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Thesis (Masters of Engineering in Chemical Engineering)--Cape Peninsula University of Technology, [2018]. / Enhancing the efficiency of large scale photocatalytic systems has been a concern for decades. Engineering design and modelling for the successful application of laboratory-scale techniques to large scale is obligatory. Among the many fields of research in heterogeneous photocatalysis, photocatalytic reaction engineering can initiate improvement and application of conservative equations for the design and scale-up of photocatalytic reactors. Various reactor configurations were considered, and the geometry of choice was the annular shape. Theory supports the view that annular geometry, in the presence of constant transport flow properties, monochromatic light, and an incompressible flow, will allow a system to respect the law of conservation of mass. The degradation of a simulated dye, methyl orange (MO), by titanium dioxide (TiO2) with a simulated solar light (halogen lamp) in a continuous recirculating batch photoreactor (CRBPR) was studied. A response surface methodology (RSM) based on central composite design (CCD) was applied to study interaction terms and individual terms and the role they play in the photocatalytic degradation of MO. The studied terms were volume (L), TiO2 (g), 2 (mL), and initial dye concentration (mg/L), to optimize these parameters and to obtain their mutual interaction during a photocatalytic process, a 24 full-factorial CCD and RSM with an alpha set to 1.5 were employed. The polynomial models obtained for the chosen responses (% degradation and reaction rate constant, k) were shown to have a good externally studentized vs normal percentage probability fit with R2 values of 0.69 and 0.77 respectively. The two responses had a common significant interaction term which was the H2O2 initial dye concentration term. The optimum degradation that was obtained in this study was a volume of 20 L, TiO2 of 10 g, H2O2 of 200 mL and the initial dye concentration of 5 mg/L which yielded 64.6% and a reaction rate constant of 0.0020 min-1. The model of percentage degradation was validated on a yield of 50% and 80% over a series of set volumes and the model validation was successful.

With the advent of polyester fibers, disperse dyes, with complex chemical carriers and surfactants have been introduced. These dispersing agents inhibited chemical treatment and passed through biological facilities untreated. Therefore, it was the purpose of this study to ascertain whether chemical treatment with polyelectrolytes could achieve an economical treatment. The study consisted of the evaluation of flocculation performance (turbidity, chemical oxygen demand, and color reductions) for treatments with alum alone and alum with polyelectrolytes. A univariant search technique was used to optimize the flocculation performance with respect to the three parameters, pH, alum concentration, and polyelectrolyte concentration. The results of the alum treatment revealed that the chemical oxygen demand reduction was inadequate, although turbidity and color reductions were sufficient, to permit disposal of the effluent to the stream. When cationic polyelectrolytes were used with alum the results were greatly improved compared to alum. Reductions of turbidity, chemical oxygen demand, and color greater than 80 per cent were attained with two cationic polyelectrolytes. The flocculation performance with anionic polyelectrolytes was inferior to treatment with alum and alum with cationic polyelectrolytes. The floc was faster settling for all polyelectrolyte treatments. The volume of sludge in alum treatment was two to 2.5 times greater than for treatment with polyelectrolytes. Considering the present value determinations, aerated lagoons were the least expensive investment and would be the obvious means of treatment. However, if restrictions such as color reduction were imposed, chemical treatment with polyelectrolytes may be justified. / Master of Science

