal efficiencies of 94.1, 97.7 and 99.1%, respectively. Sulfate was predominantly converted to element sulfur, while nitrate and nitrite were finally converted to nitrogen gas. In SR, with the help of high pH and sponge cubes with various bacteria, 97.5% of sulfide conversion efficiency and 540 mgS/L of sulfide were obtained. In MR, sulfide was removed up to 100% and was partially oxidized to sulfur. The extent of heterotrophic denitrification, which ranged from 35.8 to 59.8%, depended on the categories of electron acceptors.

scholarly journals Shallow groundwater quality assessment: use of the improved Nemerow pollution index, wavelet transform and neural networks

2017 ◽  
Vol 19 (5) ◽  
pp. 784-794 ◽  
Author(s):  
Q. Yang ◽  
J. Zhang ◽  
Z. Hou ◽  
X. Lei ◽  
W. Tai ◽  
...  
Keyword(s):  
Neural Network ◽  
Groundwater Quality ◽  
Back Propagation ◽  
Oxygen Demand ◽  
Shallow Groundwater ◽  
Pollution Index ◽  
Quality Standard ◽  
Total Hardness ◽  
Back Propagation Algorithm ◽  
National Quality

Shallow groundwater is generally of great interest to the community due to its easy availability. However, it is very sensitive to external stimulus. In this paper, shallow groundwater quality is assessed and classified with improved Nemerow pollution index, multi-layer perceptron artificial neural network (MLP-ANN) optimized with a back-propagation algorithm and wavelet neural network (WNN) methods in a coastal aquifer, Fujian Province, South China. The data used in three models were collected during the pre-monsoon over the period 2004–2011. The eight parameters, total dissolved solids, total hardness, chemical oxygen demand, chloride, sulphate, nitrate, nitrite and fluorides, were selected to characterize groundwater quality classification based on the National Quality Standard for Groundwater (GB/T 14848-93). The results of MLP-ANN and WNN are interpreted by mean absolute error, root mean square error and R2 (determination coefficient) criteria. The results obtained from three methods demonstrate that WNN has a higher accuracy compared with the other two methods. The study reveals that these methods are efficient tools for assessing groundwater quality.

The heterotrophic-combined-with-autotrophic denitrification process: performance and interaction mechanisms

2015 ◽  
Vol 71 (8) ◽  
pp. 1212-1218 ◽  
Author(s):  
Guihua Xu ◽  
Cuijie Feng ◽  
Fang Fang ◽  
Shaohua Chen ◽  
Yuanjian Xu ◽  
...  
Keyword(s):  
Chemical Oxygen Demand ◽  
Reduction Rate ◽  
Oxygen Demand ◽  
Process Performance ◽  
Autotrophic Denitrification ◽  
N Accumulation ◽  
Interaction Mechanisms ◽  
Molar Ratios ◽  
Denitrification Process ◽  
Heterotrophic Denitrification

In this work, the interaction mechanisms between an autotrophic denitrification (AD) and heterotrophic denitrification (HD) process in a heterotrophic-autotrophic denitrification (HAD) system were investigated, and the performance of the HAD system under different S/Ac− molar ratios was also evaluated. The results demonstrated that the heterotrophic-combined-with-autotrophic denitrification process is a promising technology which can remove chemical oxygen demand (COD), sulfide and nitrate simultaneously. The reduction rate of NO3− to NO2− by the HD process was much faster than that of reducing NO2− to N2, while the reduction rate of NO3− to NO2− by the AD process was slower than that of NO2− to N2. Therefore, the AD process could use the surplus NO2− produced by the HD process. This could alleviate the NO2−–N accumulation and increase the denitrification rate. In addition, the inhibition effects of acetate on AD bacteria and sulfide on HD were observed, and the inhibition was compensated by the promotion effects on NO2−. Therefore, the processes of AD and HD seem to react in parallel, without disturbing each other, in our HAD system.

Optimal operations for groundwater denitrification of drinking water using heterotrophic biological denitrification process

2006 ◽  
Vol 6 (2) ◽  
pp. 125-130
Author(s):  
C.-H. Hung ◽  
K.-H. Tsai ◽  
Y.-K. Su ◽  
C.-M. Liang ◽  
M.-H. Su ◽  
...  
Keyword(s):  
Drinking Water ◽  
Removal Efficiency ◽  
Nitrate Removal ◽  
Drinking Water Treatment ◽  
Nitrate Content ◽  
Source Water ◽  
Nitrogen Gas ◽  
Negative Effect ◽  
Denitrification Process ◽  
Heterotrophic Denitrification

