Assessing Catalyst Performance in Industrial Wastewater Treatment Plants

Thesis Abstract

The increasing burden of recalcitrant organics and micro-pollutants in industrial effluents necessitates efficient and robust catalytic remediation within treatment plants to meet stringent discharge standards and enhance downstream water reuse. This study investigates catalyst performance in industrial wastewater treatment plants (IWWTPs) with a focus on heterogeneous catalytic oxidation (HCO) and advanced oxidation processes (AOPs) integrated into conventional biological treatment lines. The aim is to quantify catalyst efficacy, identify key factors influencing activity and longevity, and develop a predictive framework for catalyst selection and operational optimization. Specific objectives are (i) to evaluate the degradation efficiency of selected catalysts (titania-based, zeolite-supported metal oxides, and carbon-based catalysts) in removing persistent organics (COD, COD fractionation, and total organic carbon) and micro-pollutants (selected pharmaceuticals and pesticides) under real plant conditions; (ii) to determine the effects of operating parameters (pH, oxidant dose, temperature, flow rate, and catalyst bed depth) on reaction kinetics and mineralization; (iii) to assess catalyst deactivation mechanisms and regeneration potential through post–treatment characterization; and (iv) to develop a multivariate regression and ANOVA-based model to predict process performance and economic viability. The methodology adopts a mixed-methods research design conducted in three large-scale IWWTPs over 12 months. The population comprises continuous-flow reactors with integrated catalysts in activated sludge and micro-pollutant polishing units; a total of 36 operating runs across plants will be sampled, yielding 216 data points for statistical robustness. Data collection instruments include online meters for pH, ORP, temperature, TOC/COD, and flow; high-performance liquid chromatography (HPLC) and gas chromatography–mass spectrometry (GC-MS) for trace organics; inductively coupled plasma optical emission spectrometry (ICP-OES) for catalyst leachates; Brunauer–Emmett–Teller (BET) analysis for surface area changes; and X-ray diffraction (XRD) for phase identification. Analytical techniques will be complemented by thermal analyses (TGA/DSC) to monitor catalyst stability. Validity and reliability will be ensured via calibration curves, replication (n=3) for critical measurements, and inter-laboratory cross-checks. The data will be analyzed using reaction kinetics modeling, including pseudo-first-order and Langmuir–Hinshelwood frameworks, complemented by multivariate regression to isolate parameter effects; ANOVA will test the significance of catalyst type and operating conditions on removal efficiencies. A hierarchical linear model will account for plant-specific variability, and a cost–benefit analysis will compare capital and operating costs associated with each catalyst. The study anticipates that catalyst performance will be strongly influenced by the interplay between oxidant usage and catalyst surface properties, with titanla-based catalysts providing rapid mineralization under moderate temperatures, while zeolite-supported metal oxides will excel in selective micro-pollutant removal but exhibit greater deactivation under high organic load. Carbon-based catalysts are expected to show high resilience but require regeneration strategies to maintain activity. Expected findings include quantitative removal rates for target pollutants (e.g., >85% COD reduction and >70% trace pharmaceutical elimination under optimized conditions), statistically significant effects of pH and temperature on kinetic constants, and identifiable deactivation pathways such as surface fouling and metal leaching. The study will contribute to knowledge by (i) elucidating real-world catalyst performance under industrial operating constraints, (ii) establishing validated predictive models for catalyst selection and process control in IWWTPs, and (iii) informing design guidelines for integration of catalytic stages with existing biological units to maximize pollutant mineralization and operational sustainability. The main conclusion is that tailored catalyst systems, when coupled with optimized process parameters and robust regeneration protocols, can substantially enhance the treatment of persistent organics and micro-pollutants in industrial wastewater. Recommendations include adopting site-specific catalyst screening protocols, implementing continuous monitoring of catalyst integrity, developing standardized regeneration cycles, and conducting life-cycle assessments to inform scale-up and policy-making for industrial wastewater management.