The feasibility of the excess lime process for color removal from textile dye wastes was evaluated. The lime dosages were optimized by using anionic, cationic, and nonionic polyelectrolytes as coagulant aids. The effect of the process on the removal of organic pollutants was determined. The time interval between coagulant additions was analyzed. Color reductions of at least 94 per cent were obtained by the lime and lime-polyelectrolyte processes. The lime dosage of 980 to 1,060 ppm was decreased by at least 30 per cent using 5 ppm polyelectrolyte dosages. The processes reduced the Total Organic Carbon concentration by 73 per cent approximately, the Chemical Oxygen Demand by 50 per cent, and suspended solids by about 85 to 90 per cent. The excess lime process was more efficient in removing organic matter than the lime-polyelectrolyte processes, and also incurred the least chemical coagulant cost. The excess lime process was most effective at 30 minutes flocculation and 30 minutes settling. The lime-polyelectrolyte processes were more effective when the polyelectrolyte was added after about 30 minutes lime flocculation and settled for 5 minutes. The lime-polyelectrolyte processes produced a floe which settled rapidly. The volume of sludge produced was about 8.1 to 12.8 per cent, resulting in a sludge to supernatant ratio range of 1:7 to 1:11. The lime-polyelectrolyte sludge volumes were usually higher than the lime sludge volumes. / Master of Science

by Chan Yu Keung. / Thesis (M.Phil.)--Chinese University of Hong Kong, 1998. / Includes bibliographical references (leaves 133-141). / Abstract also in Chinese. / Acknowledgments --- p.i / Abstract --- p.ii / Table of Content --- p.iv / List of Figures --- p.ix / List of Tables --- p.xiv / Chapter 1. --- INTRODUCTION --- p.1 / Chapter 1.1 --- Overview --- p.1 / Chapter 1.2 --- Textiles Industry in Hong Kong --- p.1 / Chapter 1.3 --- Processes Involved in Textiles Industry --- p.2 / Chapter 1.3.1 --- Typical Stages in Bleaching and Dyeing Step --- p.3 / Chapter 1.4 --- Characterization of Textile Wastewater --- p.6 / Chapter 1.4.1 --- Desizing --- p.6 / Chapter 1.4.2 --- Scouring --- p.6 / Chapter 1.4.3 --- Bleaching --- p.7 / Chapter 1.4.4 --- Mercerizing --- p.7 / Chapter 1.4.5 --- Dyeing and Printing --- p.7 / Chapter 1.4.6 --- Finishing --- p.8 / Chapter 1.5 --- Toxicity of Pollutants from Textiles Industry --- p.8 / Chapter 1.6 --- Related Environmental Legislation in Hong Kong --- p.9 / Chapter 1.6.1 --- Water Pollution Control Ordinance --- p.9 / Chapter 1.6.2 --- Waste Disposal Ordinance --- p.10 / Chapter 1.6.3 --- General Sewage Charge --- p.10 / Chapter 1.6.4 --- Trade Effluent Surcharge --- p.10 / Chapter 1.7 --- Chemical Specific Approach --- p.11 / Chapter 1.8 --- Toxicity Based Approach --- p.12 / Chapter 1.8.1 --- Selection of Organisms for Bioassays --- p.13 / Chapter 1.9 --- Whole-Effluent Toxicity (WET) Test --- p.14 / Chapter 1.10 --- Toxicity Identification Evaluation --- p.14 / Chapter 1.10.1 --- Phase I ´ؤ Toxicant Characterization --- p.15 / Chapter 1.10.2 --- Phase II - Toxicant Identification --- p.16 / Chapter 1.10.3 --- Phase III - Toxicant Confirmation --- p.16 / Chapter 1.11 --- Ecotoxicology --- p.16 / Chapter 2. --- OBJECTIVES --- p.18 / Chapter 3. --- MATERIALS AND METHODS --- p.19 / Chapter 3.1 --- Sources of Samples --- p.19 / Chapter 3.2 --- Whole Effluent Toxicity Test --- p.19 / Chapter 3.2.1 --- Microtox® test --- p.19 / Chapter 3.2.2 --- Growth inhibition test of a marine unicellular microalga Chlorella pyrenoidosa CU-2 --- p.22 / Chapter 3.2.3 --- Survival test of a marine amphipod Parhyale plumulosa --- p.25 / Chapter 3.2.4 --- Survival test of a marine fish Mylio macrocephalus --- p.29 / Chapter 3.3 --- Toxicity Identification Evaluation - Phase I --- p.33 / Chapter 3.3.1 --- pH adjustment filtration --- p.33 / Chapter 3.3.2 --- pH adjustment aeration --- p.35 / Chapter 3.3.3 --- Anion exchange --- p.37 / Chapter 3.3.4 --- Cation exchange --- p.38 / Chapter 3.3.5 --- pH adjustment C18 solid phase extraction (C18 SPE) --- p.40 / Chapter 3.3.6 --- Activated carbon extraction --- p.41 / Chapter 3.4 --- Toxicity Identification