Abstract
<p>In AOP processes, the flow of oxidant must be controlled to minimize the oxidant residuals in a post biological treatment and to maximize the total organic carbon (TOC) removal and degradation. Designing a controller to regulate the hydrogen peroxide (H2O2) begins with a dynamic model determination of a chemical process. Therefore, a step testing technique is employed to construct a dynamic model of the UV/H2O2 degradation of polyvinyl alcohol (PVA) process based on pH and TOC responses to H2O2 step change. The experimental design consists of three different initial PVA concentrations, of 60.0, 280.0, and 500.0 mg PVA/L. Eight experimental tests were conducted for different hydrogen peroxide mass flowrates ranging from 0.336 to 125 mg H2O2/min. For every test, a transfer function was experimentally determined to describe the dynamics of the UV/H2O2 photochemical reactor for the degradation of PVA. System identification toolbox in Matlab software was used to determine first order plus time delay (FOPTD), second order plus time delay (SOPTD) and ARX polynomial models. The transfer functions and ARX models are a good model representation of the pH response data of a specific step change of H2O2 concentration. For example, the standard deviation of the process gain of test # 1 and its replicate was calculated to be 1.18 and standard deviation of the time constant was calculated to be 1.27. The pH response of the first test was fitted with a FOPTD model with a data fitting score of 88.8%. Test # 2 pH response data was fitted with a SOPTD transfer function with data fitting score of 83.6%. Tests # 6 and 7’s pH response was fitted with a FOPTD model with a data fitting score of 94.3 and 87.7 % respectively. The different transfer functions obtained for the low, average, and high PVA concentrations indicate the nonlinearity aspect of polymer systems. All quality models are quite reliable estimations of the pH and TOC response data, since they were developed from experimental tests and parameter estimation techniques based on nonlinear regression approach.</p>
Highlights
The advanced oxidation processes (AOPs) technique includes two stages of reactions, the first is the production of active hydroxyl radicals (HO), that are produced from the photolysis of hydrogen peroxide (H2O2), and the second stage is the attack of long chains organic compounds by the active free hydroxyl radicals in the treated wastewater
The step testing was applied on three different polyvinyl alcohol (PVA) concentrations to cover the nonlinearity of the UV/H2O2 process
8 first order plus time delay (FOPTD) and 5 FOPTD models were determined for pH and total organic carbon (TOC) responses respectively
Summary
Treatment of water resources to get clean water is considerably important and essential for life of human beings and all other living species. Conventional biological techniques using microbes and bacteria to degrade toxic chemicals from wastewater systems, are not sufficient to degrade some organic materials. Many of these complex compounds are resistant to conventional wastewater treatment and biological degradation. In advanced oxidation processes active hydroxyl radicals are produced to degrade complex organic compounds by attacking the long molecular chains (Tabrizi and Mehrvar, 2004; Mohajerani et al, 2010 ). The AOP technique includes two stages of reactions, the first is the production of active hydroxyl radicals (HO), that are produced from the photolysis of hydrogen peroxide (H2O2), and the second stage is the attack of long chains organic compounds by the active free hydroxyl radicals in the treated wastewater
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