Due to the extensive application of artificial nitrogen-based fertilizers on land, groundwater from the central part of Taiwan faces problems of increasing concentrations of nitrate, which were measured to be well above 30 mg/L all year round. For meeting the 10 mg/L nitrate standard, optimal operations for a heterotrophic denitrification pilot plant designed for drinking water treatment was investigated. Ethanol and phosphate were added for bacteria growing on anthracite to convert nitrate to nitrogen gas. Results showed that presence of high dissolved oxygen (around 4 mg/L) in the source water did not have a significantly negative effect on nitrogen removal. When operated under a C/N ratio of 1.88, which was recommended in the literature, nitrate removal efficiency was measured to be around 70%, sometimes up to 90%. However, the reactor often underwent severe clogging problems. When operated under C/N ratio of 1.0, denitrification efficiency decreased significantly to 30%. Finally, when operated under C/N ratio of 1.5, the nitrate content of the influent was almost completely reduced at the first one-third part of the bioreactor with an overall removal efficiency of 89–91%. Another advantage for operating with a C/N ratio of 1.5 is that only one-third of the biosolids was produced compared to a C/N value of 1.88.

The comparison of trichloroethylene removal rates by methane- and aromatic-utilizing microorganisms

1998 ◽  
Vol 38 (7) ◽  
pp. 19-24 ◽  
Author(s):  
C.-J. Lu ◽  
C. M. Lee ◽  
M.-S. Chung
Keyword(s):  
Cell Concentration ◽  
Removal Rate ◽  
Carbon Sources ◽  
Batch Reactors ◽  
Initial Cell Concentration ◽  
Removal Rates ◽  
Initial Cell ◽  
Toluene Concentration ◽  
Cell Source ◽  
Removal Efficiencies

The comparison of TCE cometabolic removal by methane, toluene, and phenol utilizers was conducted with a series of batch reactors. Methane, toluene, or phenol enriched microorganisms were used as cell source. The initial cell concentration was about 107 cfu/mL. Methane, toluene, and phenol could be readily biodegraded resulting in the cometabolic removal of TCE. Among the three primary carbon sources studied, the presence of phenol provided the best cometabolic removal of TCE. When the concentration of carbon source was 3 mg-C/L, the initial TCE removal rates initiated by methane, toluene, and phenol utilizers were 1.5, 30, and 100 μg/L-hr, respectively. During the incubation period of 80 hours, TCE removal efficiencies were 26% and 96% with the presence of methane and toluene, respectively. However, it was 100% within 20 hours with the presence of phenol. For phenol utilizers, the initial TCE removal rates were about the same, when the phenol concentrations were 1.35, 2.7, and 4.5 mg/L. However, TCE removal was not proportional to the concentrations of phenol. TCE removal was hindered when the phenol concentration was higher than 4.5 mg/L because of the rapid depletion of dissolved oxygen. The presence of toluene also initiated cometabolic removal of TCE. The presence of toluene at 3 and 5 mg/L resulted in similar TCE removal. The initial TCE removal rate was about 95 μg/L-hr at toluene concentrations of 3 and 5 mg/L compared to 20 μg/L-hr at toluene concentration of 1 mg/L.

Incorporating concepts from physical theory into stochastic modelling of urban runoff pollution

1998 ◽  
Vol 37 (1) ◽  
pp. 179-185
Author(s):  
Morten Grum
Keyword(s):  
Stochastic Model ◽  
Continuous Time ◽  
Measurement Errors ◽  
Physical Theory ◽  
Oxygen Demand ◽  
Stochastic Modelling ◽  
Urban Runoff ◽  
Primary Input ◽  
Deterministic Modelling ◽  
Runoff Pollution

On evaluating the present or future state of integrated urban water systems, sewer drainage models, with rainfall as primary input, are often used to calculate the expected return periods of given detrimental acute pollution events and the uncertainty thereof. The model studied in the present paper incorporates notions of physical theory in a stochastic model of water level and particulate chemical oxygen demand (COD) at the overflow point of a Dutch combined sewer system. A stochastic model based on physical mechanisms has been formulated in continuous time. The extended Kalman filter has been used in conjunction with a maximum likelihood criteria and a non-linear state space formulation to decompose the error term into system noise terms and measurement errors. The bias generally obtained in deterministic modelling, by invariably and often inappropriately assuming all error to result from measurement inaccuracies, is thus avoided. Continuous time stochastic modelling incorporating physical, chemical and biological theory presents a possible modelling alternative. These preliminary results suggest that further work is needed in order to fully appreciate the method's potential and limitations in the field of urban runoff pollution modelling.