Evaluation - Phase II --- p.43 / Chapter 3.4.1 --- Determination of total organic carbon (TOC) --- p.43 / Chapter 3.4.2 --- Determination of metals --- p.46 / Chapter 3.4.3 --- Determination of anions --- p.48 / Chapter 4. --- RESULTS --- p.51 / Chapter 4.1 --- Sample Description --- p.51 / Chapter 4.2 --- Whole Effluent Toxicity Tests --- p.51 / Chapter 4.2.1 --- Toxicity of whole effluent samples on algal growth inhibition test using Chlorella pyrenoidosa CU-2 --- p.51 / Chapter 4.2.2 --- Toxicity of whole effluent samples on Microtox® test --- p.65 / Chapter 4.2.3 --- Toxicity of whole effluent samples on survival test of amphipod Parhyale plumulosa --- p.55 / Chapter 4.2.4 --- Toxicity of whole effluent samples on survival test of Mylio macrocephalus --- p.71 / Chapter 4.3 --- Toxicity Identification Evaluation - Phase I --- p.71 / Chapter 4.3.1 --- Effect of filtration at pH 3 on toxicity reduction --- p.71 / Chapter 4.3.2 --- Effect of filtration at pH 7 on toxicity reduction --- p.74 / Chapter 4.3.3 --- Effect of filtration at pHi on toxicity reduction --- p.74 / Chapter 4.3.4 --- Effect of aeration at pH 3 on toxicity reduction --- p.80 / Chapter 4.3.5 --- Effect of aeration at pH 7 on toxicity reduction --- p.80 / Chapter 4.3.6 --- Effect of aeration at pHi on toxicity reduction --- p.85 / Chapter 4.3.7 --- Effect of anion exchange on toxicity reduction --- p.85 / Chapter 4.3.8 --- Effect of cation exchange on toxicity reduction --- p.90 / Chapter 4.3.9 --- Effect of C18 extraction at pH3 on toxicity reduction --- p.90 / Chapter 4.3.10 --- Effect of C18 extraction at pH 7 on toxicity reduction --- p.95 / Chapter 4.3.11 --- Effect of C18 extraction at pH 9 on toxicity reduction --- p.95 / Chapter 4.3.12 --- Effect of activated carbon extraction on toxicity reduction --- p.101 / Chapter 4.4 --- Toxicity Identification Evaluation ´ؤ Phase II --- p.101 / Chapter 4.4.1 --- Effect of anion exchange on chemical reduction --- p.101 / Chapter 4.4.2 --- Effect of cation exchange on chemical reduction --- p.107 / Chapter 4.4.3 --- Effect of C18 extraction at pH 3 on chemical reduction --- p.107 / Chapter 4.4.4 --- Effect of C18 extraction at pH 7 on chemical reduction --- p.110 / Chapter 4.4.5 --- Effect of C18 extraction at pH 9 on chemical reduction --- p.110 / Chapter 4.4.6 --- Effect of activated carbon extraction on chemical reduction --- p.110 / Chapter 5. --- DISCUSSION --- p.114 / Chapter 5.1 --- Whole Effluent Toxicity Test --- p.114 / Chapter 5.1.1 --- Toxicity of whole effluent samples on algal growth inhibition test of Chlorella pyrenoidosa CU-2 --- p.114 / Chapter 5.1.2 --- Toxicity of whole effluent samples on Microtox® test --- p.116 / Chapter 5.1.3 --- Toxicity of whole effluent samples on survival test of amphipod Parhyale plumulosa --- p.117 / Chapter 5.1.4 --- Toxicity of whole effluent samples on survival test of fish Mylio macrocephalus --- p.118 / Chapter 5.1.5 --- Correlations among toxicity tests --- p.118 / Chapter 5.1.6 --- Factor analysis on whole effluent toxicity tests --- p.121 / Chapter 5.2 --- Toxicity Identification Evaluation ´ؤ Phase I --- p.122 / Chapter 5.2.1 --- pH adjustment filtration test --- p.124 / Chapter 5.2.2 --- pH adjustment aeration test --- p.124 / Chapter 5.2.3 --- Anion exchange test --- p.124 / Chapter 5.2.4 --- Cation exchange test --- p.125 / Chapter 5.2.5 --- pH adjustment C18 solid phase extraction test --- p.125 / Chapter 5.2.6 --- Activated carbon extraction test --- p.126 / Chapter 5.3 --- Toxicity Identification Evaluation Phase II --- p.126 / Chapter 5.3.1 --- Effect of anion exchange on chemical reduction --- p.126 / Chapter 5.3.2 --- Effect of cation exchange on chemical reduction --- p.127 / Chapter 5.3.3 --- Effect of C18 solid phase extraction on chemical reduction --- p.127 / Chapter 5.3.4 --- Effect of activated carbon extraction on chemical reduction --- p.127 / Chapter 5.4 --- Correlation between toxicity reduction and chemical reduction --- p.128 / Chapter 5.4.1 --- Anion exchange --- p.128 / Chapter 5.4.2 --- Cation exchange --- p.129 / Chapter 5.4.3 --- C18 solid phase extraction --- p.129 / Chapter 5.4.4 --- Activated carbon extraction --- p.130 / Chapter 6. --- CONCLUSIONS --- p.131 / Chapter 7. --- REFERENCE --- p.133

