Modified nernst model for on-line control of the chemical oxidation decoloring process

1996 ◽  
Vol 34 (3-4) ◽  
pp. 151-157 ◽  
Author(s):  
Cheng-Nan Chang ◽  
Jih-Gaw Lin ◽  
Allen C. Chao ◽  
Chu-Sung Liu
Keyword(s):  
Methyl Violet ◽  
Chemical Oxidation ◽  
Monitoring And Control ◽  
Oxidative Potential ◽  
Oxidation Reduction ◽  
Oxidation Reduction Potential ◽  
On Line ◽  
Wastewater Samples ◽  
And Control ◽  
Modified Equation

A modified Nernst equation was used to describe the decoloring reaction using the Oxidation-reduction potential (ORP) as an on-line monitoring and control parameter of the chemical reaction. In the modified equation, an “S” term is defined to indicate the oxidative potential (or decoloring potential) of dyes being studied. The laboratory study utilizes sodium hypochlorite (NaOCl) to reduce the color of wastewater spiked with textile dyes. Five dyes were used in preparing the wastewater samples: methyl red (MR), methyl violet (MV), methyl blue (MB), malachite green (MG) and methyl orange (MO). The color was measured by use of an automatic ADMI (American Dye Manufacturer Institute) measurement system in which a visible spectrophotometer was connected to a personal computer and the samples were scanned from 400 nm to 700 nm with a 10 nm interval each step. During the batch decoloring studies, several factors including ADMI, ORP, temperature and pH were continuously monitored with the computer. In this study, the potential of the decoloring compound of the dyes studies are in the following order: MG>MV>MO>MR>MB, with numeric ratios of 2.08 : 1.78 : 1.78 : 1.28 : 1.00, respectively.

Modelling of Chromium Hexavalent Reduction by Ferrous Ion in a Batch Stirred Tank

2009 ◽  
Vol 4 (1) ◽  
Author(s):  
Mohamed Kheireddine Aroua ◽  
Chun Ming Chew ◽  
Mohamed Azlan Hussain
Keyword(s):  
Reduction Process ◽  
Stirred Tank ◽  
Quasi Equilibrium ◽  
Time Data ◽  
Equilibrium Conditions ◽  
Oxidation Reduction ◽  
Oxidation Reduction Potential ◽  
On Line ◽  
And Control ◽  
Non Equilibrium

In this paper mathematical models are proposed to simulate the dynamic behaviour of the reduction of Cr(VI) with Fe(II) in a batch stirred tank. Two approaches have been adopted to represent systems in non-equilibrium and quasi-equilibrium conditions. The models derived reflect the changes of the relevant reactant species concentration based on the Oxidation Reduction Potential (ORP) of the system. An automated pilot plant has been designed and commissioned to carry out on-line/real time data acquisition and control for this Cr(VI) reduction process experimentally. Both the quasi-equilibrium and non-equilibrium models were validated experimentally. Simulated and on-line results indicate distinctive ORP profiles pattern for these two processes. The ORP profiles for non-equilibrium processes show a distinctive pattern which indicates the complete reduction of Cr(VI) in the batch sample.

Infrared Sensing for On-Line Weld Geometry Monitoring and Control

1995 ◽  
Vol 117 (3) ◽  
pp. 323-330 ◽  
Author(s):  
P. Banerjee ◽  
S. Govardhan ◽  
H. C. Wikle ◽  
J. Y. Liu ◽  
B. A. Chin
Keyword(s):  
Plate Thickness ◽  
Welding Process ◽  
Temperature Gradients ◽  
Monitoring And Control ◽  
Depth Of Penetration ◽  
Bead Width ◽  
Weld Geometry ◽  
On Line ◽  
And Control ◽  
Welding Processes

This paper describes a method for on-line weld geometry monitoring and control using a single front-side infrared sensor. Variations in plate thickness, shielding gas composition and minor element content are known to cause weld geometry changes. These changes in the weld geometry can be distinctly detected from an analysis of temperature gradients computed from infrared data. Deviations in temperature gradients were used to control the bead width and depth of penetration during the welding process. The analytical techniques described in this paper have been used to control gas tungsten arc and gas metal arc welding processes.

Performance and metabolic aspects of a novel enhanced biological phosphorus removal system with intermittent feeding and alternate aeration

2013 ◽  
Vol 69 (8) ◽  
pp. 1612-1619 ◽  
Author(s):  
Paraschos Melidis ◽  
Anastasios G. Kapagiannidis ◽  
Spyridon Ntougias ◽  
Konstantina Davididou ◽  
Alexander Aivasidis
Keyword(s):  
Phosphorus Removal ◽  
Feeding Strategy ◽  
Oxygen Demand ◽  
Enhanced Biological Phosphorus Removal ◽  
Biological Phosphorus Removal ◽  
Intermittent Feeding ◽  
Oxidation Reduction ◽  
Oxidation Reduction Potential ◽  
On Line ◽  
Biological Phosphorus

A novel enhanced biological phosphorus removal (EBPR) system, which combined the intermittent feeding design with an anaerobic selector, was examined using on-line oxidation reduction potential (ORP), nitrate and ammonium probes. Two experimental periods were investigated: the aerobic and anoxic phases were set at 40 and 20 minutes respectively for period I, and set at 30 and 30 minutes for period II. Chemical oxygen demand (COD), biochemical oxygen demand (BOD5) and P removal were measured as high as 87%, 96% and 93% respectively, while total Kjeldahl nitrogen (TKN) and NH4+ removal averaged 85% and 91%. Two specific denitrification rates (SDNRs), which corresponded to the consumption of the readily biodegradable and slowly biodegradable COD, were determined. SDNR-1 and SDNR-2 during period I were 0.235 and 0.059 g N g−1 volatile suspended solids (VSS) d−1 respectively, while the respective rates during period II were 0.105 and 0.042 g N g−1 VSS d−1. The specific nitrate formation and ammonium oxidizing rates were 0.076 and 0.064 g N g−1 VSS d−1 for period I and 0.065 and 0.081 g N g−1 VSS d−1 for period II respectively. The specific P release rates were 2.79 and 4.02 mg P g−1 VSS h−1 during period I and II, while the respective anoxic/aerobic uptake rates were 0.42 and 0.55 mg P g−1 VSS h−1. This is the first report on an EBPR scheme using the intermittent feeding strategy.

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