Considering Form and Function: A Commentary on the Review of the Early Years Learning Framework for Australia

2021 ◽  
pp. 183693912110185
Author(s):  
Caroline Cohrssen
Keyword(s):  
Early Childhood ◽  
Learning Outcomes ◽  
Quality Standard ◽  
Early Years ◽  
National Guidelines ◽  
Form And Function ◽  
Learning Framework ◽  
National Quality ◽  
Planning Cycle ◽  
Standard Quality

An important milestone in early childhood education and care is reached in 2021 as Belonging, Being and Becoming: The Early Years Learning Framework for Australia is reviewed. The Early Years Learning Framework (EYLF) was groundbreaking. It has been influential in providing national guidelines around pedagogical principles, practice and learning outcomes for children. This commentary is intended to contribute to the wider conversation that is taking place this year. It proposes that a refined EYLF retains the focus on child-centredness and playful learning, and advocates for the structure of the revised document to include continua of learning and development. The provision of learning trajectories would assist early childhood educators to enact the planning cycle, meet National Quality Standard Quality Area 1, and thus potentially increase the learning outcomes for all children.

Treatment of Palm Oil Mill Effluent (POME) Supernatants Using Aerobic Attached–Growth System: Trickling Filter as a Case Study

2012 ◽  
Author(s):  
Ahmad Zuhairi Abdullah ◽  
Mohamad Hakimi Ibrahim ◽  
Mohd. Omar Ab. Kadir
Keyword(s):  
Palm Oil ◽  
Colloidal Particles ◽  
Oxygen Demand ◽  
Cod Removal ◽  
Palm Oil Mill Effluent ◽  
Trickling Filter ◽  
Biomass Hydrolysis ◽  
Removal Efficiencies ◽  
Palm Oil Mill ◽  
Hydrolysis Of

Kertas kerja ini membincangkan tentang kecekapan penuras cucur dalam merawat supernatan kumbahan kilang kelapa sawit (POME). Supernatan POME diperoleh menerusi dua jenis perawatan. Dalam perawatan 1, pengendapan graviti digunakan untuk menyingkir pepejal boleh mendak. Perawatan 2 digunakan untuk menyingkir pepejal boleh mendak dan gumpalan partikal dengan menggunakan 350 ppm alum. Influen dialurkan secara titisan pada biojisim yang terlekat pada penyokong pepejal rawak PVC setinggi 1 m. Penuras cucur berupaya menyingkir lebih daripada 90.0% dari keperluan oksigen biologi (BOD) dan keperluan oksigen kimia (COD) di bawah 1 m3/m2–hari. Pada 2.53 m3/m2–hari, influen dengan Perawatan 1 menghasilkan kecekapan penyingkiran COD sebanyak 40.3%, berbanding 83.1% bila Perawatan 2 digunakan. Perkara ini berlaku berikutan penyingkiran bahan organik tak boleh resap semasa Perawatan 2. Kecekapan penyingkiran menurun dengan meningkatnya bebanan hidraulik kerana wujudnya kelemahan dalam hidrolisis bahan tak boleh resap kepada substratum larut. Dengan edaran semula (α=1), penyingkiran BOD dan COD yang lebih tinggi dicapai di bawah 7 m3/m2–hari. Pencapaian ini disebabkan oleh bebanan organik yang lebih rendah serta pergedaran semula enzim dan biojisim yang aktif kepada sistem. Perawatan 2 menghasilkan enap cemar yang lebih tinggi kerana penukaran substratum boleh larut kepada biojisim tak boleh larut. Hidrolisis bahan organik tak boleh resap didapati berlaku secara aktif pada bahagian atas penuras cucur sementara bahagian bawahnya cenderung mengoksidakan substratum organik. Kata kunci: POME, turas cucur, bahan organik bolehresap, penggumpalan, alir semula This paper discusses the efficiency of a trickling filter to treat Palm Oil Mill Effluent (POME) supernatants. POME supernatants were obtained via two treatments. In Treatment 1, gravity sedimentation was used to remove settleable solids. In Treatment 2, both settleable solids and colloidal particles were removed using 350 ppm of alum. The influents were allowed to trickle over biomass attached to 1 m high random PVC solid support. Below 1 m3/m2–day, the filter demonstrated Biological Oxygen Demand (BOD) and Chemical Oxygen Demand (COD) removal efficiencies of more than 90.0%. At 2.53 m3/m2–day, the influent with Treatment 1 gave a COD removal efficiency of 40.3%, but increased to 83.1% when the influent with Treatment 2 was used. This was ascribed to the removal of non–diffusible organics during Treatment 2. The removal efficiencies decreased with an increase in hydraulic loading due to limitations in the hydrolysis of non–diffusibles into soluble substrates. With recirculation (α=1), higher BOD and COD removals were achieved below 7.0 m3/m2–day, attributed to lower organic loading and the recycling of active enzyme and biomass to the system. The influent with Treatment 2 demonstrated higher sludge production due to higher conversion of soluble substrates into insoluble biomass. Hydrolysis of non–diffusible organics mainly took place at upper reaches of the filter column while lower reaches were involved in oxidizing the organic subtrates. Key words: POME, trickling filter, diffusible organic, coagulation, recirculation

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