Submitted in fulfillment of the academic requirements for the degree of Master of Technology in Engineering: Chemical Engineering, Durban University of Technology. Durban. South Africa, 2015. / The textile industry consumes large volumes of water and in turn produces substantial quantities of polluted effluents. Approximately 30% of reactive dyes used during the textile processing remain unfixed on fibres and are responsible for the colouration in effluents. Various conventional methods are being used to treat textile effluent. However, the disadvantage of these methods is that total colour removal is not achieved and chemical by-products are introduced from the use of chemicals. The water quality produced therefore does not meet the requirement for textile reuse. Membrane based processes provide interesting possibilities of separating hydrolysed dye stuff and dyeing auxiliaries, thereby reducing colouration and COD content. They can be employed to treat reactive dye bath effluent to recover the salts and water for the purpose of reuse. This study aimed at integrating membrane processes into the reactive dye bath of a textile industry. The objectives were to determine the quality of permeate produced in terms of removal of organics, ascertain its reusability for dyeing, investigate the production rate in terms of permeate fluxes and finally to investigate the cleanability and flux recovery of the membranes. Three effluent samples were chosen for this study based on the dyeing recipe; Light shade, Medium shade and Dark shade. Ultrafiltration (UF) and Nanofiltration (NF) membrane processes were employed to treat the reactive dye bath effluents to recover the salts and water. Investigations were conducted firstly with UF as a pre-treatment to NF. Secondly, evaluations were carried out on the performance of two types of NF membranes (SR90 and NF90) in terms of permeate quality and fluxes for the investigated samples. The effect of cleaning on membrane performance was done. A reusability test was carried out on the permeate samples for dyeing. It was found that the use of UF as a pre-treatment yielded an increase in permeate of 5–25% of the NF fluxes and 90% in organics reduction for all treated samples, hence increasing the water recovery. High rejection of ˃90% by NF90 for COD, TOC and colour were obtained for all the treated samples. SR90 rejection was 80–90% for colour and ˃90% for COD and TOC. Salt recovery for NF90 was 60–90% and for SR90 was 40–50%. The reusability tests carried out showed that permeate recycled from NF90 can be used for any section in the textile industry including the most critical such as dyeing on light shades, while that from SR90 can be used for dyeing dark shades only. It was then concluded that membrane based processes can be integrated into the dye bath of the textile process for the purpose of reuse, thereby saving on the cost of chemicals (salts), reducing fresh water usage and reducing the extent of final effluent treatment.

No description available.

Thesis (MTech (Chemical Engineering))--Cape Peninsula University of Technology, 2016. / The worldwide high demand for drinking water has led to the development of numerous advanced wastewater treatment processes. Photocatalysis has recently become an alternative and attractive technique for green energy production and environmental remediation. It is also a wastewater treatment technique which is considered reliable and is expected to provide a sustainable solution to the scarcity of clean water. In particular, heterogeneous photocatalysts based on TiO2 nanoparticles and sunlight have been proposed as a powerful technique for degradation and mineralisation of persistent organic pollutants (POP`s). Although this method seems promising, some critical challenges are still to be addressed: namely, low photoefficiencies, faster electron and hole (𝑒−⁄ℎ+) pair recombination, utilisation of UV light and catalyst removal after treatment of pollutants.

Dissertation submitted in fulfillment of academic requirements for the Degree of Master of Technology: Chemical Engineering, Durban University of Technology, 2008. / Currently KwaZulu-Natal (KZN) province is populated with textile industry, which produces wastewater, some of which is not biodegradable. Due to the stringent environmental regulations the wastewater cannot be discharged into the rivers or public owned treatment systems. The alternative solution is to co-dispose this wastewater with easily biodegradable waste (labile effluent). The aim of this investigation was to develop a process protocol for the codigestion of high strength and toxic organic effluents under mesophilic conditions (35°C ± 2°C), with emphasis on the effect of biomass acclimation. A total of four effluents were chosen for this study, two labile (distillery and size) and two recalcitrant (scour dye and reactive dye). Two anaerobic batch experiments and two pilot scale trials were performed. The first batch anaerobic experiment investigated the influence of biomass source in anaerobic treatability. The second batch test investigated, whether biomass acclimation enhanced the biodegradability of pollutants. The pilot scale trials were the scale up version of the biomass acclimation test. The results showed sludge from Umbilo Wastewater Treatment Works was a superior biomass source, producing more gas and methane compared to Mpumalanga waste. For the high strength organic waste, the acclimated size and distillery samples produced 50% more biogas and methane compared to non-acclimated samples. This confirms that the biomass acclimation enhances the biodegradability. The biomass acclimation did not enhance the biodegradability of the recalcitrant effluent (scour dye). The pilot scale trials did not yield meaningful data; therefore it could not be proven if acclimation works on a larger scale. / Water Research Commission

This dissertation describes the characterisation of, and development of a novel integrated waste management strategy for, hydroxide scouring effluents produced during cotton processing. Such effluents are typical of mineral salt-rich waste waters which are not significantly biodegradable in conventional treatment plants. The proposed strategy focuses on two complementary concepts: process-oriented waste minimisation adopts a systematic approach to identifying potential problems and solutions of waste reduction in the manufacturing process itself; while add-on controls reduce the impact of the waste after it has been generated, by recycling and treatment. The basic procedures for ensuring effective water and chemical management within the scouring process are described. Examples are given of factory surveys, which have resulted in significant chemical and water savings, reduced effluent discharge costs, maximum effluent concentration, and minimum pollutant loading and volume. Pilot-plant investigations demonstrate the technical and economic feasibility of a four stage treatment sequence of neutralisation (using carbon dioxide gas), cross-flow microfiltration, nanofiltration and electrochemical recovery to remove colour and impurities from the scouring effluent and produce directly reusable sodium hydroxide and water. Fouling and scaling of the cross-flow microfiltration, nanofiltration and electrochemical membranes are minimal and reversible if the operation is carried out under carefully selected conditions. A long anode coating life is predicted. Current efficiencies for the recovery of sodium hydroxide (up to 20 % concentration) are 70 to 80 % and the electrical power requirements are 3 500 to 4 000 kWh/tonne of 100 % NaOH. Pilot-plant trials are supplemented by extensive laboratory tests and semi-quantitative modelling to examine specific aspects of the nanofiltration and electrochemical stages in detail. Electromembrane fouling and cleaning techniques, and other anode materials are evaluated. The effects of solution speciation chemistry on the performance of the nanofiltration membrane is evaluated using a combination of speciation and membrane transport modelling and the predicted results are used to explain observed behaviour. Based on the results of pilot-plant trials and supplementary laboratory and theoretical work, a detailed design of an electrochemically-based treatment system and an economic analysis of the electrochemical recovery system are presented. The effects of rinsing variables, processing temperatures, and background rinse water concentrations on the plant size requirements and capital costs are determined. The implementation of the waste management concepts presented in this dissertation will have significant impact on water and sodium hydroxide consumption (decreasing these by up to 95 and 75 % respectively), as well as effluent volumes and pollutant loadings. / Thesis (Ph.D.)-University of Natal, Durban, 1994.